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<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">socketserver</span></code> — A framework for network servers</a><ul>
<li><a class="reference internal" href="#server-creation-notes">Server Creation Notes</a></li>
<li><a class="reference internal" href="#server-objects">Server Objects</a></li>
<li><a class="reference internal" href="#request-handler-objects">Request Handler Objects</a></li>
<li><a class="reference internal" href="#examples">Examples</a><ul>
<li><a class="reference internal" href="#socketserver-tcpserver-example"><code class="xref py py-class docutils literal notranslate"><span class="pre">socketserver.TCPServer</span></code> Example</a></li>
<li><a class="reference internal" href="#socketserver-udpserver-example"><code class="xref py py-class docutils literal notranslate"><span class="pre">socketserver.UDPServer</span></code> Example</a></li>
<li><a class="reference internal" href="#asynchronous-mixins">Asynchronous Mixins</a></li>
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<li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate"><span class="pre">socketserver</span></code> — A framework for network servers</a></li>
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<section id="module-socketserver">
<span id="socketserver-a-framework-for-network-servers"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">socketserver</span></code> — A framework for network servers<a class="headerlink" href="#module-socketserver" title="Link to this heading">¶</a></h1>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/socketserver.py">Lib/socketserver.py</a></p>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-socketserver" title="socketserver: A framework for network servers."><code class="xref py py-mod docutils literal notranslate"><span class="pre">socketserver</span></code></a> module simplifies the task of writing network servers.</p>
<div class="availability docutils container">
<p><a class="reference internal" href="intro.html#availability"><span class="std std-ref">Availability</span></a>: not WASI.</p>
<p>This module does not work or is not available on WebAssembly. See
<a class="reference internal" href="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">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">TCPServer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">server_address</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">RequestHandlerClass</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">bind_and_activate</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.TCPServer" title="Link to this definition">¶</a></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 class="xref py py-meth docutils literal notranslate"><span class="pre">server_bind()</span></code></a> and
<a class="reference internal" href="#socketserver.BaseServer.server_activate" title="socketserver.BaseServer.server_activate"><code class="xref py py-meth docutils literal notranslate"><span class="pre">server_activate()</span></code></a>. The other parameters are passed to
the <a class="reference internal" href="#socketserver.BaseServer" title="socketserver.BaseServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseServer</span></code></a> base class.</p>
</dd></dl>
<dl class="py class">
<dt class="sig sig-object py" id="socketserver.UDPServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">UDPServer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">server_address</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">RequestHandlerClass</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">bind_and_activate</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.UDPServer" title="Link to this definition">¶</a></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 class="xref py py-class docutils literal notranslate"><span class="pre">TCPServer</span></code></a>.</p>
</dd></dl>
<dl class="py class">
<dt class="sig sig-object py" id="socketserver.UnixStreamServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">UnixStreamServer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">server_address</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">RequestHandlerClass</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">bind_and_activate</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.UnixStreamServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.UnixDatagramServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">UnixDatagramServer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">server_address</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">RequestHandlerClass</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">bind_and_activate</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.UnixDatagramServer" title="Link to this definition">¶</a></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 class="xref py py-class docutils literal notranslate"><span class="pre">TCPServer</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">ForkingMixIn</span></code></a> and <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">BaseRequestHandler</span></code></a> class and
overriding its <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> statement. Then call the
<a class="reference internal" href="#socketserver.BaseServer.handle_request" title="socketserver.BaseServer.handle_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle_request()</span></code></a> or
<a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">serve_forever()</span></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 class="xref py py-meth docutils literal notranslate"><span class="pre">server_close()</span></code></a>
to close the socket (unless you used a <code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code> statement).</p>
<p>When inheriting from <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></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.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a>, meaning that
Python will not exit until all threads created by <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></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<a class="headerlink" href="#server-creation-notes" title="Link to this heading">¶</a></h2>
<p>There are five classes in an inheritance diagram, four of which represent
synchronous servers of four types:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="o">+------------+</span>
<span class="o">|</span> <span class="n">BaseServer</span> <span class="o">|</span>
<span class="o">+------------+</span>
<span class="o">|</span>
<span class="n">v</span>
<span class="o">+-----------+</span> <span class="o">+------------------+</span>
<span class="o">|</span> <span class="n">TCPServer</span> <span class="o">|------->|</span> <span class="n">UnixStreamServer</span> <span class="o">|</span>
<span class="o">+-----------+</span> <span class="o">+------------------+</span>
<span class="o">|</span>
<span class="n">v</span>
<span class="o">+-----------+</span> <span class="o">+--------------------+</span>
<span class="o">|</span> <span class="n">UDPServer</span> <span class="o">|------->|</span> <span class="n">UnixDatagramServer</span> <span class="o">|</span>
<span class="o">+-----------+</span> <span class="o">+--------------------+</span>
</pre></div>
</div>
<p>Note that <a class="reference internal" href="#socketserver.UnixDatagramServer" title="socketserver.UnixDatagramServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">UnixDatagramServer</span></code></a> derives from <a class="reference internal" href="#socketserver.UDPServer" title="socketserver.UDPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">UDPServer</span></code></a>, not from
<a class="reference internal" href="#socketserver.UnixStreamServer" title="socketserver.UnixStreamServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">UnixStreamServer</span></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">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ForkingMixIn</span></span><a class="headerlink" href="#socketserver.ForkingMixIn" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ThreadingMixIn">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ThreadingMixIn</span></span><a class="headerlink" href="#socketserver.ThreadingMixIn" title="Link to this definition">¶</a></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 class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingUDPServer</span></code></a>
is created as follows:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">ThreadingUDPServer</span><span class="p">(</span><span class="n">ThreadingMixIn</span><span class="p">,</span> <span class="n">UDPServer</span><span class="p">):</span>
<span class="k">pass</span>
</pre></div>
</div>
<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 class="xref py py-class docutils literal notranslate"><span class="pre">UDPServer</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">ForkingMixIn</span></code></a> and the Forking classes mentioned below are
only available on POSIX platforms that support <a class="reference internal" href="os.html#os.fork" title="os.fork"><code class="xref py py-func docutils literal notranslate"><span class="pre">fork()</span></code></a>.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.ThreadingMixIn.block_on_close">
<span class="sig-name descname"><span class="pre">block_on_close</span></span><a class="headerlink" href="#socketserver.ThreadingMixIn.block_on_close" title="Link to this definition">¶</a></dt>
<dd><p><a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">ForkingMixIn.server_close</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">block_on_close</span></code></a> attribute is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p>
