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<!DOCTYPE html>

<head>

<title>Transports and Protocols — مستندات Python3.14.6</title><meta name="viewport" content="width=device-width, initial-scale=1.0">

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<h3><a href="../contents.html">فهرست عناوین</a></h3>

<ul>

<li><a class="reference internal" href="#">Transports and Protocols</a><ul>

<li><a class="reference internal" href="#transports">Transports</a><ul>

<li><a class="reference internal" href="#transports-hierarchy">Transports Hierarchy</a></li>

<li><a class="reference internal" href="#base-transport">Base Transport</a></li>

<li><a class="reference internal" href="#read-only-transports">Read-only Transports</a></li>

<li><a class="reference internal" href="#write-only-transports">Write-only Transports</a></li>

<li><a class="reference internal" href="#datagram-transports">Datagram Transports</a></li>

<li><a class="reference internal" href="#subprocess-transports">Subprocess Transports</a></li>

</ul>

</li>

<li><a class="reference internal" href="#protocols">Protocols</a><ul>

<li><a class="reference internal" href="#base-protocols">Base Protocols</a></li>

<li><a class="reference internal" href="#base-protocol">Base Protocol</a></li>

<li><a class="reference internal" href="#streaming-protocols">Streaming Protocols</a></li>

<li><a class="reference internal" href="#buffered-streaming-protocols">Buffered Streaming Protocols</a></li>

<li><a class="reference internal" href="#datagram-protocols">Datagram Protocols</a></li>

<li><a class="reference internal" href="#subprocess-protocols">Subprocess Protocols</a></li>

</ul>

</li>

<li><a class="reference internal" href="#examples">Examples</a><ul>

<li><a class="reference internal" href="#tcp-echo-server">TCP Echo Server</a></li>

<li><a class="reference internal" href="#tcp-echo-client">TCP Echo Client</a></li>

<li><a class="reference internal" href="#udp-echo-server">UDP Echo Server</a></li>

<li><a class="reference internal" href="#udp-echo-client">UDP Echo Client</a></li>

<li><a class="reference internal" href="#connecting-existing-sockets">Connecting Existing Sockets</a></li>

<li><a class="reference internal" href="#loop-subprocess-exec-and-subprocessprotocol">loop.subprocess_exec() and SubprocessProtocol</a></li>

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<h1>Transports and Protocols<a class="headerlink" href="#transports-and-protocols" title="Link to this heading">¶</a></h1>

Preface

Transports and Protocols are used by the low-level event loop

APIs such as <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate">loop.create_connection()</code></a>. They use

callback-based programming style and enable high-performance

implementations of network or IPC protocols (e.g. HTTP).

Essentially, transports and protocols should only be used in

libraries and frameworks and never in high-level asyncio

applications.

This documentation page covers both <a class="reference internal" href="#transports">Transports</a> and <a class="reference internal" href="#protocols">Protocols</a>.

Introduction

At the highest level, the transport is concerned with how bytes

are transmitted, while the protocol determines which bytes to

transmit (and to some extent when).

A different way of saying the same thing: a transport is an

abstraction for a socket (or similar I/O endpoint) while a protocol

is an abstraction for an application, from the transport's point

of view.

Yet another view is the transport and protocol interfaces

together define an abstract interface for using network I/O and

interprocess I/O.

There is always a 1:1 relationship between transport and protocol

objects: the protocol calls transport methods to send data,

while the transport calls protocol methods to pass it data that

has been received.

Most of connection oriented event loop methods

(such as <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate">loop.create_connection()</code></a>) usually accept a

protocol_factory argument used to create a Protocol object

for an accepted connection, represented by a Transport object.

Such methods usually return a tuple of <code class="docutils literal notranslate">(transport, protocol)</code>.

Contents

This documentation page contains the following sections:

<li>The <a class="reference internal" href="#transports">Transports</a> section documents asyncio <a class="reference internal" href="#asyncio.BaseTransport" title="asyncio.BaseTransport"><code class="xref py py-class docutils literal notranslate">BaseTransport</code></a>,

<a class="reference internal" href="#asyncio.ReadTransport" title="asyncio.ReadTransport"><code class="xref py py-class docutils literal notranslate">ReadTransport</code></a>, <a class="reference internal" href="#asyncio.WriteTransport" title="asyncio.WriteTransport"><code class="xref py py-class docutils literal notranslate">WriteTransport</code></a>, <a class="reference internal" href="#asyncio.Transport" title="asyncio.Transport"><code class="xref py py-class docutils literal notranslate">Transport</code></a>,

<a class="reference internal" href="#asyncio.DatagramTransport" title="asyncio.DatagramTransport"><code class="xref py py-class docutils literal notranslate">DatagramTransport</code></a>, and <a class="reference internal" href="#asyncio.SubprocessTransport" title="asyncio.SubprocessTransport"><code class="xref py py-class docutils literal notranslate">SubprocessTransport</code></a>

classes.</li>

<li>The <a class="reference internal" href="#protocols">Protocols</a> section documents asyncio <a class="reference internal" href="#asyncio.BaseProtocol" title="asyncio.BaseProtocol"><code class="xref py py-class docutils literal notranslate">BaseProtocol</code></a>,

<a class="reference internal" href="#asyncio.Protocol" title="asyncio.Protocol"><code class="xref py py-class docutils literal notranslate">Protocol</code></a>, <a class="reference internal" href="#asyncio.BufferedProtocol" title="asyncio.BufferedProtocol"><code class="xref py py-class docutils literal notranslate">BufferedProtocol</code></a>,

