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diff --git a/devdocs/python~3.12/library%2Fsocketserver.html b/devdocs/python~3.12/library%2Fsocketserver.html new file mode 100644 index 00000000..f7ca4c12 --- /dev/null +++ b/devdocs/python~3.12/library%2Fsocketserver.html @@ -0,0 +1,304 @@ + <span id="socketserver-a-framework-for-network-servers"></span><h1>socketserver — A framework for network servers</h1> <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.12/Lib/socketserver.py">Lib/socketserver.py</a></p> <p>The <a class="reference internal" href="#module-socketserver" title="socketserver: A framework for network servers."><code>socketserver</code></a> module simplifies the task of writing network servers.</p> <div class="availability docutils container"> <p><a class="reference internal" href="https://docs.python.org/3.12/library/intro.html#availability"><span class="std std-ref">Availability</span></a>: not Emscripten, not WASI.</p> <p>This module does not work or is not available on WebAssembly platforms <code>wasm32-emscripten</code> and <code>wasm32-wasi</code>. See <a class="reference internal" href="https://docs.python.org/3.12/library/intro.html#wasm-availability"><span class="std std-ref">WebAssembly platforms</span></a> for more information.</p> </div> <p>There are four basic concrete server classes:</p> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.TCPServer"> +<code>class socketserver.TCPServer(server_address, RequestHandlerClass, bind_and_activate=True)</code> </dt> <dd> +<p>This uses the internet TCP protocol, which provides for continuous streams of data between the client and server. If <em>bind_and_activate</em> is true, the constructor automatically attempts to invoke <a class="reference internal" href="#socketserver.BaseServer.server_bind" title="socketserver.BaseServer.server_bind"><code>server_bind()</code></a> and <a class="reference internal" href="#socketserver.BaseServer.server_activate" title="socketserver.BaseServer.server_activate"><code>server_activate()</code></a>. The other parameters are passed to the <a class="reference internal" href="#socketserver.BaseServer" title="socketserver.BaseServer"><code>BaseServer</code></a> base class.</p> </dd> +</dl> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.UDPServer"> +<code>class socketserver.UDPServer(server_address, RequestHandlerClass, bind_and_activate=True)</code> </dt> <dd> +<p>This uses datagrams, which are discrete packets of information that may arrive out of order or be lost while in transit. The parameters are the same as for <a class="reference internal" href="#socketserver.TCPServer" title="socketserver.TCPServer"><code>TCPServer</code></a>.</p> </dd> +</dl> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.UnixStreamServer"> +<code>class socketserver.UnixStreamServer(server_address, RequestHandlerClass, bind_and_activate=True)</code> </dt> <dt class="sig sig-object py" id="socketserver.UnixDatagramServer"> +<code>class socketserver.UnixDatagramServer(server_address, RequestHandlerClass, bind_and_activate=True)</code> </dt> <dd> +<p>These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they’re not available on non-Unix platforms. The parameters are the same as for <a class="reference internal" href="#socketserver.TCPServer" title="socketserver.TCPServer"><code>TCPServer</code></a>.</p> </dd> +</dl> <p>These four classes process requests <em class="dfn">synchronously</em>; each request must be completed before the next request can be started. This isn’t suitable if each request takes a long time to complete, because it requires a lot of computation, or because it returns a lot of data which the client is slow to process. The solution is to create a separate process or thread to handle each request; the <a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code>ForkingMixIn</code></a> and <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> mix-in classes can be used to support asynchronous behaviour.</p> <p>Creating a server requires several steps. First, you must create a request handler class by subclassing the <a class="reference internal" href="#socketserver.BaseRequestHandler" title="socketserver.BaseRequestHandler"><code>BaseRequestHandler</code></a> class and overriding its <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method; this method will process incoming requests. Second, you must instantiate one of the server classes, passing it the server’s address and the request handler class. It is recommended to use the server in a <a class="reference internal" href="../reference/compound_stmts#with"><code>with</code></a> statement. Then call the <a class="reference internal" href="#socketserver.BaseServer.handle_request" title="socketserver.BaseServer.handle_request"><code>handle_request()</code></a> or <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code>serve_forever()</code></a> method of the server object to process one or many requests. Finally, call <a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code>server_close()</code></a> to close the socket (unless you used a <code>with</code> statement).