Zeromq request-response pattern between python and scala

I am trying to implement a request-response example using the ZeroMQ request-response pattern between python and scala. Based on the code provided by zmq documentation, I was able to successfully start the requester in scala and the server in python.

scala In python rrclient scala and rrserver python

Now I am trying to do the opposite. Request in python and responder in scala.

python TO scala rrclient python and rrserver scala

Here is the python client code

import zmq

#  Prepare our context and sockets
context = zmq.Context()
socket = context.socket(zmq.REQ)
socket.connect("tcp://localhost:5559")

#  Do 10 requests, waiting each time for a response
for request in range(1,11):
    socket.send(b"Hello")
    message = socket.recv()
    print("Received reply %s [%s]" % (request, message))

      

        
        
        
      

    

And here is the scala code

import org.zeromq.ZMQ
import org.zeromq.ZMQ.{Context,Socket}

object rrserver {
def main(args : Array[String]) {
    //  Prepare our context and socket
    val context = ZMQ.context(1)
    val receiver = context.socket(ZMQ.REP)
    receiver.connect("tcp://localhost:5559")

    while (true) {
        //  Wait for next request from client
        //  We will wait for a 0-terminated string (C string) from the client,
        //  so that this server also works with The Guide C and C++ "Hello World" clients

        //IT BLOCKS HERE
        val request = receiver.recv (0)
        println(request)
        // In order to display the 0-terminated string as a String,
        // we omit the last byte from request
        // println ("Received request: [" + new String(request,0,request.length-1)  
        //  Creates a String from request, minus the last byte
        //                        + "]")

        //  Do some 'work'
        // try {
        //   Thread.sleep (1000)
        // } catch  {
        //   case e: InterruptedException => e.printStackTrace()
        // }

        // Send reply back to client
        // We will send a 0-terminated string (C string) back to the client,
        // so that this server also works with The Guide C and C++ "Hello World" clients
        // val reply = "World ".getBytes
        // reply(reply.length-1)=0 //Sets the last byte of the reply to 0
        // receiver.send(reply, 0)
    }
}

      

        
        
        
      

    

}

In the scala example, it says it expects a 0-terminated string as a c-string.

I've already tried sending a simple string from python and 0-terminated strings, but none of them worked.

sending to python:

socket.send(b"Hello")
//or
socket.send(b"hello\x00")

      

        
        
        
      

    

in scala:

//result is always null here
val request = receiver.recv (0)

      

        
        
        
      

    

What I do? I feel like it has something to do with the python string, but I haven't been able to solve it yet.