How do we handle Python xmlrpclib Connection Refused?
I don't know what the heck I'm doing wrong here, I wrote have an RPC client trying to connect to a non-existent server, and I'm trying to handle the exception that is thrown, but no matter what I try I can't figure out how I'm supposed to handle this:
def _get_rpc():
try:
a = ServerProxy('http://dd:LNXFhcZnYshy5mKyOFfy@127.0.0.1:9001')
a = a.supervisor
return a
except:
return False
rpc = _get_rpc()
if not rpc:
print "No RPC"
Since there is no server running, I would expect the output to be "No RPC" but instead I get an exception:
Traceback (most recent call last):
File "xmlrpctest.py", line 20, in <module>
if not rpc:
File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
return self.__send(self.__name, args)
File "/usr/lib/python2.6/xmlrpclib.py", li开发者_开发百科ne 1489, in __request
verbose=self.__verbose
File "/usr/lib/python2.6/xmlrpclib.py", line 1235, in request
self.send_content(h, request_body)
File "/usr/lib/python2.6/xmlrpclib.py", line 1349, in send_content
connection.endheaders()
File "/usr/lib/python2.6/httplib.py", line 908, in endheaders
self._send_output()
File "/usr/lib/python2.6/httplib.py", line 780, in _send_output
self.send(msg)
File "/usr/lib/python2.6/httplib.py", line 739, in send
self.connect()
File "/usr/lib/python2.6/httplib.py", line 720, in connect
self.timeout)
File "/usr/lib/python2.6/socket.py", line 561, in create_connection
raise error, msg
socket.error: [Errno 111] Connection refused
_get_rpc returns a reference to unconnected ServerProxy's supervisor method. The exception isn't happening in the call to _get_rpc where you handle it; it's happening when you try to evaluate this supervisor method (in "if not rpc"). Try from the interactive prompt:
Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import xmlrpclib
>>> xmlrpclib.ServerProxy("http://127.0.0.1");
<ServerProxy for 127.0.0.1/RPC2>
>>> xmlrpclib.ServerProxy("http://127.0.0.1").supervisor;
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
return self.__send(self.__name, args)
File "/usr/lib/python2.6/xmlrpclib.py", line 1489, in __request
verbose=self.__verbose
File "/usr/lib/python2.6/xmlrpclib.py", line 1243, in request
headers
xmlrpclib.ProtocolError: <ProtocolError for 127.0.0.1/RPC2: 404 Not Found>
>>> foo = xmlrpclib.ServerProxy("http://127.0.0.1");
>>> dir (foo)
['_ServerProxy__allow_none', '_ServerProxy__encoding', '_ServerProxy__handler', '_ServerProxy__host', '_ServerProxy__request', '_ServerProxy__transport', '_ServerProxy__verbose', '__doc__', '__getattr__', '__init__', '__module__', '__repr__', '__str__']
>>> foo.supervisor
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
return self.__send(self.__name, args)
File "/usr/lib/python2.6/xmlrpclib.py", line 1489, in __request
verbose=self.__verbose
File "/usr/lib/python2.6/xmlrpclib.py", line 1243, in request
headers
xmlrpclib.ProtocolError: <ProtocolError for 127.0.0.1/RPC2: 404 Not Found>
>>> bar = foo.supervisor
>>> bar
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
return self.__send(self.__name, args)
File "/usr/lib/python2.6/xmlrpclib.py", line 1489, in __request
verbose=self.__verbose
File "/usr/lib/python2.6/xmlrpclib.py", line 1243, in request
headers
xmlrpclib.ProtocolError: <ProtocolError for 127.0.0.1/RPC2: 404 Not Found>
Note how you see the exception when trying to evaluate the .supervisor method (ServerProxy(...).supervisor, foo.supervisor, or bar), but not when just assigning it elsewhere (bar = foo.supervisor).
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