</p> <p>When inheriting from <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> for threaded connection behavior, you should explicitly declare how you want your threads to behave on an abrupt shutdown. The <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> class defines an attribute <em>daemon_threads</em>, which indicates whether or not the server should wait for thread termination. You should set the flag explicitly if you would like threads to behave autonomously; the default is <a class="reference internal" href="constants#False" title="False"><code>False</code></a>, meaning that Python will not exit until all threads created by <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> have exited.</p> <p>Server classes have the same external methods and attributes, no matter what network protocol they use.</p> <section id="server-creation-notes"> <h2>Server Creation Notes</h2> <p>There are five classes in an inheritance diagram, four of which represent synchronous servers of four types:</p> <pre data-language="python">+------------+ +| BaseServer | ++------------+ + | + v ++-----------+ +------------------+ +| TCPServer |------->| UnixStreamServer | ++-----------+ +------------------+ + | + v ++-----------+ +--------------------+ +| UDPServer |------->| UnixDatagramServer | ++-----------+ +--------------------+ +</pre> <p>Note that <a class="reference internal" href="#socketserver.UnixDatagramServer" title="socketserver.UnixDatagramServer"><code>UnixDatagramServer</code></a> derives from <a class="reference internal" href="#socketserver.UDPServer" title="socketserver.UDPServer"><code>UDPServer</code></a>, not from <a class="reference internal" href="#socketserver.UnixStreamServer" title="socketserver.UnixStreamServer"><code>UnixStreamServer</code></a> — the only difference between an IP and a Unix server is the address family.</p> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.ForkingMixIn"> +<code>class socketserver.ForkingMixIn</code> </dt> <dt class="sig sig-object py" id="socketserver.ThreadingMixIn"> +<code>class socketserver.ThreadingMixIn</code> </dt> <dd> +<p>Forking and threading versions of each type of server can be created using these mix-in classes. For instance, <a class="reference internal" href="#socketserver.ThreadingUDPServer" title="socketserver.ThreadingUDPServer"><code>ThreadingUDPServer</code></a> is created as follows:</p> <pre data-language="python">class ThreadingUDPServer(ThreadingMixIn, UDPServer): + pass +</pre> <p>The mix-in class comes first, since it overrides a method defined in <a class="reference internal" href="#socketserver.UDPServer" title="socketserver.UDPServer"><code>UDPServer</code></a>. Setting the various attributes also changes the behavior of the underlying server mechanism.</p> <p><a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code>ForkingMixIn</code></a> and the Forking classes mentioned below are only available on POSIX platforms that support <a class="reference internal" href="os#os.fork" title="os.fork"><code>fork()</code></a>.</p> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.ThreadingMixIn.block_on_close"> +<code>block_on_close</code> </dt> <dd> +<p><a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code>ForkingMixIn.server_close</code></a> waits until all child processes complete, except if <a class="reference internal" href="#socketserver.ThreadingMixIn.block_on_close" title="socketserver.ThreadingMixIn.block_on_close"><code>block_on_close</code></a> attribute is <code>False</code>.</p> <p><a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code>ThreadingMixIn.server_close</code></a> waits until all non-daemon threads complete, except if <a class="reference internal" href="#socketserver.ThreadingMixIn.block_on_close" title="socketserver.ThreadingMixIn.block_on_close"><code>block_on_close</code></a> attribute is <code>False</code>.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.ThreadingMixIn.daemon_threads"> +<code>daemon_threads</code> </dt> <dd> +<p>For <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> use daemonic threads by setting <a class="reference internal" href="#socketserver.ThreadingMixIn.daemon_threads" title="socketserver.ThreadingMixIn.daemon_threads"><code>ThreadingMixIn.daemon_threads</code></a> to <code>True</code> to not wait until threads complete.</p> </dd> +</dl> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.7: </span><a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code>ForkingMixIn.server_close</code></a> and <a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code>ThreadingMixIn.server_close</code></a> now waits until all child processes and non-daemonic threads complete. Add a new <a class="reference internal" href="#socketserver.ThreadingMixIn.block_on_close" title="socketserver.ThreadingMixIn.block_on_close"><code>ForkingMixIn.block_on_close</code></a> class attribute to opt-in for the pre-3.7 behaviour.