[Twisted-Python] xmlrpc - Possable failure to understand async concept

[Tim Hughes]

I am trying to understand this concept of async methods and i thought I had
it cracked with the code below but it doesn't seem to work as all the calls
to the xmlrpc server return one after the other like this:

Success:I started at Fri Apr 24 01:12:23 2009 and i slept 5 seconds then
woke at Fri Apr 24 01:12:28 2009
Success:I started at Fri Apr 24 01:12:28 2009 and i slept 5 seconds then
woke at Fri Apr 24 01:12:33 2009
Success:I started at Fri Apr 24 01:12:33 2009 and i slept 5 seconds then
woke at Fri Apr 24 01:12:38 2009
Success:I started at Fri Apr 24 01:12:38 2009 and i slept 5 seconds then
woke at Fri Apr 24 01:12:43 2009
Success:I started at Fri Apr 24 01:12:43 2009 and i slept 5 seconds then
woke at Fri Apr 24 01:12:48 2009
Success:I started at Fri Apr 24 01:12:48 2009 and i slept 5 seconds then
woke at Fri Apr 24 01:12:53 2009

Am I completly missing the point here or is there something incorrect with
my code. AT first I thought it was because the sleep was shutting the whole
thing down (probably is) so  I have also tried it with a long running
network call instead of the time.sleep() and have the same issue. Can
someone please point me in the right direction or give a bit of criticism of
the code concepts/thought processes


=========== Server ========================
#!/usr/bin/env python

from twisted.web import xmlrpc, server
from twisted.internet.defer import Deferred
from twisted.internet import reactor, threads
import time

class MyServer(xmlrpc.XMLRPC):

    def blocking_method(self, duration=5):
        """block the instance for a specified duration"""
        started = time.asctime()
        time.sleep(duration)
        data = "I started at %s and i slept %d seconds then woke at %s" %
(started, duration, time.asctime())
        return data


#    def xmlrpc_block_thread(self, duration=10):
#        """ pass to blocking method using thread """
#        return threads.deferToThread(self.blocking_method, duration)
#
#    def xmlrpc_block(self, duration=10):
#        """ pass to blocking method using defered """
#        d = Deferred()
#        d.callback(self.blocking_method(duration))
#        return d

    def xmlrpc_block_fixed(self, duration=5):
        """ pass to blocking method using defered """
        d = self.blocking_method_fixed(duration)  # return a defered
        d.addCallback(self.printdata)
        d.addErrback(self.printerror)
        return d

    def blocking_method_fixed(self, duration=5):
        d = Deferred()
        d.callback(self.blocking_method(duration))
        return d

    def printdata(self, val):
        return 'Success:'+val

    def printerror(self, val):
        return 'Error:'+val


if __name__ == '__main__':
    r = MyServer()
    reactor.listenTCP(8080, server.Site(r))
    reactor.run()

===============================================


========== Client ================================
#!/usr/bin/env python
import xmlrpclib
import datetime
import sys
proxy = xmlrpclib.ServerProxy("http://localhost:8080/", allow_none=True)
print "%s" % str(proxy.block_fixed(5))

===============================================




Tim Hughes
mailto:thughes at thegoldfish.org
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