<a class="reference internal" href="#asyncio.DatagramProtocol" title="asyncio.DatagramProtocol"><code class="xref py py-class docutils literal notranslate">DatagramProtocol</code></a>, and <a class="reference internal" href="#asyncio.SubprocessProtocol" title="asyncio.SubprocessProtocol"><code class="xref py py-class docutils literal notranslate">SubprocessProtocol</code></a> classes.</li>

<li>The <a class="reference internal" href="#examples">Examples</a> section showcases how to work with transports,

protocols, and low-level event loop APIs.</li>

</ul>

<h2>Transports<a class="headerlink" href="#transports" title="Link to this heading">¶</a></h2>

Source code: <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/asyncio/transports.py">Lib/asyncio/transports.py</a>

Transports are classes provided by <a class="reference internal" href="asyncio.html#module-asyncio" title="asyncio: Asynchronous I/O."><code class="xref py py-mod docutils literal notranslate">asyncio</code></a> in order to abstract

various kinds of communication channels.

Transport objects are always instantiated by an

<a class="reference internal" href="asyncio-eventloop.html#asyncio-event-loop">asyncio event loop</a>.

asyncio implements transports for TCP, UDP, SSL, and subprocess pipes.

The methods available on a transport depend on the transport's kind.

The transport classes are <a class="reference internal" href="asyncio-dev.html#asyncio-multithreading">not thread safe</a>.

<h3>Transports Hierarchy<a class="headerlink" href="#transports-hierarchy" title="Link to this heading">¶</a></h3>

<dd>Base class for all transports. Contains methods that all

asyncio transports share.

</dd></dl>

class asyncio.WriteTransport(BaseTransport)<a class="headerlink" href="#asyncio.WriteTransport" title="Link to this definition">¶</a></dt>

<dd>A base transport for write-only connections.

Instances of the WriteTransport class are returned from

the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_write_pipe" title="asyncio.loop.connect_write_pipe"><code class="xref py py-meth docutils literal notranslate">loop.connect_write_pipe()</code></a> event loop method and

are also used by subprocess-related methods like

<a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.subprocess_exec" title="asyncio.loop.subprocess_exec"><code class="xref py py-meth docutils literal notranslate">loop.subprocess_exec()</code></a>.

</dd></dl>

class asyncio.ReadTransport(BaseTransport)<a class="headerlink" href="#asyncio.ReadTransport" title="Link to this definition">¶</a></dt>

<dd>A base transport for read-only connections.

Instances of the ReadTransport class are returned from

the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_read_pipe" title="asyncio.loop.connect_read_pipe"><code class="xref py py-meth docutils literal notranslate">loop.connect_read_pipe()</code></a> event loop method and

are also used by subprocess-related methods like

</dd></dl>

class asyncio.Transport(WriteTransport, ReadTransport)<a class="headerlink" href="#asyncio.Transport" title="Link to this definition">¶</a></dt>

<dd>Interface representing a bidirectional transport, such as a

TCP connection.

The user does not instantiate a transport directly; they call a

utility function, passing it a protocol factory and other

information necessary to create the transport and protocol.

Instances of the Transport class are returned from or used by

event loop methods like <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate">loop.create_connection()</code></a>,

<a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate">loop.create_server()</code></a>, <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.sendfile" title="asyncio.loop.sendfile"><code class="xref py py-meth docutils literal notranslate">loop.sendfile()</code></a>, etc.

</dd></dl>

class asyncio.DatagramTransport(BaseTransport)<a class="headerlink" href="#asyncio.DatagramTransport" title="Link to this definition">¶</a></dt>

<dd>A transport for datagram (UDP) connections.

Instances of the DatagramTransport class are returned from

the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_datagram_endpoint" title="asyncio.loop.create_datagram_endpoint"><code class="xref py py-meth docutils literal notranslate">loop.create_datagram_endpoint()</code></a> event loop method.

</dd></dl>

class asyncio.SubprocessTransport(BaseTransport)<a class="headerlink" href="#asyncio.SubprocessTransport" title="Link to this definition">¶</a></dt>

<dd>An abstraction to represent a connection between a parent and its

child OS process.

Instances of the SubprocessTransport class are returned from

event loop methods <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.subprocess_shell" title="asyncio.loop.subprocess_shell"><code class="xref py py-meth docutils literal notranslate">loop.subprocess_shell()</code></a> and

</dd></dl>

</section>

<h3>Base Transport<a class="headerlink" href="#base-transport" title="Link to this heading">¶</a></h3>

BaseTransport.close()<a class="headerlink" href="#asyncio.BaseTransport.close" title="Link to this definition">¶</a></dt>

<dd>Close the transport.

If the transport has a buffer for outgoing

data, buffered data will be flushed asynchronously. No more data

will be received. After all buffered data is flushed, the

protocol's <a class="reference internal" href="#asyncio.BaseProtocol.connection_lost" title="asyncio.BaseProtocol.connection_lost"><code class="xref py py-meth docutils literal notranslate">protocol.connection_lost()</code></a> method will be called with

<a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a> as its argument. The transport should not be

used once it is closed.

</dd></dl>

BaseTransport.is_closing()<a class="headerlink" href="#asyncio.BaseTransport.is_closing" title="Link to this definition">¶</a></dt>

<dd>Return <code class="docutils literal notranslate">True</code> if the transport is closing or is closed.

</dd></dl>

BaseTransport.get_extra_info(name, default=None)<a class="headerlink" href="#asyncio.BaseTransport.get_extra_info" title="Link to this definition">¶</a></dt>

<dd>Return information about the transport or underlying resources

it uses.

name is a string representing the piece of transport-specific

information to get.

default is the value to return if the information is not

available, or if the transport does not support querying it

with the given third-party event loop implementation or on the

current platform.