</p> </div> </dd> +</dl> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.ForkingTCPServer"> +<code>class socketserver.ForkingTCPServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ForkingUDPServer"> +<code>class socketserver.ForkingUDPServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ThreadingTCPServer"> +<code>class socketserver.ThreadingTCPServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ThreadingUDPServer"> +<code>class socketserver.ThreadingUDPServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ForkingUnixStreamServer"> +<code>class socketserver.ForkingUnixStreamServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ForkingUnixDatagramServer"> +<code>class socketserver.ForkingUnixDatagramServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ThreadingUnixStreamServer"> +<code>class socketserver.ThreadingUnixStreamServer</code> </dt> <dt class="sig sig-object py" id="socketserver.ThreadingUnixDatagramServer"> +<code>class socketserver.ThreadingUnixDatagramServer</code> </dt> <dd> +<p>These classes are pre-defined using the mix-in classes.</p> </dd> +</dl> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.12: </span>The <code>ForkingUnixStreamServer</code> and <code>ForkingUnixDatagramServer</code> classes were added.</p> </div> <p>To implement a service, you must derive a class from <a class="reference internal" href="#socketserver.BaseRequestHandler" title="socketserver.BaseRequestHandler"><code>BaseRequestHandler</code></a> and redefine its <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method. You can then run various versions of the service by combining one of the server classes with your request handler class. The request handler class must be different for datagram or stream services. This can be hidden by using the handler subclasses <a class="reference internal" href="#socketserver.StreamRequestHandler" title="socketserver.StreamRequestHandler"><code>StreamRequestHandler</code></a> or <a class="reference internal" href="#socketserver.DatagramRequestHandler" title="socketserver.DatagramRequestHandler"><code>DatagramRequestHandler</code></a>.</p> <p>Of course, you still have to use your head! For instance, it makes no sense to use a forking server if the service contains state in memory that can be modified by different requests, since the modifications in the child process would never reach the initial state kept in the parent process and passed to each child. In this case, you can use a threading server, but you will probably have to use locks to protect the integrity of the shared data.</p> <p>On the other hand, if you are building an HTTP server where all data is stored externally (for instance, in the file system), a synchronous class will essentially render the service “deaf” while one request is being handled – which may be for a very long time if a client is slow to receive all the data it has requested. Here a threading or forking server is appropriate.</p> <p>In some cases, it may be appropriate to process part of a request synchronously, but to finish processing in a forked child depending on the request data. This can be implemented by using a synchronous server and doing an explicit fork in the request handler class <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method.</p> <p>Another approach to handling multiple simultaneous requests in an environment that supports neither threads nor <a class="reference internal" href="os#os.fork" title="os.fork"><code>fork()</code></a> (or where these are too expensive or inappropriate for the service) is to maintain an explicit table of partially finished requests and to use <a class="reference internal" href="selectors#module-selectors" title="selectors: High-level I/O multiplexing."><code>selectors</code></a> to decide which request to work on next (or whether to handle a new incoming request). This is particularly important for stream services where each client can potentially be connected for a long time (if threads or subprocesses cannot be used).</p> </section> <section id="server-objects"> <h2>Server Objects</h2> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.BaseServer"> +<code>class socketserver.BaseServer(server_address, RequestHandlerClass)</code> </dt> <dd> +<p>This is the superclass of all Server objects in the module. It defines the interface, given below, but does not implement most of the methods, which is done in subclasses. The two parameters are stored in the respective <a class="reference internal" href="#socketserver.BaseServer.server_address" title="socketserver.BaseServer.server_address"><code>server_address</code></a> and <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code>RequestHandlerClass</code></a> attributes.</p> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.fileno"> +<code>fileno()</code> </dt> <dd> +<p>Return an integer file descriptor for the socket on which the server is listening. This function is most commonly passed to <a class="reference internal" href="selectors#module-selectors" title="selectors: High-level I/O multiplexing."><code>selectors</code></a>, to allow monitoring multiple servers in the same process.