Release 2.0.0

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.17 to 1.26.18.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](https://github.com/urllib3/urllib3/compare/1.26.17...1.26.18)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.coveragerc

@@ -1,5 +0,0 @@
-[run]
-omit=
-    src/microdot_websocket_alt.py
-    src/microdot_asgi_websocket.py
-    src/microdot_ssl.py

.flake8

@@ -1,3 +0,0 @@
-[flake8]
-select = C,E,F,W,B,B950
-per-file-ignores = ./*/__init__.py:F401

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,26 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**IMPORTANT**: If you have a question, or you are not sure if you have found a bug in this package, then you are in the wrong place. Hit back in your web browser, and then open a GitHub Discussion instead. Likewise, if you are unable to provide the information requested below, open a discussion to troubleshoot your issue.
+
+**Describe the bug**
+A clear and concise description of what the bug is. If you are getting errors, please include the complete error message, including the stack trace.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: GitHub Discussions
+    url: https://github.com/miguelgrinberg/microdot/discussions
+    about: Ask questions here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/workflows/tests.yml

@@ -11,8 +11,8 @@ jobs:
     name: lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v3
       - run: python -m pip install --upgrade pip wheel
       - run: pip install tox tox-gh-actions
       - run: tox -eflake8
@@ -21,12 +21,12 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        python: ['3.8', '3.9', '3.10', '3.11', '3.12']
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v3
         with:
           python-version: ${{ matrix.python }}
       - run: python -m pip install --upgrade pip wheel
@@ -36,8 +36,8 @@ jobs:
     name: tests-micropython
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v3
       - run: python -m pip install --upgrade pip wheel
       - run: pip install tox tox-gh-actions
       - run: tox -eupy
@@ -45,18 +45,21 @@ jobs:
     name: coverage
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v3
       - run: python -m pip install --upgrade pip wheel
-      - run: pip install tox tox-gh-actions codecov
+      - run: pip install tox tox-gh-actions
       - run: tox
-      - run: codecov
+      - uses: codecov/codecov-action@v3
+        with:
+          files: ./coverage.xml
+          fail_ci_if_error: true
   benchmark:
     name: benchmark
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v3
       - run: python -m pip install --upgrade pip wheel
       - run: pip install tox tox-gh-actions
       - run: tox -ebenchmark

.gitignore

@@ -103,3 +103,8 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+# other
+*.der
+*.pem
+*_txt.py

.readthedocs.yaml

@@ -0,0 +1,16 @@
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+sphinx:
+  configuration: docs/conf.py
+
+python:
+  install:
+    - method: pip
+      path: .
+      extra_requirements:
+        - docs

CHANGES.md

@@ -1,5 +1,46 @@
 # Microdot change log
 
+**Release 2.0.0** - 2023-12-22
+
+- Major redesign switching to asyncio as the base implementation (See the [Migration Guide](https://microdot.readthedocs.io/en/stable/migrating.html) in the docs for details) [#186](https://github.com/miguelgrinberg/microdot/issues/186) ([commit](https://github.com/miguelgrinberg/microdot/commit/20ea305fe793eb206b52af9eb5c5f3c1e9f57dbb))
+
+**Release 1.3.4** - 2023-11-08
+
+- Handle change in `wait_closed()` behavior in Python 3.12 [#177](https://github.com/miguelgrinberg/microdot/issues/177) ([commit](https://github.com/miguelgrinberg/microdot/commit/5550b20cdd347d59e2aa68f6ebf9e9abffaff9fc))
+- Added missing request argument in some documentation examples [#163](https://github.com/miguelgrinberg/microdot/issues/163) ([commit](https://github.com/miguelgrinberg/microdot/commit/744548f8dc33a72512b34c4001ee9c6c1edd22ee))
+- Fix minor documentation typos [#161](https://github.com/miguelgrinberg/microdot/issues/161) ([commit](https://github.com/miguelgrinberg/microdot/commit/2e4911d10826cbb3914de4a45e495c3be36543fa)) (thanks **Andy Piper**!)
+
+**Release 1.3.3** - 2023-07-16
+
+- Handle query string arguments without value [#149](https://github.com/miguelgrinberg/microdot/issues/149) ([commit](https://github.com/miguelgrinberg/microdot/commit/3554bc91cb1523efa5b66fe3ef173f8e86e8c2a0))
+- Support empty responses with ASGI adapter ([commit](https://github.com/miguelgrinberg/microdot/commit/e09e9830f43af41d38775547637558494151a385))
+- Added CORS extension to Python package ([commit](https://github.com/miguelgrinberg/microdot/commit/304ca2ef6881fe718126b3e308211e760109d519))
+- Document access to WSGI and ASGI attributes [#153](https://github.com/miguelgrinberg/microdot/issues/153) ([commit](https://github.com/miguelgrinberg/microdot/commit/d99df2c4010ab70c60b86ab334d656903e04eb26))
+- Upgrade micropython tests to use v1.20 ([commit](https://github.com/miguelgrinberg/microdot/commit/e0f0565551966ee0238a5a1819c78a13639ad704))
+
+**Release 1.3.2** - 2023-06-13
+
+- In ASGI, return headers as strings and not binary [#144](https://github.com/miguelgrinberg/microdot/issues/144) ([commit](https://github.com/miguelgrinberg/microdot/commit/e92310fa55bbffcdcbb33f560e27c3579d7ac451))
+- Incorrect import in `static_async.py` example ([commit](https://github.com/miguelgrinberg/microdot/commit/c07a53943508e64baea160748e67efc92e75b036))
+
+**Release 1.3.1** - 2023-05-21
+
+- Support negative numbers for int path components [#137](https://github.com/miguelgrinberg/microdot/issues/137) ([commit](https://github.com/miguelgrinberg/microdot/commit/a0dd7c8ab6d681932324e56ed101aba861a105a0))
+- Use a more conservative default for socket timeout [#130](https://github.com/miguelgrinberg/microdot/issues/130) ([commit](https://github.com/miguelgrinberg/microdot/commit/239cf4ff37268a7e2467b93be44fe9f91cee8aee))
+- More robust check for socket timeout error code [#106](https://github.com/miguelgrinberg/microdot/issues/106) ([commit](https://github.com/miguelgrinberg/microdot/commit/efec9f14be7b6f3451e4d1d0fe7e528ce6ca74dc))
+- WebSocket error when handling PING packet [#129](https://github.com/miguelgrinberg/microdot/issues/129) ([commit](https://github.com/miguelgrinberg/microdot/commit/87cd098f66e24bed6bbad29b1490a129e355bbb3))
+- Explicitly set UTF-8 encoding for HTML files in examples [#132](https://github.com/miguelgrinberg/microdot/issues/132) ([commit](https://github.com/miguelgrinberg/microdot/commit/f81de6d9582f4905b9c2735d3c639b92d7e77994))
+
+**Release 1.3.0** - 2023-04-08
+
+- Cross-Origin Resource Sharing (CORS) extension [#45](https://github.com/miguelgrinberg/microdot/issues/45) ([commit](https://github.com/miguelgrinberg/microdot/commit/67798f7dbffb30018ab4b62a9aaa297f63bc9e64))
+- Respond to `HEAD` and `OPTIONS` requests ([commit](https://github.com/miguelgrinberg/microdot/commit/6a31f89673518e79fef5659c04e609b7976a5e34))
+- Tolerate slightly invalid formats in query strings [#126](https://github.com/miguelgrinberg/microdot/issues/126) ([commit](https://github.com/miguelgrinberg/microdot/commit/a1b061656fa19dae583951596b0f1f0603652a56))
+- Support compressed files in `send_file()` [#93](https://github.com/miguelgrinberg/microdot/issues/93) ([commit](https://github.com/miguelgrinberg/microdot/commit/daf1001ec55ab38e6cdfee4931729a3b7506858b))
+- Add `max_age` argument to `send_file()` ([commit](https://github.com/miguelgrinberg/microdot/commit/e684ee32d91d3e2ab9569bb5fd342986c010ffeb))
+- Add `update()` method to `NoCaseDict` class ([commit](https://github.com/miguelgrinberg/microdot/commit/ea6766cea96b756b36ed777f9c1b6a6680db09ba))
+- Set exit code to 1 for failed MicroPython test runs ([commit](https://github.com/miguelgrinberg/microdot/commit/a350e8fd1e55fac12c9e5b909cfa82d880b177ef))
+
 **Release 1.2.4** - 2023-03-03
 
 - One more attempt to correct build issues ([commit](https://github.com/miguelgrinberg/microdot/commit/cb39898829f4edc233ab4e7ba3f7ef3c5c50f196))

MANIFEST.in

@@ -0,0 +1,5 @@
+include README.md LICENSE tox.ini
+recursive-include docs *
+recursive-exclude docs/_build *
+recursive-include tests *
+exclude **/*.pyc

README.md

@@ -3,9 +3,9 @@
 
 *“The impossibly small web framework for Python and MicroPython”*
 
-Microdot is a minimalistic Python web framework inspired by Flask, and designed
-to run on systems with limited resources such as microcontrollers. It runs on
-standard Python and on MicroPython.
+Microdot is a minimalistic Python web framework inspired by Flask. Given its
+small size, it can run on systems with limited resources such as
+microcontrollers. Both standard Python (CPython) and MicroPython are supported.
 
 ```python
 from microdot import Microdot
@@ -13,13 +13,24 @@ from microdot import Microdot
 app = Microdot()
 
 @app.route('/')
-def index(request):
+async def index(request):
     return 'Hello, world!'
 
 app.run()
 ```
 
+## Migrating to Microdot 2
+
+Version 2 of Microdot incorporates feedback received from users of earlier
+releases, and attempts to improve and correct some design decisions that have
+proven to be problematic.
+
+For this reason most applications built for earlier versions will need to be
+updated to work correctly with Microdot 2. The
+[Migration Guide](https://microdot.readthedocs.io/en/stable/migrating.html)
+describes the backwards incompatible changes that were made.
+
 ## Resources
 
-- [Documentation](https://microdot.readthedocs.io/en/latest/)
+- Documentation: [Latest](https://microdot.readthedocs.io/en/latest/) [Stable](https://microdot.readthedocs.io/en/stable/) [Legacy v1.x](https://microdot.readthedocs.io/en/v1/)
 - [Change Log](https://github.com/miguelgrinberg/microdot/blob/main/CHANGES.md)

docs/api.rst

@@ -13,97 +13,53 @@ API Reference
 .. autoclass:: microdot.Response
    :members:
 
-.. autoclass:: microdot.NoCaseDict
-   :members:
 
-.. autoclass:: microdot.MultiDict
-   :members:
-
-``microdot_asyncio`` module
----------------------------
-
-.. autoclass:: microdot_asyncio.Microdot
-   :inherited-members:
-   :members:
-
-.. autoclass:: microdot_asyncio.Request
-   :inherited-members:
-   :members:
-
-.. autoclass:: microdot_asyncio.Response
-   :inherited-members:
-   :members:
-
-``microdot_utemplate`` module
------------------------------
-
-.. automodule:: microdot_utemplate
-   :members:
-
-``microdot_jinja`` module
--------------------------
-
-.. automodule:: microdot_jinja
-   :members:
-
-``microdot_session`` module
----------------------------
-
-.. automodule:: microdot_session
-   :members:
-
-``microdot_websocket`` module
-------------------------------
-
-.. automodule:: microdot_websocket
-   :members:
-
-``microdot_asyncio_websocket`` module
--------------------------------------
-
-.. automodule:: microdot_asyncio_websocket
-   :members:
-
-``microdot_asgi_websocket`` module
--------------------------------------
-
-.. automodule:: microdot_asgi_websocket
-   :members:
-
-``microdot_ssl`` module
+``websocket`` extension
 -----------------------
 
-.. automodule:: microdot_ssl
+.. automodule:: microdot.websocket
    :members:
 
-``microdot_test_client`` module
--------------------------------
+``utemplate`` templating extension
+----------------------------------
 
-.. autoclass:: microdot_test_client.TestClient
+.. automodule:: microdot.utemplate
    :members:
 
-.. autoclass:: microdot_test_client.TestResponse
+``jinja`` templating extension
+------------------------------
+
+.. automodule:: microdot.jinja
    :members:
 
-``microdot_asyncio_test_client`` module
----------------------------------------
+``session`` extension
+---------------------
 
-.. autoclass:: microdot_asyncio_test_client.TestClient
+.. automodule:: microdot.session
    :members:
 
-.. autoclass:: microdot_asyncio_test_client.TestResponse
+``cors`` extension
+------------------
+
+.. automodule:: microdot.cors
    :members:
 
-``microdot_wsgi`` module
-------------------------
+``test_client`` extension
+-------------------------
 
-.. autoclass:: microdot_wsgi.Microdot
+.. automodule:: microdot.test_client
+   :members:
+
+``asgi`` extension
+------------------
+
+.. autoclass:: microdot.asgi.Microdot
    :members:
    :exclude-members: shutdown, run
 
-``microdot_asgi`` module
-------------------------
+``wsgi`` extension
+-------------------
 
-.. autoclass:: microdot_asgi.Microdot
+.. autoclass:: microdot.wsgi.Microdot
    :members:
    :exclude-members: shutdown, run

docs/extensions.rst

@@ -2,11 +2,11 @@ Core Extensions
 ---------------
 
 Microdot is a highly extensible web application framework. The extensions
-described in this section are maintained as part of the Microdot project and
-can be obtained from the same source code repository.
+described in this section are maintained as part of the Microdot project in
+the same source code repository.
 
-Asynchronous Support with Asyncio
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+WebSocket Support
+~~~~~~~~~~~~~~~~~
 
 .. list-table::
    :align: left
@@ -15,35 +15,71 @@ Asynchronous Support with Asyncio
      - | CPython & MicroPython
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_asyncio.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asyncio.py>`_
+     -  | `websocket.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/websocket.py>`_
 
    * - Required external dependencies
-     - | CPython: None
-       | MicroPython: `uasyncio <https://github.com/micropython/micropython/tree/master/extmod/uasyncio>`_
+     - | None
 
    * - Examples
-     - | `hello_async.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_async.py>`_
+     - | `echo.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo.py>`_
 
-Microdot can be extended to use an asynchronous programming model based on the
-``asyncio`` package. When the :class:`Microdot <microdot_asyncio.Microdot>`
-class is imported from the ``microdot_asyncio`` package, an asynchronous server
-is used, and handlers can be defined as coroutines.
+The WebSocket extension gives the application the ability to handle WebSocket
+requests. The :func:`with_websocket <microdot.websocket.with_websocket>`
+decorator is used to mark a route handler as a WebSocket handler. Decorated
+routes receive a WebSocket object as a second argument. The WebSocket object
+provides ``send()`` and ``receive()`` asynchronous methods to send and receive
+messages respectively.
 
-The example that follows uses ``asyncio`` coroutines for concurrency::
+Example::
 
-    from microdot_asyncio import Microdot
+        @app.route('/echo')
+        @with_websocket
+        async def echo(request, ws):
+            while True:
+                message = await ws.receive()
+                await ws.send(message)
 
-    app = Microdot()
+Server-Sent Events Support
+~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-    @app.route('/')
-    async def hello(request):
-        return 'Hello, world!'
+.. list-table::
+   :align: left
 
-    app.run()
+   * - Compatibility
+     - | CPython & MicroPython
 
-Rendering HTML Templates
-~~~~~~~~~~~~~~~~~~~~~~~~
+   * - Required Microdot source files
+     -  | `sse.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/sse.py>`_
+
+   * - Required external dependencies
+     - | None
+
+   * - Examples
+     - | `counter.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/sse/counter.py>`_
+
+The Server-Sent Events (SSE) extension simplifies the creation of a streaming
+endpoint that follows the SSE web standard. The :func:`with_sse <microdot.sse.with_sse>`
+decorator is used to mark a route as an SSE handler. Decorated routes receive
+an SSE object as second argument. The SSE object provides a ``send()``
+asynchronous method to send an event to the client.
+
+Example::
+
+    @app.route('/events')
+    @with_sse
+    async def events(request, sse):
+        for i in range(10):
+            await asyncio.sleep(1)
+            await sse.send({'counter': i})  # unnamed event
+        await sse.send('end', event='comment')  # named event
+
+.. note::
+   The SSE protocol is unidirectional, so there is no ``receive()`` method in
+   the SSE object. For bidirectional communication with the client, use the
+   WebSocket extension.
+
+Rendering Templates
+~~~~~~~~~~~~~~~~~~~
 
 Many web applications use HTML templates for rendering content to clients.
 Microdot includes extensions to render templates with the
@@ -61,35 +97,41 @@ Using the uTemplate Engine
      - | CPython & MicroPython
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_utemplate.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_utemplate.py>`_
+     - | `utemplate.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/utemplate.py>`_
 
    * - Required external dependencies
      - | `utemplate <https://github.com/pfalcon/utemplate/tree/master/utemplate>`_
 
    * - Examples
      - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello.py>`_
-       | `hello_utemplate_async.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_utemplate_async.py>`_
 
-The :func:`render_template <microdot_utemplate.render_template>` function is
-used to render HTML templates with the uTemplate engine. The first argument is
-the template filename, relative to the templates directory, which is
-*templates* by default. Any additional arguments are passed to the template
-engine to be used as arguments.
+The :class:`Template <microdot.utemplate.Template>` class is used to load a
+template. The argument is the template filename, relative to the templates
+directory, which is *templates* by default.
+
+The ``Template`` object has a :func:`render() <microdot.utemplate.Template.render>`
+method that renders the template to a string. This method receives any
+arguments that are used by the template.
 
 Example::
 
-    from microdot_utemplate import render_template
+    from microdot.utemplate import Template
 
     @app.get('/')
-    def index(req):
-        return render_template('index.html')
+    async def index(req):
+        return Template('index.html').render()
+
+The ``Template`` object also has a :func:`generate() <microdot.utemplate.Template.generate>`
+method, which returns a generator instead of a string. The
+:func:`render_async() <microdot.utemplate.Template.render_async>` and
+:func:`generate_async() <microdot.utemplate.Template.generate_async>` methods
+are the asynchronous versions of these two methods.
 
 The default location from where templates are loaded is the *templates*
 subdirectory. This location can be changed with the
-:func:`init_templates <microdot_utemplate.init_templates>` function::
+:func:`init_templates <microdot.utemplate.init_templates>` function::
 
-    from microdot_utemplate import init_templates
+    from microdot.utemplate import init_templates
 
     init_templates('my_templates')
 
@@ -103,8 +145,7 @@ Using the Jinja Engine
      - | CPython only
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_jinja.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_jinja.py>`_
+     - | `jinja.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/jinja.py>`_
 
    * - Required external dependencies
      - | `Jinja2 <https://jinja.palletsprojects.com/>`_
@@ -112,33 +153,45 @@ Using the Jinja Engine
    * - Examples
      - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello.py>`_
 
-The :func:`render_template <microdot_jinja.render_template>` function is used
-to render HTML templates with the Jinja engine. The first argument is the
-template filename, relative to the templates directory, which is *templates* by
-default. Any additional arguments are passed to the template engine to be used
-as arguments.
+The :class:`Template <microdot.jinja.Template>` class is used to load a
+template. The argument is the template filename, relative to the templates
+directory, which is *templates* by default.
+
+The ``Template`` object has a :func:`render() <microdot.jinja.Template.render>`
+method that renders the template to a string. This method receives any
+arguments that are used by the template.
 
 Example::
 
-    from microdot_jinja import render_template
+    from microdot.jinja import Template
 
     @app.get('/')
-    def index(req):
-        return render_template('index.html')
+    async def index(req):
+        return Template('index.html').render()
+
+The ``Template`` object also has a :func:`generate() <microdot.jinja.Template.generate>`
+method, which returns a generator instead of a string.
 
 The default location from where templates are loaded is the *templates*
 subdirectory. This location can be changed with the
-:func:`init_templates <microdot_jinja.init_templates>` function::
+:func:`init_templates <microdot.utemplate.init_templates>` function::
 
-    from microdot_jinja import init_templates
+    from microdot.jinja import init_templates
 
     init_templates('my_templates')
 
+The ``init_templates()`` function also accepts ``enable_async`` argument, which
+can be set to ``True`` if asynchronous rendering of templates is desired. If
+this option is enabled, then the
+:func:`render_async() <microdot.utemplate.Template.render_async>` and
+:func:`generate_async() <microdot.utemplate.Template.generate_async>` methods
+must be used.
+
 .. note::
     The Jinja extension is not compatible with MicroPython.
 
-Maintaing Secure User Sessions
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Maintaining Secure User Sessions
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. list-table::
    :align: left
@@ -147,56 +200,48 @@ Maintaing Secure User Sessions
      - | CPython & MicroPython
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_session.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_session.py>`_
+     - | `session.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/session.py>`_
 
    * - Required external dependencies
      - | CPython: `PyJWT <https://pyjwt.readthedocs.io/>`_
        | MicroPython: `jwt.py <https://github.com/micropython/micropython-lib/blob/master/python-ecosys/pyjwt/jwt.py>`_,
-                      `hmac <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/hmac/hmac.py>`_
+                      `hmac.py <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/hmac/hmac.py>`_
 
    * - Examples
      - | `login.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/sessions/login.py>`_
 
 The session extension provides a secure way for the application to maintain
-user sessions. The session is stored as a signed cookie in the client's
+user sessions. The session data is stored as a signed cookie in the client's
 browser, in `JSON Web Token (JWT) <https://en.wikipedia.org/wiki/JSON_Web_Token>`_
 format.
 
-To work with user sessions, the application first must configure the secret key
+To work with user sessions, the application first must configure a secret key
 that will be used to sign the session cookies. It is very important that this
-key is kept secret. An attacker who is in possession of this key can generate
-valid user session cookies with any contents.
+key is kept secret, as its name implies. An attacker who is in possession of
+this key can generate valid user session cookies with any contents.
 
