172 lines
6 KiB
Python
172 lines
6 KiB
Python
# Copyright 2011, Google Inc.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following disclaimer
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# in the documentation and/or other materials provided with the
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# distribution.
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# * Neither the name of Google Inc. nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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""" A Standalone WebSocket Server for testing purposes
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mod_pywebsocket is an API that provides WebSocket functionalities with
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a standalone WebSocket server. It is intended for testing or
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experimental purposes.
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Installation
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============
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1. Follow standalone server documentation to start running the
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standalone server. It can be read by running the following command:
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$ pydoc mod_pywebsocket.standalone
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2. Once the standalone server is launched verify it by accessing
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http://localhost[:port]/console.html. Include the port number when
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specified on launch. If everything is working correctly, you
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will see a simple echo console.
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Writing WebSocket handlers
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==========================
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When a WebSocket request comes in, the resource name
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specified in the handshake is considered as if it is a file path under
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<websock_handlers> and the handler defined in
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<websock_handlers>/<resource_name>_wsh.py is invoked.
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For example, if the resource name is /example/chat, the handler defined in
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<websock_handlers>/example/chat_wsh.py is invoked.
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A WebSocket handler is composed of the following three functions:
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web_socket_do_extra_handshake(request)
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web_socket_transfer_data(request)
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web_socket_passive_closing_handshake(request)
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where:
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request: mod_python request.
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web_socket_do_extra_handshake is called during the handshake after the
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headers are successfully parsed and WebSocket properties (ws_origin,
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and ws_resource) are added to request. A handler
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can reject the request by raising an exception.
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A request object has the following properties that you can use during the
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extra handshake (web_socket_do_extra_handshake):
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- ws_resource
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- ws_origin
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- ws_version
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- ws_extensions
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- ws_deflate
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- ws_protocol
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- ws_requested_protocols
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The last two are a bit tricky. See the next subsection.
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Subprotocol Negotiation
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-----------------------
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ws_protocol is always set to None when
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web_socket_do_extra_handshake is called. If ws_requested_protocols is not
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None, you must choose one subprotocol from this list and set it to
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ws_protocol.
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Data Transfer
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-------------
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web_socket_transfer_data is called after the handshake completed
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successfully. A handler can receive/send messages from/to the client
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using request. mod_pywebsocket.msgutil module provides utilities
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for data transfer.
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You can receive a message by the following statement.
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message = request.ws_stream.receive_message()
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This call blocks until any complete text frame arrives, and the payload data
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of the incoming frame will be stored into message. When you're using IETF
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HyBi 00 or later protocol, receive_message() will return None on receiving
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client-initiated closing handshake. When any error occurs, receive_message()
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will raise some exception.
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You can send a message by the following statement.
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request.ws_stream.send_message(message)
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Closing Connection
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------------------
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Executing the following statement or just return-ing from
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web_socket_transfer_data cause connection close.
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request.ws_stream.close_connection()
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close_connection will wait
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for closing handshake acknowledgement coming from the client. When it
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couldn't receive a valid acknowledgement, raises an exception.
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web_socket_passive_closing_handshake is called after the server receives
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incoming closing frame from the client peer immediately. You can specify
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code and reason by return values. They are sent as a outgoing closing frame
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from the server. A request object has the following properties that you can
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use in web_socket_passive_closing_handshake.
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- ws_close_code
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- ws_close_reason
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Threading
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---------
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A WebSocket handler must be thread-safe. The standalone
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server uses threads by default.
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Configuring WebSocket Extension Processors
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------------------------------------------
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See extensions.py for supported WebSocket extensions. Note that they are
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unstable and their APIs are subject to change substantially.
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A request object has these extension processing related attributes.
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- ws_requested_extensions:
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A list of common.ExtensionParameter instances representing extension
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parameters received from the client in the client's opening handshake.
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You shouldn't modify it manually.
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- ws_extensions:
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A list of common.ExtensionParameter instances representing extension
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parameters to send back to the client in the server's opening handshake.
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You shouldn't touch it directly. Instead, call methods on extension
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processors.
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- ws_extension_processors:
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A list of loaded extension processors. Find the processor for the
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extension you want to configure from it, and call its methods.
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"""
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# vi:sts=4 sw=4 et tw=72
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