How can I write a socket server in a different thread from my main program (using gevent)?

Question

I\'m developing a Flask/gevent WSGIserver webserver that needs to communicate (in the background) with a hardware device over two sockets using XML.

One socket is in

Answer 1

Hope it can provide some help, In example class if we will call tenMessageSender function then it will fire up an async thread without blocking main loop and then _zmqBasedListener will start listening on separate port untill that thread is alive. and whatever message our tenMessageSender function will send, those will be received by client and respond back to zmqBasedListener.

Server Side

import threading
import zmq
import sys

class Example:
    def __init__(self):
        self.context = zmq.Context()
        self.publisher = self.context.socket(zmq.PUB)
        self.publisher.bind('tcp://127.0.0.1:9997')
        self.subscriber = self.context.socket(zmq.SUB)
        self.thread = threading.Thread(target=self._zmqBasedListener)

    def _zmqBasedListener(self):
        self.subscriber.connect('tcp://127.0.0.1:9998')
        self.subscriber.setsockopt(zmq.SUBSCRIBE, "some_key")
        while True:
            message = self.subscriber.recv()
            print message
        sys.exit()

    def tenMessageSender(self):
        self._decideListener()
        for message in range(10):
            self.publisher.send("testid : %d: I am a task" %message)

    def _decideListener(self):
        if not self.thread.is_alive():
            print "STARTING THREAD"
            self.thread.start()

Client

import zmq
context = zmq.Context()

subscriber = context.socket(zmq.SUB)
subscriber.connect('tcp://127.0.0.1:9997')
publisher = context.socket(zmq.PUB)
publisher.bind('tcp://127.0.0.1:9998')
subscriber.setsockopt(zmq.SUBSCRIBE, "testid")
count = 0
print "Listener"
while True:
    message = subscriber.recv()
    print message
    publisher.send('some_key : Message received %d' %count)
    count+=1

Instead of thread you can use greenlet etc.