-To set the secret key, use the :func:`set_session_secret_key <microdot_session.set_session_secret_key>` function::
+To initialize the session extension and configure the secret key, create a
+:class:`Session <microdot.session.Session>` object::
 
-    from microdot_session import set_session_secret_key
+    Session(app, secret_key='top-secret')
 
-    set_session_secret_key('top-secret!')
+The :func:`with_session <microdot.session.with_session>` decorator is the
+most convenient way to retrieve the session at the start of a request::
 
-To :func:`get_session <microdot_session.get_session>`,
-:func:`update_session <microdot_session.update_session>` and
-:func:`delete_session <microdot_session.delete_session>` functions are used
-inside route handlers to retrieve, store and delete session data respectively.
-The :func:`with_session <microdot_session.with_session>` decorator is provided
-as a convenient way to retrieve the session at the start of a route handler.
-
-Example::
-
-    from microdot import Microdot
-    from microdot_session import set_session_secret_key, with_session, \
-        update_session, delete_session
+    from microdot import Microdot, redirect
+    from microdot.session import Session, with_session
 
     app = Microdot()
-    set_session_secret_key('top-secret')
+    Session(app, secret_key='top-secret')
 
     @app.route('/', methods=['GET', 'POST'])
     @with_session
-    def index(req, session):
+    async def index(req, session):
         username = session.get('username')
         if req.method == 'POST':
             username = req.form.get('username')
-            update_session(req, {'username': username})
+            session['username'] = username
+            session.save()
             return redirect('/')
         if username is None:
             return 'Not logged in'
@@ -204,12 +249,17 @@ Example::
             return 'Logged in as ' + username
 
     @app.post('/logout')
-    def logout(req):
-        delete_session(req)
+    @with_session
+    async def logout(req, session):
+        session.delete()
         return redirect('/')
 
-WebSocket Support
-~~~~~~~~~~~~~~~~~
+The :func:`save() <microdot.session.SessionDict.save>` and
+:func:`delete() <microdot.session.SessionDict.delete>` methods are used to update
+and destroy the user session respectively.
+
+Cross-Origin Resource Sharing (CORS)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. list-table::
    :align: left
@@ -218,40 +268,33 @@ WebSocket Support
      - | CPython & MicroPython
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_websocket.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_websocket.py>`_
+     - | `cors.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/cors.py>`_
 
    * - Required external dependencies
      - | None
 
    * - Examples
-     - | `echo.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo.py>`_
-       | `echo_wsgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_wsgi.py>`_
+     - | `cors.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/cors/cors.py>`_
 
-The WebSocket extension provides a way for the application to handle WebSocket
-requests. The :func:`websocket <microdot_websocket.with_websocket>` decorator
-is used to mark a route handler as a WebSocket handler. The handler receives
-a WebSocket object as a second argument. The WebSocket object provides
-``send()`` and ``receive()`` methods to send and receive messages respectively.
+The CORS extension provides support for `Cross-Origin Resource Sharing
+(CORS) <https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS>`_. CORS is a
+mechanism that allows web applications running on different origins to access
+resources from each other. For example, a web application running on
+``https://example.com`` can access resources from ``https://api.example.com``.
 
+To enable CORS support, create an instance of the
+:class:`CORS <microdot.cors.CORS>` class and configure the desired options.
 Example::
 
-        @app.route('/echo')
-        @with_websocket
-        def echo(request, ws):
-            while True:
-                message = ws.receive()
-                ws.send(message)
+    from microdot import Microdot
+    from microdot.cors import CORS
 
-.. note::
-   An unsupported *microdot_websocket_alt.py* module, with the same
-   interface, is also provided. This module uses the native WebSocket support
-   in MicroPython that powers the WebREPL, and may provide slightly better
-   performance for MicroPython low-end boards. This module is not compatible
-   with CPython.
+    app = Microdot()
+    cors = CORS(app, allowed_origins=['https://example.com'],
+                allow_credentials=True)
 
-Asynchronous WebSocket
-~~~~~~~~~~~~~~~~~~~~~~
+Testing with the Test Client
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. list-table::
    :align: left
@@ -260,54 +303,18 @@ Asynchronous WebSocket
      - | CPython & MicroPython
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_asyncio.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asyncio.py>`_
-       | `microdot_websocket.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_websocket.py>`_
-       | `microdot_asyncio_websocket.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asyncio_websocket.py>`_
+     - | `test_client.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/test_client.py>`_
 
    * - Required external dependencies
-     - | CPython: None
-       | MicroPython: `uasyncio <https://github.com/micropython/micropython/tree/master/extmod/uasyncio>`_
+     - | None
 
-   * - Examples
-     - | `echo_async.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_async.py>`_
-
-This extension has the same interface as the synchronous WebSocket extension,
-but the ``receive()`` and ``send()`` methods are asynchronous.
-
-.. note::
-   An unsupported *microdot_asgi_websocket.py* module, with the same
-   interface, is also provided. This module must be used instead of
-   *microdot_asyncio_websocket.py* when the ASGI support is used. The
-   `echo_asgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_asgi.py>`_
-   example shows how to use this module.
-
-HTTPS Support
-~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_ssl.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_ssl.py>`_
-
-   * - Examples
-     - | `hello_tls.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/tls/hello_tls.py>`_
-       | `hello_async_tls.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/tls/hello_async_tls.py>`_
-
-The ``run()`` function accepts an optional ``ssl`` argument, through which an
-initialized ``SSLContext`` object can be passed. MicroPython does not currently
-have a ``SSLContext`` implementation, so the ``microdot_ssl`` module provides
-a basic implementation that can be used to create a context.
+The Microdot Test Client is a utility class that can be used in tests to send
+requests into the application without having to start a web server.
 
 Example::
 
     from microdot import Microdot
-    from microdot_ssl import create_ssl_context
+    from microdot.test_client import TestClient
 
     app = Microdot()
 
@@ -315,88 +322,13 @@ Example::
     def index(req):
         return 'Hello, World!'
 
-    sslctx = create_ssl_context('cert.der', 'key.der')
-    app.run(port=4443, debug=True, ssl=sslctx)
-
-.. note::
-   The ``microdot_ssl`` module is only needed for MicroPython. When used under
-   CPython, this module creates a standard ``SSLContext`` instance.
-
-.. note::
-   The ``uasyncio`` library for MicroPython does not currently support TLS, so
-   this feature is not available for asynchronous applications on that
-   platform. The ``asyncio`` library for CPython is fully supported.
-
-Test Client
-~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_test_client.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_test_client.py>`_
-
-   * - Required external dependencies
-     - | None
-
-The Microdot Test Client is a utility class that can be used during testing to
-send requests into the application.
-
-Example::
-
-    from microdot import Microdot
-    from microdot_test_client import TestClient
-
-    app = Microdot()
-
-    @app.route('/')
-    def index(req):
-        return 'Hello, World!'
-
-    def test_app():
-        client = TestClient(app)
-        response = client.get('/')
-        assert response.text == 'Hello, World!'
-
-See the documentation for the :class:`TestClient <microdot_test_client.TestClient>`
-class for more details.
-
-Asynchronous Test Client
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython & MicroPython
-
-   * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_asyncio.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asyncio.py>`_
-       | `microdot_test_client.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_test_client.py>`_
-       | `microdot_asyncio_test_client.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asyncio_test_client.py>`_
-
-   * - Required external dependencies
-     - | None
-
-Similar to the :class:`TestClient <microdot_test_client.TestClient>` class
-above, but for asynchronous applications.
-
-Example usage::
-
-    from microdot_asyncio_test_client import TestClient
-
     async def test_app():
         client = TestClient(app)
         response = await client.get('/')
         assert response.text == 'Hello, World!'
 
-See the :class:`reference documentation <microdot_asyncio_test_client.TestClient>`
-for details.
+See the documentation for the :class:`TestClient <microdot.test_client.TestClient>`
+class for more details.
 
 Deploying on a Production Web Server
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -404,51 +336,7 @@ Deploying on a Production Web Server
 The ``Microdot`` class creates its own simple web server. This is enough for an
 application deployed with MicroPython, but when using CPython it may be useful
 to use a separate, battle-tested web server. To address this need, Microdot
-provides extensions that implement the WSGI and ASGI protocols.
-
-Using a WSGI Web Server
-^^^^^^^^^^^^^^^^^^^^^^^
-
-.. list-table::
-   :align: left
-
-   * - Compatibility
-     - | CPython only
-
-   * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_wsgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_wsgi.py>`_
-
-   * - Required external dependencies
-     - | A WSGI web server, such as `Gunicorn <https://gunicorn.org/>`_.
-
-   * - Examples
-     - | `hello_wsgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_wsgi.py>`_
-
-
-The ``microdot_wsgi`` module provides an extended ``Microdot`` class that
-implements the WSGI protocol and can be used with a compliant WSGI web server
-such as `Gunicorn <https://gunicorn.org/>`_ or
-`uWSGI <https://uwsgi-docs.readthedocs.io/en/latest/>`_.
-
-To use a WSGI web server, the application must import the
-:class:`Microdot <microdot_wsgi.Microdot>` class from the ``microdot_wsgi``
-module::
-
-    from microdot_wsgi import Microdot
-
-    app = Microdot()
-
-    @app.route('/')
-    def index(req):
-        return 'Hello, World!'
-
-The ``app`` application instance created from this class is a WSGI application
-that can be used with any complaint WSGI web server. If the above application
-is stored in a file called *test.py*, then the following command runs the
-web application using the Gunicorn web server::
-
-    gunicorn test:app
+provides extensions that implement the ASGI and WSGI protocols.
 
 Using an ASGI Web Server
 ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -460,25 +348,25 @@ Using an ASGI Web Server
      - | CPython only
 
    * - Required Microdot source files
-     - | `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot.py>`_
-       | `microdot_asyncio.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asyncio.py>`_
-       | `microdot_asgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot_asgi.py>`_
+     - | `asgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/asgi.py>`_
 
    * - Required external dependencies
      - | An ASGI web server, such as `Uvicorn <https://uvicorn.org/>`_.
 
    * - Examples
      - | `hello_asgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_asgi.py>`_
+       | `hello_asgi.py (uTemplate) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello_asgi.py>`_
+       | `hello_asgi.py (Jinja) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello_asgi.py>`_
+       | `echo_asgi.py (WebSocket) <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_asgi.py>`_
 
-The ``microdot_asgi`` module provides an extended ``Microdot`` class that
+The ``asgi`` module provides an extended ``Microdot`` class that
 implements the ASGI protocol and can be used with a compliant ASGI server such
 as `Uvicorn <https://www.uvicorn.org/>`_.
 
 To use an ASGI web server, the application must import the
-:class:`Microdot <microdot_asgi.Microdot>` class from the ``microdot_asgi``
-module::
+:class:`Microdot <microdot.asgi.Microdot>` class from the ``asgi`` module::
 
-    from microdot_asgi import Microdot
+    from microdot.asgi import Microdot
 
     app = Microdot()
 
@@ -486,10 +374,67 @@ module::
     async def index(req):
         return 'Hello, World!'
 
-The ``app`` application instance created from this class is an ASGI application
-that can be used with any complaint ASGI web server. If the above application
-is stored in a file called *test.py*, then the following command runs the
-web application using the Uvicorn web server::
+The ``app`` application instance created from this class can be used as the
+ASGI callable with any complaint ASGI web server. If the above example
+application was stored in a file called *test.py*, then the following command
+runs the web application using the Uvicorn web server::
 
     uvicorn test:app
 
+When using the ASGI support, the ``scope`` dictionary provided by the web
+server is available to request handlers as ``request.asgi_scope``.
+
+Using a WSGI Web Server
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. list-table::
+   :align: left
+
+   * - Compatibility
+     - | CPython only
+
+   * - Required Microdot source files
+     - | `wsgi.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/wsgi.py>`_
+
+   * - Required external dependencies
+     - | A WSGI web server, such as `Gunicorn <https://gunicorn.org/>`_.
+
+   * - Examples
+     - | `hello_wsgi.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello_wsgi.py>`_
+       | `hello_wsgi.py (uTemplate) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/utemplate/hello_wsgi.py>`_
+       | `hello_wsgi.py (Jinja) <https://github.com/miguelgrinberg/microdot/blob/main/examples/templates/jinja/hello_wsgi.py>`_
+       | `echo_wsgi.py (WebSocket) <https://github.com/miguelgrinberg/microdot/blob/main/examples/websocket/echo_wsgi.py>`_
+
+
+The ``wsgi`` module provides an extended ``Microdot`` class that implements the
+WSGI protocol and can be used with a compliant WSGI web server such as 
+`Gunicorn <https://gunicorn.org/>`_ or
+`uWSGI <https://uwsgi-docs.readthedocs.io/en/latest/>`_.
+
+To use a WSGI web server, the application must import the
+:class:`Microdot <microdot.wsgi.Microdot>` class from the ``wsgi`` module::
+
+    from microdot.wsgi import Microdot
+
+    app = Microdot()
+
+    @app.route('/')
+    def index(req):
+        return 'Hello, World!'
+
+The ``app`` application instance created from this class can be used as a WSGI
+callbable with any complaint WSGI web server. If the above application
+was stored in a file called *test.py*, then the following command runs the
+web application using the Gunicorn web server::
+
+    gunicorn test:app
+
+When using the WSGI support, the ``environ`` dictionary provided by the web
+server is available to request handlers as ``request.environ``.
+
+.. note::
+    In spite of WSGI being a synchronous protocol, the Microdot application
+    internally runs under an asyncio event loop. For that reason, the
+    recommendation to prefer ``async def`` handlers over ``def`` still applies
+    under WSGI. Consult the :ref:`Concurrency` section for a discussion of how
+    the two types of functions are handled by Microdot.

docs/freezing.rst

@@ -0,0 +1,110 @@
+Cross-Compiling and Freezing Microdot (MicroPython Only)
+--------------------------------------------------------
+
+Microdot is a fairly small framework, so its size is not something you need to
+be concerned about unless you are working with MicroPython on hardware with a
+very small amount of disk space and/or RAM. In such cases every byte counts, so
+this section provides some recommendations on how to keep Microdot's footprint
+as small as possible.
+
+Choosing What Modules to Install
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Microdot has a modular design that allows you to only install the modules that
+your application needs.
+
+For minimal web application support based on the core Microdot web server
+without extensions, you can just copy `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/microdot.py>`_
+to the source directory on your device. The core Microdot web server does not
+have any dependencies, so you don't need to install anything else.
+
+If your application uses some of the provided extensions to the core web
+server, then instead of installing *microdot.py* you'll need to create a
+*microdot* subdirectory and install the following files in it:
+
+- `__init__.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/__init__.py>`_
+- `microdot.py <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot/microdot.py>`_
+- Any extension modules that you need from the `microdot <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot>`_ source directory.
+
+Some of the extensions also have dependencies of their own, so you may need to
+install those in your device as well (outside of the ``microdot``
+subdirectory). Consult the documentation of each extension to learn if any
+third-party dependencies are required.
+
+Cross-Compiling
+~~~~~~~~~~~~~~~
+
+An issue that is common with low-end microcontroller boards is that they do not
+have enough RAM for the MicroPython compiler to compile the source files, but
+once the code is compiled they are able to run it without problems.
+
+To address this, MicroPython allows you to cross-compile source files on your
+desktop or laptop computer and then upload their compiled versions to the
+device. A good strategy is to cross-compile all the dependencies that are used
+by your application, since these are not going to be updated very often. If the
+goal is to minimize the use of RAM, you can also opt to cross-compile your
+application source files.
+
+The MicroPython cross-compiler is available as a package that you can install
+on standard Python. You must determine the version of MicroPython that you will
+be running on your device, and install the compiler that matches that version.
+For example, if you plan to use MicroPython 1.21.0 on your device, you can
+install the cross-compiler for this version with the following command::
+
+    pip install mpy-cross==1.21.0
+
+Then run the cross-compiler for each source file that you want to compile.
+Since the cross-compilation happens on your computer, you will need to have
+copies of all the source files you need to compile locally on your disk. Here
+is how you can compile the *microdot.py* file, assuming you have a copy in the
+current directory in your computer::
+
+    mpy-cross microdot.py
+
+The cross-compiler will create a file with the same name as the source file,
+but with the extension changed to *.mpy*.
+
+Once you have all your dependencies compiled, you can replace the *.py* files
+in your device with their corresponding *.mpy* versions. MicroPython
+automatically recognizes *.mpy* files, so there is no need to make any changes
+to any source code to start using compiled files.
+
+Freezing
+~~~~~~~~
+
+The ultimate option to reduce the size of a MicroPython application is to
+"freeze" it. Freezing is a process that takes MicroPython source code (either
+dependencies, application code or both), pre-compiles it and incorporates it
+into a custom-built MicroPython firmware that is flashed to the device.
+
+Freezing MicroPython modules to firmware has the advantage that the code is
+imported directly from the device's ROM, leaving more RAM available for
+application use.
+
+The process to create a custom firmware is unfortunately non-trivial and
+different depending on the device, so you will need to consult the MicroPython
+documentation that applies to your device to learn how to do this.
+
+The part of the process that is common to all devices is the creation of a
+`manifest file <https://docs.micropython.org/en/latest/reference/manifest.html>`_
+to tell the MicroPython firmware builder which packages and modules to freeze.
+
+For a minimal installation of Microdot consisting only in its *microdot.py*
+source file, the manifest file that you need use to build the firmware must
+include the following declaration::
+
+    module('microdot')
+
+If instead you are working with a version of Microdot that includes some or all
+of its extensions, then the manifest file must reference the ``microdot``
+package plus any third-party dependencies that are needed. Below is a manifest
+file for a complete Microdot installation that includes all the extensions::
+
+    package('microdot')
+    package('utemplate')  # required only if templates are used
+    module('pyjwt')       # required only if user sessions are used
+
+In this example, the *microdot* and *utemplate* packages must be available in
+the directory where the manifest file is located so that the MicroPython build
+can find them. The `pyjwt` module is part of the MicroPython standard library
+and will be downloaded as part of the build.

docs/index.rst

@@ -9,15 +9,17 @@ Microdot
 *"The impossibly small web framework for Python and MicroPython"*
 
 Microdot is a minimalistic Python web framework inspired by
-`Flask <https://flask.palletsprojects.com/>`_, and designed to run on
-systems with limited resources such as microcontrollers. It runs on standard
-Python and on `MicroPython <https://micropython.org>`_.
+`Flask <https://flask.palletsprojects.com/>`_. Given its size, it can run on
+systems with limited resources such as microcontrollers. Both standard Python
+(CPython) and `MicroPython <https://micropython.org>`_ are supported.
 
 .. toctree::
    :maxdepth: 3
 
    intro
    extensions
+   migrating
+   freezing
    api
 
 * :ref:`genindex`

docs/intro.rst

@@ -1,26 +1,49 @@
 Installation
 ------------
 
-For standard Python (CPython) projects, Microdot and all of its core extensions
-can be installed with ``pip``::
+The installation method is different depending on the version of Python.
+
+CPython Installation
+~~~~~~~~~~~~~~~~~~~~
+
+For use with standard Python (CPython) projects, Microdot and all of its core
+extensions are installed with ``pip``::
 
     pip install microdot
 
-For MicroPython, you can install it with ``upip`` if that option is available,
-but the recommended approach is to manually copy *microdot.py* and any
-desired optional extension source files from the
+MicroPython Installation
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+For MicroPython, the recommended approach is to manually copy the necessary
+source files from the
 `GitHub repository <https://github.com/miguelgrinberg/microdot/tree/main/src>`_
-into your device, possibly after
+into your device, ideally after
 `compiling <https://docs.micropython.org/en/latest/reference/mpyfiles.html>`_
 them to *.mpy* files. These source files can also be
 `frozen <https://docs.micropython.org/en/latest/develop/optimizations.html?highlight=frozen#frozen-bytecode>`_
 and incorporated into a custom MicroPython firmware.
 
+Use the following guidelines to know what files to copy:
+
+- For a minimal setup with only the base web server functionality, copy
+  `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
+  into your project.
+- For a configuration that includes one or more optional extensions, create a
+  *microdot* directory in your device and copy the following files:
+   - `__init__.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/__init__.py>`_
+   - `microdot.py <https://github.com/miguelgrinberg/microdot/blob/main/src/microdot/microdot.py>`_
+   - any needed `extensions <https://github.com/miguelgrinberg/microdot/tree/main/src/microdot>`_.
+
+
 Getting Started
 ---------------
 
-This section describes the main features of Microdot in an informal manner. For
-detailed reference information, consult the :ref:`API Reference`.
+This section describes the main features of Microdot in an informal manner.
+
+For detailed reference information, consult the :ref:`API Reference`.
+
+If you are familiar with releases of Microdot before 2.x, review the
+:ref:`Migration Guide <Migrating to Microdot 2.x from Older Releases>`.
 
 A Simple Microdot Web Server
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -32,7 +55,7 @@ The following is an example of a simple web server::
     app = Microdot()
 
     @app.route('/')
-    def index(request):
+    async def index(request):
         return 'Hello, world!'
 
     app.run()
@@ -46,17 +69,23 @@ application.
 
 The ``route()`` decorator takes the path portion of the URL as an
 argument, and maps it to the decorated function, so that the function is called
-when the client requests the URL. The function is passed a
-:class:`Request <microdot.Request>` object as an argument, which provides
-access to the information passed by the client. The value returned by the
-function is sent back to the client as the response.
+when the client requests the URL.
+
+When the function is called, it is passed a :class:`Request <microdot.Request>`
+object as an argument, which provides access to the information passed by the
+client. The value returned by the function is sent back to the client as the
+response.
+
+Microdot is an asynchronous framework that uses the ``asyncio`` package. Route
+handler functions can be defined as ``async def`` or ``def`` functions, but
+``async def`` functions are recommended for performance.
 
 The :func:`run() <microdot.Microdot.run>` method starts the application's web
-server on port 5000 (or the port number passed in the ``port`` argument). This
-method blocks while it waits for connections from clients.
+server on port 5000 by default. This method blocks while it waits for
+connections from clients.
 
 Running with CPython
-~~~~~~~~~~~~~~~~~~~~
+^^^^^^^^^^^^^^^^^^^^
 
 .. list-table::
    :align: left
@@ -71,17 +100,18 @@ Running with CPython
      - | `hello.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/hello/hello.py>`_
 
 When using CPython, you can start the web server by running the script that
-defines and runs the application instance::
+has the ``app.run()`` call at the bottom::
 
     python main.py
 
-While the script is running, you can open a web browser and navigate to
-*http://localhost:5000/*, which is the default address for the Microdot web
-server. From other computers in the same network, use the IP address or
-hostname of the computer running the script instead of ``localhost``.
+After starting the script, open a web browser and navigate to
+*http://localhost:5000/* to access the application at the default address for
+the Microdot web server. From other computers in the same network, use the IP
+address or hostname of the computer running the script instead of
+``localhost``.
 
 Running with MicroPython
-~~~~~~~~~~~~~~~~~~~~~~~~
+^^^^^^^^^^^^^^^^^^^^^^^^
 
 .. list-table::
    :align: left
@@ -97,11 +127,13 @@ Running with MicroPython
        | `gpio.py <https://github.com/miguelgrinberg/microdot/blob/main/examples/gpio/gpio.py>`_
 
 When using MicroPython, you can upload a *main.py* file containing the web
-server code to your device along with *microdot.py*. MicroPython will
-automatically run *main.py* when the device is powered on, so the web server
-will automatically start. The application can be accessed on port 5000 at the
-device's IP address. As indicated above, the port can be changed by passing the
-``port`` argument to the ``run()`` method.
+server code to your device, along with the required Microdot files, as defined
+in the :ref:`MicroPython Installation` section.
+
+MicroPython will automatically run *main.py* when the device is powered on, so
+the web server will automatically start. The application can be accessed on
+port 5000 at the device's IP address. As indicated above, the port can be
+changed by passing the ``port`` argument to the ``run()`` method.
 
 .. note::
    Microdot does not configure the network interface of the device in which it
@@ -109,6 +141,41 @@ device's IP address. As indicated above, the port can be changed by passing the
    advance, for example to a Wi-Fi access point, this must be configured before
    the ``run()`` method is invoked.
 