For example, the following code attempts to get the underlying

socket object of the transport:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>sock = transport.get_extra_info('socket')

if sock is not None:

print(sock.getsockopt(...))

</pre></div>

</div>

Categories of information that can be queried on some transports:

<li>socket:

<ul>

<li><code class="docutils literal notranslate">'peername'</code>: the remote address to which the socket is

connected, result of <a class="reference internal" href="socket.html#socket.socket.getpeername" title="socket.socket.getpeername"><code class="xref py py-meth docutils literal notranslate">socket.socket.getpeername()</code></a>

(<code class="docutils literal notranslate">None</code> on error)</li>

<li><code class="docutils literal notranslate">'socket'</code>: <a class="reference internal" href="socket.html#socket.socket" title="socket.socket"><code class="xref py py-class docutils literal notranslate">socket.socket</code></a> instance</li>

<li><code class="docutils literal notranslate">'sockname'</code>: the socket's own address,

result of <a class="reference internal" href="socket.html#socket.socket.getsockname" title="socket.socket.getsockname"><code class="xref py py-meth docutils literal notranslate">socket.socket.getsockname()</code></a></li>

</ul>

</li>

<li>SSL socket:

<ul>

<li><code class="docutils literal notranslate">'compression'</code>: the compression algorithm being used as a

string, or <code class="docutils literal notranslate">None</code> if the connection isn't compressed; result

of <a class="reference internal" href="ssl.html#ssl.SSLSocket.compression" title="ssl.SSLSocket.compression"><code class="xref py py-meth docutils literal notranslate">ssl.SSLSocket.compression()</code></a></li>

<li><code class="docutils literal notranslate">'cipher'</code>: a three-value tuple containing the name of the

cipher being used, the version of the SSL protocol that defines

its use, and the number of secret bits being used; result of

<a class="reference internal" href="ssl.html#ssl.SSLSocket.cipher" title="ssl.SSLSocket.cipher"><code class="xref py py-meth docutils literal notranslate">ssl.SSLSocket.cipher()</code></a></li>

<li><code class="docutils literal notranslate">'peercert'</code>: peer certificate; result of

<a class="reference internal" href="ssl.html#ssl.SSLSocket.getpeercert" title="ssl.SSLSocket.getpeercert"><code class="xref py py-meth docutils literal notranslate">ssl.SSLSocket.getpeercert()</code></a></li>

<li><code class="docutils literal notranslate">'sslcontext'</code>: <a class="reference internal" href="ssl.html#ssl.SSLContext" title="ssl.SSLContext"><code class="xref py py-class docutils literal notranslate">ssl.SSLContext</code></a> instance</li>

<li><code class="docutils literal notranslate">'ssl_object'</code>: <a class="reference internal" href="ssl.html#ssl.SSLObject" title="ssl.SSLObject"><code class="xref py py-class docutils literal notranslate">ssl.SSLObject</code></a> or

<a class="reference internal" href="ssl.html#ssl.SSLSocket" title="ssl.SSLSocket"><code class="xref py py-class docutils literal notranslate">ssl.SSLSocket</code></a> instance</li>

</ul>

</li>

<li>pipe:

<ul>

<li><code class="docutils literal notranslate">'pipe'</code>: pipe object</li>

</ul>

</li>

<li>subprocess:

<ul>

<li><code class="docutils literal notranslate">'subprocess'</code>: <a class="reference internal" href="subprocess.html#subprocess.Popen" title="subprocess.Popen"><code class="xref py py-class docutils literal notranslate">subprocess.Popen</code></a> instance</li>

</ul>

</li>

</ul>

</dd></dl>

BaseTransport.set_protocol(protocol)<a class="headerlink" href="#asyncio.BaseTransport.set_protocol" title="Link to this definition">¶</a></dt>

<dd>Set a new protocol.

Switching protocol should only be done when both

protocols are documented to support the switch.

</dd></dl>

BaseTransport.get_protocol()<a class="headerlink" href="#asyncio.BaseTransport.get_protocol" title="Link to this definition">¶</a></dt>

<dd>Return the current protocol.

</dd></dl>

</section>

<h3>Read-only Transports<a class="headerlink" href="#read-only-transports" title="Link to this heading">¶</a></h3>

ReadTransport.is_reading()<a class="headerlink" href="#asyncio.ReadTransport.is_reading" title="Link to this definition">¶</a></dt>

<dd>Return <code class="docutils literal notranslate">True</code> if the transport is receiving new data.

Added in version 3.7.

</div>

</dd></dl>

ReadTransport.pause_reading()<a class="headerlink" href="#asyncio.ReadTransport.pause_reading" title="Link to this definition">¶</a></dt>

<dd>Pause the receiving end of the transport. No data will be passed to

the protocol's <a class="reference internal" href="#asyncio.Protocol.data_received" title="asyncio.Protocol.data_received"><code class="xref py py-meth docutils literal notranslate">protocol.data_received()</code></a>

method until <a class="reference internal" href="#asyncio.ReadTransport.resume_reading" title="asyncio.ReadTransport.resume_reading"><code class="xref py py-meth docutils literal notranslate">resume_reading()</code></a> is called.

تغییر داده شده در نسخه 3.7: The method is idempotent, i.e. it can be called when the

transport is already paused or closed.

</div>

</dd></dl>

ReadTransport.resume_reading()<a class="headerlink" href="#asyncio.ReadTransport.resume_reading" title="Link to this definition">¶</a></dt>

<dd>Resume the receiving end. The protocol's

<a class="reference internal" href="#asyncio.Protocol.data_received" title="asyncio.Protocol.data_received"><code class="xref py py-meth docutils literal notranslate">protocol.data_received()</code></a> method

will be called once again if some data is available for reading.

