Unable to send messages between Unity3d and Python using NetMQ

Question

I would like to transfer messages back and forth between Android and Python using ZMQ. I'm using NetMQ/ZMQ to do so. Following is my Requester code.

public class Requester : RunAbleThread
{
    
    protected override void Run()
    {
        ForceDotNet.Force(); 
        using (RequestSocket client = new RequestSocket())
        {
            client.Connect("tcp://localhost:5556");

            for (int i = 0; i < 10 && Running; i++)
            {
                Debug.Log("Sending Hello");
                client.SendFrame("Hello");

                string message = null;
                bool gotMessage = false;
                while (Running)
                {
                    gotMessage = client.TryReceiveFrameString(out message); 
                    if (gotMessage) break;
                }

                if (gotMessage) Debug.Log("Received " + message);
            }
        }

        NetMQConfig.Cleanup(); 
    }
}

Following is my receiver's code.

context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://*:5556")

while True:
    #  Wait for next request from client
    message = socket.recv()
    print("Received request: %s" % message)

    socket.send(b"World")

The above code works perfectly fine in Editor mode. However, when I run the same code in Android, the requester is not receiving any messages at all. What am I missing? Both devices are connected to the same WIFI hotspot.

Answer 1

You are using

client.Connect("tcp://localhost:5556")

The localhost is your device itself!

It worked in the editor since the editor and the python is both running on the same device!

Since the python server is not running on your phone it is no use to try to connect to the port 5556 of your phone ;)

You rather want to use the IP of your PC which is in the same network as your phone. Like e.g.

client.Connect("tcp://192.168.1.234:5556")