+Web Server Configuration
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The :func:`run() <microdot.Microdot.run>` method supports a few arguments to
+configure the web server.
+
+- ``port``: The port number to listen on. Pass the desired port number in this
+  argument to use a port different than the default of 5000. For example::
+
+    app.run(port=6000)
+
+- ``host``: The IP address of the network interface to listen on. By default
+  the server listens on all available interfaces. To listen only on the local
+  loopback interface, pass ``'127.0.0.1'`` as value for this argument.
+- ``debug``: when set to ``True``, the server ouputs logging information to the
+  console. The default is ``False``.
+- ``ssl``: an ``SSLContext`` instance that configures the server to use TLS
+  encryption, or ``None`` to disable TLS use. The default is ``None``. The
+  following example demonstrates how to configure the server with an SSL
+  certificate stored in *cert.pem* and *key.pem* files::
+
+    import ssl
+
+    # ...
+
+    sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+    sslctx.load_cert_chain('cert.pem', 'key.pem')
+    app.run(port=4443, debug=True, ssl=sslctx)
+
+.. note::
+   The ``ssl`` argument can only be used with CPython at this time, because
+   MicroPython's asyncio module does not currently support SSL certificates or
+   TLS encryption. Work on this is
+   `in progress <https://github.com/micropython/micropython/pull/11897>`_.
+
 Defining Routes
 ~~~~~~~~~~~~~~~
 
@@ -119,7 +186,7 @@ to the decorator is the path portion of the URL.
 The following example creates a route for the root URL of the application::
 
     @app.route('/')
-    def index(request):
+    async def index(request):
         return 'Hello, world!'
 
 When a client requests the root URL (for example, *http://localhost:5000/*),
@@ -127,11 +194,11 @@ Microdot will call the ``index()`` function, passing it a
 :class:`Request <microdot.Request>` object. The return value of the function
 is the response that is sent to the client.
 
-Below is a another example, this one with a route for a URL with two components
+Below is another example, this one with a route for a URL with two components
 in its path::
 
     @app.route('/users/active')
-    def active_users(request):
+    async def active_users(request):
         return 'Active users: Susan, Joe, and Bob'
 
 The complete URL that maps to this route is
@@ -144,46 +211,49 @@ request.
 Choosing the HTTP Method
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
-All the example routes shown above are associated with ``GET`` requests. But
-applications often need to define routes for other HTTP methods, such as
-``POST``, ``PUT``, ``PATCH`` and ``DELETE``. The ``route()`` decorator takes a
-``methods`` optional argument, in which the application can provide a list of
-HTTP methods that the route should be associated with on the given path.
+All the example routes shown above are associated with ``GET`` requests, which
+are the default. Applications often need to define routes for other HTTP
+methods, such as ``POST``, ``PUT``, ``PATCH`` and ``DELETE``. The ``route()``
+decorator takes a ``methods`` optional argument, in which the application can
+provide a list of HTTP methods that the route should be associated with on the
+given path.
 
 The following example defines a route that handles ``GET`` and ``POST``
 requests within the same function::
 
     @app.route('/invoices', methods=['GET', 'POST'])
-    def invoices(request):
+    async def invoices(request):
         if request.method == 'GET':
             return 'get invoices'
         elif request.method == 'POST':
             return 'create an invoice'
 
-In cases like the above, where a single URL is used to handle multiple HTTP
-methods, it may be desirable to write a separate function for each HTTP method.
-The above example can be implemented with two routes as follows::
+As an alternative to the example above, in which a single function is used to
+handle multiple HTTP methods, sometimes it may be desirable to write a separate
+function for each HTTP method. The above example can be implemented with two
+routes as follows::
 
     @app.route('/invoices', methods=['GET'])
-    def get_invoices(request):
+    async def get_invoices(request):
         return 'get invoices'
 
     @app.route('/invoices', methods=['POST'])
-    def create_invoice(request):
+    async def create_invoice(request):
         return 'create an invoice'
 
 Microdot provides the :func:`get() <microdot.Microdot.get>`,
 :func:`post() <microdot.Microdot.post>`, :func:`put() <microdot.Microdot.put>`,
 :func:`patch() <microdot.Microdot.patch>`, and
-:func:`delete() <microdot.Microdot.delete>` decorator shortcuts as well. The
-two example routes above can be written more concisely with them::
+:func:`delete() <microdot.Microdot.delete>` decorators as shortcuts for the
+corresponding HTTP methods. The two example routes above can be written more
+concisely with them::
 
     @app.get('/invoices')
-    def get_invoices(request):
+    async def get_invoices(request):
         return 'get invoices'
 
     @app.post('/invoices')
-    def create_invoice(request):
+    async def create_invoice(request):
         return 'create an invoice'
 
 Including Dynamic Components in the URL Path
@@ -195,19 +265,19 @@ the following route associates all URLs that have a path following the pattern
 *http://localhost:5000/users/<username>* with the ``get_user()`` function::
 
     @app.get('/users/<username>')
-    def get_user(request, username):
+    async def get_user(request, username):
         return 'User: ' + username
 
-As shown in the example, a path components that is enclosed in angle brackets
-is considered dynamic. Microdot accepts any values for that section of the URL
-path, and passes the value received to the function as an argument after
-the request object.
+As shown in the example, a path component that is enclosed in angle brackets
+is considered a placeholder. Microdot accepts any values for that portion of
+the URL path, and passes the value received to the function as an argument
+after the request object.
 
 Routes are not limited to a single dynamic component. The following route shows
 how multiple dynamic components can be included in the path::
 
     @app.get('/users/<firstname>/<lastname>')
-    def get_user(request, firstname, lastname):
+    async def get_user(request, firstname, lastname):
         return 'User: ' + firstname + ' ' + lastname
 
 Dynamic path components are considered to be strings by default. An explicit
@@ -216,7 +286,7 @@ a colon. The following route has two dynamic components declared as an integer
 and a string respectively::
 
     @app.get('/users/<int:id>/<string:username>')
-    def get_user(request, id, username):
+    async def get_user(request, id, username):
         return 'User: ' + username + ' (' + str(id) + ')'
 
 If a dynamic path component is defined as an integer, the value passed to the
@@ -225,10 +295,12 @@ integer in the corresponding section of the URL path, then the URL will not
 match and the route will not be called.
 
 A special type ``path`` can be used to capture the remainder of the path as a
-single argument::
+single argument. The difference between an argument of type ``path`` and one of
+type ``string`` is that the latter stops capturing when a ``/`` appears in the
+URL.
 
     @app.get('/tests/<path:path>')
-    def get_test(request, path):
+    async def get_test(request, path):
         return 'Test: ' + path
 
 For the most control, the ``re`` type allows the application to provide a
@@ -237,7 +309,7 @@ a route that only matches usernames that begin with an upper or lower case
 letter, followed by a sequence of letters or numbers::
 
     @app.get('/users/<re:[a-zA-Z][a-zA-Z0-9]*:username>')
-    def get_user(request, username):
+    async def get_user(request, username):
         return 'User: ' + username
 
 .. note::
@@ -255,54 +327,56 @@ resource can be obtained from a cache. The
 :func:`before_request() <microdot.Microdot.before_request>` decorator registers
 a function to be called before the request is dispatched to the route function.
 
-The following example registers a before request handler that ensures that the
+The following example registers a before-request handler that ensures that the
 client is authenticated before the request is handled::
 
     @app.before_request
-    def authenticate(request):
+    async def authenticate(request):
         user = authorize(request)
         if not user:
             return 'Unauthorized', 401
         request.g.user = user
 
-Before request handlers receive the request object as an argument. If the
+Before-request handlers receive the request object as an argument. If the
 function returns a value, Microdot sends it to the client as the response, and
-does not invoke the route function. This gives before request handlers the
+does not invoke the route function. This gives before-request handlers the
 power to intercept a request if necessary. The example above uses this
 technique to prevent an unauthorized user from accessing the requested
-resource.
+route.
 
-After request handlers registered with the
+After-request handlers registered with the
 :func:`after_request() <microdot.Microdot.after_request>` decorator are called
 after the route function returns a response. Their purpose is to perform any
-common closing or cleanup tasks. The next example shows a combination of before
-and after request handlers that print the time it takes for a request to be
-handled::
+common closing or cleanup tasks. The next example shows a combination of
+before- and after-request handlers that print the time it takes for a request
+to be handled::
 
     @app.before_request
-    def start_timer(request):
+    async def start_timer(request):
         request.g.start_time = time.time()
 
     @app.after_request
-    def end_timer(request, response):
+    async def end_timer(request, response):
         duration = time.time() - request.g.start_time
         print(f'Request took {duration:0.2f} seconds')
 
-After request handlers receive the request and response objects as arguments.
-The function can return a modified response object to replace the original. If
-the function does not return a value, then the original response object is
-used.
+After-request handlers receive the request and response objects as arguments,
+and they can return a modified response object to replace the original. If
+no value is returned from an after-request handler, then the original response
+object is used.
 
-The after request handlers are only invoked for successful requests. The
+The after-request handlers are only invoked for successful requests. The
 :func:`after_error_request() <microdot.Microdot.after_error_request>`
 decorator can be used to register a function that is called after an error
 occurs. The function receives the request and the error response and is
-expected to return an updated response object.
+expected to return an updated response object after performing any necessary
+cleanup.
 
 .. note::
-   The :ref:`request.g <The "g" Object>` object is a special object that allows
-   the before and after request handlers, as well sa the route function to
-   share data during the life of the request.
+   The :ref:`request.g <The "g" Object>` object used in many of the above
+   examples is a special object that allows the before- and after-request
+   handlers, as well as the route function to share data during the life of the
+   request.
 
 Error Handlers
 ^^^^^^^^^^^^^^
@@ -312,10 +386,11 @@ the client receives an appropriate error response. Some of the common errors
 automatically handled by Microdot are:
 
 - 400 for malformed requests.
-- 404 for URLs that are not defined.
-- 405 for URLs that are defined, but not for the requested HTTP method.
+- 404 for URLs that are unknown.
+- 405 for URLs that are known, but not implemented for the requested HTTP
+  method.
 - 413 for requests that are larger than the allowed size.
-- 500 when the application raises an exception.
+- 500 when the application raises an unhandled exception.
 
 While the above errors are fully complaint with the HTTP specification, the
 application might want to provide custom responses for them. The
@@ -324,30 +399,31 @@ functions to respond to specific error codes. The following example shows a
 custom error handler for 404 errors::
 
     @app.errorhandler(404)
-    def not_found(request):
+    async def not_found(request):
         return {'error': 'resource not found'}, 404
 
 The ``errorhandler()`` decorator has a second form, in which it takes an
-exception class as an argument. Microdot will then invoke the handler when the
-exception is an instance of the given class is raised. The next example
-provides a custom response for division by zero errors::
+exception class as an argument. Microdot will invoke the handler when an
+unhandled exception that is an instance of the given class is raised. The next
+example provides a custom response for division by zero errors::
 
     @app.errorhandler(ZeroDivisionError)
-    def division_by_zero(request, exception):
+    async def division_by_zero(request, exception):
         return {'error': 'division by zero'}, 500
 
 When the raised exception class does not have an error handler defined, but
-one or more of its base classes do, Microdot makes an attempt to invoke the
+one or more of its parent classes do, Microdot makes an attempt to invoke the
 most specific handler.
 
 Mounting a Sub-Application
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Small Microdot applications can be written an a single source file, but this
-is not the best option for applications that past certain size. To make it
+Small Microdot applications can be written as a single source file, but this
+is not the best option for applications that past a certain size. To make it
 simpler to write large applications, Microdot supports the concept of
 sub-applications that can be "mounted" on a larger application, possibly with
-a common URL prefix applied to all of its routes.
+a common URL prefix applied to all of its routes. For developers familiar with
+the Flask framework, this is a similar concept to Flask's blueprints.
 
 Consider, for example, a *customers.py* sub-application that implements
 operations on customers::
@@ -357,14 +433,14 @@ operations on customers::
     customers_app = Microdot()
 
     @customers_app.get('/')
-    def get_customers(request):
+    async def get_customers(request):
         # return all customers
 
     @customers_app.post('/')
-    def new_customer(request):
+    async def new_customer(request):
         # create a new customer
 
-In the same way, the *orders.py* sub-application implements operations on
+Similar to the above, the *orders.py* sub-application implements operations on
 customer orders::
 
     from microdot import Microdot
@@ -372,21 +448,21 @@ customer orders::
     orders_app = Microdot()
 
     @orders_app.get('/')
-    def get_orders(request):
+    async def get_orders(request):
         # return all orders
 
     @orders_app.post('/')
-    def new_order(request):
+    async def new_order(request):
         # create a new order
 
 Now the main application, which is stored in *main.py*, can import and mount
-the sub-applications to build the combined application::
+the sub-applications to build the larger combined application::
 
     from microdot import Microdot
     from customers import customers_app
     from orders import orders_app
 
-    def create_app():
+    async def create_app():
         app = Microdot()
         app.mount(customers_app, url_prefix='/customers')
         app.mount(orders_app, url_prefix='/orders')
@@ -399,7 +475,7 @@ The resulting application will have the customer endpoints available at
 */customers/* and the order endpoints available at */orders/*.
 
 .. note::
-   Before request, after request and error handlers defined in the
+   Before-request, after-request and error handlers defined in the
    sub-application are also copied over to the main application at mount time.
    Once installed in the main application, these handlers will apply to the
    whole application and not just the sub-application in which they were
@@ -416,16 +492,20 @@ during the handling of a route to gracefully shut down the server when that
 request completes. The next example shows how to use this feature::
 
     @app.get('/shutdown')
-    def shutdown(request):
+    async def shutdown(request):
         request.app.shutdown()
         return 'The server is shutting down...'
 
+The request that invokes the ``shutdown()`` method will complete, and then the
+server will not accept any new requests and stop once any remaining requests
+complete. At this point the ``app.run()`` call will return.
+
 The Request Object
 ~~~~~~~~~~~~~~~~~~
 
 The :class:`Request <microdot.Request>` object encapsulates all the information
 passed by the client. It is passed as an argument to route handlers, as well as
-to before request, after request and error handlers.
+to before-request, after-request and error handlers.
 
 Request Attributes
 ^^^^^^^^^^^^^^^^^^
@@ -448,6 +528,9 @@ The request object provides access to the request attributes, including:
   the client, as a tuple (host, port).
 - :attr:`app <microdot.Request.app>`: The application instance that created the
   request.
+- :attr:`g <microdot.Request.g>`: The ``g`` object, where handlers can store
+  request-specific data to be shared among handlers. See :ref:`The "g" Object`
+  for details.
 
 JSON Payloads
 ^^^^^^^^^^^^^
@@ -458,7 +541,7 @@ application can access the parsed JSON data using the
 to use this attribute::
 
     @app.post('/customers')
-    def create_customer(request):
+    async def create_customer(request):
         customer = request.json
         # do something with customer
         return {'success': True}
@@ -475,7 +558,7 @@ The request object also supports standard HTML form submissions through the
 as a :class:`MultiDict <microdot.MultiDict>` object. Example::
 
     @app.route('/', methods=['GET', 'POST'])
-    def index(req):
+    async def index(req):
         name = 'Unknown'
         if req.method == 'POST':
             name = req.form.get('name')
@@ -493,14 +576,17 @@ For cases in which neither JSON nor form data is expected, the
 :attr:`body <microdot.Request.body>` request attribute returns the entire body
 of the request as a byte sequence.
 
-If the expected body is too large to fit in memory, the application can use the
-:attr:`stream <microdot.Request.stream>` request attribute to read the body
-contents as a file-like object.
+If the expected body is too large to fit safely in memory, the application can
+use the :attr:`stream <microdot.Request.stream>` request attribute to read the
+body contents as a file-like object. The
+:attr:`max_body_length <microdot.Request.max_body_length>` attribute of the
+request object defines the size at which bodies are streamed instead of loaded
+into memory.
 
 Cookies
 ^^^^^^^
 
-Cookies that are sent by the client are made available throught the
+Cookies that are sent by the client are made available through the
 :attr:`cookies <microdot.Request.cookies>` attribute of the request object in
 dictionary form.
 
@@ -508,41 +594,40 @@ The "g" Object
 ^^^^^^^^^^^^^^
 
 Sometimes applications need to store data during the lifetime of a request, so
-that it can be shared between the before or after request handlers and the
-route function. The request object provides the :attr:`g <microdot.Request.g>`
-attribute for that purpose.
+that it can be shared between the before- and after-request handlers, the
+route function and any error handlers. The request object provides the
+:attr:`g <microdot.Request.g>` attribute for that purpose.
 
-In the following example, a before request handler
-authorizes the client and stores the username so that the route function can
-use it::
+In the following example, a before request handler authorizes the client and
+stores the username so that the route function can use it::
 
     @app.before_request
-    def authorize(request):
+    async def authorize(request):
         username = authenticate_user(request)
         if not username:
             return 'Unauthorized', 401
         request.g.username = username
 
     @app.get('/')
-    def index(request):
+    async def index(request):
         return f'Hello, {request.g.username}!'
 
-Request-Specific After Request Handlers
+Request-Specific After-Request Handlers
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Sometimes applications need to perform operations on the response object,
+Sometimes applications need to perform operations on the response object
 before it is sent to the client, for example to set or remove a cookie. A good
-option to use for this is to define a request-specific after request handler
+option to use for this is to define a request-specific after-request handler
 using the :func:`after_request <microdot.Microdot.after_request>` decorator.
-Request-specific after request handlers are called by Microdot after the route
-function returns and all the application's after request handlers have been
+Request-specific after-request handlers are called by Microdot after the route
+function returns and all the application-wide after-request handlers have been
 called.
 
 The next example shows how a cookie can be updated using a request-specific
-after request handler defined inside a route function::
+after-request handler defined inside a route function::
 
     @app.post('/logout')
-    def logout(request):
+    async def logout(request):
         @request.after_request
         def reset_session(request, response):
             response.set_cookie('session', '', http_only=True)
@@ -556,22 +641,24 @@ Request Limits
 To help prevent malicious attacks, Microdot provides some configuration options
 to limit the amount of information that is accepted:
 
-- :attr:`max_content_length <microdot.Microdot.max_content_length>`: The
+- :attr:`max_content_length <microdot.Request.max_content_length>`: The
   maximum size accepted for the request body, in bytes. When a client sends a
   request that is larger than this, the server will respond with a 413 error.
   The default is 16KB.
-- :attr:`max_body_length <microdot.Microdot.max_body_length>`: The maximum
+- :attr:`max_body_length <microdot.Request.max_body_length>`: The maximum
   size that is loaded in the :attr:`body <microdot.Request.body>` attribute, in
   bytes. Requests that have a body that is larger than this size but smaller
   than the size set for ``max_content_length`` can only be accessed through the
   :attr:`stream <microdot.Request.stream>` attribute. The default is also 16KB.
-- :attr:`max_readline <microdot.Microdot.max_readline>`: The maximum allowed
+- :attr:`max_readline <microdot.Request.max_readline>`: The maximum allowed
   size for a request line, in bytes. The default is 2KB.
 
 The following example configures the application to accept requests with
-payloads up to 1MB big, but prevents requests that are larger than 8KB from
+payloads up to 1MB in size, but prevents requests that are larger than 8KB from
 being loaded into memory::
 
+    from microdot import Request
+
     Request.max_content_length = 1024 * 1024
     Request.max_body_length = 8 * 1024
 
@@ -589,33 +676,34 @@ Route functions can return one, two or three values. The first or only value is
 always returned to the client in the response body::
 
     @app.get('/')
-    def index(request):
+    async def index(request):
         return 'Hello, World!'
 
 In the above example, Microdot issues a standard 200 status code response, and
-inserts the necessary headers.
+inserts default headers.
 
-The applicaton can provide its own status code as a second value returned from
-the route. The example below returns a 202 status code::
-
-    @app.get('/')
-    def index(request):
-        return 'Hello, World!', 202
-
-The application can also return a third value, a dictionary with additional
-headers that are added to, or replace the default ones provided by Microdot.
-The next example returns an HTML response, instead of a default text response::
-
-    @app.get('/')
-    def index(request):
-        return '<h1>Hello, World!</h1>', 202, {'Content-Type': 'text/html'}
-
-If the application needs to return custom headers, but does not need to change
-the default status code, then it can return two values, omitting the stauts
+The application can provide its own status code as a second value returned from
+the route to override the 200 default. The example below returns a 202 status
 code::
 
     @app.get('/')
-    def index(request):
+    async def index(request):
+        return 'Hello, World!', 202
+
+The application can also return a third value, a dictionary with additional
+headers that are added to, or replace the default ones included by Microdot.
+The next example returns an HTML response, instead of a default text response::
+
+    @app.get('/')
+    async def index(request):
+        return '<h1>Hello, World!</h1>', 202, {'Content-Type': 'text/html'}
+
+If the application needs to return custom headers, but does not need to change
+the default status code, then it can return two values, omitting the status
+code::
+
+    @app.get('/')
+    async def index(request):
         return '<h1>Hello, World!</h1>', {'Content-Type': 'text/html'}
 
 The application can also return a :class:`Response <microdot.Response>` object
@@ -631,7 +719,7 @@ automatically format the response as JSON.
 Example::
 
     @app.get('/')
-    def index(request):
+    async def index(request):
         return {'hello': 'world'}
 
 .. note::
@@ -647,7 +735,7 @@ creates redirect responses::
     from microdot import redirect
 
     @app.get('/')
-    def index(request):
+    async def index(request):
         return redirect('/about')
 
 File Responses
@@ -659,9 +747,18 @@ object for a file::
         from microdot import send_file
 
         @app.get('/')
-        def index(request):
+        async def index(request):
             return send_file('/static/index.html')
 
+A suggested caching duration can be returned to the client in the ``max_age``
+argument::
+
+        from microdot import send_file
+
+        @app.get('/')
+        async def image(request):
+            return send_file('/static/image.jpg', max_age=3600)  # in seconds
+
 .. note::
    Unlike other web frameworks, Microdot does not automatically configure a
    route to serve static files. The following is an example route that can be
@@ -669,22 +766,22 @@ object for a file::
    the project::
 
         @app.route('/static/<path:path>')
-        def static(request, path):
+        async def static(request, path):
             if '..' in path:
                 # directory traversal is not allowed
                 return 'Not found', 404
-            return send_file('static/' + path)
+            return send_file('static/' + path, max_age=86400)
 
 Streaming Responses
 ^^^^^^^^^^^^^^^^^^^
 
 Instead of providing a response as a single value, an application can opt to
-return a response that is generated in chunks by returning a generator. The
-example below returns all the numbers in the fibonacci sequence below 100::
+return a response that is generated in chunks, by returning a Python generator.
+The example below returns all the numbers in the fibonacci sequence below 100::
 
     @app.get('/fibonacci')
-    def fibonacci(request):
-        def generate_fibonacci():
+    async def fibonacci(request):
+        async def generate_fibonacci():
             a, b = 0, 1
             while a < 100:
                 yield str(a) + '\n'
@@ -692,6 +789,14 @@ example below returns all the numbers in the fibonacci sequence below 100::
 
         return generate_fibonacci()
 
+.. note::
+   Under CPython, the generator function can be a ``def`` or ``async def``
+   function, as well as a class-based generator.
+
+   Under MicroPython, asynchronous generator functions are not supported, so
+   only ``def`` generator functions can be used. Asynchronous class-based
+   generators are supported.
+
 Changing the Default Response Content Type
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -719,14 +824,14 @@ object to add a properly formatted cookie header to the response.
 