<p><a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">ThreadingMixIn.server_close</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">block_on_close</span></code></a> attribute is <code class="docutils literal notranslate"><span class="pre">False</span></code>.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.ThreadingMixIn.daemon_threads">
<span class="sig-name descname"><span class="pre">daemon_threads</span></span><a class="headerlink" href="#socketserver.ThreadingMixIn.daemon_threads" title="Link to this definition">¶</a></dt>
<dd><p>For <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></code></a> use daemonic threads by setting
<a class="reference internal" href="#socketserver.ThreadingMixIn.daemon_threads" title="socketserver.ThreadingMixIn.daemon_threads"><code class="xref py py-data docutils literal notranslate"><span class="pre">ThreadingMixIn.daemon_threads</span></code></a>
to <code class="docutils literal notranslate"><span class="pre">True</span></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 class="xref py py-meth docutils literal notranslate"><span class="pre">ForkingMixIn.server_close</span></code></a> and
<a class="reference internal" href="#socketserver.BaseServer.server_close" title="socketserver.BaseServer.server_close"><code class="xref py py-meth docutils literal notranslate"><span class="pre">ThreadingMixIn.server_close</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">ForkingMixIn.block_on_close</span></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">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ForkingTCPServer</span></span><a class="headerlink" href="#socketserver.ForkingTCPServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ForkingUDPServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ForkingUDPServer</span></span><a class="headerlink" href="#socketserver.ForkingUDPServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ThreadingTCPServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ThreadingTCPServer</span></span><a class="headerlink" href="#socketserver.ThreadingTCPServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ThreadingUDPServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ThreadingUDPServer</span></span><a class="headerlink" href="#socketserver.ThreadingUDPServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ForkingUnixStreamServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ForkingUnixStreamServer</span></span><a class="headerlink" href="#socketserver.ForkingUnixStreamServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ForkingUnixDatagramServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ForkingUnixDatagramServer</span></span><a class="headerlink" href="#socketserver.ForkingUnixDatagramServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ThreadingUnixStreamServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ThreadingUnixStreamServer</span></span><a class="headerlink" href="#socketserver.ThreadingUnixStreamServer" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.ThreadingUnixDatagramServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">ThreadingUnixDatagramServer</span></span><a class="headerlink" href="#socketserver.ThreadingUnixDatagramServer" title="Link to this definition">¶</a></dt>
<dd><p>These classes are pre-defined using the mix-in classes.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified added">Added in version 3.12: </span>The <code class="docutils literal notranslate"><span class="pre">ForkingUnixStreamServer</span></code> and <code class="docutils literal notranslate"><span class="pre">ForkingUnixDatagramServer</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">BaseRequestHandler</span></code></a>
and redefine its <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">StreamRequestHandler</span></code></a> or <a class="reference internal" href="#socketserver.DatagramRequestHandler" title="socketserver.DatagramRequestHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">DatagramRequestHandler</span></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 class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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.html#os.fork" title="os.fork"><code class="xref py py-func docutils literal notranslate"><span class="pre">fork()</span></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.html#module-selectors" title="selectors: High-level I/O multiplexing."><code class="xref py py-mod docutils literal notranslate"><span class="pre">selectors</span></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<a class="headerlink" href="#server-objects" title="Link to this heading">¶</a></h2>
<dl class="py class">
<dt class="sig sig-object py" id="socketserver.BaseServer">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">BaseServer</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">server_address</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">RequestHandlerClass</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer" title="Link to this definition">¶</a></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 class="xref py py-attr docutils literal notranslate"><span class="pre">server_address</span></code></a> and <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code class="xref py py-attr docutils literal notranslate"><span class="pre">RequestHandlerClass</span></code></a> attributes.</p>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.fileno">
<span class="sig-name descname"><span class="pre">fileno</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.fileno" title="Link to this definition">¶</a></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.html#module-selectors" title="selectors: High-level I/O multiplexing."><code class="xref py py-mod docutils literal notranslate"><span class="pre">selectors</span></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">
<span class="sig-name descname"><span class="pre">handle_request</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.handle_request" title="Link to this definition">¶</a></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 class="xref py py-meth docutils literal notranslate"><span class="pre">get_request()</span></code></a>, <a class="reference internal" href="#socketserver.BaseServer.verify_request" title="socketserver.BaseServer.verify_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">verify_request()</span></code></a>, and
<a class="reference internal" href="#socketserver.BaseServer.process_request" title="socketserver.BaseServer.process_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">process_request()</span></code></a>. If the user-provided
<a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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 class="xref py py-meth docutils literal notranslate"><span class="pre">handle_error()</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">timeout</span></code></a>
seconds, <a class="reference internal" href="#socketserver.BaseServer.handle_timeout" title="socketserver.BaseServer.handle_timeout"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle_timeout()</span></code></a> will be called and <a class="reference internal" href="#socketserver.BaseServer.handle_request" title="socketserver.BaseServer.handle_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle_request()</span></code></a>
will return.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.serve_forever">
<span class="sig-name descname"><span class="pre">serve_forever</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">poll_interval</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">0.5</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.serve_forever" title="Link to this definition">¶</a></dt>
<dd><p>Handle requests until an explicit <a class="reference internal" href="#socketserver.BaseServer.shutdown" title="socketserver.BaseServer.shutdown"><code class="xref py py-meth docutils literal notranslate"><span class="pre">shutdown()</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">timeout</span></code></a> attribute. It
also calls <a class="reference internal" href="#socketserver.BaseServer.service_actions" title="socketserver.BaseServer.service_actions"><code class="xref py py-meth docutils literal notranslate"><span class="pre">service_actions()</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">ForkingMixIn</span></code></a> class uses <a class="reference internal" href="#socketserver.BaseServer.service_actions" title="socketserver.BaseServer.service_actions"><code class="xref py py-meth docutils literal notranslate"><span class="pre">service_actions()</span></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 class="docutils literal notranslate"><span class="pre">service_actions</span></code> call to the <code class="docutils literal notranslate"><span class="pre">serve_forever</span></code> method.</p>
</div>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.service_actions">
<span class="sig-name descname"><span class="pre">service_actions</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.service_actions" title="Link to this definition">¶</a></dt>
<dd><p>This is called in the <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">serve_forever()</span></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">Added in version 3.3.</span></p>
</div>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.shutdown">
<span class="sig-name descname"><span class="pre">shutdown</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.shutdown" title="Link to this definition">¶</a></dt>
<dd><p>Tell the <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">serve_forever()</span></code></a> loop to stop and wait until it does.
