symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/socketserver.rst
author Peter Fordham <peter.fordham@gmail.com>
Mon, 31 May 2010 16:05:54 -0700
branchCompilerCompatibility
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permissions -rw-r--r--
Bug 1806 - Simplify/Remove use of inline assembler.
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:mod:`SocketServer` --- A framework for network servers
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=======================================================
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.. module:: SocketServer
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   :synopsis: A framework for network servers.
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.. note::
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   The :mod:`SocketServer` module has been renamed to `socketserver` in Python
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   3.0.  The :term:`2to3` tool will automatically adapt imports when converting
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   your sources to 3.0.
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The :mod:`SocketServer` module simplifies the task of writing network servers.
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There are four basic server classes: :class:`TCPServer` uses the Internet TCP
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protocol, which provides for continuous streams of data between the client and
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server.  :class:`UDPServer` uses datagrams, which are discrete packets of
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information that may arrive out of order or be lost while in transit.  The more
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infrequently used :class:`UnixStreamServer` and :class:`UnixDatagramServer`
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classes are similar, but use Unix domain sockets; they're not available on
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non-Unix platforms.  For more details on network programming, consult a book
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such as
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W. Richard Steven's UNIX Network Programming or Ralph Davis's Win32 Network
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Programming.
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These four classes process requests :dfn:`synchronously`; each request must be
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completed before the next request can be started.  This isn't suitable if each
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request takes a long time to complete, because it requires a lot of computation,
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or because it returns a lot of data which the client is slow to process.  The
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solution is to create a separate process or thread to handle each request; the
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:class:`ForkingMixIn` and :class:`ThreadingMixIn` mix-in classes can be used to
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support asynchronous behaviour.
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Creating a server requires several steps.  First, you must create a request
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handler class by subclassing the :class:`BaseRequestHandler` class and
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overriding its :meth:`handle` method; this method will process incoming
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requests.  Second, you must instantiate one of the server classes, passing it
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the server's address and the request handler class.  Finally, call the
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:meth:`handle_request` or :meth:`serve_forever` method of the server object to
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process one or many requests.
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When inheriting from :class:`ThreadingMixIn` for threaded connection behavior,
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you should explicitly declare how you want your threads to behave on an abrupt
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shutdown. The :class:`ThreadingMixIn` class defines an attribute
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*daemon_threads*, which indicates whether or not the server should wait for
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thread termination. You should set the flag explicitly if you would like threads
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to behave autonomously; the default is :const:`False`, meaning that Python will
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not exit until all threads created by :class:`ThreadingMixIn` have exited.
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Server classes have the same external methods and attributes, no matter what
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network protocol they use.
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Server Creation Notes
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---------------------
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There are five classes in an inheritance diagram, four of which represent
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synchronous servers of four types::
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   +------------+
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   | BaseServer |
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   +------------+
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         |
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         v
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   +-----------+        +------------------+
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   | TCPServer |------->| UnixStreamServer |
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   +-----------+        +------------------+
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         |
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         v
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   +-----------+        +--------------------+
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   | UDPServer |------->| UnixDatagramServer |
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   +-----------+        +--------------------+
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Note that :class:`UnixDatagramServer` derives from :class:`UDPServer`, not from
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:class:`UnixStreamServer` --- the only difference between an IP and a Unix
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stream server is the address family, which is simply repeated in both Unix
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server classes.
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Forking and threading versions of each type of server can be created using the
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:class:`ForkingMixIn` and :class:`ThreadingMixIn` mix-in classes.  For instance,
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a threading UDP server class is created as follows::
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   class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
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The mix-in class must come first, since it overrides a method defined in
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:class:`UDPServer`.  Setting the various member variables also changes the
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behavior of the underlying server mechanism.
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To implement a service, you must derive a class from :class:`BaseRequestHandler`
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and redefine its :meth:`handle` method.  You can then run various versions of
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the service by combining one of the server classes with your request handler
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class.  The request handler class must be different for datagram or stream
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services.  This can be hidden by using the handler subclasses
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:class:`StreamRequestHandler` or :class:`DatagramRequestHandler`.
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Of course, you still have to use your head!  For instance, it makes no sense to
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use a forking server if the service contains state in memory that can be
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modified by different requests, since the modifications in the child process
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would never reach the initial state kept in the parent process and passed to
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each child.  In this case, you can use a threading server, but you will probably
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have to use locks to protect the integrity of the shared data.
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On the other hand, if you are building an HTTP server where all data is stored
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externally (for instance, in the file system), a synchronous class will
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essentially render the service "deaf" while one request is being handled --
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which may be for a very long time if a client is slow to receive all the data it
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has requested.  Here a threading or forking server is appropriate.