 Given that route functions do not normally work directly with the response
 object, the recommended way to set a cookie is to do it in a
-:ref:`Request-Specific After Request Handler <Request-Specific After Request Handlers>`.
+:ref:`request-specific after-request handler <Request-Specific After-Request Handlers>`.
 
 Example::
 
     @app.get('/')
-    def index(request):
+    async def index(request):
         @request.after_request
-        def set_cookie(request, response):
+        async def set_cookie(request, response):
             response.set_cookie('name', 'value')
             return response
 
@@ -735,7 +840,7 @@ Example::
 Another option is to create a response object directly in the route function::
 
     @app.get('/')
-    def index(request):
+    async def index(request):
         response = Response('Hello, World!')
         response.set_cookie('name', 'value')
         return response
@@ -744,21 +849,24 @@ Another option is to create a response object directly in the route function::
    Standard cookies do not offer sufficient privacy and security controls, so
    never store sensitive information in them unless you are adding additional
    protection mechanisms such as encryption or cryptographic signing. The
-   :ref:`session <Maintaing Secure User Sessions>` extension implements signed
+   :ref:`session <Maintaining Secure User Sessions>` extension implements signed
    cookies that prevent tampering by malicious actors.
 
 Concurrency
 ~~~~~~~~~~~
 
-By default, Microdot runs in synchronous (single-threaded) mode. However, if
-the ``threading`` module is available, each request will be started on a
-separate thread and requests will be handled concurrently.
+Microdot implements concurrency through the ``asyncio`` package. Applications
+must ensure their handlers do not block, as this will prevent other concurrent
+requests from being handled.
 
-Be aware that most microcontroller boards support a very limited form of
-multi-threading that is not appropriate for concurrent request handling. For
-that reason, use of the `threading <https://github.com/micropython/micropython-lib/blob/master/python-stdlib/threading/threading.py>`_
-module on microcontroller platforms is not recommended.
+When running under CPython, ``async def`` handler functions run as native 
+asyncio tasks, while ``def`` handler functions are executed in a
+`thread executor <https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.run_in_executor>`_
+to prevent them from blocking the asynchronous loop.
 
-The :ref:`micropython_asyncio <Asynchronous Support with Asyncio>` extension
-provides a more robust concurrency option that is supported even on low-end
-MicroPython boards.
+Under MicroPython the situation is different. Most microcontroller boards
+implementing MicroPython do not have threading support or executors, so ``def``
+handler functions in this platform can only run in the main and only thread.
+These functions will block the asynchronous loop when they take too long to
+complete so ``async def`` handlers properly written to allow other handlers to
+run in parallel should be preferred.

docs/migrating.rst

@@ -0,0 +1,142 @@
+Migrating to Microdot 2.x from Older Releases
+---------------------------------------------
+
+Version 2 of Microdot incorporates feedback received from users of earlier
+releases, and attempts to improve and correct some design decisions that have
+proven to be problematic.
+
+For this reason most applications built for earlier versions will need to be
+updated to work correctly with Microdot 2. This section describes the backwards
+incompatible changes that were made.
+
+Code reorganization
+~~~~~~~~~~~~~~~~~~~
+
+The Microdot source code has been moved into a ``microdot`` package,
+eliminating the need for each extension to be named with a *microdot_* prefix.
+
+As a result of this change, all extensions have been renamed to shorter names.
+For example, the *microdot_cors.py* module is now called *cors.py*.
+
+This change affects the way extensions are imported. Instead of this::
+
+    from microdot_cors import CORS
+
+the import statement should be::
+
+    from microdot.cors import CORS
+
+No more synchronous web server
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In earlier releases of Microdot the core web server was built on synchronous
+Python, and asynchronous support was enabled with the asyncio extension.
+
+Microdot 2 eliminates the synchronous web server, and implements the core
+server logic directly with asyncio, eliminating the need for an asyncio
+extension.
+
+Any applications built using the asyncio extension will need to update their
+imports from this::
+
+    from microdot.asyncio import Microdot
+
+to this::
+
+    from microdot import Microdot
+
+Applications that were built using the synchronous web server do not need to
+change their imports, but will now work asynchronously. Review the
+:ref:`Concurrency` section to learn about the potential issues when using
+``def`` function handlers, and the benefits of transitioning to ``async def``
+handlers.
+
+Removed extensions
+~~~~~~~~~~~~~~~~~~
+
+Some extensions became unnecessary and have been removed or merged with other
+extensions:
+
+- *microdot_asyncio.py*: this is now the core web server.
+- *microdot_asyncio_websocket.py*: this is now the main WebSocket extension.
+- *microdot_asyncio_test_client.py*: this is now the main test client
+  extension.
+- *microdot_asgi_websocket.py*: the functionality in this extension is now
+  available in the ASGI extension.
+- *microdot_ssl.py*: this extension was only used with the synchronous web
+  server, so it is not needed anymore.
+- *microdot_websocket_alt.py*: this extension was only used with the
+  synchronous web server, so it is not needed anymore.
+
+No more ``render_template()`` function
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Jinja and uTemplate extensions have been redesigned to work better under
+the asynchronous engine, and as a result, the ``render_template()`` function
+has been eliminated.
+
+Instead of this::
+
+    return render_template('index.html', title='Home')
+
+use this::
+
+    return Template('index.html').render(title='Home')
+
+As a result of this change, it is now possible to use asynchronous rendering::
+
+    return await Template('index.html').render_async(title='Home')
+
+Also thanks to this redesign, the template can be streamed instead of returned
+as a single string::
+
+    return Template('index.html').generate(title='Home')
+
+Streamed templates also have an asynchronous version::
+
+    return await Template('index.html').generate_async(title='Home')
+
+Class-based user sessions
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The session extension has been completely redesigned. To initialize session
+support for the application, create a ``Session`` object::
+
+    app = Microdot()
+    Session(app, secret_key='top-secret!')
+
+The ``@with_session`` decorator is used to include the session in a request::
+
+    @app.get('/')
+    @with_session
+    async def index(request, session):
+        # ...
+
+The ``session`` can be used as a dictionary to retrieve or change the session.
+To save the session when it has been modified, call its ``save()`` method::
+
+    @app.get('/')
+    @with_session
+    async def index(request, session):
+        # ...
+        session.save()
+        return 'OK'
+
+To delete the session, call its ``delete()`` method before returning from the
+request.
+
+WSGI extension redesign
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Given that the synchronous web server has been removed, the WSGI extension has
+been redesigned to work as a synchronous wrapper for the asynchronous web
+server.
+
+Applications using the WSGI extension continue to run under an asynchronous
+loop and should try to use the recommended ``async def`` handlers, but can be
+deployed with standard WSGI servers such as Gunicorn.
+
+WebSocket support when using the WSGI extension is enabled when using a
+compatible web server. At this time only Gunicorn is supported for WebSocket.
+
+As before, the WSGI extension is not available under MicroPython.

examples/benchmark/mem.py

@@ -4,7 +4,7 @@ app = Microdot()
 
 
 @app.get('/')
-def index(req):
+async def index(req):
     return {'hello': 'world'}
 
 

examples/benchmark/mem_asgi.py

@@ -1,4 +1,4 @@
-from microdot_asgi import Microdot
+from microdot.asgi import Microdot
 
 app = Microdot()
 

examples/benchmark/mem_async.py

@@ -1,11 +0,0 @@
-from microdot_asyncio import Microdot
-
-app = Microdot()
-
-
-@app.get('/')
-async def index(req):
-    return {'hello': 'world'}
-
-
-app.run()

examples/benchmark/mem_fastapi.py

@@ -4,5 +4,5 @@ app = FastAPI()
 
 
 @app.get('/')
-def index():
+async def index():
     return {'hello': 'world'}

examples/benchmark/mem_quart.py

@@ -4,5 +4,5 @@ app = Quart(__name__)
 
 
 @app.get('/')
-def index():
+async def index():
     return {'hello': 'world'}

examples/benchmark/mem_wsgi.py

@@ -1,4 +1,4 @@
-from microdot_wsgi import Microdot
+from microdot.wsgi import Microdot
 
 app = Microdot()
 

examples/benchmark/requirements.in

@@ -0,0 +1,9 @@
+pip-tools
+flask
+quart
+fastapi
+gunicorn
+uvicorn
+requests
+psutil
+humanize

examples/benchmark/requirements.txt

@@ -1,33 +1,115 @@
-aiofiles==0.8.0
-anyio==3.6.1
-blinker==1.5
-certifi==2022.12.7
-charset-normalizer==2.1.0
-click==8.1.3
-fastapi==0.79.0
-Flask==2.2.1
-gunicorn==20.1.0
-h11==0.13.0
+#
+# This file is autogenerated by pip-compile with Python 3.12
+# by the following command:
+#
+#    pip-compile requirements.in
+#
+aiofiles==23.2.1
+    # via quart
+annotated-types==0.6.0
+    # via pydantic
+anyio==3.7.1
+    # via
+    #   fastapi
+    #   starlette
+blinker==1.7.0
+    # via
+    #   flask
+    #   quart
+build==1.0.3
+    # via pip-tools
+certifi==2023.11.17
+    # via requests
+charset-normalizer==3.3.2
+    # via requests
+click==8.1.7
+    # via
+    #   flask
+    #   pip-tools
+    #   quart
+    #   uvicorn
+fastapi==0.104.1
+    # via -r requirements.in
+flask==3.0.0
+    # via
+    #   -r requirements.in
+    #   quart
+gunicorn==21.2.0
+    # via -r requirements.in
+h11==0.14.0
+    # via
+    #   hypercorn
+    #   uvicorn
+    #   wsproto
 h2==4.1.0
+    # via hypercorn
 hpack==4.0.0
-humanize==4.3.0
-hypercorn==0.13.2
+    # via h2
+humanize==4.9.0
+    # via -r requirements.in
+hypercorn==0.15.0
+    # via quart
 hyperframe==6.0.1
-idna==3.3
+    # via h2
+idna==3.6
+    # via
+    #   anyio
+    #   requests
 itsdangerous==2.1.2
-Jinja2==3.1.2
-MarkupSafe==2.1.1
-microdot
+    # via
+    #   flask
+    #   quart
+jinja2==3.1.2
+    # via
+    #   flask
+    #   quart
+markupsafe==2.1.3
+    # via
+    #   jinja2
+    #   quart
+    #   werkzeug
+packaging==23.2
+    # via
+    #   build
+    #   gunicorn
+pip-tools==7.3.0
+    # via -r requirements.in
 priority==2.0.0
-psutil==5.9.1
-pydantic==1.9.1
-quart==0.18.0
-requests==2.28.1
-sniffio==1.2.0
-starlette==0.25.0
-toml==0.10.2
-typing_extensions==4.3.0
-urllib3==1.26.11
-uvicorn==0.18.2
-Werkzeug==2.2.3
-wsproto==1.1.0
+    # via hypercorn
+psutil==5.9.6
+    # via -r requirements.in
+pydantic==2.5.2
+    # via fastapi
+pydantic-core==2.14.5
+    # via pydantic
+pyproject-hooks==1.0.0
+    # via build
+quart==0.19.4
+    # via -r requirements.in
+requests==2.31.0
+    # via -r requirements.in
+sniffio==1.3.0
+    # via anyio
+starlette==0.27.0
+    # via fastapi
+typing-extensions==4.9.0
+    # via
+    #   fastapi
+    #   pydantic
+    #   pydantic-core
+urllib3==2.1.0
+    # via requests
+uvicorn==0.24.0.post1
+    # via -r requirements.in
+werkzeug==3.0.1
+    # via
+    #   flask
+    #   quart
+wheel==0.42.0
+    # via pip-tools
+wsproto==1.2.0
+    # via hypercorn
+
+# The following packages are considered to be unsafe in a requirements file:
+# pip
+# setuptools

examples/benchmark/run.py

@@ -14,13 +14,8 @@ apps = [
     ),
     (
         'micropython mem.py',
-        {'MICROPYPATH': '../../src'},
-        'microdot-micropython-sync'
-    ),
-    (
-        'micropython mem_async.py',
         {'MICROPYPATH': '../../src:../../libs/micropython'},
-        'microdot-micropython-async'
+        'microdot-micropython'
     ),
     (
         ['python', '-c', 'import time; time.sleep(10)'],
@@ -30,47 +25,42 @@ apps = [
     (
         'python mem.py',
         {'PYTHONPATH': '../../src'},
-        'microdot-cpython-sync'
-    ),
-    (
-        'python mem_async.py',
-        {'PYTHONPATH': '../../src'},
-        'microdot-cpython-async'
-    ),
-    (
-        'gunicorn --workers 1 --bind :5000 mem_wsgi:app',
-        {'PYTHONPATH': '../../src'},
-        'microdot-gunicorn-sync'
+        'microdot-cpython'
     ),
     (
         'uvicorn --workers 1 --port 5000 mem_asgi:app',
         {'PYTHONPATH': '../../src'},
-        'microdot-uvicorn-async'
+        'microdot-uvicorn'
+    ),
+    (
+        'gunicorn --workers 1 --bind :5000 mem_wsgi:app',
+        {'PYTHONPATH': '../../src'},
+        'microdot-gunicorn'
     ),
     (
         'flask run',
         {'FLASK_APP': 'mem_flask.py'},
-        'flask-run-sync'
+        'flask-run'
     ),
     (
         'quart run',
         {'QUART_APP': 'mem_quart.py'},
-        'quart-run-async'
+        'quart-run'
     ),
     (
         'gunicorn --workers 1 --bind :5000 mem_flask:app',
         {},
-        'flask-gunicorn-sync'
+        'flask-gunicorn'
     ),
     (
         'uvicorn --workers 1 --port 5000 mem_quart:app',
         {},
-        'quart-uvicorn-async'
+        'quart-uvicorn'
     ),
     (
         'uvicorn --workers 1 --port 5000 mem_fastapi:app',
         {},
-        'fastapi-uvicorn-async'
+        'fastapi-uvicorn'
     ),
 ]
 

examples/cors/README.md

@@ -0,0 +1 @@
+This directory contains Cross-Origin Resource Sharing (CORS) examples.

examples/cors/app.py

@@ -0,0 +1,14 @@
+from microdot import Microdot
+from microdot.cors import CORS
+
+app = Microdot()
+CORS(app, allowed_origins=['https://example.org'], allow_credentials=True)
+
+
+@app.route('/')
+def index(request):
+    return 'Hello World!'
+
+
+if __name__ == '__main__':
+    app.run()

examples/gpio/gpio.html

@@ -2,6 +2,7 @@
 <html>
     <head>
         <title>Microdot GPIO Example</title>
+        <meta charset="UTF-8">
         <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
         <script>
             function getCookie(name) {

examples/hello/hello.py

@@ -2,10 +2,11 @@ from microdot import Microdot
 
 app = Microdot()
 
-htmldoc = '''<!DOCTYPE html>
+html = '''<!DOCTYPE html>
 <html>
     <head>
         <title>Microdot Example Page</title>
+        <meta charset="UTF-8">
     </head>
     <body>
         <div>
@@ -19,12 +20,12 @@ htmldoc = '''<!DOCTYPE html>
 
 
 @app.route('/')
-def hello(request):
-    return htmldoc, 200, {'Content-Type': 'text/html'}
+async def hello(request):
+    return html, 200, {'Content-Type': 'text/html'}
 
 
 @app.route('/shutdown')
-def shutdown(request):
+async def shutdown(request):
     request.app.shutdown()
     return 'The server is shutting down...'
 

examples/hello/hello_asgi.py

@@ -1,11 +1,12 @@
-from microdot_asgi import Microdot
+from microdot.asgi import Microdot
 
 app = Microdot()
 
-htmldoc = '''<!DOCTYPE html>
+html = '''<!DOCTYPE html>
 <html>
     <head>
         <title>Microdot Example Page</title>
+        <meta charset="UTF-8">
     </head>
     <body>
         <div>
@@ -20,7 +21,7 @@ htmldoc = '''<!DOCTYPE html>
 
 @app.route('/')
 async def hello(request):
-    return htmldoc, 200, {'Content-Type': 'text/html'}
+    return html, 200, {'Content-Type': 'text/html'}
 
 
 @app.route('/shutdown')

examples/hello/hello_async.py

@@ -1,32 +0,0 @@
-from microdot_asyncio import Microdot
-
-app = Microdot()
-
-htmldoc = '''<!DOCTYPE html>
-<html>
-    <head>
-        <title>Microdot Example Page</title>
-    </head>
-    <body>
-        <div>
-            <h1>Microdot Example Page</h1>
-            <p>Hello from Microdot!</p>
-            <p><a href="/shutdown">Click to shutdown the server</a></p>
-        </div>
-    </body>
-</html>
-'''
-
-
-@app.route('/')
-async def hello(request):
-    return htmldoc, 200, {'Content-Type': 'text/html'}
-
-
-@app.route('/shutdown')
-async def shutdown(request):
-    request.app.shutdown()
-    return 'The server is shutting down...'
-
-
-app.run(debug=True)

examples/hello/hello_wsgi.py

@@ -1,11 +1,12 @@
-from microdot_wsgi import Microdot
+from microdot.wsgi import Microdot
 
 app = Microdot()
 
-htmldoc = '''<!DOCTYPE html>
+html = '''<!DOCTYPE html>
 <html>
     <head>
         <title>Microdot Example Page</title>
+        <meta charset="UTF-8">
     </head>
     <body>
         <div>
@@ -20,7 +21,7 @@ htmldoc = '''<!DOCTYPE html>
 
 @app.route('/')
 def hello(request):
-    return htmldoc, 200, {'Content-Type': 'text/html'}
+    return html, 200, {'Content-Type': 'text/html'}
 
 
 @app.route('/shutdown')

examples/sessions/login.py

@@ -1,11 +1,11 @@
 from microdot import Microdot, Response, redirect
-from microdot_session import set_session_secret_key, with_session, \
-    update_session, delete_session
+from microdot.session import Session, with_session
 
 BASE_TEMPLATE = '''<!doctype html>
 <html>
   <head>
     <title>Microdot login example</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Microdot login example</h1>
@@ -17,7 +17,7 @@ LOGGED_OUT = '''<p>You are not logged in.</p>
 <form method="POST">
   <p>
     Username:
-    <input type="text" name="username" autofocus />
+    <input name="username" autofocus />
   </p>
   <input type="submit" value="Submit" />
 </form>'''
@@ -28,18 +28,19 @@ LOGGED_IN = '''<p>Hello <b>{username}</b>!</p>
 </form>'''
 
 app = Microdot()
-set_session_secret_key('top-secret')
+Session(app, secret_key='top-secret')
 Response.default_content_type = 'text/html'
 
 
 @app.get('/')
 @app.post('/')
 @with_session
-def index(req, session):
+async def index(req, session):
     username = session.get('username')
     if req.method == 'POST':
         username = req.form.get('username')
-        update_session(req, {'username': username})
+        session['username'] = username
+        session.save()
         return redirect('/')
     if username is None:
         return BASE_TEMPLATE.format(content=LOGGED_OUT)
@@ -49,8 +50,9 @@ def index(req, session):
 
 
 @app.post('/logout')
-def logout(req):
-    delete_session(req)
+@with_session
+async def logout(req, session):
+    session.delete()
     return redirect('/')
 
 

examples/sse/counter.py

@@ -0,0 +1,16 @@
+import asyncio
+from microdot import Microdot
+from microdot.sse import with_sse
+
+app = Microdot()
+
+
+@app.route('/events')
+@with_sse
+async def events(request, sse):
+    for i in range(10):
+        await asyncio.sleep(1)
+        await sse.send({'counter': i})
+
+
+app.run(debug=True)

examples/static/gzstatic.py

@@ -0,0 +1,20 @@
+from microdot import Microdot, send_file
+
+app = Microdot()
+
+
+@app.route('/')
+def index(request):
+    return send_file('gzstatic/index.html', compressed=True,
+                     file_extension='.gz')
+
+
+@app.route('/static/<path:path>')
+def static(request, path):
+    if '..' in path:
+        # directory traversal is not allowed
+        return 'Not found', 404
+    return send_file('gzstatic/' + path, compressed=True, file_extension='.gz')
+
+
+app.run(debug=True)

examples/static/static.py

@@ -1,15 +1,14 @@
 from microdot import Microdot, send_file
-
 app = Microdot()
 
 
 @app.route('/')
-def index(request):
+async def index(request):
     return send_file('static/index.html')
 
 
 @app.route('/static/<path:path>')
-def static(request, path):
+async def static(request, path):
     if '..' in path:
         # directory traversal is not allowed
         return 'Not found', 404

examples/static/static/index.css

@@ -0,0 +1,10 @@
+p {
+  font-family: Arial, Helvetica, sans-serif;
+  color: #333333;
+}
+
+h1 {
+  font-family: Arial, Helvetica, sans-serif;
+  color: #3070b3;
+  text-align: center;
+}

examples/static/static/index.html

@@ -2,6 +2,7 @@
 <html>
   <head>
     <title>Static File Serving Demo</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Static File Serving Demo</h1>

examples/static/static_async.py

@@ -1,19 +0,0 @@
-from microdot_asyncio import Microdot
-from microdot import send_file
-app = Microdot()
-
-
-@app.route('/')
-async def index(request):
-    return send_file('static/index.html')
-
-
-@app.route('/static/<path:path>')
-async def static(request, path):
-    if '..' in path:
-        # directory traversal is not allowed
-        return 'Not found', 404
-    return send_file('static/' + path)
-
-
-app.run(debug=True)

examples/streaming/video_stream.py

@@ -1,8 +1,5 @@
-try:
-    import utime as time
-except ImportError:
-    import time
-
+import sys
+import asyncio
 from microdot import Microdot
 
 app = Microdot()
@@ -14,11 +11,12 @@ for file in ['1.jpg', '2.jpg', '3.jpg']:
 
 
 @app.route('/')
-def index(request):
+async def index(request):
     return '''<!doctype html>
 <html>
   <head>
     <title>Microdot Video Streaming</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Microdot Video Streaming</h1>
@@ -28,14 +26,38 @@ def index(request):
 
 
 @app.route('/video_feed')
-def video_feed(request):
-    def stream():
+async def video_feed(request):
+    print('Starting video stream.')
+
+    if sys.implementation.name != 'micropython':
+        # CPython supports async generator function
+        async def stream():
+            try:
                 yield b'--frame\r\n'
                 while True:
                     for frame in frames:
                         yield b'Content-Type: image/jpeg\r\n\r\n' + frame + \
                             b'\r\n--frame\r\n'
-                time.sleep(1)
+                        await asyncio.sleep(1)
+            except GeneratorExit:
+                print('Stopping video stream.')
+    else:
+        # MicroPython can only use class-based async generators
+        class stream():
+            def __init__(self):
+                self.i = 0
+
+            def __aiter__(self):
+                return self
+
+            async def __anext__(self):
+                await asyncio.sleep(1)
+                self.i = (self.i + 1) % len(frames)
+                return b'Content-Type: image/jpeg\r\n\r\n' + \
+                    frames[self.i] + b'\r\n--frame\r\n'
+
+            async def aclose(self):
+                print('Stopping video stream.')
 
     return stream(), 200, {'Content-Type':
                            'multipart/x-mixed-replace; boundary=frame'}

examples/streaming/video_stream_async.py

@@ -1,64 +0,0 @@
-import sys
-
-try:
-    import uasyncio as asyncio
-except ImportError:
-    import asyncio
-
-from microdot_asyncio import Microdot
-
-app = Microdot()
-
-frames = []
-for file in ['1.jpg', '2.jpg', '3.jpg']:
-    with open(file, 'rb') as f:
-        frames.append(f.read())
-
-
-@app.route('/')
-def index(request):
-    return '''<!doctype html>
-<html>
-  <head>
-    <title>Microdot Video Streaming</title>
-  </head>
-  <body>
-    <h1>Microdot Video Streaming</h1>
-    <img src="/video_feed">
-  </body>
-</html>''', 200, {'Content-Type': 'text/html'}
-
-
-@app.route('/video_feed')
-async def video_feed(request):
-    if sys.implementation.name != 'micropython':
-        # CPython supports yielding async generators
-        async def stream():
-            yield b'--frame\r\n'
-            while True:
-                for frame in frames:
-                    yield b'Content-Type: image/jpeg\r\n\r\n' + frame + \
-                        b'\r\n--frame\r\n'
-                    await asyncio.sleep(1)
-
-    else:
-        # MicroPython can only use class-based async generators
-        class stream():
-            def __init__(self):
-                self.i = 0
-
-            def __aiter__(self):
-                return self
-
-            async def __anext__(self):
-                await asyncio.sleep(1)
-                self.i = (self.i + 1) % len(frames)
-                return b'Content-Type: image/jpeg\r\n\r\n' + \
-                    frames[self.i] + b'\r\n--frame\r\n'
-
-    return stream(), 200, {'Content-Type':
-                           'multipart/x-mixed-replace; boundary=frame'}
-
-
-if __name__ == '__main__':
-    app.run(debug=True)

examples/templates/jinja/async_template.py

@@ -0,0 +1,18 @@
+from microdot import Microdot, Response
+from microdot.jinja import template, init_templates
+
+init_templates('templates', enable_async=True)
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return await template('index.html').render_async(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/jinja/bootstrap.py

@@ -1,18 +1,18 @@
 from microdot import Microdot, Response
-from microdot_jinja import render_template
+from microdot.jinja import template
 
 app = Microdot()
 Response.default_content_type = 'text/html'
 
 
 @app.route('/')
-def index(req):
-    return render_template('page1.html', page='Page 1')
+async def index(req):
+    return template('page1.html').render(page='Page 1')
 
 
 @app.route('/page2')
-def page2(req):
-    return render_template('page2.html', page='Page 2')
+async def page2(req):