تغییر داده شده در نسخه 3.7: The method is idempotent, i.e. it can be called when the

transport is already reading.

</div>

</dd></dl>

</section>

<h3>Write-only Transports<a class="headerlink" href="#write-only-transports" title="Link to this heading">¶</a></h3>

WriteTransport.abort()<a class="headerlink" href="#asyncio.WriteTransport.abort" title="Link to this definition">¶</a></dt>

<dd>Close the transport immediately, without waiting for pending operations

to complete. Buffered data will be lost. No more data will be received.

The protocol's <a class="reference internal" href="#asyncio.BaseProtocol.connection_lost" title="asyncio.BaseProtocol.connection_lost"><code class="xref py py-meth docutils literal notranslate">protocol.connection_lost()</code></a> method will eventually be

called with <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a> as its argument.

</dd></dl>

WriteTransport.can_write_eof()<a class="headerlink" href="#asyncio.WriteTransport.can_write_eof" title="Link to this definition">¶</a></dt>

<dd>Return <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate">True</code></a> if the transport supports

<a class="reference internal" href="#asyncio.WriteTransport.write_eof" title="asyncio.WriteTransport.write_eof"><code class="xref py py-meth docutils literal notranslate">write_eof()</code></a>, <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate">False</code></a> if not.

</dd></dl>

WriteTransport.get_write_buffer_size()<a class="headerlink" href="#asyncio.WriteTransport.get_write_buffer_size" title="Link to this definition">¶</a></dt>

<dd>Return the current size of the output buffer used by the transport.

</dd></dl>

WriteTransport.get_write_buffer_limits()<a class="headerlink" href="#asyncio.WriteTransport.get_write_buffer_limits" title="Link to this definition">¶</a></dt>

<dd>Get the high and low watermarks for write flow control. Return a

tuple <code class="docutils literal notranslate">(low, high)</code> where low and high are positive number of

bytes.

Use <a class="reference internal" href="#asyncio.WriteTransport.set_write_buffer_limits" title="asyncio.WriteTransport.set_write_buffer_limits"><code class="xref py py-meth docutils literal notranslate">set_write_buffer_limits()</code></a> to set the limits.

Added in version 3.4.2.

</div>

</dd></dl>

WriteTransport.set_write_buffer_limits(high=None, low=None)<a class="headerlink" href="#asyncio.WriteTransport.set_write_buffer_limits" title="Link to this definition">¶</a></dt>

<dd>Set the high and low watermarks for write flow control.

These two values (measured in number of

bytes) control when the protocol's

<a class="reference internal" href="#asyncio.BaseProtocol.pause_writing" title="asyncio.BaseProtocol.pause_writing"><code class="xref py py-meth docutils literal notranslate">protocol.pause_writing()</code></a>

and <a class="reference internal" href="#asyncio.BaseProtocol.resume_writing" title="asyncio.BaseProtocol.resume_writing"><code class="xref py py-meth docutils literal notranslate">protocol.resume_writing()</code></a>

methods are called. If specified, the low watermark must be less

than or equal to the high watermark. Neither high nor low

can be negative.

<a class="reference internal" href="#asyncio.BaseProtocol.pause_writing" title="asyncio.BaseProtocol.pause_writing"><code class="xref py py-meth docutils literal notranslate">pause_writing()</code></a> is called when the buffer size

becomes greater than or equal to the high value. If writing has

been paused, <a class="reference internal" href="#asyncio.BaseProtocol.resume_writing" title="asyncio.BaseProtocol.resume_writing"><code class="xref py py-meth docutils literal notranslate">resume_writing()</code></a> is called when

the buffer size becomes less than or equal to the low value.

The defaults are implementation-specific. If only the

high watermark is given, the low watermark defaults to an

implementation-specific value less than or equal to the

high watermark. Setting high to zero forces low to zero as

well, and causes <a class="reference internal" href="#asyncio.BaseProtocol.pause_writing" title="asyncio.BaseProtocol.pause_writing"><code class="xref py py-meth docutils literal notranslate">pause_writing()</code></a> to be called

whenever the buffer becomes non-empty. Setting low to zero causes

<a class="reference internal" href="#asyncio.BaseProtocol.resume_writing" title="asyncio.BaseProtocol.resume_writing"><code class="xref py py-meth docutils literal notranslate">resume_writing()</code></a> to be called only once the

buffer is empty. Use of zero for either limit is generally

sub-optimal as it reduces opportunities for doing I/O and

computation concurrently.

Use <a class="reference internal" href="#asyncio.WriteTransport.get_write_buffer_limits" title="asyncio.WriteTransport.get_write_buffer_limits"><code class="xref py py-meth docutils literal notranslate">get_write_buffer_limits()</code></a>

to get the limits.

</dd></dl>

WriteTransport.write(data)<a class="headerlink" href="#asyncio.WriteTransport.write" title="Link to this definition">¶</a></dt>

<dd>Write some data bytes to the transport.

This method does not block; it buffers the data and arranges for it

to be sent out asynchronously.

</dd></dl>

WriteTransport.writelines(list_of_data)<a class="headerlink" href="#asyncio.WriteTransport.writelines" title="Link to this definition">¶</a></dt>

<dd>Write a list (or any iterable) of data bytes to the transport.

This is functionally equivalent to calling <a class="reference internal" href="#asyncio.WriteTransport.write" title="asyncio.WriteTransport.write"><code class="xref py py-meth docutils literal notranslate">write()</code></a> on each

element yielded by the iterable, but may be implemented more

efficiently.

