Example for using websocket with protobuf?

[geohuz]

I'm trying to use the protobuf with websocket, but I'm stuck on very simple 
case like send and receive message, my code is sth like below:
    
    
    const protoSpec = """
    syntax = "proto3";
    package DS;
    
    enum TOPIC {
      UNKNOWN = 0;
      PARSER = 1;
      CONNECTION = 2;
      AUTH = 3;
      EVENT = 4;
      RECORD = 5;
      RPC = 6;
      PRESENCE = 7;
      MONITORING = 8;
      CLUSTER = 9;
      LOCK = 10;
      STATE_REGISTRY = 11;
      ERROR = 100;
    }
    
    enum CONNECTION_ACTION {
      UNKNOWN = 0;
      
      ERROR = 1;
      PING = 2;
      PONG = 3;
      ACCEPT = 4;
      CHALLENGE = 5;
      REJECT = 6;
      REDIRECT = 7;
      CLOSING = 8;
      CLOSED = 9;
      
      AUTHENTICATION_TIMEOUT = 100;
      INVALID_MESSAGE = 101;
    }
    
    message Msg {
      TOPIC topic = 1;
      CONNECTION_ACTION action = 2;
      string url = 3;
      string protocolVersion = 5;
    }
    """
    
    parseProto(protoSpec)
    var msg = new DS_Msg
    msg.topic = DS_TOPIC.CONNECTION
    msg.action = DS_CONNECTION_ACTION.CHALLENGE
    msg.url = "ws://localhost:6020"
    msg.protocolVersion = "0.1a"
    
    var stream = newStringStream()
    stream.write msg
    
    let ws = waitFor newAsyncWebsocketClient("localhost", Port(6020), path="/")
    echo "Connected!"
    echo "Sending a challenge"
    discard ws.sendBinary(stream.data) # is this correct?
    
    proc ping() {.async.} =
      while true:
        await sleepAsync(6000)
        echo "ping"
        await ws.sendPing()
    
    proc read() {.async.} =
      while true:
        let (opcode, data) = await ws.readData()
        echo "(opcode: ", opcode, ", data: ", data, ")"
    
    asyncCheck read()
    asyncCheck ping()
    runForever()
    
    
    Run

My question are:

  1. how to serialize the protocol encoded payload and send through websocket?
  2. how to read and parse the protocol encoded payload from peer?