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.handle_request"> +<code>handle_request()</code> </dt> <dd> +<p>Process a single request. This function calls the following methods in order: <a class="reference internal" href="#socketserver.BaseServer.get_request" title="socketserver.BaseServer.get_request"><code>get_request()</code></a>, <a class="reference internal" href="#socketserver.BaseServer.verify_request" title="socketserver.BaseServer.verify_request"><code>verify_request()</code></a>, and <a class="reference internal" href="#socketserver.BaseServer.process_request" title="socketserver.BaseServer.process_request"><code>process_request()</code></a>. If the user-provided <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method of the handler class raises an exception, the server’s <a class="reference internal" href="#socketserver.BaseServer.handle_error" title="socketserver.BaseServer.handle_error"><code>handle_error()</code></a> method will be called. If no request is received within <a class="reference internal" href="#socketserver.BaseServer.timeout" title="socketserver.BaseServer.timeout"><code>timeout</code></a> seconds, <a class="reference internal" href="#socketserver.BaseServer.handle_timeout" title="socketserver.BaseServer.handle_timeout"><code>handle_timeout()</code></a> will be called and <a class="reference internal" href="#socketserver.BaseServer.handle_request" title="socketserver.BaseServer.handle_request"><code>handle_request()</code></a> will return.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.serve_forever"> +<code>serve_forever(poll_interval=0.5)</code> </dt> <dd> +<p>Handle requests until an explicit <a class="reference internal" href="#socketserver.BaseServer.shutdown" title="socketserver.BaseServer.shutdown"><code>shutdown()</code></a> request. Poll for shutdown every <em>poll_interval</em> seconds. Ignores the <a class="reference internal" href="#socketserver.BaseServer.timeout" title="socketserver.BaseServer.timeout"><code>timeout</code></a> attribute. It also calls <a class="reference internal" href="#socketserver.BaseServer.service_actions" title="socketserver.BaseServer.service_actions"><code>service_actions()</code></a>, which may be used by a subclass or mixin to provide actions specific to a given service. For example, the <a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code>ForkingMixIn</code></a> class uses <a class="reference internal" href="#socketserver.BaseServer.service_actions" title="socketserver.BaseServer.service_actions"><code>service_actions()</code></a> to clean up zombie child processes.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.3: </span>Added <code>service_actions</code> call to the <code>serve_forever</code> method.</p> </div> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.service_actions"> +<code>service_actions()</code> </dt> <dd> +<p>This is called in the <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code>serve_forever()</code></a> loop. This method can be overridden by subclasses or mixin classes to perform actions specific to a given service, such as cleanup actions.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.3.</span></p> </div> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.shutdown"> +<code>shutdown()</code> </dt> <dd> +<p>Tell the <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code>serve_forever()</code></a> loop to stop and wait until it does. <a class="reference internal" href="#socketserver.BaseServer.shutdown" title="socketserver.BaseServer.shutdown"><code>shutdown()</code></a> must be called while <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code>serve_forever()</code></a> is running in a different thread otherwise it will deadlock.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.server_close"> +<code>server_close()</code> </dt> <dd> +<p>Clean up the server. May be overridden.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.address_family"> +<code>address_family</code> </dt> <dd> +<p>The family of protocols to which the server’s socket belongs. Common examples are <a class="reference internal" href="socket#socket.AF_INET" title="socket.AF_INET"><code>socket.AF_INET</code></a> and <a class="reference internal" href="socket#socket.AF_UNIX" title="socket.AF_UNIX"><code>socket.AF_UNIX</code></a>.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.RequestHandlerClass"> +<code>RequestHandlerClass</code> </dt> <dd> +<p>The user-provided request handler class; an instance of this class is created for each request.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.server_address"> +<code>server_address</code> </dt> <dd> +<p>The address on which the server is listening. The format of addresses varies depending on the protocol family; see the documentation for the <a class="reference internal" href="socket#module-socket" title="socket: Low-level networking interface."><code>socket</code></a> module for details. For internet protocols, this is a tuple containing a string giving the address, and an integer port number: <code>('127.0.0.1', 80)</code>, for example.