</dd></dl>

WriteTransport.write_eof()<a class="headerlink" href="#asyncio.WriteTransport.write_eof" title="Link to this definition">¶</a></dt>

<dd>Close the write end of the transport after flushing all buffered data.

Data may still be received.

This method can raise <a class="reference internal" href="exceptions.html#NotImplementedError" title="NotImplementedError"><code class="xref py py-exc docutils literal notranslate">NotImplementedError</code></a> if the transport

(e.g. SSL) doesn't support half-closed connections.

</dd></dl>

</section>

<h3>Datagram Transports<a class="headerlink" href="#datagram-transports" title="Link to this heading">¶</a></h3>

DatagramTransport.sendto(data, addr=None)<a class="headerlink" href="#asyncio.DatagramTransport.sendto" title="Link to this definition">¶</a></dt>

<dd>Send the data bytes to the remote peer given by addr (a

transport-dependent target address). If addr is <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a>,

the data is sent to the target address given on transport

creation.

This method does not block; it buffers the data and arranges

for it to be sent out asynchronously.

تغییر داده شده در نسخه 3.13: This method can be called with an empty bytes object to send a

zero-length datagram. The buffer size calculation used for flow

control is also updated to account for the datagram header.

</div>

</dd></dl>

DatagramTransport.abort()<a class="headerlink" href="#asyncio.DatagramTransport.abort" title="Link to this definition">¶</a></dt>

<dd>Close the transport immediately, without waiting for pending

operations to complete. Buffered data will be lost.

No more data will be received. The protocol's

<a class="reference internal" href="#asyncio.BaseProtocol.connection_lost" title="asyncio.BaseProtocol.connection_lost"><code class="xref py py-meth docutils literal notranslate">protocol.connection_lost()</code></a>

method will eventually be called with <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a> as its argument.

</dd></dl>

</section>

<h3>Subprocess Transports<a class="headerlink" href="#subprocess-transports" title="Link to this heading">¶</a></h3>

SubprocessTransport.get_pid()<a class="headerlink" href="#asyncio.SubprocessTransport.get_pid" title="Link to this definition">¶</a></dt>

<dd>Return the subprocess process id as an integer.

</dd></dl>

SubprocessTransport.get_pipe_transport(fd)<a class="headerlink" href="#asyncio.SubprocessTransport.get_pipe_transport" title="Link to this definition">¶</a></dt>

<dd>Return the transport for the communication pipe corresponding to the

integer file descriptor fd:

<li><code class="docutils literal notranslate">0</code>: writable streaming transport of the standard input (stdin),

or <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a> if the subprocess was not created with <code class="docutils literal notranslate">stdin=PIPE</code></li>

<li><code class="docutils literal notranslate">1</code>: readable streaming transport of the standard output (stdout),

<li><code class="docutils literal notranslate">2</code>: readable streaming transport of the standard error (stderr),

<li>other fd: <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a></li>

</ul>

</dd></dl>

SubprocessTransport.get_returncode()<a class="headerlink" href="#asyncio.SubprocessTransport.get_returncode" title="Link to this definition">¶</a></dt>

<dd>Return the subprocess return code as an integer or <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a>

if it hasn't returned, which is similar to the

<a class="reference internal" href="subprocess.html#subprocess.Popen.returncode" title="subprocess.Popen.returncode"><code class="xref py py-attr docutils literal notranslate">subprocess.Popen.returncode</code></a> attribute.

</dd></dl>

SubprocessTransport.kill()<a class="headerlink" href="#asyncio.SubprocessTransport.kill" title="Link to this definition">¶</a></dt>

<dd>Kill the subprocess.

On POSIX systems, the function sends SIGKILL to the subprocess.

On Windows, this method is an alias for <a class="reference internal" href="#asyncio.SubprocessTransport.terminate" title="asyncio.SubprocessTransport.terminate"><code class="xref py py-meth docutils literal notranslate">terminate()</code></a>.

See also <a class="reference internal" href="subprocess.html#subprocess.Popen.kill" title="subprocess.Popen.kill"><code class="xref py py-meth docutils literal notranslate">subprocess.Popen.kill()</code></a>.

</dd></dl>

SubprocessTransport.send_signal(signal)<a class="headerlink" href="#asyncio.SubprocessTransport.send_signal" title="Link to this definition">¶</a></dt>

<dd>Send the signal number to the subprocess, as in

<a class="reference internal" href="subprocess.html#subprocess.Popen.send_signal" title="subprocess.Popen.send_signal"><code class="xref py py-meth docutils literal notranslate">subprocess.Popen.send_signal()</code></a>.

</dd></dl>

SubprocessTransport.terminate()<a class="headerlink" href="#asyncio.SubprocessTransport.terminate" title="Link to this definition">¶</a></dt>

<dd>Stop the subprocess.

On POSIX systems, this method sends <a class="reference internal" href="signal.html#signal.SIGTERM" title="signal.SIGTERM"><code class="xref py py-const docutils literal notranslate">SIGTERM</code></a> to the subprocess.

On Windows, the Windows API function <code class="xref c c-func docutils literal notranslate">TerminateProcess()</code> is called to

stop the subprocess.

See also <a class="reference internal" href="subprocess.html#subprocess.Popen.terminate" title="subprocess.Popen.terminate"><code class="xref py py-meth docutils literal notranslate">subprocess.Popen.terminate()</code></a>.

