ampclient.py

from twisted.internet import reactor, defer
from twisted.internet.protocol import ClientCreator
from twisted.protocols import amp
from ampserver import Sum, Divide


def doMath():
    try:
       a = raw_input('What number for a ? \n >')
       b = raw_input('What number for b? \n >')
       a = int(a)
       b = int(b)
    except ValueError:
       print 'That\'s not a number.'
       doMath()   
         
    d1 = ClientCreator(reactor, amp.AMP).connectTCP(
        '192.168.2.10', 1234).addCallback(
            lambda p: p.callRemote(Sum, a=a, b=b)).addCallback(
                lambda result: result['total'])
    def trapZero(result):
        result.trap(ZeroDivisionError)
        print "Divided by zero: returning INF"
        return 1e1000
    d2 = ClientCreator(reactor, amp.AMP).connectTCP(
        '192.168.2.10', 1234).addCallback(
            lambda p: p.callRemote(Divide, numerator=1234,
                                   denominator=0)).addErrback(trapZero)
    def done(result):
        print 'Done with math:', result
    d = defer.Deferred()
    d.addCallback(done(d2))

if __name__ == '__main__':
    doMath()
    reactor.run()

ampserver.py

from twisted.protocols import amp

class Sum(amp.Command):
    arguments = [('a', amp.Integer()),
                 ('b', amp.Integer())]
    response = [('total', amp.Integer())]


class Divide(amp.Command):
    arguments = [('numerator', amp.Integer()),
                 ('denominator', amp.Integer())]
    response = [('result', amp.Float())]
    errors = {ZeroDivisionError: 'ZERO_DIVISION'}


class Math(amp.AMP):
    def sum(self, a, b):
        total = a + b
        print 'Did a sum: %d + %d = %d' % (a, b, total)
        return {'total': total}
    Sum.responder(sum)

    def divide(self, numerator, denominator):
        result = float(numerator) / denominator
        print 'Divided: %d / %d = %f' % (numerator, denominator, result)
        return {'result': result}
    Divide.responder(divide)


def main():
    from twisted.internet import reactor
    from twisted.internet.protocol import Factory
    pf = Factory()
    pf.protocol = Math
    reactor.listenTCP(1234, pf)
    print 'started'
    reactor.run()

if __name__ == '__main__':
    main()

error

Done with math: <Deferred at 0xb6de5d8cL>
Traceback (most recent call last):
  File "ampclient.py", line 35, in <module>
    doMath()
  File "ampclient.py", line 32, in doMath
    d.addCallback(done(d2))
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 298, in addCallback
    callbackKeywords=kw)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 280, in addCallbacks
    assert callable(callback)
AssertionError

gistfile1.txt

http://dreid.org/2012/03/30/deferreds-are-a-dataflow-abstraction/

terminal

# client 
python ampclient.py
What number for a ? 
 >123
What number for b? 
 >123



# server 
python ampserver.py