<a class="reference internal" href="#socketserver.BaseServer.shutdown" title="socketserver.BaseServer.shutdown"><code class="xref py py-meth docutils literal notranslate"><span class="pre">shutdown()</span></code></a> must be called while <a class="reference internal" href="#socketserver.BaseServer.serve_forever" title="socketserver.BaseServer.serve_forever"><code class="xref py py-meth docutils literal notranslate"><span class="pre">serve_forever()</span></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">
<span class="sig-name descname"><span class="pre">server_close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.server_close" title="Link to this definition">¶</a></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">
<span class="sig-name descname"><span class="pre">address_family</span></span><a class="headerlink" href="#socketserver.BaseServer.address_family" title="Link to this definition">¶</a></dt>
<dd><p>The family of protocols to which the server’s socket belongs. Common
examples are <a class="reference internal" href="socket.html#socket.AF_INET" title="socket.AF_INET"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.AF_INET</span></code></a>, <a class="reference internal" href="socket.html#socket.AF_INET6" title="socket.AF_INET6"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.AF_INET6</span></code></a>, and
<a class="reference internal" href="socket.html#socket.AF_UNIX" title="socket.AF_UNIX"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.AF_UNIX</span></code></a>. Subclass the TCP or UDP server classes in this
module with class attribute <code class="docutils literal notranslate"><span class="pre">address_family</span> <span class="pre">=</span> <span class="pre">AF_INET6</span></code> set if you
want IPv6 server classes.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.BaseServer.RequestHandlerClass">
<span class="sig-name descname"><span class="pre">RequestHandlerClass</span></span><a class="headerlink" href="#socketserver.BaseServer.RequestHandlerClass" title="Link to this definition">¶</a></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">
<span class="sig-name descname"><span class="pre">server_address</span></span><a class="headerlink" href="#socketserver.BaseServer.server_address" title="Link to this definition">¶</a></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.html#module-socket" title="socket: Low-level networking interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">socket</span></code></a> module
for details. For internet protocols, this is a tuple containing a string giving
the address, and an integer port number: <code class="docutils literal notranslate"><span class="pre">('127.0.0.1',</span> <span class="pre">80)</span></code>, for example.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.BaseServer.socket">
<span class="sig-name descname"><span class="pre">socket</span></span><a class="headerlink" href="#socketserver.BaseServer.socket" title="Link to this definition">¶</a></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">
<span class="sig-name descname"><span class="pre">allow_reuse_address</span></span><a class="headerlink" href="#socketserver.BaseServer.allow_reuse_address" title="Link to this definition">¶</a></dt>
<dd><p>Whether the server will allow the reuse of an address. This defaults to
<a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></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">
<span class="sig-name descname"><span class="pre">request_queue_size</span></span><a class="headerlink" href="#socketserver.BaseServer.request_queue_size" title="Link to this definition">¶</a></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 class="xref py py-attr docutils literal notranslate"><span class="pre">request_queue_size</span></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">
<span class="sig-name descname"><span class="pre">socket_type</span></span><a class="headerlink" href="#socketserver.BaseServer.socket_type" title="Link to this definition">¶</a></dt>
<dd><p>The type of socket used by the server; <a class="reference internal" href="socket.html#socket.SOCK_STREAM" title="socket.SOCK_STREAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.SOCK_STREAM</span></code></a> and
<a class="reference internal" href="socket.html#socket.SOCK_DGRAM" title="socket.SOCK_DGRAM"><code class="xref py py-const docutils literal notranslate"><span class="pre">socket.SOCK_DGRAM</span></code></a> are two common values.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.BaseServer.timeout">
<span class="sig-name descname"><span class="pre">timeout</span></span><a class="headerlink" href="#socketserver.BaseServer.timeout" title="Link to this definition">¶</a></dt>
<dd><p>Timeout duration, measured in seconds, or <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a> if no timeout is
desired. If <a class="reference internal" href="#socketserver.BaseServer.handle_request" title="socketserver.BaseServer.handle_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle_request()</span></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 class="xref py py-meth docutils literal notranslate"><span class="pre">handle_timeout()</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">TCPServer</span></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">
<span class="sig-name descname"><span class="pre">finish_request</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">request</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">client_address</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.finish_request" title="Link to this definition">¶</a></dt>
<dd><p>Actually processes the request by instantiating <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code class="xref py py-attr docutils literal notranslate"><span class="pre">RequestHandlerClass</span></code></a> and
calling its <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></code></a> method.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.get_request">
<span class="sig-name descname"><span class="pre">get_request</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.get_request" title="Link to this definition">¶</a></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">
<span class="sig-name descname"><span class="pre">handle_error</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">request</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">client_address</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.handle_error" title="Link to this definition">¶</a></dt>
<dd><p>This function is called if the <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></code></a>
method of a <a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code class="xref py py-attr docutils literal notranslate"><span class="pre">RequestHandlerClass</span></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.html#Exception" title="Exception"><code class="xref py py-exc docutils literal notranslate"><span class="pre">Exception</span></code></a>
class.</p>