</dd></dl>

SubprocessTransport.close()<a class="headerlink" href="#asyncio.SubprocessTransport.close" title="Link to this definition">¶</a></dt>

<dd>Kill the subprocess by calling the <a class="reference internal" href="#asyncio.SubprocessTransport.kill" title="asyncio.SubprocessTransport.kill"><code class="xref py py-meth docutils literal notranslate">kill()</code></a> method.

If the subprocess hasn't returned yet, and close transports of

stdin, stdout, and stderr pipes.

</dd></dl>

</section>

<h2>Protocols<a class="headerlink" href="#protocols" title="Link to this heading">¶</a></h2>

Source code: <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.14/Lib/asyncio/protocols.py">Lib/asyncio/protocols.py</a>

asyncio provides a set of abstract base classes that should be used

to implement network protocols. Those classes are meant to be used

together with <a class="reference internal" href="#asyncio-transport">transports</a>.

Subclasses of abstract base protocol classes may implement some or

all methods. All these methods are callbacks: they are called by

transports on certain events, for example when some data is received.

A base protocol method should be called by the corresponding transport.

<h3>Base Protocols<a class="headerlink" href="#base-protocols" title="Link to this heading">¶</a></h3>

<dd>Base protocol with methods that all protocols share.

</dd></dl>

class asyncio.Protocol(BaseProtocol)<a class="headerlink" href="#asyncio.Protocol" title="Link to this definition">¶</a></dt>

<dd>The base class for implementing streaming protocols

(TCP, Unix sockets, etc).

</dd></dl>

class asyncio.BufferedProtocol(BaseProtocol)<a class="headerlink" href="#asyncio.BufferedProtocol" title="Link to this definition">¶</a></dt>

<dd>A base class for implementing streaming protocols with manual

control of the receive buffer.

</dd></dl>

class asyncio.DatagramProtocol(BaseProtocol)<a class="headerlink" href="#asyncio.DatagramProtocol" title="Link to this definition">¶</a></dt>

<dd>The base class for implementing datagram (UDP) protocols.

</dd></dl>

class asyncio.SubprocessProtocol(BaseProtocol)<a class="headerlink" href="#asyncio.SubprocessProtocol" title="Link to this definition">¶</a></dt>

<dd>The base class for implementing protocols communicating with child

processes (unidirectional pipes).

</dd></dl>

</section>

<h3>Base Protocol<a class="headerlink" href="#base-protocol" title="Link to this heading">¶</a></h3>

All asyncio protocols can implement Base Protocol callbacks.

Connection Callbacks

Connection callbacks are called on all protocols, exactly once per

a successful connection. All other protocol callbacks can only be

called between those two methods.

BaseProtocol.connection_made(transport)<a class="headerlink" href="#asyncio.BaseProtocol.connection_made" title="Link to this definition">¶</a></dt>

<dd>Called when a connection is made.

The transport argument is the transport representing the

connection. The protocol is responsible for storing the reference

to its transport.

</dd></dl>

BaseProtocol.connection_lost(exc)<a class="headerlink" href="#asyncio.BaseProtocol.connection_lost" title="Link to this definition">¶</a></dt>

<dd>Called when the connection is lost or closed.

The argument is either an exception object or <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate">None</code></a>.

The latter means a regular EOF is received, or the connection was

aborted or closed by this side of the connection.

</dd></dl>

Flow Control Callbacks

Flow control callbacks can be called by transports to pause or

resume writing performed by the protocol.

See the documentation of the <a class="reference internal" href="#asyncio.WriteTransport.set_write_buffer_limits" title="asyncio.WriteTransport.set_write_buffer_limits"><code class="xref py py-meth docutils literal notranslate">set_write_buffer_limits()</code></a>

method for more details.

BaseProtocol.pause_writing()<a class="headerlink" href="#asyncio.BaseProtocol.pause_writing" title="Link to this definition">¶</a></dt>

<dd>Called when the transport's buffer goes over the high watermark.

</dd></dl>

BaseProtocol.resume_writing()<a class="headerlink" href="#asyncio.BaseProtocol.resume_writing" title="Link to this definition">¶</a></dt>

<dd>Called when the transport's buffer drains below the low watermark.

</dd></dl>

If the buffer size equals the high watermark,

go strictly over.

Conversely, <a class="reference internal" href="#asyncio.BaseProtocol.resume_writing" title="asyncio.BaseProtocol.resume_writing"><code class="xref py py-meth docutils literal notranslate">resume_writing()</code></a> is called when the

buffer size is equal or lower than the low watermark. These end

conditions are important to ensure that things go as expected when

either mark is zero.

</section>

<h3>Streaming Protocols<a class="headerlink" href="#streaming-protocols" title="Link to this heading">¶</a></h3>

Event methods, such as <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate">loop.create_server()</code></a>,

<a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_unix_server" title="asyncio.loop.create_unix_server"><code class="xref py py-meth docutils literal notranslate">loop.create_unix_server()</code></a>, <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate">loop.create_connection()</code></a>,

<a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_unix_connection" title="asyncio.loop.create_unix_connection"><code class="xref py py-meth docutils literal notranslate">loop.create_unix_connection()</code></a>, <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_accepted_socket" title="asyncio.loop.connect_accepted_socket"><code class="xref py py-meth docutils literal notranslate">loop.connect_accepted_socket()</code></a>,

<a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_read_pipe" title="asyncio.loop.connect_read_pipe"><code class="xref py py-meth docutils literal notranslate">loop.connect_read_pipe()</code></a>, and <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.connect_write_pipe" title="asyncio.loop.connect_write_pipe"><code class="xref py py-meth docutils literal notranslate">loop.connect_write_pipe()</code></a>

accept factories that return streaming protocols.

