Http Server旨在处理HttpRequest并返回HttpResponse，不同WebFramework具备不同的Routing、View等机制，可都遵循WSGI接口处理Http请求，这样所有的请求就都可以运行在基于WSGI的服务器上，从而实现接口。
在Python中写一个WebFramework是一个很简单的事情，当然入口方法最核心的在于以下此函数：
from werkzeug.serving import run_simple
run_simple(t.cast(str, host), port, self, **options)此代码仅仅是给大家一个直观的感受，后续我将逐渐剖析几个主流WebFramework中的核心技巧和源码实现。
Flask 源码
app.py
- http handler entry point
def __call__(self, environ: dict, start_response: t.Callable) -> t.Any:
"""The WSGI server calls the Flask application object as the
WSGI application. This calls :meth:`wsgi_app`, which can be
wrapped to apply middleware.
"""
return self.wsgi_app(environ, start_response)第一个参数就是http request header的字典类型，此时如何处理header在不同请求头里面的。
start_response 负责status code 和 exception等情况的处理。
- dispatch request
def dispatch_request(self) -> ResponseReturnValue:
"""Does the request dispatching. Matches the URL and returns the
return value of the view or error handler. This does not have to
be a response object. In order to convert the return value to a
proper response object, call :func:`make_response`.
.. versionchanged:: 0.7
This no longer does the exception handling, this code was
moved to the new :meth:`full_dispatch_request`.
"""
req = _request_ctx_stack.top.request
if req.routing_exception is not None:
self.raise_routing_exception(req)
rule = req.url_rule
# if we provide automatic options for this URL and the
# request came with the OPTIONS method, reply automatically
if (
getattr(rule, "provide_automatic_options", False)
and req.method == "OPTIONS"
):
return self.make_default_options_response()
# otherwise dispatch to the handler for that endpoint
return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)其中view_functions为字典类型，key是module-method identifier，value 是view function。
此类方法看似很简单，其实就这样设计即可实现功能
view.py
这个模块整体比较简单，
Route
def route(self, rule: str, **options: t.Any) -> t.Callable:
"""Decorate a view function to register it with the given URL
rule and options. Calls :meth:`add_url_rule`, which has more
details about the implementation.
.. code-block:: python
@app.route("/")
def index():
return "Hello, World!"
See :ref:`url-route-registrations`.
The endpoint name for the route defaults to the name of the view
function if the ``endpoint`` parameter isn't passed.
The ``methods`` parameter defaults to ``["GET"]``. ``HEAD`` and
``OPTIONS`` are added automatically.
:param rule: The URL rule string.
:param options: Extra options passed to the
:class:`~werkzeug.routing.Rule` object.
"""
def decorator(f: t.Callable) -> t.Callable:
endpoint = options.pop("endpoint", None)
self.add_url_rule(rule, endpoint, f, **options)
return f
return decorator此函数就负责最常使用的route函数，是不是很简单，并不需要很复杂的设计，只需要完成功能即可。