Merge pull request #73 from valum-framework/0.1/server-documentation

Server documentation.

Author: arteymix

docs/vsgi/server.rst

@@ -0,0 +1,135 @@
+Server
+======
+
+Server provide HTTP technologies integrations under a common interface. They
+inherit from `GLib.Application`_, providing an optimal integration with the
+host environment.
+
+The following implementations are available:
+
+-  libsoup built-in HTTP server
+-  FastCGI
+
+Basically, you have access to a `DBusConnection`_ to communicate with other
+process and a `GLib.MainLoop`_ to process events and asynchronous work.
+
+-  an application id to identify primary instance
+-  ``startup`` signal emmited right after the registration
+-  ``shutdown`` signal just before the server exits
+-  a resource base path
+-  ability to handle CLI arguments
+
+.. _DBusConnection: http://valadoc.org/#!api=gio-2.0/GLib.DBusConnection
+.. _GLib.MainLoop: http://valadoc.org/#!api=glib-2.0/GLib.MainLoop
+
+DBus connection
+---------------
+
+`GLib.Application`_ will automatically register to the session DBus bus, making
+IPC (Inter-Process Communication) an easy thing.
+
+It can be used to expose runtime information such as a database connection
+details or the amount of processing requests. See this `example of DBus server`_
+for code examples.
+
+.. _example of DBus server: https://wiki.gnome.org/Projects/Vala/DBusServerSample
+
+To identify your workers, you can use the ``set_application_id`` function.
+
+.. code:: vala
+
+    server.set_application_id ("worker");
+
+This can be used to request services and communicate between your workers and
+interact with the runtime.
+
+.. code:: vala
+
+    var connection = server.get_dbus_connection ()
+
+    connection.call ()
+
+.. _GLib.Application: http://valadoc.org/#!api=gio-2.0/GLib.Application
+
+Options
+-------
+
+Each server implementation can optionally take arguments that parametrize their
+runtime. Generally, you can set the following options:
+
+-  a socket path or a TCP port
+-  backlog
+-  inactivity timeout
+
+If you build your application in a main block, it is not possible to obtain the
+CLI arguments, so you must write your code in a ``main`` function.
+
+.. code:: vala
+
+    public static int main (string[] args) {
+        var app = new Router;
+
+        app.get ("", (req, res) => {
+            res.write ("Hello world!".data);
+        });
+
+        return new Server (app).run (args);
+    }
+
+If you specify the ``--help`` flag, you can get more information on the
+available options.
+
+.. code:: bash
+
+    build/examples/fastcgi --help
+
+.. code:: bash
+
+    Usage:
+      fastcgi [OPTION...]
+
+    Help Options:
+      -h, --help                 Show help options
+      --help-all                 Show all help options
+      --help-gapplication        Show GApplication options
+
+    Application Options:
+      -s, --socket               path to the UNIX socket
+      -p, --port                 TCP port on this host
+      -b, --backlog=0            listen queue depth used in the listen() call
+      -t, --timeout=0            inactivity timeout in ms
+
+Socket
+~~~~~~
+
+In some context, you do not want to serve your application over a TCP socket,
+but just a local socket. Either this or ``--port`` can be specified, but not
+both.
+
+Port
+~~~~
+
+This is the TCP port on which the application will be exposed on the local
+host.
+
+Backlog
+~~~~~~~
+
+The backlog correspond to the depth on the ``listen`` call and is used if you
+have multiple listener on a socket.
+
+Inactivity timeout
+~~~~~~~~~~~~~~~~~~
+
+An inactivity timeout can be set to exit automatically after a certain amount
+of milliseconds if no request is being processed.
+
+The server keeps track of the number of processing requests with ``hold`` and
+``release`` from `GLib.Application`_. When the amount reaches 0, the server
+will exit automatically after the value of the inactivity timeout.
+
+This option is enabled if the default timeout value is greater than 0.
+
+.. _GLib.Application: http://valadoc.org/#!api=gio-2.0/GLib.Application
+
+