CODEWITHSUNDEEP
pythonzeromq
Shane Morris
Shane Morris

Reputation: 95

Python and ZeroMQ subscriber acknowledgement to publisher

I am trying to get an acknowledgement from my subscriber back to my publisher using ZeroMQ in Python.

I tried a few code examples, using a zmq.PUSH and zmq.PULL code sequence, but to no avail.

My code as it stands:

PUB_SERVER.PY

import zmq
import random
import sys
import time

port = "5556"
if len( sys.argv ) > 1:
   port =  sys.argv[1]
   int( port )

   context = zmq.Context()
   socket  = context.socket( zmq.PUB )
   socket.bind( "tcp://*:%s" % port )

   while True:
      # topic = random.randrange( 9999, 10005 )
      topic       = 10000
      messagedata = random.randrange( 1, 215 ) - 80
      print        "%d %d" % ( topic, messagedata )
      socket.send( "%d %d" % ( topic, messagedata ) )
      time.sleep( 1 )

SUB_CLIENT.PY

import sys
import zmq

port = "5556"
if len( sys.argv ) > 1:
   port =  sys.argv[1]
   int( port )

   if len( sys.argv ) > 2:
      port1   =  sys.argv[2]
      int( port1 )

      # Socket to talk to server
      context = zmq.Context()
      socket  = context.socket( zmq.SUB )

      print "Collecting updates from weather server..."
      socket.connect( "tcp://192.168.0.21:%s" % port )

if len( sys.argv ) > 2:
   socket.connect(    "tcp://192.168.0.21:%s" % port1 )

   # Subscribe to zipcode, default is NYC, 10001
   topicfilter = "10000"
   socket.setsockopt( zmq.SUBSCRIBE, topicfilter )

   # Process 5 updates
   total_value = 0
   for update_nbr in range( 5 ):
      string = socket.recv()
      topic, messagedata = string.split()
      total_value += int( messagedata )
      print topic, messagedata

   print "Average messagedata value for topic '%s' was %dF" % ( topicfilter, total_value / update_nbr )

That code gives me the output of the server in one SSH window (on a Parallella), and the received filtered messages of the client in another SSH window (on a RaspberryPi) which is working great.

Where I am lost is, once the client has gotten a filtered message from the server, how would it acknowledge that filtered message being received, and then have the server log those acknowledged messages?

Eventually, I'd want to do some intelligent decision making of sending a file to the subscriber who acknowledges.

Upvotes: 1

Views: 2057

Answers (1)

user3666197
user3666197

Reputation: 1

How to acknowledge?

May create a parallel messaging structure for a soft-signalling for that purpose.

Extend PUB_SERVER.PY with a .SUB Rx access point:

anAckRxSOCKET  = context.socket( zmq.SUB )               # create SUB side
anAckRxSOCKET.bind( "tcp://*:%s" % aServerAckPORT ) )    # .bind()
anAckRxSOCKET.setsockopt( zmq.SUBSCRIBE, "" )            # SUB to *-anything
# ...
anAckRxSTRING = anAckRxSOCKET.recv()                     # .recv()

Extend SUB_CLIENT.PY with a .PUB Tx socket to the Server side access point:

anAckTxSOCKET  = context.socket( zmq.PUB )               # create PUB side(s)
anAckTxSOCKET.connect( "tcp://192.168.0.21:%s" % aServerAckPORT ) )

and send ACK(s) with "a-proxy-ID" for any server-side processing you may want or need

anAckTxSOCKET.send( topicfilter )                        # ACK with an "identity"-proxy

Upvotes: 2

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