How to process concurrent client requests?

Question

Here is sample code of the request / response pattern with zeroMQ in python. I would like to know if there is way to process requests from multiple clients concurrently?

import zmq 
import time 

def main():
    context = zmq.Context()
    serverSocket = StartServer(context,"9999")
    processRequests(serverSocket)

def processRequests (socket):
    while True:
        print "waiting for request"
        msg = socket.recv()
        print msg
        time.sleep(10)
        socket.send("Request processed")



def StartServer(context, port):
    socket = context.socket(zmq.REP)
    socket.bind("tcp://*:%s" % port)

    print "started server on", port 
    return socket 




if __name__ == '__main__':
    print "starting IPC server"
    main()

Answer 1

The REQ-REP pattern is a synchronous pattern. If there are two REQ sockets connected to the same REP socket, the REP socket will process requests serially.

If you want to do asynchronous request-reply, you'll want to look into the ROUTER-DEALER pattern, which is the generalized analogue of REQ-REP.

If you want a brokered asynchronous request-reply, look at the "Figure 16 - Extended Request-Reply" section here.