Continuing with the ZeroMQ examples. This article shows the use of the PUB/SUB pattern as in the zeroMQ article part 4 .

The difference is in the transport definition: part 4 uses tcp and this time epgm will be used, which is for multicast.

The example shown is based on the article by Saghul Ibarra on Saghul Ibarra's blog. The producer creates a command line where the text is passed to the consumer; the consumer receives the text and only the text defined in the subscription is shown on screen.

In the producer some options are set on the socket; the ZeroMQ site has an explanation of the options for creating the socket. LINGER with a zero parameter makes unsent messages be discarded.

The producer code is shown below:

#!/usr/bin/env python

# 

# producer

#Se importa ZeroMQ

import zmq

#Se crea la instancia de la clase Context.

context = zmq.Context()

#Se define el socket con parametro PUB

socket = context.socket(zmq.PUB)

#Se define unas opciones en el socket

#esta opcion LINGER con valor cero, descarta mensajes no enviados

socket.setsockopt(zmq.LINGER, 0)    

#Se conecta al socket a la IP y puerto

#por medio de multicast

socket.connect('epgm://192.168.10.96:5000')

#Se crea un ciclo

#si se envia el texto salir, se envia y luego finaliza el ciclo

#si no, se envia el texto

while True:

 mensaje = raw_input("->")

 print mensaje

 socket.send(mensaje)

 if mensaje == "salir": break

socket.close()

The consumer program code is the following:

#!/usr/bin/env python

#Importar zeroMQ

import zmq

#Se crea la instancia de la clase contexto

context = zmq.Context()

#Se define el socket con parametro SUB

socket = context.socket(zmq.SUB)

#Se conecta el socket a la IP y puerto del productor

#con el transporte epgm

socket.connect('epgm://192.168.10.96:5000')

#Se define los textos que se recibe la informacion.

#prueba, hora y salir.

socket.setsockopt(zmq.SUBSCRIBE, 'prueba')

socket.setsockopt(zmq.SUBSCRIBE, 'hora')

socket.setsockopt(zmq.SUBSCRIBE, 'salir')

#Se define un ciclo,

#se recibe la informacion

#Si el texto es salir se muestra en pantalla 

#finaliza el ciclo, si no se muestra

#el texto en pantalla

while True:

    rcv = socket.recv()

    print rcv

    if rcv == "salir": break

The following figures show the result of running both programs: Producer:

Consumer:

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