app.js

const WebSocket = require('ws');
const util = require('util')

console.log("Starting...")

const ws = new WebSocket('ws://localhost:10000',
    {
        rejectUnauthorized: false
    });

const sub = {"type": "message","message": {"messageId": 8,"type": "subscribeRequest","subscriptions": [{"index": 3,"type": "calls","elements": ["name","participants"]}]}}

ws.on('connection', function (ws) {
  console.log("WS Connected");
});

ws.on('open', function open() {
  ws.send(JSON.stringify(sub));
});

ws.on('message', function incoming(data) {
  console.log(data);
  //Implement a function to ACK messages from server
});

ws.on('error', function incoming(error) {
    console.log("ERROR!")
    console.log(util.inspect(error, true, null));
});

I want to monitor callRoster but i don't know the format of "const sub" . plz help me, I want one example.

@ngockham12312

If you haven't looked already you'll want to check out the official docs here

Page 6. Starts the description of the three types you can subscribe to. callInfo, callRoster, and calls
Page 20. Actually has an example of a subscribe message that is subscribing to the callRoster for a call.

{
  "index": 1,
  "type": "callRoster",
  "call": "97c771ae-fc2e-4257-b129-30ee818e034b",
  "elements": [
    "name",
    "uri",
    "state",
    "importance"
  ]
}

The docs don't call out the model of the objects explicitly, but you can infer how to construct the subscribe messages by looking at the tables on Page 6. The table name is your type, all the types can be passed a call in the root of the object, and anything listed as "Subscribable elements" can be placed in the elements array.