srv_message_broker.py

import json
import asyncio
import websockets


LOCAL_SERVER_HOSTNAME = 'localhost'
LOCAL_SERVER_PORT = 5000


connected = set()


async def echo_broadcast(websocket, path):
  # when room connects, this function add it to the connected (no messages to read)
  connected.add(websocket)  # register websocket (no duplicates, it's a set)
  to_be_removed = []
  try:
    async for message in websocket:
      reply = f'broker recieved data as: {message}!'
      print(f'{reply}')

      for conn in connected:
        try:
          if conn != websocket:  # don't get back to the sender
            print(f'broker is forwarding to the recipient: [{conn} - {message}]')
            await conn.send(message)
            print('recipient confirmed')
          else:
            print('broker replying to the sender')
            _d = {'event': 'broker_confirm', 'data': {}, 'sender': 'broker'}
            await conn.send(json.dumps(_d))
            print('sender confirmed')
        except Exception:
          to_be_removed.append(conn)
  except websockets.ConnectionClosed as e:
      print(f'Terminated:', e)

  for conn in to_be_removed:
    try:
      connected.remove(conn)  # unregister
    except Exception:
      pass
  print(connected)  # debug
  to_be_removed = []


# async def echo(websocket):
#   async for message in websocket:
#     reply = f'Data recieved as: {message}!'
#     print(f'Room server is repling: {reply}')
#     await websocket.send(reply)


async def main():
  async with websockets.serve(echo_broadcast, LOCAL_SERVER_HOSTNAME, LOCAL_SERVER_PORT):
    await asyncio.Future()  # run forever

if __name__ == "__main__":
  asyncio.run(main())