</div>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.handle_timeout">
<span class="sig-name descname"><span class="pre">handle_timeout</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.handle_timeout" title="Link to this definition">¶</a></dt>
<dd><p>This function is called when the <a class="reference internal" href="#socketserver.BaseServer.timeout" title="socketserver.BaseServer.timeout"><code class="xref py py-attr docutils literal notranslate"><span class="pre">timeout</span></code></a> attribute has been set to a
value other than <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></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">
<span class="sig-name descname"><span class="pre">process_request</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">request</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">client_address</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.process_request" title="Link to this definition">¶</a></dt>
<dd><p>Calls <a class="reference internal" href="#socketserver.BaseServer.finish_request" title="socketserver.BaseServer.finish_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">finish_request()</span></code></a> to create an instance of the
<a class="reference internal" href="#socketserver.BaseServer.RequestHandlerClass" title="socketserver.BaseServer.RequestHandlerClass"><code class="xref py py-attr docutils literal notranslate"><span class="pre">RequestHandlerClass</span></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 class="xref py py-class docutils literal notranslate"><span class="pre">ForkingMixIn</span></code></a> and
<a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></code></a> classes do this.</p>
</dd></dl>
<dl class="py method">
<dt class="sig sig-object py" id="socketserver.BaseServer.server_activate">
<span class="sig-name descname"><span class="pre">server_activate</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.server_activate" title="Link to this definition">¶</a></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.html#socket.socket.listen" title="socket.socket.listen"><code class="xref py py-meth docutils literal notranslate"><span class="pre">listen()</span></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">
<span class="sig-name descname"><span class="pre">server_bind</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.server_bind" title="Link to this definition">¶</a></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">
<span class="sig-name descname"><span class="pre">verify_request</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">request</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">client_address</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseServer.verify_request" title="Link to this definition">¶</a></dt>
<dd><p>Must return a Boolean value; if the value is <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a>, the request will
be processed, and if it’s <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></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.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></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.html#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 class="xref py py-meth docutils literal notranslate"><span class="pre">server_close()</span></code></a>.</p>
</div>
</dd></dl>
</section>
<section id="request-handler-objects">
<h2>Request Handler Objects<a class="headerlink" href="#request-handler-objects" title="Link to this heading">¶</a></h2>
<dl class="py class">
<dt class="sig sig-object py" id="socketserver.BaseRequestHandler">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">BaseRequestHandler</span></span><a class="headerlink" href="#socketserver.BaseRequestHandler" title="Link to this definition">¶</a></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 class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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">
<span class="sig-name descname"><span class="pre">setup</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseRequestHandler.setup" title="Link to this definition">¶</a></dt>
<dd><p>Called before the <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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">
<span class="sig-name descname"><span class="pre">handle</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseRequestHandler.handle" title="Link to this definition">¶</a></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 class="xref py py-attr docutils literal notranslate"><span class="pre">request</span></code></a>; the client
address as <a class="reference internal" href="#socketserver.BaseRequestHandler.client_address" title="socketserver.BaseRequestHandler.client_address"><code class="xref py py-attr docutils literal notranslate"><span class="pre">client_address</span></code></a>; and the server instance as
<a class="reference internal" href="#socketserver.BaseRequestHandler.server" title="socketserver.BaseRequestHandler.server"><code class="xref py py-attr docutils literal notranslate"><span class="pre">server</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">request</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">request</span></code></a> is a socket object; for
datagram services, <a class="reference internal" href="#socketserver.BaseRequestHandler.request" title="socketserver.BaseRequestHandler.request"><code class="xref py py-attr docutils literal notranslate"><span class="pre">request</span></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">
<span class="sig-name descname"><span class="pre">finish</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#socketserver.BaseRequestHandler.finish" title="Link to this definition">¶</a></dt>
<dd><p>Called after the <a class="reference internal" href="#socketserver.BaseRequestHandler.handle" title="socketserver.BaseRequestHandler.handle"><code class="xref py py-meth docutils literal notranslate"><span class="pre">handle()</span></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 class="xref py py-meth docutils literal notranslate"><span class="pre">setup()</span></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">
<span class="sig-name descname"><span class="pre">request</span></span><a class="headerlink" href="#socketserver.BaseRequestHandler.request" title="Link to this definition">¶</a></dt>
<dd><p>The <em>new</em> <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate"><span class="pre">socket.socket</span></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">
<span class="sig-name descname"><span class="pre">client_address</span></span><a class="headerlink" href="#socketserver.BaseRequestHandler.client_address" title="Link to this definition">¶</a></dt>
<dd><p>Client address returned by <a class="reference internal" href="#socketserver.BaseServer.get_request" title="socketserver.BaseServer.get_request"><code class="xref py py-meth docutils literal notranslate"><span class="pre">BaseServer.get_request()</span></code></a>.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.BaseRequestHandler.server">