+    return template('page2.html').render(page='Page 2')
 
 
 if __name__ == '__main__':

examples/templates/jinja/hello.py

@@ -1,16 +1,16 @@
 from microdot import Microdot, Response
-from microdot_jinja import render_template
+from microdot.jinja import template
 
 app = Microdot()
 Response.default_content_type = 'text/html'
 
 
 @app.route('/', methods=['GET', 'POST'])
-def index(req):
+async def index(req):
     name = None
     if req.method == 'POST':
         name = req.form.get('name')
-    return render_template('index.html', name=name)
+    return template('index.html').render(name=name)
 
 
 if __name__ == '__main__':

examples/templates/jinja/hello_asgi.py

@@ -1,5 +1,5 @@
-from microdot_asyncio import Microdot, Response
-from microdot_utemplate import render_template
+from microdot.asgi import Microdot, Response
+from microdot.jinja import template
 
 app = Microdot()
 Response.default_content_type = 'text/html'
@@ -10,7 +10,7 @@ async def index(req):
     name = None
     if req.method == 'POST':
         name = req.form.get('name')
-    return render_template('index.html', name=name)
+    return template('index.html').render(name=name)
 
 
 if __name__ == '__main__':

examples/templates/jinja/hello_wsgi.py

@@ -0,0 +1,17 @@
+from microdot.wsgi import Microdot, Response
+from microdot.jinja import template
+
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return template('index.html').render(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/jinja/streaming.py

@@ -0,0 +1,17 @@
+from microdot import Microdot, Response
+from microdot.jinja import template
+
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return template('index.html').generate(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/jinja/templates/index.html

@@ -2,6 +2,7 @@
 <html>
   <head>
     <title>Microdot + Jinja example</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Microdot + Jinja example</h1>

examples/templates/utemplate/async_template.py

@@ -0,0 +1,17 @@
+from microdot import Microdot, Response
+from microdot.utemplate import template
+
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return await template('index.html').render_async(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/utemplate/bootstrap.py

@@ -1,18 +1,18 @@
 from microdot import Microdot, Response
-from microdot_utemplate import render_template
+from microdot.utemplate import template
 
 app = Microdot()
 Response.default_content_type = 'text/html'
 
 
 @app.route('/')
-def index(req):
-    return render_template('page1.html', page='Page 1')
+async def index(req):
+    return template('page1.html').render(page='Page 1')
 
 
 @app.route('/page2')
-def page2(req):
-    return render_template('page2.html', page='Page 2')
+async def page2(req):
+    return template('page2.html').render(page='Page 2')
 
 
 if __name__ == '__main__':

examples/templates/utemplate/hello.py

@@ -1,16 +1,16 @@
 from microdot import Microdot, Response
-from microdot_utemplate import render_template
+from microdot.utemplate import template
 
 app = Microdot()
 Response.default_content_type = 'text/html'
 
 
 @app.route('/', methods=['GET', 'POST'])
-def index(req):
+async def index(req):
     name = None
     if req.method == 'POST':
         name = req.form.get('name')
-    return render_template('index.html', name=name)
+    return template('index.html').render(name=name)
 
 
 if __name__ == '__main__':

examples/templates/utemplate/hello_asgi.py

@@ -0,0 +1,17 @@
+from microdot.asgi import Microdot, Response
+from microdot.utemplate import template
+
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return template('index.html').render(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/utemplate/hello_wsgi.py

@@ -0,0 +1,17 @@
+from microdot.wsgi import Microdot, Response
+from microdot.utemplate import template
+
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return template('index.html').render(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/utemplate/streaming.py

@@ -0,0 +1,17 @@
+from microdot import Microdot, Response
+from microdot.utemplate import template
+
+app = Microdot()
+Response.default_content_type = 'text/html'
+
+
+@app.route('/', methods=['GET', 'POST'])
+async def index(req):
+    name = None
+    if req.method == 'POST':
+        name = req.form.get('name')
+    return template('index.html').generate(name=name)
+
+
+if __name__ == '__main__':
+    app.run()

examples/templates/utemplate/templates/index.html

@@ -3,6 +3,7 @@
 <html>
   <head>
     <title>Microdot + uTemplate example</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Microdot + uTemplate example</h1>

examples/tls/echo_async_tls.py

@@ -1,23 +0,0 @@
-import ssl
-from microdot_asyncio import Microdot, send_file
-from microdot_asyncio_websocket import with_websocket
-
-app = Microdot()
-
-
-@app.route('/')
-def index(request):
-    return send_file('index.html')
-
-
-@app.route('/echo')
-@with_websocket
-async def echo(request, ws):
-    while True:
-        data = await ws.receive()
-        await ws.send(data)
-
-
-sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
-sslctx.load_cert_chain('cert.pem', 'key.pem')
-app.run(port=4443, debug=True, ssl=sslctx)

examples/tls/echo_tls.py

@@ -1,24 +0,0 @@
-import sys
-from microdot import Microdot, send_file
-from microdot_websocket import with_websocket
-from microdot_ssl import create_ssl_context
-
-app = Microdot()
-
-
-@app.route('/')
-def index(request):
-    return send_file('index.html')
-
-
-@app.route('/echo')
-@with_websocket
-def echo(request, ws):
-    while True:
-        data = ws.receive()
-        ws.send(data)
-
-
-ext = 'der' if sys.implementation.name == 'micropython' else 'pem'
-sslctx = create_ssl_context('cert.' + ext, 'key.' + ext)
-app.run(port=4443, debug=True, ssl=sslctx)

examples/tls/hello.py

@@ -1,12 +1,13 @@
 import ssl
-from microdot_asyncio import Microdot
+from microdot import Microdot
 
 app = Microdot()
 
-htmldoc = '''<!DOCTYPE html>
+html = '''<!DOCTYPE html>
 <html>
     <head>
         <title>Microdot Example Page</title>
+        <meta charset="UTF-8">
     </head>
     <body>
         <div>
@@ -21,7 +22,7 @@ htmldoc = '''<!DOCTYPE html>
 
 @app.route('/')
 async def hello(request):
-    return htmldoc, 200, {'Content-Type': 'text/html'}
+    return html, 200, {'Content-Type': 'text/html'}
 
 
 @app.route('/shutdown')

examples/tls/hello_tls.py

@@ -1,36 +0,0 @@
-import sys
-from microdot import Microdot
-from microdot_ssl import create_ssl_context
-
-app = Microdot()
-
-htmldoc = '''<!DOCTYPE html>
-<html>
-    <head>
-        <title>Microdot Example Page</title>
-    </head>
-    <body>
-        <div>
-            <h1>Microdot Example Page</h1>
-            <p>Hello from Microdot!</p>
-            <p><a href="/shutdown">Click to shutdown the server</a></p>
-        </div>
-    </body>
-</html>
-'''
-
-
-@app.route('/')
-def hello(request):
-    return htmldoc, 200, {'Content-Type': 'text/html'}
-
-
-@app.route('/shutdown')
-def shutdown(request):
-    request.app.shutdown()
-    return 'The server is shutting down...'
-
-
-ext = 'der' if sys.implementation.name == 'micropython' else 'pem'
-sslctx = create_ssl_context('cert.' + ext, 'key.' + ext)
-app.run(port=4443, debug=True, ssl=sslctx)

examples/tls/index.html

@@ -1,35 +0,0 @@
-<!doctype html>
-<html>
-  <head>
-    <title>Microdot TLS WebSocket Demo</title>
-  </head>
-  <body>
-    <h1>Microdot TLS WebSocket Demo</h1>
-    <div id="log"></div>
-    <br>
-    <form id="form">
-      <label for="text">Input: </label>
-      <input type="text" id="text" autofocus>
-    </form>
-    <script>
-      const log = (text, color) => {
-        document.getElementById('log').innerHTML += `<span style="color: ${color}">${text}</span><br>`;
-      };
-
-      const socket = new WebSocket('wss://' + location.host + '/echo');
-      socket.addEventListener('message', ev => {
-        log('<<< ' + ev.data, 'blue');
-      });
-      socket.addEventListener('close', ev => {
-        log('<<< closed');
-      });
-      document.getElementById('form').onsubmit = ev => {
-        ev.preventDefault();
-        const textField = document.getElementById('text');
-        log('>>> ' + textField.value, 'red');
-        socket.send(textField.value);
-        textField.value = '';
-      };
-    </script>
-  </body>
-</html>

examples/uploads/index.html

@@ -2,6 +2,7 @@
 <html>
   <head>
     <title>Microdot Upload Example</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Microdot Upload Example</h1>

examples/uploads/uploads.py

@@ -5,12 +5,12 @@ Request.max_content_length = 1024 * 1024  # 1MB (change as needed)
 
 
 @app.get('/')
-def index(request):
+async def index(request):
     return send_file('index.html')
 
 
 @app.post('/upload')
-def upload(request):
+async def upload(request):
     # obtain the filename and size from request headers
     filename = request.headers['Content-Disposition'].split(
         'filename=')[1].strip('"')
@@ -22,7 +22,7 @@ def upload(request):
     # write the file to the files directory in 1K chunks
     with open('files/' + filename, 'wb') as f:
         while size > 0:
-            chunk = request.stream.read(min(size, 1024))
+            chunk = await request.stream.read(min(size, 1024))
             f.write(chunk)
             size -= len(chunk)
 

examples/uploads/uploads_async.py

@@ -1,34 +0,0 @@
-from microdot_asyncio import Microdot, send_file, Request
-
-app = Microdot()
-Request.max_content_length = 1024 * 1024  # 1MB (change as needed)
-
-
-@app.get('/')
-async def index(request):
-    return send_file('index.html')
-
-
-@app.post('/upload')
-async def upload(request):
-    # obtain the filename and size from request headers
-    filename = request.headers['Content-Disposition'].split(
-        'filename=')[1].strip('"')
-    size = int(request.headers['Content-Length'])
-
-    # sanitize the filename
-    filename = filename.replace('/', '_')
-
-    # write the file to the files directory in 1K chunks
-    with open('files/' + filename, 'wb') as f:
-        while size > 0:
-            chunk = await request.stream.read(min(size, 1024))
-            f.write(chunk)
-            size -= len(chunk)
-
-    print('Successfully saved file: ' + filename)
-    return ''
-
-
-if __name__ == '__main__':
-    app.run(debug=True)

examples/websocket/echo.py

@@ -1,20 +1,20 @@
 from microdot import Microdot, send_file
-from microdot_websocket import with_websocket
+from microdot.websocket import with_websocket
 
 app = Microdot()
 
 
 @app.route('/')
-def index(request):
+async def index(request):
     return send_file('index.html')
 
 
 @app.route('/echo')
 @with_websocket
-def echo(request, ws):
+async def echo(request, ws):
     while True:
-        data = ws.receive()
-        ws.send(data)
+        data = await ws.receive()
+        await ws.send(data)
 
 
 app.run()

examples/websocket/echo_asgi.py

@@ -1,11 +1,10 @@
-from microdot_asgi import Microdot, send_file
-from microdot_asgi_websocket import with_websocket
+from microdot.asgi import Microdot, send_file, with_websocket
 
 app = Microdot()
 
 
 @app.route('/')
-def index(request):
+async def index(request):
     return send_file('index.html')
 
 
@@ -15,3 +14,7 @@ async def echo(request, ws):
     while True:
         data = await ws.receive()
         await ws.send(data)
+
+
+if __name__ == '__main__':
+    app.run()

examples/websocket/echo_async.py

@@ -1,20 +0,0 @@
-from microdot_asyncio import Microdot, send_file
-from microdot_asyncio_websocket import with_websocket
-
-app = Microdot()
-
-
-@app.route('/')
-def index(request):
-    return send_file('index.html')
-
-
-@app.route('/echo')
-@with_websocket
-async def echo(request, ws):
-    while True:
-        data = await ws.receive()
-        await ws.send(data)
-
-
-app.run()

examples/websocket/echo_wsgi.py

@@ -1,17 +1,20 @@
-from microdot_wsgi import Microdot, send_file
-from microdot_websocket import with_websocket
+from microdot.wsgi import Microdot, send_file, with_websocket
 
 app = Microdot()
 
 
 @app.route('/')
-def index(request):
+async def index(request):
     return send_file('index.html')
 
 
 @app.route('/echo')
 @with_websocket
-def echo(request, ws):
+async def echo(request, ws):
     while True:
-        data = ws.receive()
-        ws.send(data)
+        data = await ws.receive()
+        await ws.send(data)
+
+
+if __name__ == '__main__':
+    app.run()

examples/websocket/index.html

@@ -2,6 +2,7 @@
 <html>
   <head>
     <title>Microdot WebSocket Demo</title>
+    <meta charset="UTF-8">
   </head>
   <body>
     <h1>Microdot WebSocket Demo</h1>

libs/common/utemplate/README.md

@@ -1,8 +1,6 @@
 utemplate
 =========
 
-*Release: 1.4.1, Source: https://github.com/pfalcon/utemplate*
-
 `utemplate` is a lightweight and memory-efficient template engine for
 Python, primarily designed for use with Pycopy, a lightweight Python
 implementation (https://github.com/pfalcon/pycopy). It is also fully

libs/micropython/asyncio/__init__.py

@@ -1,4 +1,4 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019 Damien P. George
 
 from .core import *
@@ -18,6 +18,7 @@ _attrs = {
     "StreamWriter": "stream",
 }
 
+
 # Lazy loader, effectively does:
 #   global attr
 #   from .mod import attr

libs/micropython/asyncio/core.py

@@ -1,4 +1,4 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019 Damien P. George
 
 from time import ticks_ms as ticks, ticks_diff, ticks_add
@@ -6,7 +6,7 @@ import sys, select
 
 # Import TaskQueue and Task, preferring built-in C code over Python code
 try:
-    from _uasyncio import TaskQueue, Task
+    from _asyncio import TaskQueue, Task
 except:
     from .task import TaskQueue, Task
 
@@ -30,6 +30,7 @@ _exc_context = {"message": "Task exception wasn't retrieved", "exception": None,
 ################################################################################
 # Sleep functions
 
+
 # "Yield" once, then raise StopIteration
 class SingletonGenerator:
     def __init__(self):
@@ -132,6 +133,7 @@ class IOQueue:
 ################################################################################
 # Main run loop
 
+
 # Ensure the awaitable is a task
 def _promote_to_task(aw):
     return aw if isinstance(aw, Task) else create_task(aw)
@@ -270,9 +272,9 @@ class Loop:
         return Loop._exc_handler
 
     def default_exception_handler(loop, context):
-        print(context["message"])
-        print("future:", context["future"], "coro=", context["future"].coro)
-        sys.print_exception(context["exception"])
+        print(context["message"], file=sys.stderr)
+        print("future:", context["future"], "coro=", context["future"].coro, file=sys.stderr)
+        sys.print_exception(context["exception"], sys.stderr)
 
     def call_exception_handler(context):
         (Loop._exc_handler or Loop.default_exception_handler)(Loop, context)

libs/micropython/asyncio/event.py

@@ -1,8 +1,9 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019-2020 Damien P. George
 
 from . import core
 
+
 # Event class for primitive events that can be waited on, set, and cleared
 class Event:
     def __init__(self):
@@ -23,7 +24,8 @@ class Event:
     def clear(self):
         self.state = False
 
-    async def wait(self):
+    # async
+    def wait(self):
         if not self.state:
             # Event not set, put the calling task on the event's waiting queue
             self.waiting.push(core.cur_task)
@@ -38,16 +40,16 @@ class Event:
 # that asyncio will poll until a flag is set.
 # Note: Unlike Event, this is self-clearing after a wait().
 try:
-    import uio
+    import io
 
-    class ThreadSafeFlag(uio.IOBase):
+    class ThreadSafeFlag(io.IOBase):
         def __init__(self):
             self.state = 0
 
         def ioctl(self, req, flags):
             if req == 3:  # MP_STREAM_POLL
                 return self.state * flags
-            return None
+            return -1  # Other requests are unsupported
 
         def set(self):
             self.state = 1

libs/micropython/asyncio/funcs.py

@@ -1,10 +1,10 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019-2022 Damien P. George
 
 from . import core
 
 
-def _run(waiter, aw):
+async def _run(waiter, aw):
     try:
         result = await aw
         status = True
@@ -61,7 +61,8 @@ class _Remove:
         pass
 
 
-async def gather(*aws, return_exceptions=False):
+# async
+def gather(*aws, return_exceptions=False):
     if not aws:
         return []
 
@@ -122,7 +123,7 @@ async def gather(*aws, return_exceptions=False):
 
     # Either this gather was cancelled, or one of the sub-tasks raised an exception with
     # return_exceptions==False, so reraise the exception here.
-    if state is not 0:
+    if state:
         raise state
 
     # Return the list of return values of each sub-task.

libs/micropython/asyncio/lock.py

@@ -1,8 +1,9 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019-2020 Damien P. George
 
 from . import core
 
+
 # Lock class for primitive mutex capability
 class Lock:
     def __init__(self):
@@ -28,7 +29,8 @@ class Lock:
             # No Task waiting so unlock
             self.state = 0
 
-    async def acquire(self):
+    # async
+    def acquire(self):
         if self.state != 0:
             # Lock unavailable, put the calling Task on the waiting queue
             self.waiting.push(core.cur_task)

libs/micropython/asyncio/manifest.py

@@ -1,7 +1,7 @@
 # This list of package files doesn't include task.py because that's provided
 # by the C module.
 package(
-    "uasyncio",
+    "asyncio",
     (
         "__init__.py",
         "core.py",
@@ -13,3 +13,6 @@ package(
     base_path="..",
     opt=3,
 )
+
+# Backwards-compatible uasyncio module.
+module("uasyncio.py", opt=3)

libs/micropython/asyncio/stream.py

@@ -1,4 +1,4 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019-2020 Damien P. George
 
 from . import core
@@ -26,7 +26,8 @@ class Stream:
         # TODO yield?
         self.s.close()
 
-    async def read(self, n=-1):
+    # async
+    def read(self, n=-1):
         r = b""
         while True:
             yield core._io_queue.queue_read(self.s)
@@ -38,11 +39,13 @@ class Stream:
                     return r
                 r += r2
 
-    async def readinto(self, buf):
+    # async
+    def readinto(self, buf):
         yield core._io_queue.queue_read(self.s)
         return self.s.readinto(buf)
 
-    async def readexactly(self, n):
+    # async
+    def readexactly(self, n):
         r = b""
         while n:
             yield core._io_queue.queue_read(self.s)
@@ -54,7 +57,8 @@ class Stream:
                 n -= len(r2)
         return r
 
-    async def readline(self):
+    # async
+    def readline(self):
         l = b""
         while True:
             yield core._io_queue.queue_read(self.s)
@@ -73,10 +77,11 @@ class Stream:
                 buf = buf[ret:]
         self.out_buf += buf
 
-    async def drain(self):
+    # async
+    def drain(self):
         if not self.out_buf:
             # Drain must always yield, so a tight loop of write+drain can't block the scheduler.
-            return await core.sleep_ms(0)
+            return (yield from core.sleep_ms(0))
         mv = memoryview(self.out_buf)
         off = 0
         while off < len(mv):
@@ -93,9 +98,11 @@ StreamWriter = Stream
 
 
 # Create a TCP stream connection to a remote host
-async def open_connection(host, port):
-    from uerrno import EINPROGRESS
-    import usocket as socket
+#
+# async
+def open_connection(host, port):
+    from errno import EINPROGRESS
+    import socket
 
     ai = socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM)[0]  # TODO this is blocking!
     s = socket.socket(ai[0], ai[1], ai[2])
@@ -120,20 +127,30 @@ class Server:
         await self.wait_closed()
 
     def close(self):
+        # Note: the _serve task must have already started by now due to the sleep
+        # in start_server, so `state` won't be clobbered at the start of _serve.
+        self.state = True
         self.task.cancel()
 
     async def wait_closed(self):
         await self.task
 
     async def _serve(self, s, cb):
+        self.state = False
         # Accept incoming connections
         while True:
             try:
                 yield core._io_queue.queue_read(s)
-            except core.CancelledError:
-                # Shutdown server
+            except core.CancelledError as er:
+                # The server task was cancelled, shutdown server and close socket.
                 s.close()
+                if self.state:
+                    # If the server was explicitly closed, ignore the cancellation.
                     return
+                else:
+                    # Otherwise e.g. the parent task was cancelled, propagate
+                    # cancellation.
+                    raise er
             try:
                 s2, addr = s.accept()
             except:
@@ -147,7 +164,7 @@ class Server:
 # Helper function to start a TCP stream server, running as a new task
 # TODO could use an accept-callback on socket read activity instead of creating a task
 async def start_server(cb, host, port, backlog=5):
-    import usocket as socket
+    import socket
 
     # Create and bind server socket.
     host = socket.getaddrinfo(host, port)[0]  # TODO this is blocking!
@@ -160,6 +177,16 @@ async def start_server(cb, host, port, backlog=5):
     # Create and return server object and task.
     srv = Server()
     srv.task = core.create_task(srv._serve(s, cb))
+    try:
+        # Ensure that the _serve task has been scheduled so that it gets to
+        # handle cancellation.
+        await core.sleep_ms(0)
+    except core.CancelledError as er:
+        # If the parent task is cancelled during this first sleep, then
+        # we will leak the task and it will sit waiting for the socket, so
+        # cancel it.
+        srv.task.cancel()
+        raise er
     return srv
 
 

libs/micropython/asyncio/task.py

@@ -1,4 +1,4 @@
-# MicroPython uasyncio module
+# MicroPython asyncio module
 # MIT license; Copyright (c) 2019-2020 Damien P. George
 
 # This file contains the core TaskQueue based on a pairing heap, and the core Task class.

libs/micropython/asyncio/uasyncio.py

@@ -0,0 +1,8 @@
+# This module just allows `import uasyncio` to work. It lazy-loads from
+# `asyncio` without duplicating its globals dict.
+
+
+def __getattr__(attr):
+    import asyncio
+
+    return getattr(asyncio, attr)

libs/micropython/ffilib.py

@@ -1,4 +1,5 @@
 import sys
+
 try:
     import ffi
 except ImportError:
@@ -6,6 +7,7 @@ except ImportError:
 
 _cache = {}
 
+
 def open(name, maxver=10, extra=()):
     if not ffi:
         return None
@@ -13,16 +15,18 @@ def open(name, maxver=10, extra=()):
         return _cache[name]
     except KeyError:
         pass
+
     def libs():
         if sys.platform == "linux":
-            yield '%s.so' % name
+            yield "%s.so" % name
             for i in range(maxver, -1, -1):
-                yield '%s.so.%u' % (name, i)
+                yield "%s.so.%u" % (name, i)
         else:
-            for ext in ('dylib', 'dll'):
-                yield '%s.%s' % (name, ext)
+            for ext in ("dylib", "dll"):
+                yield "%s.%s" % (name, ext)
         for n in extra:
             yield n
+
     err = None
     for n in libs():
         try:
@@ -33,9 +37,11 @@ def open(name, maxver=10, extra=()):
             err = e
     raise err
 
+
 def libc():
     return open("libc", 6)
 
+
 # Find out bitness of the platform, even if long ints are not supported
 # TODO: All bitness differences should be removed from micropython-lib, and
 # this snippet too.

libs/micropython/time.py

@@ -1,76 +1,79 @@
 from utime import *
-from ucollections import namedtuple
-import ustruct
-import uctypes
-import ffi
-import ffilib
-import array
+from micropython import const
 
-libc = ffilib.libc()
+_TS_YEAR = const(0)
+_TS_MON = const(1)
+_TS_MDAY = const(2)
+_TS_HOUR = const(3)
+_TS_MIN = const(4)
+_TS_SEC = const(5)
+_TS_WDAY = const(6)
+_TS_YDAY = const(7)
+_TS_ISDST = const(8)
 
-# struct tm *gmtime(const time_t *timep);
-# struct tm *localtime(const time_t *timep);
-# size_t strftime(char *s, size_t max, const char *format,
-#                       const struct tm *tm);
-gmtime_ = libc.func("P", "gmtime", "P")
-localtime_ = libc.func("P", "localtime", "P")
-strftime_ = libc.func("i", "strftime", "sisP")
-mktime_ = libc.func("i", "mktime", "P")
-
-_struct_time = namedtuple("struct_time",
-    ["tm_year", "tm_mon", "tm_mday", "tm_hour", "tm_min", "tm_sec", "tm_wday", "tm_yday", "tm_isdst"])
-
-def _tuple_to_c_tm(t):
-    return ustruct.pack("@iiiiiiiii", t[5], t[4], t[3], t[2], t[1] - 1, t[0] - 1900, (t[6] + 1) % 7, t[7] - 1, t[8])
+_WDAY = const(("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"))
+_MDAY = const(
+    (
+        "January",
+        "February",
+        "March",
+        "April",
+        "May",
+        "June",
+        "July",
+        "August",
+        "September",
+        "October",
+        "November",
+        "December",
+    )
+)
 
 
-def _c_tm_to_tuple(tm):
-    t = ustruct.unpack("@iiiiiiiii", tm)
-    return _struct_time(t[5] + 1900, t[4] + 1, t[3], t[2], t[1], t[0], (t[6] - 1) % 7, t[7] + 1, t[8])
