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56 | <H2><A NAME="SECTION0082940000000000000000"></A><A NAME="network-logging"></A> | |
57 | <BR> | |
58 | 6.29.4 Sending and receiving logging events across a network | |
59 | ||
60 | </H2> | |
61 | ||
62 | <P> | |
63 | Let's say you want to send logging events across a network, and handle them | |
64 | at the receiving end. A simple way of doing this is attaching a | |
65 | <tt class="class">SocketHandler</tt> instance to the root logger at the sending end: | |
66 | ||
67 | <P> | |
68 | <div class="verbatim"><pre> | |
69 | import logging, logging.handlers | |
70 | ||
71 | rootLogger = logging.getLogger('') | |
72 | rootLogger.setLevel(logging.DEBUG) | |
73 | socketHandler = logging.handlers.SocketHandler('localhost', | |
74 | logging.handlers.DEFAULT_TCP_LOGGING_PORT) | |
75 | # don't bother with a formatter, since a socket handler sends the event as | |
76 | # an unformatted pickle | |
77 | rootLogger.addHandler(socketHandler) | |
78 | ||
79 | # Now, we can log to the root logger, or any other logger. First the root... | |
80 | logging.info('Jackdaws love my big sphinx of quartz.') | |
81 | ||
82 | # Now, define a couple of other loggers which might represent areas in your | |
83 | # application: | |
84 | ||
85 | logger1 = logging.getLogger('myapp.area1') | |
86 | logger2 = logging.getLogger('myapp.area2') | |
87 | ||
88 | logger1.debug('Quick zephyrs blow, vexing daft Jim.') | |
89 | logger1.info('How quickly daft jumping zebras vex.') | |
90 | logger2.warning('Jail zesty vixen who grabbed pay from quack.') | |
91 | logger2.error('The five boxing wizards jump quickly.') | |
92 | </pre></div> | |
93 | ||
94 | <P> | |
95 | At the receiving end, you can set up a receiver using the | |
96 | <tt class="module">SocketServer</tt> module. Here is a basic working example: | |
97 | ||
98 | <P> | |
99 | <div class="verbatim"><pre> | |
100 | import cPickle | |
101 | import logging | |
102 | import logging.handlers | |
103 | import SocketServer | |
104 | import struct | |
105 | ||
106 | ||
107 | class LogRecordStreamHandler(SocketServer.StreamRequestHandler): | |
108 | """Handler for a streaming logging request. | |
109 | ||
110 | This basically logs the record using whatever logging policy is | |
111 | configured locally. | |
112 | """ | |
113 | ||
114 | def handle(self): | |
115 | """ | |
116 | Handle multiple requests - each expected to be a 4-byte length, | |
117 | followed by the LogRecord in pickle format. Logs the record | |
118 | according to whatever policy is configured locally. | |
119 | """ | |
120 | while 1: | |
121 | chunk = self.connection.recv(4) | |
122 | if len(chunk) < 4: | |
123 | break | |
124 | slen = struct.unpack(">L", chunk)[0] | |
125 | chunk = self.connection.recv(slen) | |
126 | while len(chunk) < slen: | |
127 | chunk = chunk + self.connection.recv(slen - len(chunk)) | |
128 | obj = self.unPickle(chunk) | |
129 | record = logging.makeLogRecord(obj) | |
130 | self.handleLogRecord(record) | |
131 | ||
132 | def unPickle(self, data): | |
133 | return cPickle.loads(data) | |
134 | ||
135 | def handleLogRecord(self, record): | |
136 | # if a name is specified, we use the named logger rather than the one | |
137 | # implied by the record. | |
138 | if self.server.logname is not None: | |
139 | name = self.server.logname | |
140 | else: | |
141 | name = record.name | |
142 | logger = logging.getLogger(name) | |
143 | # N.B. EVERY record gets logged. This is because Logger.handle | |
144 | # is normally called AFTER logger-level filtering. If you want | |
145 | # to do filtering, do it at the client end to save wasting | |
146 | # cycles and network bandwidth! | |
147 | logger.handle(record) | |
148 | ||
149 | class LogRecordSocketReceiver(SocketServer.ThreadingTCPServer): | |
150 | """simple TCP socket-based logging receiver suitable for testing. | |
151 | """ | |
152 | ||
153 | allow_reuse_address = 1 | |
154 | ||
155 | def __init__(self, host='localhost', | |
156 | port=logging.handlers.DEFAULT_TCP_LOGGING_PORT, | |
157 | handler=LogRecordStreamHandler): | |
158 | SocketServer.ThreadingTCPServer.__init__(self, (host, port), handler) | |
159 | self.abort = 0 | |
160 | self.timeout = 1 | |
161 | self.logname = None | |
162 | ||
163 | def serve_until_stopped(self): | |
164 | import select | |
165 | abort = 0 | |
166 | while not abort: | |
167 | rd, wr, ex = select.select([self.socket.fileno()], | |
168 | [], [], | |
169 | self.timeout) | |
170 | if rd: | |
171 | self.handle_request() | |
172 | abort = self.abort | |
173 | ||
174 | def main(): | |
175 | logging.basicConfig( | |
176 | format="%(relativeCreated)5d %(name)-15s %(levelname)-8s %(message)s") | |
177 | tcpserver = LogRecordSocketReceiver() | |
178 | print "About to start TCP server..." | |
179 | tcpserver.serve_until_stopped() | |
180 | ||
181 | if __name__ == "__main__": | |
182 | main() | |
183 | </pre></div> | |
184 | ||
185 | <P> | |
186 | First run the server, and then the client. On the client side, nothing is | |
187 | printed on the console; on the server side, you should see something like: | |
188 | ||
189 | <P> | |
190 | <div class="verbatim"><pre> | |
191 | About to start TCP server... | |
192 | 59 root INFO Jackdaws love my big sphinx of quartz. | |
193 | 59 myapp.area1 DEBUG Quick zephyrs blow, vexing daft Jim. | |
194 | 69 myapp.area1 INFO How quickly daft jumping zebras vex. | |
195 | 69 myapp.area2 WARNING Jail zesty vixen who grabbed pay from quack. | |
196 | 69 myapp.area2 ERROR The five boxing wizards jump quickly. | |
197 | </pre></div> | |
198 | ||
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