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.socket"> +<code>socket</code> </dt> <dd> +<p>The socket object on which the server will listen for incoming requests.</p> </dd> +</dl> <p>The server classes support the following class variables:</p> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.allow_reuse_address"> +<code>allow_reuse_address</code> </dt> <dd> +<p>Whether the server will allow the reuse of an address. This defaults to <a class="reference internal" href="constants#False" title="False"><code>False</code></a>, and can be set in subclasses to change the policy.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.request_queue_size"> +<code>request_queue_size</code> </dt> <dd> +<p>The size of the request queue. If it takes a long time to process a single request, any requests that arrive while the server is busy are placed into a queue, up to <a class="reference internal" href="#socketserver.BaseServer.request_queue_size" title="socketserver.BaseServer.request_queue_size"><code>request_queue_size</code></a> requests. Once the queue is full, further requests from clients will get a “Connection denied” error. The default value is usually 5, but this can be overridden by subclasses.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.socket_type"> +<code>socket_type</code> </dt> <dd> +<p>The type of socket used by the server; <a class="reference internal" href="socket#socket.SOCK_STREAM" title="socket.SOCK_STREAM"><code>socket.SOCK_STREAM</code></a> and <a class="reference internal" href="socket#socket.SOCK_DGRAM" title="socket.SOCK_DGRAM"><code>socket.SOCK_DGRAM</code></a> are two common values.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseServer.timeout"> +<code>timeout</code> </dt> <dd> +<p>Timeout duration, measured in seconds, or <a class="reference internal" href="constants#None" title="None"><code>None</code></a> if no timeout is desired. If <a class="reference internal" href="#socketserver.BaseServer.handle_request" title="socketserver.BaseServer.handle_request"><code>handle_request()</code></a> receives no incoming requests within the timeout period, the <a class="reference internal" href="#socketserver.BaseServer.handle_timeout" title="socketserver.BaseServer.handle_timeout"><code>handle_timeout()</code></a> method is called.</p> </dd> +</dl> <p>There are various server methods that can be overridden by subclasses of base server classes like <a class="reference internal" href="#socketserver.TCPServer" title="socketserver.TCPServer"><code>TCPServer</code></a>; these methods aren’t useful to external users of the server object.</p> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.finish_request"> +<code>finish_request(request, client_address)</code> </dt> <dd> +<p>Actually processes the request by instantiating <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code>RequestHandlerClass</code></a> and calling its <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.get_request"> +<code>get_request()</code> </dt> <dd> +<p>Must accept a request from the socket, and return a 2-tuple containing the <em>new</em> socket object to be used to communicate with the client, and the client’s address.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.handle_error"> +<code>handle_error(request, client_address)</code> </dt> <dd> +<p>This function is called if the <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method of a <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code>RequestHandlerClass</code></a> instance raises an exception. The default action is to print the traceback to standard error and continue handling further requests.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span>Now only called for exceptions derived from the <a class="reference internal" href="exceptions#Exception" title="Exception"><code>Exception</code></a> class.</p> </div> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.handle_timeout"> +<code>handle_timeout()</code> </dt> <dd> +<p>This function is called when the <a class="reference internal" href="#socketserver.BaseServer.timeout" title="socketserver.BaseServer.timeout"><code>timeout</code></a> attribute has been set to a value other than <a class="reference internal" href="constants#None" title="None"><code>None</code></a> and the timeout period has passed with no requests being received. The default action for forking servers is to collect the status of any child processes that have exited, while in threading servers this method does nothing.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.process_request"> +<code>process_request(request, client_address)</code> </dt> <dd> +<p>Calls <a class="reference internal" href="#socketserver.BaseServer.finish_request" title="socketserver.BaseServer.finish_request"><code>finish_request()</code></a> to create an instance of the <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code>RequestHandlerClass</code></a>. If desired, this function can create a new process or thread to handle the request; the <a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code>ForkingMixIn</code></a> and <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> classes do this.