+def strftime(datefmt, ts):
+    from io import StringIO
 
-def struct_time(tm):
-    return _struct_time(*tm)
-
-
-def strftime(format, t=None):
-    if t is None:
-        t = localtime()
-
-    buf = bytearray(32)
-    l = strftime_(buf, 32, format, _tuple_to_c_tm(t))
-    return str(buf[:l], "utf-8")
-
-
-def localtime(t=None):
-    if t is None:
-        t = time()
-
-    t = int(t)
-    a = ustruct.pack('l', t)
-    tm_p = localtime_(a)
-    return _c_tm_to_tuple(uctypes.bytearray_at(tm_p, 36))
-
-
-def gmtime(t=None):
-    if t is None:
-        t = time()
-
-    t = int(t)
-    a = ustruct.pack('l', t)
-    tm_p = gmtime_(a)
-    return _c_tm_to_tuple(uctypes.bytearray_at(tm_p, 36))
-
-
-def mktime(tt):
-    return mktime_(_tuple_to_c_tm(tt))
-
-
-def perf_counter():
-    return time()
-
-def process_time():
-    return clock()
-
-
-daylight = 0
-timezone = 0
+    fmtsp = False
+    ftime = StringIO()
+    for k in datefmt:
+        if fmtsp:
+            if k == "a":
+                ftime.write(_WDAY[ts[_TS_WDAY]][0:3])
+            elif k == "A":
+                ftime.write(_WDAY[ts[_TS_WDAY]])
+            elif k == "b":
+                ftime.write(_MDAY[ts[_TS_MON] - 1][0:3])
+            elif k == "B":
+                ftime.write(_MDAY[ts[_TS_MON] - 1])
+            elif k == "d":
+                ftime.write("%02d" % ts[_TS_MDAY])
+            elif k == "H":
+                ftime.write("%02d" % ts[_TS_HOUR])
+            elif k == "I":
+                ftime.write("%02d" % (ts[_TS_HOUR] % 12))
+            elif k == "j":
+                ftime.write("%03d" % ts[_TS_YDAY])
+            elif k == "m":
+                ftime.write("%02d" % ts[_TS_MON])
+            elif k == "M":
+                ftime.write("%02d" % ts[_TS_MIN])
+            elif k == "P":
+                ftime.write("AM" if ts[_TS_HOUR] < 12 else "PM")
+            elif k == "S":
+                ftime.write("%02d" % ts[_TS_SEC])
+            elif k == "w":
+                ftime.write(str(ts[_TS_WDAY]))
+            elif k == "y":
+                ftime.write("%02d" % (ts[_TS_YEAR] % 100))
+            elif k == "Y":
+                ftime.write(str(ts[_TS_YEAR]))
+            else:
+                ftime.write(k)
+            fmtsp = False
+        elif k == "%":
+            fmtsp = True
+        else:
+            ftime.write(k)
+    val = ftime.getvalue()
+    ftime.close()
+    return val

libs/micropython/unittest.py

@@ -300,6 +300,7 @@ class TestResult:
         return self.errorsNum == 0 and self.failuresNum == 0
 
     def printErrors(self):
+        if self.errors or self.failures:
             print()
             self.printErrorList(self.errors)
             self.printErrorList(self.failures)

libs/refresh.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+# this script downloads updated versions of all the MicroPython libraries
+
+cd micropython
+curl https://codeload.github.com/micropython/micropython/tar.gz/master | tar -xz --strip=2 micropython-master/extmod/asyncio
+curl https://raw.githubusercontent.com/micropython/micropython-lib/master/python-stdlib/datetime/datetime.py > datetime.py
+curl https://raw.githubusercontent.com/micropython/micropython-lib/d8e163bb5f3ef45e71e145c27bc4f207beaad70f/unix-ffi/ffilib/ffilib.py > ffilib.py
+curl https://raw.githubusercontent.com/micropython/micropython-lib/master/python-stdlib/hmac/hmac.py > hmac.py
+curl https://raw.githubusercontent.com/micropython/micropython-lib/master/python-stdlib/time/time.py > time.py
+curl https://raw.githubusercontent.com/micropython/micropython-lib/master/python-stdlib/unittest/unittest/__init__.py > unittest.py
+cd ../common
+curl https://raw.githubusercontent.com/pfalcon/utemplate/master/README.md > utemplate/README.md
+curl https://codeload.github.com/pfalcon/utemplate/tar.gz/master | tar -xz --strip=1 utemplate-master/utemplate
+cd ..

pyproject.toml

@@ -1,6 +1,48 @@
+[project]
+name = "microdot"
+version = "2.0.0"
+authors = [
+    { name = "Miguel Grinberg", email = "miguel.grinberg@gmail.com" },
+]
+description = "The impossibly small web framework for MicroPython"
+classifiers = [
+    "Environment :: Web Environment",
+    "Intended Audience :: Developers",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: Implementation :: MicroPython",
+    "License :: OSI Approved :: MIT License",
+    "Operating System :: OS Independent",
+]
+requires-python = ">=3.8"
+
+[project.readme]
+file = "README.md"
+content-type = "text/markdown"
+
+[project.urls]
+Homepage = "https://github.com/miguelgrinberg/microdot"
+"Bug Tracker" = "https://github.com/miguelgrinberg/microdot/issues"
+
+[project.optional-dependencies]
+docs = [
+    "sphinx",
+]
+
+[tool.setuptools]
+zip-safe = false
+include-package-data = true
+
+[tool.setuptools.package-dir]
+"" = "src"
+
+[tool.setuptools.packages.find]
+where = [
+    "src",
+]
+namespaces = false
+
 [build-system]
 requires = [
-    "setuptools>=42",
-    "wheel"
+    "setuptools>=61.2",
 ]
 build-backend = "setuptools.build_meta"

run_tests.py

@@ -6,4 +6,5 @@ sys.path.insert(3, 'libs/micropython')
 
 import unittest
 
-unittest.main('tests')
+if not unittest.main('tests').wasSuccessful():
+    sys.exit(1)

setup.cfg

@@ -1,38 +0,0 @@
-[metadata]
-name = microdot
-version = 1.2.4
-author = Miguel Grinberg
-author_email = miguel.grinberg@gmail.com
-description = The impossibly small web framework for MicroPython
-long_description = file: README.md
-long_description_content_type = text/markdown
-url = https://github.com/miguelgrinberg/microdot
-project_urls =
-    Bug Tracker = https://github.com/miguelgrinberg/microdot/issues
-classifiers =
-    Environment :: Web Environment
-    Intended Audience :: Developers
-    Programming Language :: Python :: 3
-    Programming Language :: Python :: Implementation :: MicroPython
-    License :: OSI Approved :: MIT License
-    Operating System :: OS Independent
-
-[options]
-zip_safe = False
-include_package_data = True
-package_dir =
-    = src
-py_modules =
-    microdot
-    microdot_asyncio
-    microdot_utemplate
-    microdot_jinja
-    microdot_session
-    microdot_websocket
-    microdot_websocket_alt
-    microdot_asyncio_websocket
-    microdot_test_client
-    microdot_asyncio_test_client
-    microdot_wsgi
-    microdot_asgi
-    microdot_asgi_websocket

setup.py

@@ -1,3 +0,0 @@
-import setuptools
-
-setuptools.setup()

src/microdot/__init__.py

@@ -0,0 +1,2 @@
+from microdot.microdot import Microdot, Request, Response, abort, redirect, \
+    send_file  # noqa: F401

src/microdot/asgi.py

@@ -1,10 +1,10 @@
 import asyncio
 import os
 import signal
-from microdot_asyncio import *  # noqa: F401, F403
-from microdot_asyncio import Microdot as BaseMicrodot
-from microdot_asyncio import Request
-from microdot import NoCaseDict
+from microdot import *  # noqa: F401, F403
+from microdot.microdot import Microdot as BaseMicrodot, Request, Response, \
+    NoCaseDict, abort
+from microdot.websocket import WebSocket as BaseWebSocket, websocket_wrapper
 
 
 class _BodyStream:  # pragma: no cover
@@ -21,7 +21,7 @@ class _BodyStream:  # pragma: no cover
 
     async def read(self, n=-1):
         while self.more and len(self.data) < n:
-            self.read_more()
+            await self.read_more()
         if len(self.data) < n:
             data = self.data
             self.data = b''
@@ -32,14 +32,14 @@ class _BodyStream:  # pragma: no cover
         return data
 
     async def readline(self):
-        return self.readuntil()
+        return await self.readuntil()
 
     async def readexactly(self, n):
-        return self.read(n)
+        return await self.read(n)
 
     async def readuntil(self, separator=b'\n'):
         if self.more and separator not in self.data:
-            self.read_more()
+            await self.read_more()
         data, self.data = self.data.split(separator, 1)
         return data
 
@@ -59,8 +59,9 @@ class Microdot(BaseMicrodot):
         headers = NoCaseDict()
         content_length = 0
         for key, value in scope.get('headers', []):
-            headers[key] = value
-            if key.lower() == 'content-length':
+            key = key.decode().title()
+            headers[key] = value.decode()
+            if key == 'Content-Length':
                 content_length = int(value)
 
         if content_length and content_length <= Request.max_body_length:
@@ -112,25 +113,31 @@ class Microdot(BaseMicrodot):
 
             while True:
                 event = await receive()
-                if event['type'] == 'http.disconnect':  # pragma: no branch
+                if event is None or \
+                        event['type'] == 'http.disconnect':  # pragma: no cover
                     cancelled = True
                     break
 
-        asyncio.ensure_future(cancel_monitor())
+        monitor_task = asyncio.ensure_future(cancel_monitor())
 
         body_iter = res.body_iter().__aiter__()
+        res_body = b''
         try:
-            body = await body_iter.__anext__()
+            res_body = await body_iter.__anext__()
             while not cancelled:  # pragma: no branch
                 next_body = await body_iter.__anext__()
                 await send({'type': 'http.response.body',
-                            'body': body,
+                            'body': res_body,
                             'more_body': True})
-                body = next_body
+                res_body = next_body
         except StopAsyncIteration:
             await send({'type': 'http.response.body',
-                        'body': body,
+                        'body': res_body,
                         'more_body': False})
+        if hasattr(body_iter, 'aclose'):  # pragma: no branch
+            await body_iter.aclose()
+        cancelled = True
+        await monitor_task
 
     async def __call__(self, scope, receive, send):
         return await self.asgi_app(scope, receive, send)
@@ -150,3 +157,79 @@ class Microdot(BaseMicrodot):
         """
         self.embedded_server = True
         super().run(host=host, port=port, debug=debug, **options)
+
+
+class WebSocket(BaseWebSocket):  # pragma: no cover
+    async def handshake(self):
+        connect = await self.request.sock[0]()
+        if connect['type'] != 'websocket.connect':
+            abort(400)
+        await self.request.sock[1]({'type': 'websocket.accept'})
+
+    async def receive(self):
+        message = await self.request.sock[0]()
+        if message['type'] == 'websocket.disconnect':
+            raise OSError(32, 'Websocket connection closed')
+        elif message['type'] != 'websocket.receive':
+            raise OSError(32, 'Websocket message type not supported')
+        return message.get('bytes', message.get('text'))
+
+    async def send(self, data):
+        if isinstance(data, str):
+            await self.request.sock[1](
+                {'type': 'websocket.send', 'text': data})
+        else:
+            await self.request.sock[1](
+                {'type': 'websocket.send', 'bytes': data})
+
+    async def close(self):
+        if not self.closed:
+            self.closed = True
+            try:
+                await self.request.sock[1]({'type': 'websocket.close'})
+            except:  # noqa E722
+                pass
+
+
+async def websocket_upgrade(request):  # pragma: no cover
+    """Upgrade a request handler to a websocket connection.
+
+    This function can be called directly inside a route function to process a
+    WebSocket upgrade handshake, for example after the user's credentials are
+    verified. The function returns the websocket object::
+
+        @app.route('/echo')
+        async def echo(request):
+            if not (await authenticate_user(request)):
+                abort(401)
+            ws = await websocket_upgrade(request)
+            while True:
+                message = await ws.receive()
+                await ws.send(message)
+    """
+    ws = WebSocket(request) if not request.app.embedded_server else \
+        BaseWebSocket(request)
+    await ws.handshake()
+
+    @request.after_request
+    async def after_request(request, response):
+        return Response.already_handled
+
+    return ws
+
+
+def with_websocket(f):  # pragma: no cover
+    """Decorator to make a route a WebSocket endpoint.
+
+    This decorator is used to define a route that accepts websocket
+    connections. The route then receives a websocket object as a second
+    argument that it can use to send and receive messages::
+
+        @app.route('/echo')
+        @with_websocket
+        async def echo(request, ws):
+            while True:
+                message = await ws.receive()
+                await ws.send(message)
+    """
+    return websocket_wrapper(f, websocket_upgrade)

src/microdot/cors.py

@@ -0,0 +1,110 @@
+class CORS:
+    """Add CORS headers to HTTP responses.
+
+    :param app: The application to add CORS headers to.
+    :param allowed_origins: A list of origins that are allowed to make
+                            cross-site requests. If set to '*', all origins are
+                            allowed.
+    :param allow_credentials: If set to True, the
+                              ``Access-Control-Allow-Credentials`` header will
+                              be set to ``true`` to indicate to the browser
+                              that it can expose cookies and authentication
+                              headers.
+    :param allowed_methods: A list of methods that are allowed to be used when
+                            making cross-site requests. If not set, all methods
+                            are allowed.
+    :param expose_headers: A list of headers that the browser is allowed to
+                           exposed.
+    :param allowed_headers: A list of headers that are allowed to be used when
+                            making cross-site requests. If not set, all headers
+                            are allowed.
+    :param max_age: The maximum amount of time in seconds that the browser
+                    should cache the results of a preflight request.
+    :param handle_cors: If set to False, CORS headers will not be added to
+                        responses. This can be useful if you want to add CORS
+                        headers manually.
+    """
+    def __init__(self, app=None, allowed_origins=None, allow_credentials=False,
+                 allowed_methods=None, expose_headers=None,
+                 allowed_headers=None, max_age=None, handle_cors=True):
+        self.allowed_origins = allowed_origins
+        self.allow_credentials = allow_credentials
+        self.allowed_methods = allowed_methods
+        self.expose_headers = expose_headers
+        self.allowed_headers = None if allowed_headers is None \
+            else [h.lower() for h in allowed_headers]
+        self.max_age = max_age
+        if app is not None:
+            self.initialize(app, handle_cors=handle_cors)
+
+    def initialize(self, app, handle_cors=True):
+        """Initialize the CORS object for the given application.
+
+        :param app: The application to add CORS headers to.
+        :param handle_cors: If set to False, CORS headers will not be added to
+                            responses. This can be useful if you want to add
+                            CORS headers manually.
+        """
+        self.default_options_handler = app.options_handler
+        if handle_cors:
+            app.options_handler = self.options_handler
+            app.after_request(self.after_request)
+            app.after_error_request(self.after_request)
+
+    def options_handler(self, request):
+        headers = self.default_options_handler(request)
+        headers.update(self.get_cors_headers(request))
+        return headers
+
+    def get_cors_headers(self, request):
+        """Return a dictionary of CORS headers to add to a given request.
+
+        :param request: The request to add CORS headers to.
+        """
+        cors_headers = {}
+        origin = request.headers.get('Origin')
+        if self.allowed_origins == '*':
+            cors_headers['Access-Control-Allow-Origin'] = origin or '*'
+            if origin:
+                cors_headers['Vary'] = 'Origin'
+        elif origin in (self.allowed_origins or []):
+            cors_headers['Access-Control-Allow-Origin'] = origin
+            cors_headers['Vary'] = 'Origin'
+        if self.allow_credentials and \
+                'Access-Control-Allow-Origin' in cors_headers:
+            cors_headers['Access-Control-Allow-Credentials'] = 'true'
+        if self.expose_headers:
+            cors_headers['Access-Control-Expose-Headers'] = \
+                ', '.join(self.expose_headers)
+
+        if request.method == 'OPTIONS':
+            # handle preflight request
+            if self.max_age:
+                cors_headers['Access-Control-Max-Age'] = str(self.max_age)
+
+            method = request.headers.get('Access-Control-Request-Method')
+            if method:
+                method = method.upper()
+                if self.allowed_methods is None or \
+                        method in self.allowed_methods:
+                    cors_headers['Access-Control-Allow-Methods'] = method
+
+            headers = request.headers.get('Access-Control-Request-Headers')
+            if headers:
+                if self.allowed_headers is None:
+                    cors_headers['Access-Control-Allow-Headers'] = headers
+                else:
+                    headers = [h.strip() for h in headers.split(',')]
+                    headers = [h for h in headers
+                               if h.lower() in self.allowed_headers]
+                    cors_headers['Access-Control-Allow-Headers'] = \
+                        ', '.join(headers)
+
+        return cors_headers
+
+    def after_request(self, request, response):
+        saved_vary = response.headers.get('Vary')
+        response.headers.update(self.get_cors_headers(request))
+        if saved_vary and saved_vary != response.headers.get('Vary'):
+            response.headers['Vary'] = (
+                saved_vary + ', ' + response.headers['Vary'])

src/microdot/jinja.py

@@ -0,0 +1,58 @@
+from jinja2 import Environment, FileSystemLoader, select_autoescape
+
+_jinja_env = None
+
+
+def init_templates(template_dir='templates', enable_async=False, **kwargs):
+    """Initialize the templating subsystem.
+
+    :param template_dir: the directory where templates are stored. This
+                         argument is optional. The default is to load templates
+                         from a *templates* subdirectory.
+    :param enable_async: set to ``True`` to enable the async rendering engine
+                         in Jinja, and the ``render_async()`` and
+                         ``generate_async()`` methods.
+    :param kwargs: any additional options to be passed to Jinja's
+                   ``Environment`` class.
+    """
+    global _jinja_env
+    _jinja_env = Environment(
+        loader=FileSystemLoader(template_dir),
+        autoescape=select_autoescape(),
+        enable_async=enable_async,
+        **kwargs
+    )
+
+
+class Template:
+    """A template object.
+
+    :param template: The filename of the template to render, relative to the
+                     configured template directory.
+    """
+    def __init__(self, template):
+        if _jinja_env is None:  # pragma: no cover
+            init_templates()
+        #: The name of the template
+        self.name = template
+        self.template = _jinja_env.get_template(template)
+
+    def generate(self, *args, **kwargs):
+        """Return a generator that renders the template in chunks, with the
+        given arguments."""
+        return self.template.generate(*args, **kwargs)
+
+    def render(self, *args, **kwargs):
+        """Render the template with the given arguments and return it as a
+        string."""
+        return self.template.render(*args, **kwargs)
+
+    def generate_async(self, *args, **kwargs):
+        """Return an asynchronous generator that renders the template in
+        chunks, using the given arguments."""
+        return self.template.generate_async(*args, **kwargs)
+
+    async def render_async(self, *args, **kwargs):
+        """Render the template with the given arguments asynchronously and
+        return it as a string."""
+        return await self.template.render_async(*args, **kwargs)

src/microdot/microdot.py

@@ -3,9 +3,43 @@ microdot
 --------
 
 The ``microdot`` module defines a few classes that help implement HTTP-based
-servers for MicroPython and standard Python, with multithreading support for
-Python interpreters that support it.
+servers for MicroPython and standard Python.
 """
+import asyncio
+import io
+import json
+import re
+import time
+
+try:
+    from inspect import iscoroutinefunction, iscoroutine
+
+    async def invoke_handler(handler, *args, **kwargs):
+        """Invoke a handler and return the result.
+
+        This method runs sync handlers in a thread pool executor.
+        """
+        if iscoroutinefunction(handler):
+            ret = await handler(*args, **kwargs)
+        else:
+            ret = await asyncio.get_running_loop().run_in_executor(
+                None, handler, *args, **kwargs)
+        return ret
+except ImportError:  # pragma: no cover
+    def iscoroutine(coro):
+        return hasattr(coro, 'send') and hasattr(coro, 'throw')
+
+    async def invoke_handler(handler, *args, **kwargs):
+        """Invoke a handler and return the result.
+
+        This method runs sync handlers in the asyncio thread, which can
+        potentially cause blocking and performance issues.
+        """
+        ret = handler(*args, **kwargs)
+        if iscoroutine(ret):
+            ret = await ret
+        return ret
+
 try:
     from sys import print_exception
 except ImportError:  # pragma: no cover
@@ -13,45 +47,6 @@ except ImportError:  # pragma: no cover
 
     def print_exception(exc):
         traceback.print_exc()
-try:
-    import uerrno as errno
-except ImportError:
-    import errno
-
-concurrency_mode = 'threaded'
-
-try:  # pragma: no cover
-    import threading
-
-    def create_thread(f, *args, **kwargs):
-        # use the threading module
-        threading.Thread(target=f, args=args, kwargs=kwargs).start()
-except ImportError:  # pragma: no cover
-    def create_thread(f, *args, **kwargs):
-        # no threads available, call function synchronously
-        f(*args, **kwargs)
-
-    concurrency_mode = 'sync'
-
-try:
-    import ujson as json
-except ImportError:
-    import json
-
-try:
-    import ure as re
-except ImportError:
-    import re
-
-socket_timeout_error = OSError
-try:
-    import usocket as socket
-except ImportError:
-    try:
-        import socket
-        socket_timeout_error = socket.timeout
-    except ImportError:  # pragma: no cover
-        socket = None
 
 MUTED_SOCKET_ERRORS = [
     32,  # Broken pipe
@@ -146,6 +141,10 @@ class NoCaseDict(dict):
         kl = key.lower()
         return super().get(self.keymap.get(kl, kl), default)
 
+    def update(self, other_dict):
+        for key, value in other_dict.items():
+            self[key] = value
+
 
 def mro(cls):  # pragma: no cover
     """Return the method resolution order of a class.
@@ -271,7 +270,31 @@ class MultiDict(dict):
         return values
 
 
-class Request():
+class AsyncBytesIO:
+    """An async wrapper for BytesIO."""
+    def __init__(self, data):
+        self.stream = io.BytesIO(data)
+
+    async def read(self, n=-1):
+        return self.stream.read(n)
+
+    async def readline(self):  # pragma: no cover
+        return self.stream.readline()
+
+    async def readexactly(self, n):  # pragma: no cover
+        return self.stream.read(n)
+
+    async def readuntil(self, separator=b'\n'):  # pragma: no cover
+        return self.stream.readuntil(separator=separator)
+
+    async def awrite(self, data):  # pragma: no cover
+        return self.stream.write(data)
+
+    async def aclose(self):  # pragma: no cover
+        pass
+
+
+class Request:
     """An HTTP request."""
     #: Specify the maximum payload size that is accepted. Requests with larger
     #: payloads will be rejected with a 413 status code. Applications can
@@ -302,11 +325,6 @@ class Request():
     #:    Request.max_readline = 16 * 1024  # 16KB lines allowed
     max_readline = 2 * 1024
 
-    #: Specify a suggested read timeout to use when reading the request. Set to
-    #: 0 to disable the use of a timeout. This timeout should be considered a
-    #: suggestion only, as some platforms may not support it.
-    socket_read_timeout = 0.1
-
     class G:
         pass
 
@@ -356,82 +374,84 @@ class Request():
         self._body = body
         self.body_used = False
         self._stream = stream
-        self.stream_used = False
         self.sock = sock
         self._json = None
         self._form = None
         self.after_request_handlers = []
 
     @staticmethod
-    def create(app, client_stream, client_addr, client_sock=None):
+    async def create(app, client_reader, client_writer, client_addr):