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In some cases, it may be appropriate to process part of a request synchronously,
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but to finish processing in a forked child depending on the request data.  This
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can be implemented by using a synchronous server and doing an explicit fork in
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the request handler class :meth:`handle` method.
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Another approach to handling multiple simultaneous requests in an environment
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that supports neither threads nor :func:`fork` (or where these are too expensive
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or inappropriate for the service) is to maintain an explicit table of partially
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finished requests and to use :func:`select` to decide which request to work on
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next (or whether to handle a new incoming request).  This is particularly
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important for stream services where each client can potentially be connected for
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a long time (if threads or subprocesses cannot be used). See :mod:`asyncore` for
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another way to manage this.
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.. XXX should data and methods be intermingled, or separate?
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   how should the distinction between class and instance variables be drawn?
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Server Objects
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--------------
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.. function:: fileno()
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   Return an integer file descriptor for the socket on which the server is
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   listening.  This function is most commonly passed to :func:`select.select`, to
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   allow monitoring multiple servers in the same process.
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.. function:: handle_request()
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   Process a single request.  This function calls the following methods in
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   order: :meth:`get_request`, :meth:`verify_request`, and
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   :meth:`process_request`.  If the user-provided :meth:`handle` method of the
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   handler class raises an exception, the server's :meth:`handle_error` method
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   will be called.  If no request is received within :attr:`self.timeout`
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   seconds, :meth:`handle_timeout` will be called and :meth:`handle_request`
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   will return.
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.. function:: serve_forever(poll_interval=0.5)
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   Handle requests until an explicit :meth:`shutdown` request.  Polls for
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   shutdown every *poll_interval* seconds.
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.. function:: shutdown()
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   Tells the :meth:`serve_forever` loop to stop and waits until it does.
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   .. versionadded:: 2.6
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.. data:: address_family
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   The family of protocols to which the server's socket belongs.
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   Common examples are :const:`socket.AF_INET` and :const:`socket.AF_UNIX`.
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.. data:: RequestHandlerClass
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   The user-provided request handler class; an instance of this class is created
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   for each request.
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.. data:: server_address
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   The address on which the server is listening.  The format of addresses varies
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   depending on the protocol family; see the documentation for the socket module
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   for details.  For Internet protocols, this is a tuple containing a string giving
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   the address, and an integer port number: ``('127.0.0.1', 80)``, for example.
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.. data:: socket
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   The socket object on which the server will listen for incoming requests.
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The server classes support the following class variables:
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.. XXX should class variables be covered before instance variables, or vice versa?
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.. data:: allow_reuse_address
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   Whether the server will allow the reuse of an address. This defaults to
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   :const:`False`, and can be set in subclasses to change the policy.
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.. data:: request_queue_size
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   The size of the request queue.  If it takes a long time to process a single
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   request, any requests that arrive while the server is busy are placed into a
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   queue, up to :attr:`request_queue_size` requests.  Once the queue is full,
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   further requests from clients will get a "Connection denied" error.  The default
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   value is usually 5, but this can be overridden by subclasses.
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.. data:: socket_type
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   The type of socket used by the server; :const:`socket.SOCK_STREAM` and
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   :const:`socket.SOCK_DGRAM` are two common values.
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.. data:: timeout
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   Timeout duration, measured in seconds, or :const:`None` if no timeout is
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   desired.  If :meth:`handle_request` receives no incoming requests within the
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   timeout period, the :meth:`handle_timeout` method is called.
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There are various server methods that can be overridden by subclasses of base
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server classes like :class:`TCPServer`; these methods aren't useful to external
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users of the server object.
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.. XXX should the default implementations of these be documented, or should
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   it be assumed that the user will look at SocketServer.py?
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.. function:: finish_request()
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   Actually processes the request by instantiating :attr:`RequestHandlerClass` and
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   calling its :meth:`handle` method.
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.. function:: get_request()
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   Must accept a request from the socket, and return a 2-tuple containing the *new*
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   socket object to be used to communicate with the client, and the client's
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   address.
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.. function:: handle_error(request, client_address)
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   This function is called if the :attr:`RequestHandlerClass`'s :meth:`handle`
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   method raises an exception.  The default action is to print the traceback to
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   standard output and continue handling further requests.
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.. function:: handle_timeout()
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   This function is called when the :attr:`timeout` attribute has been set to a
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   value other than :const:`None` and the timeout period has passed with no
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   requests being received.  The default action for forking servers is
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   to collect the status of any child processes that have exited, while
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   in threading servers this method does nothing.
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.. function:: process_request(request, client_address)
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   Calls :meth:`finish_request` to create an instance of the
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   :attr:`RequestHandlerClass`.  If desired, this function can create a new process
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   or thread to handle the request; the :class:`ForkingMixIn` and
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   :class:`ThreadingMixIn` classes do this.
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.. Is there any point in documenting the following two functions?
