On Wed, 6 Sep 2006 17:12:29 -0400, Stan Benrsteen <sbernste@mitre.org> wrote:

All,

I want to write a client that connects to a Twisted Server using pb. I want my client to make several connections. For example:

from twisted.spread import pb from twisted.internet import defer

from twisted.internet.tcp import Connector from twisted.internet import reactor PORT = 8992

class ModelCalculator: def __init__(self, host, port): self.host = host self.port = port

def add(self, a, b): self.factory = pb.PBClientFactory() deferred = self.factory.getRootObject() deferred.addCallback(self.connected, a, b) deferred.addErrback(self.failure) reactor.run() return self.result

Instead, use this definition of add: def add(self, a, b): self.factory = pb.PBClientFactory() deferred = self.factory.getRootObject() deferred.addCallback(self.connected, a, b) deferred.addErrback(self.failure) return deferred

def connected(self, perspective, a, b): deferred = perspective.callRemote('calculate', a, b) deferred.addCallback(self.success, perspective) deferred.addErrback(self.failure)

And this definition of connected: def connected(self, perspective, a, b): return perspective.callRemote('calculate', a, b)

def success(self, result, perspective): self.result = result self.stopReactor()

def failure(self, reason): self.result = None self.stopReactor()

def stopReactor(self): reactor.stop()

Now you don't need any of these methods.

if __name__ == '__main__': calculator = ModelCalculator("127.0.0.1", PORT) print calculator.add(4,5) print calculator.add(14,5) print calculator.add(24,5) print calculator.add(34,5)

Rewrite this as: def reportSums(sums): for s in sums: print s def reportFailure(err): err.printTraceback() if __name__ == '__main__': calls = [] calculator = ModelCalculator("127.0.0.1", PORT) for sums in [(4, 5), (14, 5), (24, 5), (34, 5)]: calls.append(calculator.add(*sums)) d = defer.gatherResults(sums) d.addCallbacks(reportSumsm, reportFailure) d.addCallback(lambda ignored: reactor.stop()) reactor.run()

As you see, I want to add many numbers and print out the result. This doesn't work because the reactor is been stopped in the stopReactor() method that is invoked in either success() or failure (). How can I change it so I can call my remote add() method many times without waiting for the reactor to be stopped? Is there a way that I can use the PB stuff without the reactor?

Deferreds are the abstraction Twisted provides for dealing with callbacks. It provides this abstraction because Twisted applications use callbacks /a lot/. You won't be able to avoid using them. You need to structure your programs in the way I have demonstrated above. Jean-Paul