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.server_activate"> +<code>server_activate()</code> </dt> <dd> +<p>Called by the server’s constructor to activate the server. The default behavior for a TCP server just invokes <a class="reference internal" href="socket#socket.socket.listen" title="socket.socket.listen"><code>listen()</code></a> on the server’s socket. May be overridden.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.server_bind"> +<code>server_bind()</code> </dt> <dd> +<p>Called by the server’s constructor to bind the socket to the desired address. May be overridden.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseServer.verify_request"> +<code>verify_request(request, client_address)</code> </dt> <dd> +<p>Must return a Boolean value; if the value is <a class="reference internal" href="constants#True" title="True"><code>True</code></a>, the request will be processed, and if it’s <a class="reference internal" href="constants#False" title="False"><code>False</code></a>, the request will be denied. This function can be overridden to implement access controls for a server. The default implementation always returns <a class="reference internal" href="constants#True" title="True"><code>True</code></a>.</p> </dd> +</dl> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span>Support for the <a class="reference internal" href="../glossary#term-context-manager"><span class="xref std std-term">context manager</span></a> protocol was added. Exiting the context manager is equivalent to calling <a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code>server_close()</code></a>.</p> </div> </dd> +</dl> </section> <section id="request-handler-objects"> <h2>Request Handler Objects</h2> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler"> +<code>class socketserver.BaseRequestHandler</code> </dt> <dd> +<p>This is the superclass of all request handler objects. It defines the interface, given below. A concrete request handler subclass must define a new <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method, and can override any of the other methods. A new instance of the subclass is created for each request.</p> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler.setup"> +<code>setup()</code> </dt> <dd> +<p>Called before the <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method to perform any initialization actions required. The default implementation does nothing.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler.handle"> +<code>handle()</code> </dt> <dd> +<p>This function must do all the work required to service a request. The default implementation does nothing. Several instance attributes are available to it; the request is available as <a class="reference internal" href="#socketserver.BaseRequestHandler.request" title="socketserver.BaseRequestHandler.request"><code>request</code></a>; the client address as <a class="reference internal" href="#socketserver.BaseRequestHandler.client_address" title="socketserver.BaseRequestHandler.client_address"><code>client_address</code></a>; and the server instance as <a class="reference internal" href="#socketserver.BaseRequestHandler.server" title="socketserver.BaseRequestHandler.server"><code>server</code></a>, in case it needs access to per-server information.</p> <p>The type of <a class="reference internal" href="#socketserver.BaseRequestHandler.request" title="socketserver.BaseRequestHandler.request"><code>request</code></a> is different for datagram or stream services. For stream services, <a class="reference internal" href="#socketserver.BaseRequestHandler.request" title="socketserver.BaseRequestHandler.request"><code>request</code></a> is a socket object; for datagram services, <a class="reference internal" href="#socketserver.BaseRequestHandler.request" title="socketserver.BaseRequestHandler.request"><code>request</code></a> is a pair of string and socket.</p> </dd> +</dl> <dl class="py method"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler.finish"> +<code>finish()</code> </dt> <dd> +<p>Called after the <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code>handle()</code></a> method to perform any clean-up actions required. The default implementation does nothing. If <a class="reference internal" href="#socketserver.BaseRequestHandler.setup" title="socketserver.BaseRequestHandler.setup"><code>setup()</code></a> raises an exception, this function will not be called.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler.request"> +<code>request</code> </dt> <dd> +<p>The <em>new</em> <a class="reference internal" href="socket#socket.socket" title="socket.socket"><code>socket.socket</code></a> object to be used to communicate with the client.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler.client_address"> +<code>client_address</code> </dt> <dd> +<p>Client address returned by <a class="reference internal" href="#socketserver.BaseServer.get_request" title="socketserver.BaseServer.get_request"><code>BaseServer.get_request()</code></a>.