Web Server Tutorial
===================

Create a simple web server with ASAB.


The code
--------

.. include:: web1/app.py
   :code: python

| To start the application, store above code in a file ``app.py``.
| Execute ``$ python3 ./app.py`` to run it.

The ASAB web server is now available at http://localhost:8080/.


Deeper look
-----------

**ASAB Application**

.. code:: python

    #!/usr/bin/env python3
    import asab.web.rest

    class MyWebApplication(asab.Application):

        def __init__(self):
            super().__init__()

    if __name__ == '__main__':
        app = MyWebApplication()
        app.run()

This is a ASAB code that declares the application class and runs it.


**Create a Web server**

The ``asab.web`` module provides a ``create_web_server()`` function that simplifies creation of the Web server in the ASAB application.


.. code:: python

    web = asab.web.create_web_server(self)


**Install the handler**

.. code:: python

    web.add_get('/hello', self.hello)

    ...
    
    async def hello(self, request):
        return asab.web.rest.json_response(
            request,
            data="Hello, world!\n"
        )


The handler method ``hello()`` is installed at the web server at ``/hello`` endpoint.
HTTP method is ``GET``.

It means that if you access the web server with a path ``/hello``, it will be handled by a ``hello(...)`` method. A handler method must be a coroutine.