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If mod_pywebsocket is not in the Python path, specify the following. is the directory where mod_pywebsocket is installed. PythonPath "sys.path+['']" Always specify the following. is the directory where user-written WebSocket handlers are placed. PythonOption mod_pywebsocket.handler_root PythonHeaderParserHandler mod_pywebsocket.headerparserhandler To limit the search for WebSocket handlers to a directory under , configure as follows: PythonOption mod_pywebsocket.handler_scan is useful in saving scan time when contains many non-WebSocket handler files. If you want to allow handlers whose canonical path is not under the root directory (i.e. symbolic link is in root directory but its target is not), configure as follows: PythonOption mod_pywebsocket.allow_handlers_outside_root_dir On Example snippet of httpd.conf: (mod_pywebsocket is in /websock_lib, WebSocket handlers are in /websock_handlers, port is 80 for ws, 443 for wss.) PythonPath "sys.path+['/websock_lib']" PythonOption mod_pywebsocket.handler_root /websock_handlers PythonHeaderParserHandler mod_pywebsocket.headerparserhandler 2. Tune Apache parameters for serving WebSocket. We'd like to note that at least TimeOut directive from core features and RequestReadTimeout directive from mod_reqtimeout should be modified not to kill connections in only a few seconds of idle time. 3. Verify installation. You can use example/console.html to poke the server. Writing WebSocket handlers ========================== When a WebSocket request comes in, the resource name specified in the handshake is considered as if it is a file path under and the handler defined in /_wsh.py is invoked. For example, if the resource name is /example/chat, the handler defined in /example/chat_wsh.py is invoked. A WebSocket handler is composed of the following three functions: web_socket_do_extra_handshake(request) web_socket_transfer_data(request) web_socket_passive_closing_handshake(request) where: request: mod_python request. web_socket_do_extra_handshake is called during the handshake after the headers are successfully parsed and WebSocket properties (ws_location, ws_origin, and ws_resource) are added to request. A handler can reject the request by raising an exception. A request object has the following properties that you can use during the extra handshake (web_socket_do_extra_handshake): - ws_resource - ws_origin - ws_version - ws_location (HyBi 00 only) - ws_extensions (HyBi 06 and later) - ws_deflate (HyBi 06 and later) - ws_protocol - ws_requested_protocols (HyBi 06 and later) The last two are a bit tricky. See the next subsection. Subprotocol Negotiation ----------------------- For HyBi 06 and later, ws_protocol is always set to None when web_socket_do_extra_handshake is called. If ws_requested_protocols is not None, you must choose one subprotocol from this list and set it to ws_protocol. For HyBi 00, when web_socket_do_extra_handshake is called, ws_protocol is set to the value given by the client in Sec-WebSocket-Protocol header or None if such header was not found in the opening handshake request. Finish extra handshake with ws_protocol untouched to accept the request subprotocol. Then, Sec-WebSocket-Protocol header will be sent to the client in response with the same value as requested. Raise an exception in web_socket_do_extra_handshake to reject the requested subprotocol. Data Transfer ------------- web_socket_transfer_data is called after the handshake completed successfully. A handler can receive/send messages from/to the client using request. mod_pywebsocket.msgutil module provides utilities for data transfer. You can receive a message by the following statement. message = request.ws_stream.receive_message() This call blocks until any complete text frame arrives, and the payload data of the incoming frame will be stored into message. When you're using IETF HyBi 00 or later protocol, receive_message() will return None on receiving client-initiated closing handshake. When any error occurs, receive_message() will raise some exception. You can send a message by the following statement. request.ws_stream.send_message(message) Closing Connection ------------------ Executing the following statement or just return-ing from web_socket_transfer_data cause connection close. request.ws_stream.close_connection() close_connection will wait for closing handshake acknowledgement coming from the client. When it couldn't receive a valid acknowledgement, raises an exception. web_socket_passive_closing_handshake is called after the server receives incoming closing frame from the client peer immediately. You can specify code and reason by return values. They are sent as a outgoing closing frame from the server. A request object has the following properties that you can use in web_socket_passive_closing_handshake. - ws_close_code - ws_close_reason Threading --------- A WebSocket handler must be thread-safe if the server (Apache or standalone.py) is configured to use threads. Configuring WebSocket Extension Processors ------------------------------------------ See extensions.py for supported WebSocket extensions. Note that they are unstable and their APIs are subject to change substantially. A request object has these extension processing related attributes. - ws_requested_extensions: A list of common.ExtensionParameter instances representing extension parameters received from the client in the client's opening handshake. You shouldn't modify it manually. - ws_extensions: A list of common.ExtensionParameter instances representing extension parameters to send back to the client in the server's opening handshake. You shouldn't touch it directly. Instead, call methods on extension processors. - ws_extension_processors: A list of loaded extension processors. Find the processor for the extension you want to configure from it, and call its methods. """ # vi:sts=4 sw=4 et tw=72