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.BaseRequestHandler.server"> +<code>server</code> </dt> <dd> +<p><a class="reference internal" href="#socketserver.BaseServer" title="socketserver.BaseServer"><code>BaseServer</code></a> object used for handling the request.</p> </dd> +</dl> </dd> +</dl> <dl class="py class"> <dt class="sig sig-object py" id="socketserver.StreamRequestHandler"> +<code>class socketserver.StreamRequestHandler</code> </dt> <dt class="sig sig-object py" id="socketserver.DatagramRequestHandler"> +<code>class socketserver.DatagramRequestHandler</code> </dt> <dd> +<p>These <a class="reference internal" href="#socketserver.BaseRequestHandler" title="socketserver.BaseRequestHandler"><code>BaseRequestHandler</code></a> subclasses override the <a class="reference internal" href="#socketserver.BaseRequestHandler.setup" title="socketserver.BaseRequestHandler.setup"><code>setup()</code></a> and <a class="reference internal" href="#socketserver.BaseRequestHandler.finish" title="socketserver.BaseRequestHandler.finish"><code>finish()</code></a> methods, and provide <a class="reference internal" href="#socketserver.DatagramRequestHandler.rfile" title="socketserver.DatagramRequestHandler.rfile"><code>rfile</code></a> and <a class="reference internal" href="#socketserver.DatagramRequestHandler.wfile" title="socketserver.DatagramRequestHandler.wfile"><code>wfile</code></a> attributes.</p> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.DatagramRequestHandler.rfile"> +<code>rfile</code> </dt> <dd> +<p>A file object from which receives the request is read. Support the <a class="reference internal" href="io#io.BufferedIOBase" title="io.BufferedIOBase"><code>io.BufferedIOBase</code></a> readable interface.</p> </dd> +</dl> <dl class="py attribute"> <dt class="sig sig-object py" id="socketserver.DatagramRequestHandler.wfile"> +<code>wfile</code> </dt> <dd> +<p>A file object to which the reply is written. Support the <a class="reference internal" href="io#io.BufferedIOBase" title="io.BufferedIOBase"><code>io.BufferedIOBase</code></a> writable interface</p> </dd> +</dl> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span><a class="reference internal" href="#socketserver.DatagramRequestHandler.wfile" title="socketserver.DatagramRequestHandler.wfile"><code>wfile</code></a> also supports the <a class="reference internal" href="io#io.BufferedIOBase" title="io.BufferedIOBase"><code>io.BufferedIOBase</code></a> writable interface.</p> </div> </dd> +</dl> </section> <section id="examples"> <h2>Examples</h2> <section id="socketserver-tcpserver-example"> <h3> +<a class="reference internal" href="#socketserver.TCPServer" title="socketserver.TCPServer"><code>socketserver.TCPServer</code></a> Example</h3> <p>This is the server side:</p> <pre data-language="python">import socketserver + +class MyTCPHandler(socketserver.BaseRequestHandler): + """ + The request handler class for our server. + + It is instantiated once per connection to the server, and must + override the handle() method to implement communication to the + client. + """ + + def handle(self): + # self.request is the TCP socket connected to the client + self.data = self.request.recv(1024).strip() + print("{} wrote:".format(self.client_address[0])) + print(self.data) + # just send back the same data, but upper-cased + self.request.sendall(self.data.upper()) + +if __name__ == "__main__": + HOST, PORT = "localhost", 9999 + + # Create the server, binding to localhost on port 9999 + with socketserver.TCPServer((HOST, PORT), MyTCPHandler) as server: + # Activate the server; this will keep running until you + # interrupt the program with Ctrl-C + server.serve_forever() +</pre> <p>An alternative request handler class that makes use of streams (file-like objects that simplify communication by providing the standard file interface):</p> <pre data-language="python">class MyTCPHandler(socketserver.StreamRequestHandler): + + def handle(self): + # self.rfile is a file-like object created by the handler; + # we can now use e.g. readline() instead of raw recv() calls + self.data = self.rfile.readline().strip() + print("{} wrote:".format(self.client_address[0])) + print(self.data) + # Likewise, self.wfile is a file-like object used to write back + # to the client + self.wfile.write(self.data.upper()) +</pre> <p>The difference is that the <code>readline()</code> call in the second handler will call <code>recv()</code> multiple times until it encounters a newline character, while the single <code>recv()</code> call in the first handler will just return what has been sent from the client in one <code>sendall()</code> call.