<span class="sig-name descname"><span class="pre">server</span></span><a class="headerlink" href="#socketserver.BaseRequestHandler.server" title="Link to this definition">¶</a></dt>
<dd><p><a class="reference internal" href="#socketserver.BaseServer" title="socketserver.BaseServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseServer</span></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">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">StreamRequestHandler</span></span><a class="headerlink" href="#socketserver.StreamRequestHandler" title="Link to this definition">¶</a></dt>
<dt class="sig sig-object py" id="socketserver.DatagramRequestHandler">
<em class="property"><span class="k"><span class="pre">class</span></span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">socketserver.</span></span><span class="sig-name descname"><span class="pre">DatagramRequestHandler</span></span><a class="headerlink" href="#socketserver.DatagramRequestHandler" title="Link to this definition">¶</a></dt>
<dd><p>These <a class="reference internal" href="#socketserver.BaseRequestHandler" title="socketserver.BaseRequestHandler"><code class="xref py py-class docutils literal notranslate"><span class="pre">BaseRequestHandler</span></code></a> subclasses override the
<a class="reference internal" href="#socketserver.BaseRequestHandler.setup" title="socketserver.BaseRequestHandler.setup"><code class="xref py py-meth docutils literal notranslate"><span class="pre">setup()</span></code></a> and <a class="reference internal" href="#socketserver.BaseRequestHandler.finish" title="socketserver.BaseRequestHandler.finish"><code class="xref py py-meth docutils literal notranslate"><span class="pre">finish()</span></code></a>
methods, and provide <a class="reference internal" href="#socketserver.DatagramRequestHandler.rfile" title="socketserver.DatagramRequestHandler.rfile"><code class="xref py py-attr docutils literal notranslate"><span class="pre">rfile</span></code></a> and <a class="reference internal" href="#socketserver.DatagramRequestHandler.wfile" title="socketserver.DatagramRequestHandler.wfile"><code class="xref py py-attr docutils literal notranslate"><span class="pre">wfile</span></code></a> attributes.</p>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.DatagramRequestHandler.rfile">
<span class="sig-name descname"><span class="pre">rfile</span></span><a class="headerlink" href="#socketserver.DatagramRequestHandler.rfile" title="Link to this definition">¶</a></dt>
<dd><p>A file object from which receives the request is read.
Support the <a class="reference internal" href="io.html#io.BufferedIOBase" title="io.BufferedIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedIOBase</span></code></a> readable interface.</p>
</dd></dl>
<dl class="py attribute">
<dt class="sig sig-object py" id="socketserver.DatagramRequestHandler.wfile">
<span class="sig-name descname"><span class="pre">wfile</span></span><a class="headerlink" href="#socketserver.DatagramRequestHandler.wfile" title="Link to this definition">¶</a></dt>
<dd><p>A file object to which the reply is written.
Support the <a class="reference internal" href="io.html#io.BufferedIOBase" title="io.BufferedIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedIOBase</span></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 class="xref py py-attr docutils literal notranslate"><span class="pre">wfile</span></code></a> also supports the
<a class="reference internal" href="io.html#io.BufferedIOBase" title="io.BufferedIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedIOBase</span></code></a> writable interface.</p>
</div>
</dd></dl>
</section>
<section id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading">¶</a></h2>
<section id="socketserver-tcpserver-example">
<h3><a class="reference internal" href="#socketserver.TCPServer" title="socketserver.TCPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">socketserver.TCPServer</span></code></a> Example<a class="headerlink" href="#socketserver-tcpserver-example" title="Link to this heading">¶</a></h3>
<p>This is the server side:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">socketserver</span>
<span class="k">class</span><span class="w"> </span><span class="nc">MyTCPHandler</span><span class="p">(</span><span class="n">socketserver</span><span class="o">.</span><span class="n">BaseRequestHandler</span><span class="p">):</span>
<span class="w"> </span><span class="sd">"""</span>
<span class="sd"> The request handler class for our server.</span>
<span class="sd"> It is instantiated once per connection to the server, and must</span>
<span class="sd"> override the handle() method to implement communication to the</span>
<span class="sd"> client.</span>
<span class="sd"> """</span>
<span class="k">def</span><span class="w"> </span><span class="nf">handle</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c1"># self.request is the TCP socket connected to the client</span>
<span class="n">pieces</span> <span class="o">=</span> <span class="p">[</span><span class="sa">b</span><span class="s1">''</span><span class="p">]</span>
<span class="n">total</span> <span class="o">=</span> <span class="mi">0</span>
<span class="k">while</span> <span class="sa">b</span><span class="s1">'</span><span class="se">\n</span><span class="s1">'</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">pieces</span><span class="p">[</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span> <span class="ow">and</span> <span class="n">total</span> <span class="o"><</span> <span class="mi">10_000</span><span class="p">:</span>
<span class="n">pieces</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">2000</span><span class="p">))</span>
<span class="n">total</span> <span class="o">+=</span> <span class="nb">len</span><span class="p">(</span><span class="n">pieces</span><span class="p">[</span><span class="o">-</span><span class="mi">1</span><span class="p">])</span>
<span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="sa">b</span><span class="s1">''</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">pieces</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">"Received from </span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">client_address</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="si">}</span><span class="s2">:"</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s2">"utf-8"</span><span class="p">))</span>
<span class="c1"># just send back the same data, but upper-cased</span>
<span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="o">.</span><span class="n">sendall</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">upper</span><span class="p">())</span>
<span class="c1"># after we return, the socket will be closed.</span>
<span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
<span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span> <span class="o">=</span> <span class="s2">"localhost"</span><span class="p">,</span> <span class="mi">9999</span>