Protocol.data_received(data)<a class="headerlink" href="#asyncio.Protocol.data_received" title="Link to this definition">¶</a></dt>

<dd>Called when some data is received. data is a non-empty bytes

object containing the incoming data.

Whether the data is buffered, chunked or reassembled depends on

the transport. In general, you shouldn't rely on specific semantics

and instead make your parsing generic and flexible. However,

data is always received in the correct order.

The method can be called an arbitrary number of times while

a connection is open.

However, <a class="reference internal" href="#asyncio.Protocol.eof_received" title="asyncio.Protocol.eof_received"><code class="xref py py-meth docutils literal notranslate">protocol.eof_received()</code></a>

is called at most once. Once <code class="docutils literal notranslate">eof_received()</code> is called,

<code class="docutils literal notranslate">data_received()</code> is not called anymore.

</dd></dl>

Protocol.eof_received()<a class="headerlink" href="#asyncio.Protocol.eof_received" title="Link to this definition">¶</a></dt>

<dd>Called when the other end signals it won't send any more data

(for example by calling <a class="reference internal" href="#asyncio.WriteTransport.write_eof" title="asyncio.WriteTransport.write_eof"><code class="xref py py-meth docutils literal notranslate">transport.write_eof()</code></a>, if the other end also uses

asyncio).

This method may return a false value (including <code class="docutils literal notranslate">None</code>), in which case

the transport will close itself. Conversely, if this method returns a

true value, the protocol used determines whether to close the transport.

Since the default implementation returns <code class="docutils literal notranslate">None</code>, it implicitly closes the

connection.

Some transports, including SSL, don't support half-closed connections,

in which case returning true from this method will result in the connection

being closed.

</dd></dl>

State machine:

<div class="highlight-none notranslate"><div class="highlight"><pre>start -> connection_made

[-> data_received]*

[-> eof_received]?

-> connection_lost -> end

</pre></div>

</div>

</section>

<h3>Buffered Streaming Protocols<a class="headerlink" href="#buffered-streaming-protocols" title="Link to this heading">¶</a></h3>

Added in version 3.7.

</div>

Buffered Protocols can be used with any event loop method

that supports <a class="reference internal" href="#streaming-protocols">Streaming Protocols</a>.

<code class="docutils literal notranslate">BufferedProtocol</code> implementations allow explicit manual allocation

and control of the receive buffer. Event loops can then use the buffer

provided by the protocol to avoid unnecessary data copies. This

can result in noticeable performance improvement for protocols that

receive big amounts of data. Sophisticated protocol implementations

can significantly reduce the number of buffer allocations.

The following callbacks are called on <a class="reference internal" href="#asyncio.BufferedProtocol" title="asyncio.BufferedProtocol"><code class="xref py py-class docutils literal notranslate">BufferedProtocol</code></a>

instances:

BufferedProtocol.get_buffer(sizehint)<a class="headerlink" href="#asyncio.BufferedProtocol.get_buffer" title="Link to this definition">¶</a></dt>

<dd>Called to allocate a new receive buffer.

sizehint is the recommended minimum size for the returned

buffer. It is acceptable to return smaller or larger buffers

than what sizehint suggests. When set to -1, the buffer size

can be arbitrary. It is an error to return a buffer with a zero size.

<code class="docutils literal notranslate">get_buffer()</code> must return an object implementing the

<a class="reference internal" href="../c-api/buffer.html#bufferobjects">buffer protocol</a>.

</dd></dl>

BufferedProtocol.buffer_updated(nbytes)<a class="headerlink" href="#asyncio.BufferedProtocol.buffer_updated" title="Link to this definition">¶</a></dt>

<dd>Called when the buffer was updated with the received data.

nbytes is the total number of bytes that were written to the buffer.

</dd></dl>

BufferedProtocol.eof_received()<a class="headerlink" href="#asyncio.BufferedProtocol.eof_received" title="Link to this definition">¶</a></dt>

<dd>See the documentation of the <a class="reference internal" href="#asyncio.Protocol.eof_received" title="asyncio.Protocol.eof_received"><code class="xref py py-meth docutils literal notranslate">protocol.eof_received()</code></a> method.

</dd></dl>

<a class="reference internal" href="#asyncio.BufferedProtocol.get_buffer" title="asyncio.BufferedProtocol.get_buffer"><code class="xref py py-meth docutils literal notranslate">get_buffer()</code></a> can be called an arbitrary number

of times during a connection. However, <a class="reference internal" href="#asyncio.Protocol.eof_received" title="asyncio.Protocol.eof_received"><code class="xref py py-meth docutils literal notranslate">protocol.eof_received()</code></a> is called at most once

and, if called, <code class="xref py py-meth docutils literal notranslate">get_buffer()</code> and

<a class="reference internal" href="#asyncio.BufferedProtocol.buffer_updated" title="asyncio.BufferedProtocol.buffer_updated"><code class="xref py py-meth docutils literal notranslate">buffer_updated()</code></a> won't be called after it.

State machine:

<div class="highlight-none notranslate"><div class="highlight"><pre>start -> connection_made

[-> get_buffer

[-> buffer_updated]?

[-> eof_received]?

-> connection_lost -> end

</pre></div>

</div>

</section>

<h3>Datagram Protocols<a class="headerlink" href="#datagram-protocols" title="Link to this heading">¶</a></h3>

Datagram Protocol instances should be constructed by protocol

factories passed to the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_datagram_endpoint" title="asyncio.loop.create_datagram_endpoint"><code class="xref py py-meth docutils literal notranslate">loop.create_datagram_endpoint()</code></a> method.

