How to prevent websocket from closing after certain time in angular5? - websocket

Question

I am using 'rxjs-websockets' to connect with websockets. But after certain time (approx 2min)
the connection gets closed. How can I hold the connection until it is manually closed.
Here is the code snippet I use
constructor(private socketService: WebSocketService) {}
this.socketService.connect('/endpoint');
this.socketSubscription = this.socketService.messages
.subscribe(result => {
// perform operation
});
This is the WebSocketService
import {Injectable} from '#angular/core';
import {QueueingSubject} from 'queueing-subject';
import {Observable} from 'rxjs/Observable';
import websocketConnect from 'rxjs-websockets';
import 'rxjs/add/operator/share';
import 'rxjs/add/operator/retryWhen';
import 'rxjs/add/operator/delay';
#Injectable()
export class WebSocketService {
private inputStream: QueueingSubject<string>;
public messages: Observable<string>;
constructor() {
}
public connect(socketUrl) {
this.messages = websocketConnect(
socketUrl,
this.inputStream = new QueueingSubject<string>()
).messages.retryWhen(errors => errors.delay(1000))
.map(message => JSON.parse(message))
.share();
}
public send(message: string): void {
this.inputStream.next(message);
}
}

Answer 1

Websockets usually holds the connection for a long time interval with the help of some message exchange.
In our case we can call it as 'ping => pong', client sends message 'ping' and server may respond with message 'pong'.
You can send ping every 30 seconds as follows.
setInterval(() => {
this.socketService.send('ping');
}, 30000);
As you are converting every message received at WebSocketService into JSON, you have to make these change
to avaoid JSON Parsing error.
export class WebSocketService {
.
.
.
public connect(socketUrl) {
this.messages = websocketConnect(
socketUrl,
this.inputStream = new QueueingSubject<string>()
).messages.retryWhen(errors => errors.delay(1000))
//parse messages except pong to avoid JSON parsing error
.map(message => message === 'pong' ? message : JSON.parse(message))
.share();
}
.
.
.
}