         """Create a request object.
 
-
         :param app: The Microdot application instance.
-        :param client_stream: An input stream from where the request data can
+        :param client_reader: An input stream from where the request data can
                               be read.
+        :param client_writer: An output stream where the response data can be
+                              written.
         :param client_addr: The address of the client, as a tuple.
-        :param client_sock: The low-level socket associated with the request.
 
-        This method returns a newly created ``Request`` object.
+        This method is a coroutine. It returns a newly created ``Request``
+        object.
         """
         # request line
-        line = Request._safe_readline(client_stream).strip().decode()
-        if not line:
+        line = (await Request._safe_readline(client_reader)).strip().decode()
+        if not line:  # pragma: no cover
             return None
         method, url, http_version = line.split()
         http_version = http_version.split('/', 1)[1]
 
         # headers
         headers = NoCaseDict()
+        content_length = 0
         while True:
-            line = Request._safe_readline(client_stream).strip().decode()
+            line = (await Request._safe_readline(
+                client_reader)).strip().decode()
             if line == '':
                 break
             header, value = line.split(':', 1)
             value = value.strip()
             headers[header] = value
+            if header.lower() == 'content-length':
+                content_length = int(value)
+
+        # body
+        body = b''
+        if content_length and content_length <= Request.max_body_length:
+            body = await client_reader.readexactly(content_length)
+            stream = None
+        else:
+            body = b''
+            stream = client_reader
 
         return Request(app, client_addr, method, url, http_version, headers,
-                       stream=client_stream, sock=client_sock)
+                       body=body, stream=stream,
+                       sock=(client_reader, client_writer))
 
     def _parse_urlencoded(self, urlencoded):
         data = MultiDict()
-        if len(urlencoded) > 0:
+        if len(urlencoded) > 0:  # pragma: no branch
             if isinstance(urlencoded, str):
-                for k, v in [pair.split('=', 1)
-                             for pair in urlencoded.split('&')]:
-                    data[urldecode_str(k)] = urldecode_str(v)
+                for kv in [pair.split('=', 1)
+                           for pair in urlencoded.split('&') if pair]:
+                    data[urldecode_str(kv[0])] = urldecode_str(kv[1]) \
+                        if len(kv) > 1 else ''
             elif isinstance(urlencoded, bytes):  # pragma: no branch
-                for k, v in [pair.split(b'=', 1)
-                             for pair in urlencoded.split(b'&')]:
-                    data[urldecode_bytes(k)] = urldecode_bytes(v)
+                for kv in [pair.split(b'=', 1)
+                           for pair in urlencoded.split(b'&') if pair]:
+                    data[urldecode_bytes(kv[0])] = urldecode_bytes(kv[1]) \
+                        if len(kv) > 1 else b''
         return data
 
     @property
     def body(self):
         """The body of the request, as bytes."""
-        if self.stream_used:
-            raise RuntimeError('Cannot use both stream and body')
-        if self._body is None:
-            self._body = b''
-            if self.content_length and \
-                    self.content_length <= Request.max_body_length:
-                while len(self._body) < self.content_length:
-                    data = self._stream.read(
-                        self.content_length - len(self._body))
-                    if len(data) == 0:  # pragma: no cover
-                        raise EOFError()
-                    self._body += data
-                self.body_used = True
         return self._body
 
     @property
     def stream(self):
-        """The input stream, containing the request body."""
-        if self.body_used:
-            raise RuntimeError('Cannot use both stream and body')
-        self.stream_used = True
+        """The body of the request, as a bytes stream."""
+        if self._stream is None:
+            self._stream = AsyncBytesIO(self._body)
         return self._stream
 
     @property
@@ -487,21 +507,21 @@ class Request():
         return f
 
     @staticmethod
-    def _safe_readline(stream):
-        line = stream.readline(Request.max_readline + 1)
+    async def _safe_readline(stream):
+        line = (await stream.readline())
         if len(line) > Request.max_readline:
             raise ValueError('line too long')
         return line
 
 
-class Response():
+class Response:
     """An HTTP response class.
 
     :param body: The body of the response. If a dictionary or list is given,
                  a JSON formatter is used to generate the body. If a file-like
-                 object or a generator is given, a streaming response is used.
-                 If a string is given, it is encoded from UTF-8. Else, the
-                 body should be a byte sequence.
+                 object or an async generator is given, a streaming response is
+                 used. If a string is given, it is encoded from UTF-8. Else,
+                 the body should be a byte sequence.
     :param status_code: The numeric HTTP status code of the response. The
                         default is 200.
     :param headers: A dictionary of headers to include in the response.
@@ -519,12 +539,17 @@ class Response():
         'png': 'image/png',
         'txt': 'text/plain',
     }
+
     send_file_buffer_size = 1024
 
     #: The content type to use for responses that do not explicitly define a
     #: ``Content-Type`` header.
     default_content_type = 'text/plain'
 
+    #: The default cache control max age used by :meth:`send_file`. A value
+    #: of ``None`` means that no ``Cache-Control`` header is added.
+    default_send_file_max_age = None
+
     #: Special response used to signal that a response does not need to be
     #: written to the client. Used to exit WebSocket connections cleanly.
     already_handled = None
@@ -544,9 +569,11 @@ class Response():
         else:
             # this applies to bytes, file-like objects or generators
             self.body = body
+        self.is_head = False
 
     def set_cookie(self, cookie, value, path=None, domain=None, expires=None,
-                   max_age=None, secure=False, http_only=False):
+                   max_age=None, secure=False, http_only=False,
+                   partitioned=False):
         """Add a cookie to the response.
 
         :param cookie: The cookie's name.
@@ -558,6 +585,7 @@ class Response():
         :param max_age: The cookie's ``Max-Age`` value.
         :param secure: The cookie's ``secure`` flag.
         :param http_only: The cookie's ``HttpOnly`` flag.
+        :param partitioned: Whether the cookie is partitioned.
         """
         http_cookie = '{cookie}={value}'.format(cookie=cookie, value=value)
         if path:
@@ -568,19 +596,31 @@ class Response():
             if isinstance(expires, str):
                 http_cookie += '; Expires=' + expires
             else:
-                http_cookie += '; Expires=' + expires.strftime(
-                    '%a, %d %b %Y %H:%M:%S GMT')
+                http_cookie += '; Expires=' + time.strftime(
+                    '%a, %d %b %Y %H:%M:%S GMT', expires.timetuple())
         if max_age:
             http_cookie += '; Max-Age=' + str(max_age)
         if secure:
             http_cookie += '; Secure'
         if http_only:
             http_cookie += '; HttpOnly'
+        if partitioned:
+            http_cookie += '; Partitioned'
         if 'Set-Cookie' in self.headers:
             self.headers['Set-Cookie'].append(http_cookie)
         else:
             self.headers['Set-Cookie'] = [http_cookie]
 
+    def delete_cookie(self, cookie, **kwargs):
+        """Delete a cookie.
+
+        :param cookie: The cookie's name.
+        :param kwargs: Any cookie opens and flags supported by
+                       ``set_cookie()`` except ``expires``.
+        """
+        self.set_cookie(cookie, '', expires='Thu, 01 Jan 1970 00:00:01 GMT',
+                        **kwargs)
+
     def complete(self):
         if isinstance(self.body, bytes) and \
                 'Content-Length' not in self.headers:
@@ -590,53 +630,101 @@ class Response():
             if 'charset=' not in self.headers['Content-Type']:
                 self.headers['Content-Type'] += '; charset=UTF-8'
 
-    def write(self, stream):
+    async def write(self, stream):
         self.complete()
 
+        try:
             # status code
             reason = self.reason if self.reason is not None else \
                 ('OK' if self.status_code == 200 else 'N/A')
-        stream.write('HTTP/1.0 {status_code} {reason}\r\n'.format(
+            await stream.awrite('HTTP/1.0 {status_code} {reason}\r\n'.format(
                 status_code=self.status_code, reason=reason).encode())
 
             # headers
             for header, value in self.headers.items():
                 values = value if isinstance(value, list) else [value]
                 for value in values:
-                stream.write('{header}: {value}\r\n'.format(
+                    await stream.awrite('{header}: {value}\r\n'.format(
                         header=header, value=value).encode())
-        stream.write(b'\r\n')
+            await stream.awrite(b'\r\n')
 
             # body
-        can_flush = hasattr(stream, 'flush')
-        try:
-            for body in self.body_iter():
+            if not self.is_head:
+                iter = self.body_iter()
+                async for body in iter:
                     if isinstance(body, str):  # pragma: no cover
                         body = body.encode()
-                stream.write(body)
-                if can_flush:  # pragma: no cover
-                    stream.flush()
+                    try:
+                        await stream.awrite(body)
                     except OSError as exc:  # pragma: no cover
-            if exc.errno in MUTED_SOCKET_ERRORS:
+                        if exc.errno in MUTED_SOCKET_ERRORS or \
+                                exc.args[0] == 'Connection lost':
+                            if hasattr(iter, 'aclose'):
+                                await iter.aclose()
+                        raise
+                if hasattr(iter, 'aclose'):  # pragma: no branch
+                    await iter.aclose()
+
+        except OSError as exc:  # pragma: no cover
+            if exc.errno in MUTED_SOCKET_ERRORS or \
+                    exc.args[0] == 'Connection lost':
                 pass
             else:
                 raise
 
     def body_iter(self):
-        if self.body:
-            if hasattr(self.body, 'read'):
-                while True:
-                    buf = self.body.read(self.send_file_buffer_size)
-                    if len(buf):
-                        yield buf
-                    if len(buf) < self.send_file_buffer_size:
-                        break
-                if hasattr(self.body, 'close'):  # pragma: no cover
-                    self.body.close()
-            elif hasattr(self.body, '__next__'):
-                yield from self.body
+        if hasattr(self.body, '__anext__'):
+            # response body is an async generator
+            return self.body
+
+        response = self
+
+        class iter:
+            ITER_UNKNOWN = 0
+            ITER_SYNC_GEN = 1
+            ITER_FILE_OBJ = 2
+            ITER_NO_BODY = -1
+
+            def __aiter__(self):
+                if response.body:
+                    self.i = self.ITER_UNKNOWN  # need to determine type
                 else:
-                yield self.body
+                    self.i = self.ITER_NO_BODY
+                return self
+
+            async def __anext__(self):
+                if self.i == self.ITER_NO_BODY:
+                    await self.aclose()
+                    raise StopAsyncIteration
+                if self.i == self.ITER_UNKNOWN:
+                    if hasattr(response.body, 'read'):
+                        self.i = self.ITER_FILE_OBJ
+                    elif hasattr(response.body, '__next__'):
+                        self.i = self.ITER_SYNC_GEN
+                        return next(response.body)
+                    else:
+                        self.i = self.ITER_NO_BODY
+                        return response.body
+                elif self.i == self.ITER_SYNC_GEN:
+                    try:
+                        return next(response.body)
+                    except StopIteration:
+                        await self.aclose()
+                        raise StopAsyncIteration
+                buf = response.body.read(response.send_file_buffer_size)
+                if iscoroutine(buf):  # pragma: no cover
+                    buf = await buf
+                if len(buf) < response.send_file_buffer_size:
+                    self.i = self.ITER_NO_BODY
+                return buf
+
+            async def aclose(self):
+                if hasattr(response.body, 'close'):
+                    result = response.body.close()
+                    if iscoroutine(result):  # pragma: no cover
+                        await result
+
+        return iter()
 
     @classmethod
     def redirect(cls, location, status_code=302):
@@ -651,7 +739,9 @@ class Response():
         return cls(status_code=status_code, headers={'Location': location})
 
     @classmethod
-    def send_file(cls, filename, status_code=200, content_type=None):
+    def send_file(cls, filename, status_code=200, content_type=None,
+                  stream=None, max_age=None, compressed=False,
+                  file_extension=''):
         """Send file contents in a response.
 
         :param filename: The filename of the file.
@@ -659,7 +749,25 @@ class Response():
                             default is 302.
         :param content_type: The ``Content-Type`` header to use in the
                              response. If omitted, it is generated
-                             automatically from the file extension.
+                             automatically from the file extension of the
+                             ``filename`` parameter.
+        :param stream: A file-like object to read the file contents from. If
+                       a stream is given, the ``filename`` parameter is only
+                       used when generating the ``Content-Type`` header.
+        :param max_age: The ``Cache-Control`` header's ``max-age`` value in
+                        seconds. If omitted, the value of the
+                        :attr:`Response.default_send_file_max_age` attribute is
+                        used.
+        :param compressed: Whether the file is compressed. If ``True``, the
+                           ``Content-Encoding`` header is set to ``gzip``. A
+                           string with the header value can also be passed.
+                           Note that when using this option the file must have
+                           been compressed beforehand. This option only sets
+                           the header.
+        :param file_extension: A file extension to append to the ``filename``
+                               parameter when opening the file, including the
+                               dot. The extension given here is not considered
+                               when generating the ``Content-Type`` header.
 
         Security note: The filename is assumed to be trusted. Never pass
         filenames provided by the user without validating and sanitizing them
@@ -671,9 +779,19 @@ class Response():
                 content_type = Response.types_map[ext]
             else:
                 content_type = 'application/octet-stream'
-        f = open(filename, 'rb')
-        return cls(body=f, status_code=status_code,
-                   headers={'Content-Type': content_type})
+        headers = {'Content-Type': content_type}
+
+        if max_age is None:
+            max_age = cls.default_send_file_max_age
+        if max_age is not None:
+            headers['Cache-Control'] = 'max-age={}'.format(max_age)
+
+        if compressed:
+            headers['Content-Encoding'] = compressed \
+                if isinstance(compressed, str) else 'gzip'
+
+        f = stream or open(filename + file_extension, 'rb')
+        return cls(body=f, status_code=status_code, headers=headers)
 
 
 class URLPattern():
@@ -695,7 +813,7 @@ class URLPattern():
                 if type_ == 'string':
                     pattern = '[^/]+'
                 elif type_ == 'int':
-                    pattern = '\\d+'
+                    pattern = '-?\\d+'
                 elif type_ == 'path':
                     pattern = '.+'
                 elif type_.startswith('re:'):
@@ -738,7 +856,7 @@ class HTTPException(Exception):
         return 'HTTPException: {}'.format(self.status_code)
 
 
-class Microdot():
+class Microdot:
     """An HTTP application class.
 
     This class implements an HTTP application instance and is heavily
@@ -759,6 +877,7 @@ class Microdot():
         self.after_error_request_handlers = []
         self.error_handlers = {}
         self.shutdown_requested = False
+        self.options_handler = self.default_options_handler
         self.debug = False
         self.server = None
 
@@ -794,7 +913,8 @@ class Microdot():
         """
         def decorated(f):
             self.url_map.append(
-                (methods or ['GET'], URLPattern(url_pattern), f))
+                ([m.upper() for m in (methods or ['GET'])],
+                 URLPattern(url_pattern), f))
             return f
         return decorated
 
@@ -1003,6 +1123,88 @@ class Microdot():
         """
         raise HTTPException(status_code, reason)
 
+    async def start_server(self, host='0.0.0.0', port=5000, debug=False,
+                           ssl=None):
+        """Start the Microdot web server as a coroutine. This coroutine does
+        not normally return, as the server enters an endless listening loop.
+        The :func:`shutdown` function provides a method for terminating the
+        server gracefully.
+
+        :param host: The hostname or IP address of the network interface that
+                     will be listening for requests. A value of ``'0.0.0.0'``
+                     (the default) indicates that the server should listen for
+                     requests on all the available interfaces, and a value of
+                     ``127.0.0.1`` indicates that the server should listen
+                     for requests only on the internal networking interface of
+                     the host.
+        :param port: The port number to listen for requests. The default is
+                     port 5000.
+        :param debug: If ``True``, the server logs debugging information. The
+                      default is ``False``.
+        :param ssl: An ``SSLContext`` instance or ``None`` if the server should
+                    not use TLS. The default is ``None``.
+
+        This method is a coroutine.
+
+        Example::
+
+            import asyncio
+            from microdot_asyncio import Microdot
+
+            app = Microdot()
+
+            @app.route('/')
+            async def index(request):
+                return 'Hello, world!'
+
+            async def main():
+                await app.start_server(debug=True)
+
+            asyncio.run(main())
+        """
+        self.debug = debug
+
+        async def serve(reader, writer):
+            if not hasattr(writer, 'awrite'):  # pragma: no cover
+                # CPython provides the awrite and aclose methods in 3.8+
+                async def awrite(self, data):
+                    self.write(data)
+                    await self.drain()
+
+                async def aclose(self):
+                    self.close()
+                    await self.wait_closed()
+
+                from types import MethodType
+                writer.awrite = MethodType(awrite, writer)
+                writer.aclose = MethodType(aclose, writer)
+
+            await self.handle_request(reader, writer)
+
+        if self.debug:  # pragma: no cover
+            print('Starting async server on {host}:{port}...'.format(
+                host=host, port=port))
+
+        try:
+            self.server = await asyncio.start_server(serve, host, port,
+                                                     ssl=ssl)
+        except TypeError:  # pragma: no cover
+            self.server = await asyncio.start_server(serve, host, port)
+
+        while True:
+            try:
+                if hasattr(self.server, 'serve_forever'):  # pragma: no cover
+                    try:
+                        await self.server.serve_forever()
+                    except asyncio.CancelledError:
+                        pass
+                await self.server.wait_closed()
+                break
+            except AttributeError:  # pragma: no cover
+                # the task hasn't been initialized in the server object yet
+                # wait a bit and try again
+                await asyncio.sleep(0.1)
+
     def run(self, host='0.0.0.0', port=5000, debug=False, ssl=None):
         """Start the web server. This function does not normally return, as
         the server enters an endless listening loop. The :func:`shutdown`
@@ -1024,45 +1226,18 @@ class Microdot():
 
         Example::
 
-            from microdot import Microdot
+            from microdot_asyncio import Microdot
 
             app = Microdot()
 
             @app.route('/')
-            def index():
+            async def index(request):
                 return 'Hello, world!'
 
             app.run(debug=True)
         """
-        self.debug = debug
-        self.shutdown_requested = False
-
-        self.server = socket.socket()
-        ai = socket.getaddrinfo(host, port)
-        addr = ai[0][-1]
-
-        if self.debug:  # pragma: no cover
-            print('Starting {mode} server on {host}:{port}...'.format(
-                mode=concurrency_mode, host=host, port=port))
-        self.server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        self.server.bind(addr)
-        self.server.listen(5)
-
-        if ssl:
-            self.server = ssl.wrap_socket(self.server, server_side=True)
-
-        while not self.shutdown_requested:
-            try:
-                sock, addr = self.server.accept()
-            except OSError as exc:  # pragma: no cover
-                if exc.errno == errno.ECONNABORTED:
-                    break
-                else:
-                    print_exception(exc)
-            except Exception as exc:  # pragma: no cover
-                print_exception(exc)
-            else:
-                create_thread(self.handle_request, sock, addr)
+        asyncio.run(self.start_server(host=host, port=port, debug=debug,
+                                      ssl=ssl))  # pragma: no cover
 
     def shutdown(self):
         """Request a server shutdown. The server will then exit its request
@@ -1077,65 +1252,64 @@ class Microdot():
                 request.app.shutdown()
                 return 'The server is shutting down...'
         """
-        self.shutdown_requested = True
+        self.server.close()
 
     def find_route(self, req):
+        method = req.method.upper()
+        if method == 'OPTIONS' and self.options_handler:
+            return self.options_handler(req)
+        if method == 'HEAD':
+            method = 'GET'
         f = 404
         for route_methods, route_pattern, route_handler in self.url_map:
             req.url_args = route_pattern.match(req.path)
             if req.url_args is not None:
-                if req.method in route_methods:
+                if method in route_methods:
                     f = route_handler
                     break
                 else:
                     f = 405
         return f
 
-    def handle_request(self, sock, addr):
-        if Request.socket_read_timeout and \
-                hasattr(sock, 'settimeout'):  # pragma: no cover
-            sock.settimeout(Request.socket_read_timeout)
-        if not hasattr(sock, 'readline'):  # pragma: no cover
-            stream = sock.makefile("rwb")
-        else:
-            stream = sock
+    def default_options_handler(self, req):
+        allow = []
+        for route_methods, route_pattern, route_handler in self.url_map:
+            if route_pattern.match(req.path) is not None:
+                allow.extend(route_methods)
+        if 'GET' in allow:
+            allow.append('HEAD')
+        allow.append('OPTIONS')
+        return {'Allow': ', '.join(allow)}
 
+    async def handle_request(self, reader, writer):
         req = None
-        res = None
         try:
-            req = Request.create(self, stream, addr, sock)
-            res = self.dispatch_request(req)