DatagramProtocol.datagram_received(data, addr)<a class="headerlink" href="#asyncio.DatagramProtocol.datagram_received" title="Link to this definition">¶</a></dt>

<dd>Called when a datagram is received. data is a bytes object containing

the incoming data. addr is the address of the peer sending the data;

the exact format depends on the transport.

</dd></dl>

DatagramProtocol.error_received(exc)<a class="headerlink" href="#asyncio.DatagramProtocol.error_received" title="Link to this definition">¶</a></dt>

<dd>Called when a previous send or receive operation raises an

<a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-class docutils literal notranslate">OSError</code></a>. exc is the <code class="xref py py-class docutils literal notranslate">OSError</code> instance.

This method is called in rare conditions, when the transport (e.g. UDP)

detects that a datagram could not be delivered to its recipient.

In many conditions though, undeliverable datagrams will be silently

dropped.

</dd></dl>

توجه

On BSD systems (macOS, FreeBSD, etc.) flow control is not supported

for datagram protocols, because there is no reliable way to detect send

failures caused by writing too many packets.

The socket always appears 'ready' and excess packets are dropped. An

<a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-class docutils literal notranslate">OSError</code></a> with <code class="docutils literal notranslate">errno</code> set to <a class="reference internal" href="errno.html#errno.ENOBUFS" title="errno.ENOBUFS"><code class="xref py py-const docutils literal notranslate">errno.ENOBUFS</code></a> may

or may not be raised; if it is raised, it will be reported to

<a class="reference internal" href="#asyncio.DatagramProtocol.error_received" title="asyncio.DatagramProtocol.error_received"><code class="xref py py-meth docutils literal notranslate">DatagramProtocol.error_received()</code></a> but otherwise ignored.

</div>

</section>

<h3>Subprocess Protocols<a class="headerlink" href="#subprocess-protocols" title="Link to this heading">¶</a></h3>

Subprocess Protocol instances should be constructed by protocol

factories passed to the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.subprocess_exec" title="asyncio.loop.subprocess_exec"><code class="xref py py-meth docutils literal notranslate">loop.subprocess_exec()</code></a> and

<a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.subprocess_shell" title="asyncio.loop.subprocess_shell"><code class="xref py py-meth docutils literal notranslate">loop.subprocess_shell()</code></a> methods.

SubprocessProtocol.pipe_data_received(fd, data)<a class="headerlink" href="#asyncio.SubprocessProtocol.pipe_data_received" title="Link to this definition">¶</a></dt>

<dd>Called when the child process writes data into its stdout or stderr

pipe.

fd is the integer file descriptor of the pipe.

data is a non-empty bytes object containing the received data.

</dd></dl>

SubprocessProtocol.pipe_connection_lost(fd, exc)<a class="headerlink" href="#asyncio.SubprocessProtocol.pipe_connection_lost" title="Link to this definition">¶</a></dt>

<dd>Called when one of the pipes communicating with the child process

is closed.

fd is the integer file descriptor that was closed.

</dd></dl>

SubprocessProtocol.process_exited()<a class="headerlink" href="#asyncio.SubprocessProtocol.process_exited" title="Link to this definition">¶</a></dt>

<dd>Called when the child process has exited.

It can be called before <a class="reference internal" href="#asyncio.SubprocessProtocol.pipe_data_received" title="asyncio.SubprocessProtocol.pipe_data_received"><code class="xref py py-meth docutils literal notranslate">pipe_data_received()</code></a> and

<a class="reference internal" href="#asyncio.SubprocessProtocol.pipe_connection_lost" title="asyncio.SubprocessProtocol.pipe_connection_lost"><code class="xref py py-meth docutils literal notranslate">pipe_connection_lost()</code></a> methods.

</dd></dl>

</section>

<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading">¶</a></h2>

<h3>TCP Echo Server<a class="headerlink" href="#tcp-echo-server" title="Link to this heading">¶</a></h3>

Create a TCP echo server using the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_server" title="asyncio.loop.create_server"><code class="xref py py-meth docutils literal notranslate">loop.create_server()</code></a> method, send back

received data, and close the connection:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>import asyncio

class EchoServerProtocol(asyncio.Protocol):

def connection_made(self, transport):

peername = transport.get_extra_info('peername')

print('Connection from {}'.format(peername))

self.transport = transport

def data_received(self, data):

message = data.decode()

print('Data received: {!r}'.format(message))

print('Send: {!r}'.format(message))

self.transport.write(data)

print('Close the client socket')

self.transport.close()

async def main():

# Get a reference to the event loop as we plan to use

# low-level APIs.

loop = asyncio.get_running_loop()

server = await loop.create_server(

EchoServerProtocol,

'127.0.0.1', 8888)

async with server:

await server.serve_forever()

asyncio.run(main())

</pre></div>

</div>

همچنین ملاحظه نمائید

The <a class="reference internal" href="asyncio-stream.html#asyncio-tcp-echo-server-streams">TCP echo server using streams</a>

example uses the high-level <a class="reference internal" href="asyncio-stream.html#asyncio.start_server" title="asyncio.start_server"><code class="xref py py-func docutils literal notranslate">asyncio.start_server()</code></a> function.

</div>

</section>

<h3>TCP Echo Client<a class="headerlink" href="#tcp-echo-client" title="Link to this heading">¶</a></h3>

A TCP echo client using the <a class="reference internal" href="asyncio-eventloop.html#asyncio.loop.create_connection" title="asyncio.loop.create_connection"><code class="xref py py-meth docutils literal notranslate">loop.create_connection()</code></a> method, sends

data, and waits until the connection is closed:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>import asyncio

class EchoClientProtocol(asyncio.Protocol):

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