ROUTER-ROUTER communication example

[jcpinto54]

Here is an example of a ROUTER-ROUTER communication for anyone who is building a P2P application and needs a socket that is able to connect to several other peers simultaneously, while also being able to receive messages. I'm posting this here because I didn't find an example anywhere and it might be useful for someone.

The program takes two arguments:

1. "s" or "c", meaning server or client.
2. If the first argument is "c", then this argument is used as the identity of the peer. Can be any string.

Note that starting the program as a server sets the peer identity in the connection as "server".

import zmq
import sys

context = zmq.Context()

socket = context.socket(zmq.ROUTER)

if sys.argv[1] == "s":
    socket.setsockopt_string(zmq.IDENTITY, 'server')
    socket.bind("tcp://*:4000")

    while True:
        print("waiting for msg")
        req = socket.recv_multipart()
        print(req)
        #                      identity of receptionist   empty frame     message content
        socket.send_multipart([req[0],                    bytes(),      bytes("whatup", encoding="utf-8")])

elif sys.argv[1] == "c":
    socket.setsockopt_string(zmq.IDENTITY, sys.argv[2])
    socket.connect("tcp://localhost:4000")

    while True:
        input("enter to send msg")
        #                       identity of receptionist          empty frame     message content
        socket.send_multipart([bytes("server", encoding="utf-8"), bytes(),     bytes("cheers", encoding="utf-8")])

        rep = socket.recv_multipart()
        print(rep)

# In real applications do not forget to disconnect when the connection is not needed anymore

[frobnitzem]

Well, I've been spoiling to put in an example of aiowire, so I've created PR #1652 to add this example into the asyncio examples subdirectory. From your comments above, I assume you intended to use CC0 (public domain copyright).

[mrvn]

How would this example look with CURVE encryption?

In my code I'm setting:

        socket.setsockopt(zmq.CURVE_SERVER, True)
        socket.setsockopt(zmq.CURVE_SECRETKEY, secret_key)
        socket.setsockopt(zmq.CURVE_PUBLICKEY, public_key)
        socket.setsockopt(zmq.CURVE_SERVERKEY, public_key)

but then I get

  File "Router.py", line 762, in connect
    socket.connect(socket_path)
  File "/usr/lib/python3/dist-packages/zmq/sugar/socket.py", line 251, in connect
    super().connect(addr)
  File "zmq/backend/cython/socket.pyx", line 595, in zmq.backend.cython.socket.Socket.connect
  File "zmq/backend/cython/checkrc.pxd", line 28, in zmq.backend.cython.checkrc._check_rc
zmq.error.ZMQError: Invalid argument