</p> <p>This is the client side:</p> <pre data-language="python">import socket +import sys + +HOST, PORT = "localhost", 9999 +data = " ".join(sys.argv[1:]) + +# Create a socket (SOCK_STREAM means a TCP socket) +with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock: + # Connect to server and send data + sock.connect((HOST, PORT)) + sock.sendall(bytes(data + "\n", "utf-8")) + + # Receive data from the server and shut down + received = str(sock.recv(1024), "utf-8") + +print("Sent: {}".format(data)) +print("Received: {}".format(received)) +</pre> <p>The output of the example should look something like this:</p> <p>Server:</p> <pre data-language="shell">$ python TCPServer.py +127.0.0.1 wrote: +b'hello world with TCP' +127.0.0.1 wrote: +b'python is nice' +</pre> <p>Client:</p> <pre data-language="shell">$ python TCPClient.py hello world with TCP +Sent: hello world with TCP +Received: HELLO WORLD WITH TCP +$ python TCPClient.py python is nice +Sent: python is nice +Received: PYTHON IS NICE +</pre> </section> <section id="socketserver-udpserver-example"> <h3> +<a class="reference internal" href="#socketserver.UDPServer" title="socketserver.UDPServer"><code>socketserver.UDPServer</code></a> Example</h3> <p>This is the server side:</p> <pre data-language="python">import socketserver + +class MyUDPHandler(socketserver.BaseRequestHandler): + """ + This class works similar to the TCP handler class, except that + self.request consists of a pair of data and client socket, and since + there is no connection the client address must be given explicitly + when sending data back via sendto(). + """ + + def handle(self): + data = self.request[0].strip() + socket = self.request[1] + print("{} wrote:".format(self.client_address[0])) + print(data) + socket.sendto(data.upper(), self.client_address) + +if __name__ == "__main__": + HOST, PORT = "localhost", 9999 + with socketserver.UDPServer((HOST, PORT), MyUDPHandler) as server: + server.serve_forever() +</pre> <p>This is the client side:</p> <pre data-language="python">import socket +import sys + +HOST, PORT = "localhost", 9999 +data = " ".join(sys.argv[1:]) + +# SOCK_DGRAM is the socket type to use for UDP sockets +sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) + +# As you can see, there is no connect() call; UDP has no connections. +# Instead, data is directly sent to the recipient via sendto(). +sock.sendto(bytes(data + "\n", "utf-8"), (HOST, PORT)) +received = str(sock.recv(1024), "utf-8") + +print("Sent: {}".format(data)) +print("Received: {}".format(received)) +</pre> <p>The output of the example should look exactly like for the TCP server example.</p> </section> <section id="asynchronous-mixins"> <h3>Asynchronous Mixins</h3> <p>To build asynchronous handlers, use the <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> and <a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code>ForkingMixIn</code></a> classes.</p> <p>An example for the <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code>ThreadingMixIn</code></a> class:</p> <pre data-language="python">import socket +import threading +import socketserver + +class ThreadedTCPRequestHandler(socketserver.BaseRequestHandler): + + def handle(self): + data = str(self.request.recv(1024), 'ascii') + cur_thread = threading.current_thread() + response = bytes("{}: {}".format(cur_thread.name, data), 'ascii') + self.request.sendall(response) + +class ThreadedTCPServer(socketserver.ThreadingMixIn, socketserver.TCPServer): + pass + +def client(ip, port, message): + with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock: + sock.connect((ip, port)) + sock.sendall(bytes(message, 'ascii')) + response = str(sock.recv(1024), 'ascii') + print("Received: {}".format(response)) + +if __name__ == "__main__": + # Port 0 means to select an arbitrary unused port + HOST, PORT = "localhost", 0 + + server = ThreadedTCPServer((HOST, PORT), ThreadedTCPRequestHandler) + with server: + ip, port = server.server_address + + # Start a thread with the server -- that thread will then start one + # more thread for each request + server_thread = threading.Thread(target=server.serve_forever) + # Exit the server thread when the main thread terminates + server_thread.daemon = True + server_thread.start() + print("Server loop running in thread:", server_thread.name) + + client(ip, port, "Hello World 1") + client(ip, port, "Hello World 2") + client(ip, port, "Hello World 3") + + server.shutdown() +</pre> <p>The output of the example should look something like this:</p> <pre data-language="shell">$ python ThreadedTCPServer.py +Server loop running in thread: Thread-1 +Received: Thread-2: Hello World 1 +Received: Thread-3: Hello World 2 +Received: Thread-4: Hello World 3 +</pre> <p>The <a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code>ForkingMixIn</code></a> class is used in the same way, except that the server will spawn a new process for each request. Available only on POSIX platforms that support <a class="reference internal" href="os#os.fork" title="os.fork"><code>fork()</code></a>.</p> </section> </section> <div class="_attribution"> + <p class="_attribution-p"> + © 2001–2023 Python Software Foundation<br>Licensed under the PSF License.<br> + <a href="https://docs.python.org/3.12/library/socketserver.html" class="_attribution-link">https://docs.python.org/3.12/library/socketserver.html</a> + </p> +</div> |