<span class="c1"># Create the server, binding to localhost on port 9999</span>
<span class="k">with</span> <span class="n">socketserver</span><span class="o">.</span><span class="n">TCPServer</span><span class="p">((</span><span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span><span class="p">),</span> <span class="n">MyTCPHandler</span><span class="p">)</span> <span class="k">as</span> <span class="n">server</span><span class="p">:</span>
<span class="c1"># Activate the server; this will keep running until you</span>
<span class="c1"># interrupt the program with Ctrl-C</span>
<span class="n">server</span><span class="o">.</span><span class="n">serve_forever</span><span class="p">()</span>
</pre></div>
</div>
<p>An alternative request handler class that makes use of streams (file-like
objects that simplify communication by providing the standard file interface):</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span><span class="w"> </span><span class="nc">MyTCPHandler</span><span class="p">(</span><span class="n">socketserver</span><span class="o">.</span><span class="n">StreamRequestHandler</span><span class="p">):</span>
<span class="k">def</span><span class="w"> </span><span class="nf">handle</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c1"># self.rfile is a file-like object created by the handler.</span>
<span class="c1"># We can now use e.g. readline() instead of raw recv() calls.</span>
<span class="c1"># We limit ourselves to 10000 bytes to avoid abuse by the sender.</span>
<span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">rfile</span><span class="o">.</span><span class="n">readline</span><span class="p">(</span><span class="mi">10000</span><span class="p">)</span><span class="o">.</span><span class="n">rstrip</span><span class="p">()</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">"</span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">client_address</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="si">}</span><span class="s2"> wrote:"</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="s2">"utf-8"</span><span class="p">))</span>
<span class="c1"># Likewise, self.wfile is a file-like object used to write back</span>
<span class="c1"># to the client</span>
<span class="bp">self</span><span class="o">.</span><span class="n">wfile</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="o">.</span><span class="n">upper</span><span class="p">())</span>
</pre></div>
</div>
<p>The difference is that the <code class="docutils literal notranslate"><span class="pre">readline()</span></code> call in the second handler will call
<code class="docutils literal notranslate"><span class="pre">recv()</span></code> multiple times until it encounters a newline character, while the
the first handler had to use a <code class="docutils literal notranslate"><span class="pre">recv()</span></code> loop to accumulate data until a
newline itself. If it had just used a single <code class="docutils literal notranslate"><span class="pre">recv()</span></code> without the loop it
would just have returned what has been received so far from the client.
TCP is stream based: data arrives in the order it was sent, but there no
correlation between client <code class="docutils literal notranslate"><span class="pre">send()</span></code> or <code class="docutils literal notranslate"><span class="pre">sendall()</span></code> calls and the number
of <code class="docutils literal notranslate"><span class="pre">recv()</span></code> calls on the server required to receive it.</p>
<p>This is the client side:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">socket</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">sys</span>
<span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span> <span class="o">=</span> <span class="s2">"localhost"</span><span class="p">,</span> <span class="mi">9999</span>
<span class="n">data</span> <span class="o">=</span> <span class="s2">" "</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">argv</span><span class="p">[</span><span class="mi">1</span><span class="p">:])</span>
<span class="c1"># Create a socket (SOCK_STREAM means a TCP socket)</span>
<span class="k">with</span> <span class="n">socket</span><span class="o">.</span><span class="n">socket</span><span class="p">(</span><span class="n">socket</span><span class="o">.</span><span class="n">AF_INET</span><span class="p">,</span> <span class="n">socket</span><span class="o">.</span><span class="n">SOCK_STREAM</span><span class="p">)</span> <span class="k">as</span> <span class="n">sock</span><span class="p">:</span>
<span class="c1"># Connect to server and send data</span>
<span class="n">sock</span><span class="o">.</span><span class="n">connect</span><span class="p">((</span><span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span><span class="p">))</span>
<span class="n">sock</span><span class="o">.</span><span class="n">sendall</span><span class="p">(</span><span class="nb">bytes</span><span class="p">(</span><span class="n">data</span><span class="p">,</span> <span class="s2">"utf-8"</span><span class="p">))</span>
<span class="n">sock</span><span class="o">.</span><span class="n">sendall</span><span class="p">(</span><span class="sa">b</span><span class="s2">"</span><span class="se">\n</span><span class="s2">"</span><span class="p">)</span>
<span class="c1"># Receive data from the server and shut down</span>
<span class="n">received</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="n">sock</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">1024</span><span class="p">),</span> <span class="s2">"utf-8"</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Sent: "</span><span class="p">,</span> <span class="n">data</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Received:"</span><span class="p">,</span> <span class="n">received</span><span class="p">)</span>
</pre></div>
</div>
<p>The output of the example should look something like this:</p>
<p>Server:</p>
<div class="highlight-shell-session notranslate"><div class="highlight"><pre><span></span><span class="gp">$ </span>python<span class="w"> </span>TCPServer.py
<span class="go">127.0.0.1 wrote:</span>
<span class="go">b'hello world with TCP'</span>
<span class="go">127.0.0.1 wrote:</span>
<span class="go">b'python is nice'</span>
</pre></div>
</div>
<p>Client:</p>
<div class="highlight-shell-session notranslate"><div class="highlight"><pre><span></span><span class="gp">$ </span>python<span class="w"> </span>TCPClient.py<span class="w"> </span>hello<span class="w"> </span>world<span class="w"> </span>with<span class="w"> </span>TCP
<span class="go">Sent: hello world with TCP</span>
<span class="go">Received: HELLO WORLD WITH TCP</span>
<span class="gp">$ </span>python<span class="w"> </span>TCPClient.py<span class="w"> </span>python<span class="w"> </span>is<span class="w"> </span>nice
<span class="go">Sent: python is nice</span>
<span class="go">Received: PYTHON IS NICE</span>