-        except socket_timeout_error as exc:  # pragma: no cover
-            if exc.errno and exc.errno not in [60, 110]:
-                print_exception(exc)  # not a timeout
+            req = await Request.create(self, reader, writer,
+                                       writer.get_extra_info('peername'))
         except Exception as exc:  # pragma: no cover
             print_exception(exc)
+
+        res = await self.dispatch_request(req)
+        if res != Response.already_handled:  # pragma: no branch
+            await res.write(writer)
         try:
-            if res and res != Response.already_handled:  # pragma: no branch
-                res.write(stream)
-            stream.close()
+            await writer.aclose()
         except OSError as exc:  # pragma: no cover
             if exc.errno in MUTED_SOCKET_ERRORS:
                 pass
             else:
-                print_exception(exc)
-        except Exception as exc:  # pragma: no cover
-            print_exception(exc)
-        if stream != sock:  # pragma: no cover
-            sock.close()
-        if self.shutdown_requested:  # pragma: no cover
-            self.server.close()
+                raise
         if self.debug and req:  # pragma: no cover
             print('{method} {path} {status_code}'.format(
                 method=req.method, path=req.path,
                 status_code=res.status_code))
 
-    def dispatch_request(self, req):
+    async def dispatch_request(self, req):
         after_request_handled = False
         if req:
             if req.content_length > req.max_content_length:
                 if 413 in self.error_handlers:
-                    res = self.error_handlers[413](req)
+                    res = await invoke_handler(self.error_handlers[413], req)
                 else:
                     res = 'Payload too large', 413
             else:
@@ -1144,11 +1318,12 @@ class Microdot():
                     res = None
                     if callable(f):
                         for handler in self.before_request_handlers:
-                            res = handler(req)
+                            res = await invoke_handler(handler, req)
                             if res:
                                 break
                         if res is None:
-                            res = f(req, **req.url_args)
+                            res = await invoke_handler(
+                                f, req, **req.url_args)
                         if isinstance(res, tuple):
                             body = res[0]
                             if isinstance(res[1], int):
@@ -1161,12 +1336,16 @@ class Microdot():
                         elif not isinstance(res, Response):
                             res = Response(res)
                         for handler in self.after_request_handlers:
-                            res = handler(req, res) or res
+                            res = await invoke_handler(
+                                handler, req, res) or res
                         for handler in req.after_request_handlers:
-                            res = handler(req, res) or res
+                            res = await invoke_handler(
+                                handler, req, res) or res
                         after_request_handled = True
+                    elif isinstance(f, dict):
+                        res = Response(headers=f)
                     elif f in self.error_handlers:
-                        res = self.error_handlers[f](req)
+                        res = await invoke_handler(self.error_handlers[f], req)
                     else:
                         res = 'Not found', f
                 except HTTPException as exc:
@@ -1187,31 +1366,35 @@ class Microdot():
                                 break
                     if exc_class:
                         try:
-                            res = self.error_handlers[exc_class](req, exc)
+                            res = await invoke_handler(
+                                self.error_handlers[exc_class], req, exc)
                         except Exception as exc2:  # pragma: no cover
                             print_exception(exc2)
                     if res is None:
                         if 500 in self.error_handlers:
-                            res = self.error_handlers[500](req)
+                            res = await invoke_handler(
+                                self.error_handlers[500], req)
                         else:
                             res = 'Internal server error', 500
         else:
             if 400 in self.error_handlers:
-                res = self.error_handlers[400](req)
+                res = await invoke_handler(self.error_handlers[400], req)
             else:
                 res = 'Bad request', 400
-
         if isinstance(res, tuple):
             res = Response(*res)
         elif not isinstance(res, Response):
             res = Response(res)
         if not after_request_handled:
             for handler in self.after_error_request_handlers:
-                res = handler(req, res) or res
+                res = await invoke_handler(
+                    handler, req, res) or res
+        res.is_head = (req and req.method == 'HEAD')
         return res
 
 
-abort = Microdot.abort
 Response.already_handled = Response()
+
+abort = Microdot.abort
 redirect = Response.redirect
 send_file = Response.send_file

src/microdot/session.py

@@ -0,0 +1,148 @@
+import jwt
+from microdot.microdot import invoke_handler
+
+secret_key = None
+
+
+class SessionDict(dict):
+    """A session dictionary.
+
+    The session dictionary is a standard Python dictionary that has been
+    extended with convenience ``save()`` and ``delete()`` methods.
+    """
+    def __init__(self, request, session_dict):
+        super().__init__(session_dict)
+        self.request = request
+
+    def save(self):
+        """Update the session cookie."""
+        self.request.app._session.update(self.request, self)
+
+    def delete(self):
+        """Delete the session cookie."""
+        self.request.app._session.delete(self.request)
+
+
+class Session:
+    """
+    :param app: The application instance.
+    :param key: The secret key, as a string or bytes object.
+    """
+    secret_key = None
+
+    def __init__(self, app=None, secret_key=None):
+        self.secret_key = secret_key
+        if app is not None:
+            self.initialize(app)
+
+    def initialize(self, app, secret_key=None):
+        if secret_key is not None:
+            self.secret_key = secret_key
+        app._session = self
+
+    def get(self, request):
+        """Retrieve the user session.
+
+        :param request: The client request.
+
+        The return value is a session dictionary with the data stored in the
+        user's session, or ``{}`` if the session data is not available or
+        invalid.
+        """
+        if not self.secret_key:
+            raise ValueError('The session secret key is not configured')
+        if hasattr(request.g, '_session'):
+            return request.g._session
+        session = request.cookies.get('session')
+        if session is None:
+            request.g._session = SessionDict(request, {})
+            return request.g._session
+        try:
+            session = jwt.decode(session, self.secret_key,
+                                 algorithms=['HS256'])
+        except jwt.exceptions.PyJWTError:  # pragma: no cover
+            request.g._session = SessionDict(request, {})
+        else:
+            request.g._session = SessionDict(request, session)
+        return request.g._session
+
+    def update(self, request, session):
+        """Update the user session.
+
+        :param request: The client request.
+        :param session: A dictionary with the update session data for the user.
+
+        Applications would normally not call this method directly, instead they
+        would use the :meth:`SessionDict.save` method on the session
+        dictionary, which calls this method. For example::
+
+            @app.route('/')
+            @with_session
+            def index(request, session):
+                session['foo'] = 'bar'
+                session.save()
+                return 'Hello, World!'
+
+        Calling this method adds a cookie with the updated session to the
+        request currently being processed.
+        """
+        if not self.secret_key:
+            raise ValueError('The session secret key is not configured')
+
+        encoded_session = jwt.encode(session, self.secret_key,
+                                     algorithm='HS256')
+
+        @request.after_request
+        def _update_session(request, response):
+            response.set_cookie('session', encoded_session, http_only=True)
+            return response
+
+    def delete(self, request):
+        """Remove the user session.
+
+        :param request: The client request.
+
+        Applications would normally not call this method directly, instead they
+        would use the :meth:`SessionDict.delete` method on the session
+        dictionary, which calls this method. For example::
+
+            @app.route('/')
+            @with_session
+            def index(request, session):
+                session.delete()
+                return 'Hello, World!'
+
+        Calling this method adds a cookie removal header to the request
+        currently being processed.
+        """
+        @request.after_request
+        def _delete_session(request, response):
+            response.set_cookie('session', '', http_only=True,
+                                expires='Thu, 01 Jan 1970 00:00:01 GMT')
+            return response
+
+
+def with_session(f):
+    """Decorator that passes the user session to the route handler.
+
+    The session dictionary is passed to the decorated function as an argument
+    after the request object. Example::
+
+        @app.route('/')
+        @with_session
+        def index(request, session):
+            return 'Hello, World!'
+
+    Note that the decorator does not save the session. To update the session,
+    call the :func:`update_session <microdot.session.update_session>` function.
+    """
+    async def wrapper(request, *args, **kwargs):
+        return await invoke_handler(
+            f, request, request.app._session.get(request), *args, **kwargs)
+
+    for attr in ['__name__', '__doc__', '__module__', '__qualname__']:
+        try:
+            setattr(wrapper, attr, getattr(f, attr))
+        except AttributeError:  # pragma: no cover
+            pass
+    return wrapper

src/microdot/sse.py

@@ -0,0 +1,95 @@
+import asyncio
+import json
+
+
+class SSE:
+    def __init__(self):
+        self.event = asyncio.Event()
+        self.queue = []
+
+    async def send(self, data, event=None):
+        if isinstance(data, (dict, list)):
+            data = json.dumps(data)
+        elif not isinstance(data, str):
+            data = str(data)
+        data = f'data: {data}\n\n'
+        if event:
+            data = f'event: {event}\n{data}'
+        self.queue.append(data)
+        self.event.set()
+
+
+def sse_response(request, event_function, *args, **kwargs):
+    """Return a response object that initiates an event stream.
+
+    :param request: the request object.
+    :param event_function: an asynchronous function that will send events to
+                           the client. The function is invoked with ``request``
+                           and an ``sse`` object. The function should use
+                           ``sse.send()`` to send events to the client.
+    :param args: additional positional arguments to be passed to the response.
+    :param kwargs: additional keyword arguments to be passed to the response.
+
+    Example::
+
+        @app.route('/events')
+        async def events_route(request):
+            async def events(request, sse):
+                # send an unnamed event with string data
+                await sse.send('hello')
+                # send an unnamed event with JSON data
+                await sse.send({'foo': 'bar'})
+                # send a named event
+                await sse.send('hello', event='greeting')
+
+            return sse_response(request, events)
+    """
+    sse = SSE()
+
+    async def sse_task_wrapper():
+        await event_function(request, sse, *args, **kwargs)
+        sse.event.set()
+
+    task = asyncio.create_task(sse_task_wrapper())
+
+    class sse_loop:
+        def __aiter__(self):
+            return self
+
+        async def __anext__(self):
+            event = None
+            while sse.queue or not task.done():
+                try:
+                    event = sse.queue.pop(0)
+                    break
+                except IndexError:
+                    await sse.event.wait()
+                    sse.event.clear()
+            if event is None:
+                raise StopAsyncIteration
+            return event
+
+        async def aclose(self):
+            task.cancel()
+
+    return sse_loop(), 200, {'Content-Type': 'text/event-stream'}
+
+
+def with_sse(f):
+    """Decorator to make a route a Server-Sent Events endpoint.
+
+    This decorator is used to define a route that accepts SSE connections. The
+    route then receives a sse object as a second argument that it can use to
+    send events to the client::
+
+        @app.route('/events')
+        @with_sse
+        async def events(request, sse):
+            for i in range(10):
+                await asyncio.sleep(1)
+                await sse.send(f'{i}')
+    """
+    async def sse_handler(request, *args, **kwargs):
+        return sse_response(request, f, *args, **kwargs)
+
+    return sse_handler

src/microdot/test_client.py

@@ -1,11 +1,13 @@
-from io import BytesIO
 import json
-from microdot import Request, Response, NoCaseDict
+from microdot.microdot import Request, Response, AsyncBytesIO
+
 try:
-    from microdot_websocket import WebSocket
+    from microdot.websocket import WebSocket
 except:  # pragma: no cover  # noqa: E722
     WebSocket = None
 
+__all__ = ['TestClient', 'TestResponse']
+
 
 class TestResponse:
     """A response object issued by the Microdot test client."""
@@ -32,12 +34,15 @@ class TestResponse:
         self.reason = res.reason
         self.headers = res.headers
 
-    def _initialize_body(self, res):
+    async def _initialize_body(self, res):
         self.body = b''
-        for body in res.body_iter():
+        iter = res.body_iter()
+        async for body in iter:  # pragma: no branch
             if isinstance(body, str):
                 body = body.encode()
             self.body += body
+        if hasattr(iter, 'aclose'):  # pragma: no branch
+            await iter.aclose()
 
     def _process_text_body(self):
         try:
@@ -52,10 +57,11 @@ class TestResponse:
                 self.json = json.loads(self.text)
 
     @classmethod
-    def create(cls, res):
+    async def create(cls, res):
         test_res = cls()
         test_res._initialize_response(res)
-        test_res._initialize_body(res)
+        if not res.is_head:
+            await test_res._initialize_body(res)
             test_res._process_text_body()
             test_res._process_json_body()
         return test_res
@@ -71,17 +77,17 @@ class TestClient:
     The following example shows how to create a test client for an application
     and send a test request::
 
-        from microdot import Microdot
+        from microdot_asyncio import Microdot
 
         app = Microdot()
 
         @app.get('/')
-        def index():
+        async def index():
             return 'Hello, World!'
 
-        def test_hello_world(self):
+        async def test_hello_world(self):
             client = TestClient(app)
-            res = client.get('/')
+            res = await client.get('/')
             assert res.status_code == 200
             assert res.text == 'Hello, World!'
     """
@@ -149,23 +155,30 @@ class TestClient:
             else:
                 self.cookies[cookie_name] = cookie_options[0]
 
-    def request(self, method, path, headers=None, body=None, sock=None):
-        headers = NoCaseDict(headers or {})
+    async def request(self, method, path, headers=None, body=None, sock=None):
+        headers = headers or {}
         body, headers = self._process_body(body, headers)
         cookies, headers = self._process_cookies(headers)
         request_bytes = self._render_request(method, path, headers, body)
+        if sock:
+            reader = sock[0]
+            reader.buffer = request_bytes
+            writer = sock[1]
+        else:
+            reader = AsyncBytesIO(request_bytes)
+            writer = AsyncBytesIO(b'')
 
-        req = Request.create(self.app, BytesIO(request_bytes),
-                             ('127.0.0.1', 1234), client_sock=sock)
-        res = self.app.dispatch_request(req)
+        req = await Request.create(self.app, reader, writer,
+                                   ('127.0.0.1', 1234))
+        res = await self.app.dispatch_request(req)
         if res == Response.already_handled:
             return None
         res.complete()
 
         self._update_cookies(res)
-        return TestResponse.create(res)
+        return await TestResponse.create(res)
 
-    def get(self, path, headers=None):
+    async def get(self, path, headers=None):
         """Send a GET request to the application.
 
         :param path: The request URL.
@@ -174,9 +187,9 @@ class TestClient:
         This method returns a
         :class:`TestResponse <microdot_test_client.TestResponse>` object.
         """
-        return self.request('GET', path, headers=headers)
+        return await self.request('GET', path, headers=headers)
 
-    def post(self, path, headers=None, body=None):
+    async def post(self, path, headers=None, body=None):
         """Send a POST request to the application.
 
         :param path: The request URL.
@@ -188,9 +201,9 @@ class TestClient:
         This method returns a
         :class:`TestResponse <microdot_test_client.TestResponse>` object.
         """
-        return self.request('POST', path, headers=headers, body=body)
+        return await self.request('POST', path, headers=headers, body=body)
 
-    def put(self, path, headers=None, body=None):
+    async def put(self, path, headers=None, body=None):
         """Send a PUT request to the application.
 
         :param path: The request URL.
@@ -202,9 +215,9 @@ class TestClient:
         This method returns a
         :class:`TestResponse <microdot_test_client.TestResponse>` object.
         """
-        return self.request('PUT', path, headers=headers, body=body)
+        return await self.request('PUT', path, headers=headers, body=body)
 
-    def patch(self, path, headers=None, body=None):
+    async def patch(self, path, headers=None, body=None):
         """Send a PATCH request to the application.
 
         :param path: The request URL.
@@ -216,9 +229,9 @@ class TestClient:
         This method returns a
         :class:`TestResponse <microdot_test_client.TestResponse>` object.
         """
-        return self.request('PATCH', path, headers=headers, body=body)
+        return await self.request('PATCH', path, headers=headers, body=body)
 
-    def delete(self, path, headers=None):
+    async def delete(self, path, headers=None):
         """Send a DELETE request to the application.
 
         :param path: The request URL.
@@ -227,9 +240,9 @@ class TestClient:
         This method returns a
         :class:`TestResponse <microdot_test_client.TestResponse>` object.
         """
-        return self.request('DELETE', path, headers=headers)
+        return await self.request('DELETE', path, headers=headers)
 
-    def websocket(self, path, client, headers=None):
+    async def websocket(self, path, client, headers=None):
         """Send a websocket connection request to the application.
 
         :param path: The request URL.
@@ -244,27 +257,39 @@ class TestClient:
                 self.closed = False
                 self.buffer = b''
 
-            def _next(self, data=None):
+            async def _next(self, data=None):
                 try:
-                    data = gen.send(data)
-                except StopIteration:
-                    if self.closed:  # pragma: no cover
-                        return
+                    data = (await gen.asend(data)) if hasattr(gen, 'asend') \
+                        else gen.send(data)
+                except (StopIteration, StopAsyncIteration):
+                    if not self.closed:
                         self.closed = True
                         raise OSError(32, 'Websocket connection closed')
+                    return  # pragma: no cover
                 opcode = WebSocket.TEXT if isinstance(data, str) \
                     else WebSocket.BINARY
                 return WebSocket._encode_websocket_frame(opcode, data)
 
-            def recv(self, n):
-                self.started = True
+            async def read(self, n):
                 if not self.buffer:
-                    self.buffer = self._next()
+                    self.started = True
+                    self.buffer = await self._next()
                 data = self.buffer[:n]
                 self.buffer = self.buffer[n:]
                 return data
 
-            def send(self, data):
+            async def readexactly(self, n):  # pragma: no cover
+                return await self.read(n)
+
+            async def readline(self):
+                line = b''
+                while True:
+                    line += await self.read(1)
+                    if line[-1] in [b'\n', 10]:
+                        break
+                return line
+
+            async def awrite(self, data):
                 if self.started:
                     h = WebSocket._parse_frame_header(data[0:2])
                     if h[3] < 0:
@@ -273,7 +298,7 @@ class TestClient:
                         data = data[2:]
                     if h[1] == WebSocket.TEXT:
                         data = data.decode()
-                    self.buffer = self._next(data)
+                    self.buffer = await self._next(data)
 
         ws_headers = {
             'Upgrade': 'websocket',
@@ -282,5 +307,6 @@ class TestClient:
             'Sec-WebSocket-Key': 'dGhlIHNhbXBsZSBub25jZQ==',
         }
         ws_headers.update(headers or {})
-        return self.request('GET', path, headers=ws_headers,
-                            sock=FakeWebSocket())
+        sock = FakeWebSocket()
+        return await self.request('GET', path, headers=ws_headers,
+                                  sock=(sock, sock))

src/microdot/utemplate.py

@@ -0,0 +1,68 @@
+from utemplate import recompile
+
+_loader = None
+
+
+def init_templates(template_dir='templates', loader_class=recompile.Loader):
+    """Initialize the templating subsystem.
+
+    :param template_dir: the directory where templates are stored. This
+                         argument is optional. The default is to load templates
+                         from a *templates* subdirectory.
+    :param loader_class: the ``utemplate.Loader`` class to use when loading
+                         templates. This argument is optional. The default is
+                         the ``recompile.Loader`` class, which automatically
+                         recompiles templates when they change.
+    """
+    global _loader
+    _loader = loader_class(None, template_dir)
+
+
+class Template:
+    """A template object.
+
+    :param template: The filename of the template to render, relative to the
+                     configured template directory.
+    """
+    def __init__(self, template):
+        if _loader is None:  # pragma: no cover
+            init_templates()
+        #: The name of the template
+        self.name = template
+        self.template = _loader.load(template)
+
+    def generate(self, *args, **kwargs):
+        """Return a generator that renders the template in chunks, with the
+        given arguments."""
+        return self.template(*args, **kwargs)
+
+    def render(self, *args, **kwargs):
+        """Render the template with the given arguments and return it as a
+        string."""
+        return ''.join(self.generate(*args, **kwargs))
+
+    def generate_async(self, *args, **kwargs):
+        """Return an asynchronous generator that renders the template in
+        chunks, using the given arguments."""
+        class sync_to_async_iter():
+            def __init__(self, iter):
+                self.iter = iter
+
+            def __aiter__(self):
+                return self
+
+            async def __anext__(self):
+                try:
+                    return next(self.iter)
+                except StopIteration:
+                    raise StopAsyncIteration
+
+        return sync_to_async_iter(self.generate(*args, **kwargs))
+
+    async def render_async(self, *args, **kwargs):
+        """Render the template with the given arguments asynchronously and
+        return it as a string."""
+        response = ''
+        async for chunk in self.generate_async(*args, **kwargs):
+            response += chunk
+        return response