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   What would the purpose of overriding them be: initializing server
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   instance variables, adding new network families?
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.. function:: server_activate()
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   Called by the server's constructor to activate the server.  The default behavior
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   just :meth:`listen`\ s to the server's socket. May be overridden.
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.. function:: server_bind()
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   Called by the server's constructor to bind the socket to the desired address.
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   May be overridden.
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.. function:: verify_request(request, client_address)
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   Must return a Boolean value; if the value is :const:`True`, the request will be
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   processed, and if it's :const:`False`, the request will be denied. This function
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   can be overridden to implement access controls for a server. The default
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   implementation always returns :const:`True`.
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RequestHandler Objects
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----------------------
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The request handler class must define a new :meth:`handle` method, and can
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override any of the following methods.  A new instance is created for each
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request.
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.. function:: finish()
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   Called after the :meth:`handle` method to perform any clean-up actions
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   required.  The default implementation does nothing.  If :meth:`setup` or
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   :meth:`handle` raise an exception, this function will not be called.
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.. function:: handle()
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   This function must do all the work required to service a request.  The
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   default implementation does nothing.  Several instance attributes are
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   available to it; the request is available as :attr:`self.request`; the client
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   address as :attr:`self.client_address`; and the server instance as
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   :attr:`self.server`, in case it needs access to per-server information.
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   The type of :attr:`self.request` is different for datagram or stream
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   services.  For stream services, :attr:`self.request` is a socket object; for
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   datagram services, :attr:`self.request` is a pair of string and socket.
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   However, this can be hidden by using the request handler subclasses
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   :class:`StreamRequestHandler` or :class:`DatagramRequestHandler`, which
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   override the :meth:`setup` and :meth:`finish` methods, and provide
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   :attr:`self.rfile` and :attr:`self.wfile` attributes.  :attr:`self.rfile` and
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   :attr:`self.wfile` can be read or written, respectively, to get the request
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   data or return data to the client.
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.. function:: setup()
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   Called before the :meth:`handle` method to perform any initialization actions
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   required.  The default implementation does nothing.
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Examples
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--------
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:class:`SocketServer.TCPServer` Example
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This is the server side::
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   import SocketServer
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   class MyTCPHandler(SocketServer.BaseRequestHandler):
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       """
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       The RequestHandler class for our server.
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       It is instantiated once per connection to the server, and must
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       override the handle() method to implement communication to the
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       client.
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       """
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       def handle(self):
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           # self.request is the TCP socket connected to the client
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           self.data = self.request.recv(1024).strip()
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           print "%s wrote:" % self.client_address[0]
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           print self.data
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           # just send back the same data, but upper-cased
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           self.request.send(self.data.upper())
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   if __name__ == "__main__":
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       HOST, PORT = "localhost", 9999
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       # Create the server, binding to localhost on port 9999
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       server = SocketServer.TCPServer((HOST, PORT), MyTCPHandler)
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       # Activate the server; this will keep running until you
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       # interrupt the program with Ctrl-C
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       server.serve_forever()
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diff changeset
   362
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   363
An alternative request handler class that makes use of streams (file-like
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   364
objects that simplify communication by providing the standard file interface)::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   365
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   366
   class MyTCPHandler(SocketServer.StreamRequestHandler):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   367
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   368
       def handle(self):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   369
           # self.rfile is a file-like object created by the handler;
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   370
           # we can now use e.g. readline() instead of raw recv() calls
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   371
           self.data = self.rfile.readline().strip()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   372
           print "%s wrote:" % self.client_address[0]
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   373
           print self.data
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   374
           # Likewise, self.wfile is a file-like object used to write back
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   375
           # to the client
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   376
           self.wfile.write(self.data.upper())
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   377
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   378
The difference is that the ``readline()`` call in the second handler will call
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   379
``recv()`` multiple times until it encounters a newline character, while the
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   380
single ``recv()`` call in the first handler will just return what has been sent
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   381
from the client in one ``send()`` call.
