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Viewing changes to doc/howto/listings/pclients/single-pb.py

  • Committer: Bazaar Package Importer
  • Author(s): Matthias Klose
  • Date: 2007-01-17 14:52:35 UTC
  • mfrom: (1.1.5 upstream) (2.1.2 etch)
  • Revision ID: james.westby@ubuntu.com-20070117145235-btmig6qfmqfen0om
Tags: 2.5.0-0ubuntu1
New upstream version, compatible with python2.5.

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doc/howto/listings/pclients/single-pb.py
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from twisted.cred import error
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from twisted.spread import pb
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class PerspectiveInUse(error.Unauthorized):
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    """Raised when a client requests a perspective already connected to another.
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    """
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    # XXX: Is there any information this exception should carry, i.e.
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    #   the Perspective in question.
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    #   the client it's currently attached to.
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    #   the Identity which attached it.
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class SingleClientPerspective_PB(pb.Perspective):
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    """One client may attach to me at a time.
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    With verbose logging and some detection for lost connections.
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    """
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    client = None
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    # This example is from cvstoys.actions.pb.Notifiee.
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    def brokerAttached(self, ref, identity, broker):
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        log.msg("%(identityName)s<auth%(authID)X>@"
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                "%(peer)s<broker%(brokerID)X> "
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                "requests attaching client %(client)s to "
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                "%(perspectiveName)s@%(serviceName)s" %
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                {'identityName': identity.name,
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                 'authID': id(identity.authorizer),
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                 'peer': broker.transport.getPeer(),
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                 'brokerID': id(broker),
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                 'client': ref,
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                 'perspectiveName': self.getPerspectiveName(),
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                 'serviceName': self.service.getServiceName(),
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                 })
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        if self.client:
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            oldclient, oldid, oldbroker = self.client
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            if oldbroker:
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                brokerstr = "<broker%X>" % (id(oldbroker),)
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            else:
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                brokerstr = "<no broker>"
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            log.msg(
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                "%(pn)s@%(sn)s already has client %(client)s "
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                "from %(id)s@%(broker)s" %
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                {'pn': self.getPerspectiveName(),
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                 'sn': self.service.getServiceName(),
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                 'id': oldid.name,
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                 'client': oldclient,
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                 'broker': brokerstr})
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            # Here's the part that checks is the currently connected client
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            # has a stale connection.  It *shouldn't* happen, but if it did,
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            # it would suck to not be able to sign back on because the system
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            # wouldn't believe you were logged off.
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            if (not oldbroker) or (oldbroker.connected and oldbroker.transport):
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                if oldbroker:
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                    brokerstr = "%s%s" % (oldbroker.transport.getPeer(),
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                                          brokerstr)
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                log.msg("%s@%s refusing new client %s from broker %s." %
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                        (self.getPerspectiveName(),
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                         self.service.getServiceName(),
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                         ref, broker))
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                raise PerspectiveInUse("This perspective %r already has a "
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                                       "client.  (Connected by %r from %s.)"
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                                       % (self, oldid.name, brokerstr))
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            elif oldbroker:
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                log.msg("BUG: Broker %s disconnected but client %s never"
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                        "detached.\n(I'm dropping the old client and "
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                        "allowing a new one to attach.)" %
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                        (oldbroker, self.client,))
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                self.brokerDetached(self, self.client, identity, oldbroker)
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                # proceed with normal attach
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        #endif self.client
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        self.client = (ref, identity, broker)
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        return self
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    def detached(self, ref, identity):
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        del self.client
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    def sendMessage(self, message):
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        """Send a message to my client.
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        (This isn't a defined Perspective method, just an example of something
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        you would define in your sub-class to use to talk to your client.)
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        """
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        # Using 'assert' in this case is probably not a good idea for real
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        # code.  Define an exception, or choose to let it pass without comment,
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        # as your needs see fit.
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        assert self.client is not None, "No client to send a message to!"
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        # This invokes remote_message(message) on the client object.
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        self.client.callRemote("message", message)
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    def __getstate__(self):
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        state = styles.Versioned.__getstate__(self)
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        try:
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            del state['client']
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        except KeyError:
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            pass
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        return state