</pre></div>
</div>
</section>
<section id="socketserver-udpserver-example">
<h3><a class="reference internal" href="#socketserver.UDPServer" title="socketserver.UDPServer"><code class="xref py py-class docutils literal notranslate"><span class="pre">socketserver.UDPServer</span></code></a> Example<a class="headerlink" href="#socketserver-udpserver-example" title="Link to this heading">¶</a></h3>
<p>This is the server side:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">socketserver</span>
<span class="k">class</span><span class="w"> </span><span class="nc">MyUDPHandler</span><span class="p">(</span><span class="n">socketserver</span><span class="o">.</span><span class="n">BaseRequestHandler</span><span class="p">):</span>
<span class="w"> </span><span class="sd">"""</span>
<span class="sd"> This class works similar to the TCP handler class, except that</span>
<span class="sd"> self.request consists of a pair of data and client socket, and since</span>
<span class="sd"> there is no connection the client address must be given explicitly</span>
<span class="sd"> when sending data back via sendto().</span>
<span class="sd"> """</span>
<span class="k">def</span><span class="w"> </span><span class="nf">handle</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">data</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">strip</span><span class="p">()</span>
<span class="n">socket</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>
<span class="nb">print</span><span class="p">(</span><span class="sa">f</span><span class="s2">"</span><span class="si">{</span><span class="bp">self</span><span class="o">.</span><span class="n">client_address</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="si">}</span><span class="s2"> wrote:"</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="n">data</span><span class="p">)</span>
<span class="n">socket</span><span class="o">.</span><span class="n">sendto</span><span class="p">(</span><span class="n">data</span><span class="o">.</span><span class="n">upper</span><span class="p">(),</span> <span class="bp">self</span><span class="o">.</span><span class="n">client_address</span><span class="p">)</span>
<span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
<span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span> <span class="o">=</span> <span class="s2">"localhost"</span><span class="p">,</span> <span class="mi">9999</span>
<span class="k">with</span> <span class="n">socketserver</span><span class="o">.</span><span class="n">UDPServer</span><span class="p">((</span><span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span><span class="p">),</span> <span class="n">MyUDPHandler</span><span class="p">)</span> <span class="k">as</span> <span class="n">server</span><span class="p">:</span>
<span class="n">server</span><span class="o">.</span><span class="n">serve_forever</span><span class="p">()</span>
</pre></div>
</div>
<p>This is the client side:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">socket</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">sys</span>
<span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span> <span class="o">=</span> <span class="s2">"localhost"</span><span class="p">,</span> <span class="mi">9999</span>
<span class="n">data</span> <span class="o">=</span> <span class="s2">" "</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">sys</span><span class="o">.</span><span class="n">argv</span><span class="p">[</span><span class="mi">1</span><span class="p">:])</span>
<span class="c1"># SOCK_DGRAM is the socket type to use for UDP sockets</span>
<span class="n">sock</span> <span class="o">=</span> <span class="n">socket</span><span class="o">.</span><span class="n">socket</span><span class="p">(</span><span class="n">socket</span><span class="o">.</span><span class="n">AF_INET</span><span class="p">,</span> <span class="n">socket</span><span class="o">.</span><span class="n">SOCK_DGRAM</span><span class="p">)</span>
<span class="c1"># As you can see, there is no connect() call; UDP has no connections.</span>
<span class="c1"># Instead, data is directly sent to the recipient via sendto().</span>
<span class="n">sock</span><span class="o">.</span><span class="n">sendto</span><span class="p">(</span><span class="nb">bytes</span><span class="p">(</span><span class="n">data</span> <span class="o">+</span> <span class="s2">"</span><span class="se">\n</span><span class="s2">"</span><span class="p">,</span> <span class="s2">"utf-8"</span><span class="p">),</span> <span class="p">(</span><span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span><span class="p">))</span>
<span class="n">received</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="n">sock</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">1024</span><span class="p">),</span> <span class="s2">"utf-8"</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Sent: "</span><span class="p">,</span> <span class="n">data</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Received:"</span><span class="p">,</span> <span class="n">received</span><span class="p">)</span>
</pre></div>
</div>
<p>The output of the example should look exactly like for the TCP server example.</p>
</section>
<section id="asynchronous-mixins">
<h3>Asynchronous Mixins<a class="headerlink" href="#asynchronous-mixins" title="Link to this heading">¶</a></h3>
<p>To build asynchronous handlers, use the <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></code></a> and
<a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ForkingMixIn</span></code></a> classes.</p>
<p>An example for the <a class="reference internal" href="#socketserver.ThreadingMixIn" title="socketserver.ThreadingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ThreadingMixIn</span></code></a> class:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span><span class="w"> </span><span class="nn">socket</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">threading</span>
<span class="kn">import</span><span class="w"> </span><span class="nn">socketserver</span>
<span class="k">class</span><span class="w"> </span><span class="nc">ThreadedTCPRequestHandler</span><span class="p">(</span><span class="n">socketserver</span><span class="o">.</span><span class="n">BaseRequestHandler</span><span class="p">):</span>
<span class="k">def</span><span class="w"> </span><span class="nf">handle</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">data</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">1024</span><span class="p">),</span> <span class="s1">'ascii'</span><span class="p">)</span>
<span class="n">cur_thread</span> <span class="o">=</span> <span class="n">threading</span><span class="o">.</span><span class="n">current_thread</span><span class="p">()</span>