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   382
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   383
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   384
This is the client side::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   385
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   386
   import socket
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   387
   import sys
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   388
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   389
   HOST, PORT = "localhost", 9999
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   390
   data = " ".join(sys.argv[1:])
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   391
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   392
   # Create a socket (SOCK_STREAM means a TCP socket)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   393
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   394
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   395
   # Connect to server and send data
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   396
   sock.connect((HOST, PORT))
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   397
   sock.send(data + "\n")
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   398
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   399
   # Receive data from the server and shut down
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   400
   received = sock.recv(1024)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   401
   sock.close()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   402
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   403
   print "Sent:     %s" % data
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   404
   print "Received: %s" % received
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   405
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   406
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   407
The output of the example should look something like this:
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   408
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   409
Server::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   410
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   411
   $ python TCPServer.py
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   412
   127.0.0.1 wrote:
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   413
   hello world with TCP
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   414
   127.0.0.1 wrote:
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   415
   python is nice
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   416
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   417
Client::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   418
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   419
   $ python TCPClient.py hello world with TCP
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   420
   Sent:     hello world with TCP
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   421
   Received: HELLO WORLD WITH TCP
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   422
   $ python TCPClient.py python is nice
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   423
   Sent:     python is nice
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   424
   Received: PYTHON IS NICE
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   425
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   426
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   427
:class:`SocketServer.UDPServer` Example
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   428
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   429
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   430
This is the server side::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   431
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   432
   import SocketServer
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   433
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   434
   class MyUDPHandler(SocketServer.BaseRequestHandler):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   435
       """
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   436
       This class works similar to the TCP handler class, except that
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   437
       self.request consists of a pair of data and client socket, and since
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   438
       there is no connection the client address must be given explicitly
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   439
       when sending data back via sendto().
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   440
       """
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   441
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   442
       def handle(self):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   443
           data = self.request[0].strip()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   444
           socket = self.request[1]
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   445
           print "%s wrote:" % self.client_address[0]
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   446
           print data
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   447
           socket.sendto(data.upper(), self.client_address)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   448
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   449
   if __name__ == "__main__":
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   450
      HOST, PORT = "localhost", 9999
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   451
      server = SocketServer.UDPServer((HOST, PORT), BaseUDPRequestHandler)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   452
      server.serve_forever()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   453
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   454
This is the client side::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   455
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   456
   import socket
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   457
   import sys
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   458
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   459
   HOST, PORT = "localhost"
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   460
   data = " ".join(sys.argv[1:])
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   461
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   462
   # SOCK_DGRAM is the socket type to use for UDP sockets
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   463
   sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   464
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   465
   # As you can see, there is no connect() call; UDP has no connections.
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   466
   # Instead, data is directly sent to the recipient via sendto().
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   467
   sock.sendto(data + "\n", (HOST, PORT))
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   468
   received = sock.recv(1024)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   469
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   470
   print "Sent:     %s" % data
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   471
   print "Received: %s" % received
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   472
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   473
The output of the example should look exactly like for the TCP server example.
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   474
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   475
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   476
Asynchronous Mixins
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   477
~~~~~~~~~~~~~~~~~~~
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   478
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   479
To build asynchronous handlers, use the :class:`ThreadingMixIn` and
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   480
:class:`ForkingMixIn` classes.
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   481
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   482
An example for the :class:`ThreadingMixIn` class::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   483
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   484
   import socket
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   485
   import threading
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   486
   import SocketServer
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   487
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   488
   class ThreadedTCPRequestHandler(SocketServer.BaseRequestHandler):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   489
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   490
       def handle(self):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   491
           data = self.request.recv(1024)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   492
           cur_thread = threading.currentThread()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   493
           response = "%s: %s" % (cur_thread.getName(), data)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   494
           self.request.send(response)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   495
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   496
   class ThreadedTCPServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   497
       pass
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   498
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   499
   def client(ip, port, message):
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   500
       sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   501
       sock.connect((ip, port))
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   502
       sock.send(message)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   503
       response = sock.recv(1024)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   504
       print "Received: %s" % response
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   505
       sock.close()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   506
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   507
   if __name__ == "__main__":
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   508
       # Port 0 means to select an arbitrary unused port
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   509
       HOST, PORT = "localhost", 0
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   510
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   511
       server = ThreadedTCPServer((HOST, PORT), ThreadedTCPRequestHandler)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   512
       ip, port = server.server_address
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   513
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   514
       # Start a thread with the server -- that thread will then start one
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   515
       # more thread for each request
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   516
       server_thread = threading.Thread(target=server.serve_forever)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   517
       # Exit the server thread when the main thread terminates
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   518
       server_thread.setDaemon(True)
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   519
       server_thread.start()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   520
       print "Server loop running in thread:", t.getName()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   521
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   522
       client(ip, port, "Hello World 1")
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   523
       client(ip, port, "Hello World 2")
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   524
       client(ip, port, "Hello World 3")
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   525
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   526
       server.shutdown()
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   527
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   528
The output of the example should look something like this::
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   529
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   530
   $ python ThreadedTCPServer.py
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   531
   Server loop running in thread: Thread-1
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   532
   Received: Thread-2: Hello World 1
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   533
   Received: Thread-3: Hello World 2
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   534
   Received: Thread-4: Hello World 3
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   535
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   536
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   537
The :class:`ForkingMixIn` class is used in the same way, except that the server
2fb8b9db1c86 Initial QEMU (symbian-qemu-0.9.1-12) import
martin.trojer@nokia.com
parents:
diff changeset
   538
will spawn a new process for each request.