<span class="n">response</span> <span class="o">=</span> <span class="nb">bytes</span><span class="p">(</span><span class="s2">"</span><span class="si">{}</span><span class="s2">: </span><span class="si">{}</span><span class="s2">"</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">cur_thread</span><span class="o">.</span><span class="n">name</span><span class="p">,</span> <span class="n">data</span><span class="p">),</span> <span class="s1">'ascii'</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="o">.</span><span class="n">sendall</span><span class="p">(</span><span class="n">response</span><span class="p">)</span>
<span class="k">class</span><span class="w"> </span><span class="nc">ThreadedTCPServer</span><span class="p">(</span><span class="n">socketserver</span><span class="o">.</span><span class="n">ThreadingMixIn</span><span class="p">,</span> <span class="n">socketserver</span><span class="o">.</span><span class="n">TCPServer</span><span class="p">):</span>
<span class="k">pass</span>
<span class="k">def</span><span class="w"> </span><span class="nf">client</span><span class="p">(</span><span class="n">ip</span><span class="p">,</span> <span class="n">port</span><span class="p">,</span> <span class="n">message</span><span class="p">):</span>
<span class="k">with</span> <span class="n">socket</span><span class="o">.</span><span class="n">socket</span><span class="p">(</span><span class="n">socket</span><span class="o">.</span><span class="n">AF_INET</span><span class="p">,</span> <span class="n">socket</span><span class="o">.</span><span class="n">SOCK_STREAM</span><span class="p">)</span> <span class="k">as</span> <span class="n">sock</span><span class="p">:</span>
<span class="n">sock</span><span class="o">.</span><span class="n">connect</span><span class="p">((</span><span class="n">ip</span><span class="p">,</span> <span class="n">port</span><span class="p">))</span>
<span class="n">sock</span><span class="o">.</span><span class="n">sendall</span><span class="p">(</span><span class="nb">bytes</span><span class="p">(</span><span class="n">message</span><span class="p">,</span> <span class="s1">'ascii'</span><span class="p">))</span>
<span class="n">response</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="n">sock</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="mi">1024</span><span class="p">),</span> <span class="s1">'ascii'</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Received: </span><span class="si">{}</span><span class="s2">"</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">response</span><span class="p">))</span>
<span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
<span class="c1"># Port 0 means to select an arbitrary unused port</span>
<span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span> <span class="o">=</span> <span class="s2">"localhost"</span><span class="p">,</span> <span class="mi">0</span>
<span class="n">server</span> <span class="o">=</span> <span class="n">ThreadedTCPServer</span><span class="p">((</span><span class="n">HOST</span><span class="p">,</span> <span class="n">PORT</span><span class="p">),</span> <span class="n">ThreadedTCPRequestHandler</span><span class="p">)</span>
<span class="k">with</span> <span class="n">server</span><span class="p">:</span>
<span class="n">ip</span><span class="p">,</span> <span class="n">port</span> <span class="o">=</span> <span class="n">server</span><span class="o">.</span><span class="n">server_address</span>
<span class="c1"># Start a thread with the server -- that thread will then start one</span>
<span class="c1"># more thread for each request</span>
<span class="n">server_thread</span> <span class="o">=</span> <span class="n">threading</span><span class="o">.</span><span class="n">Thread</span><span class="p">(</span><span class="n">target</span><span class="o">=</span><span class="n">server</span><span class="o">.</span><span class="n">serve_forever</span><span class="p">)</span>
<span class="c1"># Exit the server thread when the main thread terminates</span>
<span class="n">server_thread</span><span class="o">.</span><span class="n">daemon</span> <span class="o">=</span> <span class="kc">True</span>
<span class="n">server_thread</span><span class="o">.</span><span class="n">start</span><span class="p">()</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Server loop running in thread:"</span><span class="p">,</span> <span class="n">server_thread</span><span class="o">.</span><span class="n">name</span><span class="p">)</span>
<span class="n">client</span><span class="p">(</span><span class="n">ip</span><span class="p">,</span> <span class="n">port</span><span class="p">,</span> <span class="s2">"Hello World 1"</span><span class="p">)</span>
<span class="n">client</span><span class="p">(</span><span class="n">ip</span><span class="p">,</span> <span class="n">port</span><span class="p">,</span> <span class="s2">"Hello World 2"</span><span class="p">)</span>
<span class="n">client</span><span class="p">(</span><span class="n">ip</span><span class="p">,</span> <span class="n">port</span><span class="p">,</span> <span class="s2">"Hello World 3"</span><span class="p">)</span>
<span class="n">server</span><span class="o">.</span><span class="n">shutdown</span><span class="p">()</span>
</pre></div>
</div>
<p>The output of the example should look something like this:</p>
<div class="highlight-shell-session notranslate"><div class="highlight"><pre><span></span><span class="gp">$ </span>python<span class="w"> </span>ThreadedTCPServer.py
<span class="go">Server loop running in thread: Thread-1</span>
<span class="go">Received: Thread-2: Hello World 1</span>
<span class="go">Received: Thread-3: Hello World 2</span>
<span class="go">Received: Thread-4: Hello World 3</span>
</pre></div>
</div>
<p>The <a class="reference internal" href="#socketserver.ForkingMixIn" title="socketserver.ForkingMixIn"><code class="xref py py-class docutils literal notranslate"><span class="pre">ForkingMixIn</span></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.html#os.fork" title="os.fork"><code class="xref py py-func docutils literal notranslate"><span class="pre">fork()</span></code></a>.</p>
</section>
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<ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate"><span class="pre">socketserver</span></code> — A framework for network servers</a><ul>
<li><a class="reference internal" href="#server-creation-notes">Server Creation Notes</a></li>
<li><a class="reference internal" href="#server-objects">Server Objects</a></li>
<li><a class="reference internal" href="#request-handler-objects">Request Handler Objects</a></li>
<li><a class="reference internal" href="#examples">Examples</a><ul>
<li><a class="reference internal" href="#socketserver-tcpserver-example"><code class="xref py py-class docutils literal notranslate"><span class="pre">socketserver.TCPServer</span></code> Example</a></li>
<li><a class="reference internal" href="#socketserver-udpserver-example"><code class="xref py py-class docutils literal notranslate"><span class="pre">socketserver.UDPServer</span></code> Example</a></li>
<li><a class="reference internal" href="#asynchronous-mixins">Asynchronous Mixins</a></li>
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