How reconnect (resubscribe) to websocket on typescript

I have an Ionic3 app that on a certain view, connect on view enter and subscribe to a websocket observable/observer service:

subscribtion: Subscription;


ionViewDidEnter() {
    this.subscribtion =  this.socket.message.subscribe(msg => {
    let configs = <Configs>msg.data 
    this.inputs = configs.inputs;
  });
  this.socket.message.next(this.enterMessage);
}

Then, when leaving view, unsubscribe:

ionViewWillLeave() {
  this.socket.message.next(this.quitMessage);
  this.subscribtion.unsubscribe();
}

But if I reenter the view, It will not reconnect to the websocket. How should I do it?

Here the socket and websocket.ts :

@Injectable()
export class SocketProvider {

public message: Subject<Message>;

  constructor(private socket: WebsocketProvider, @Inject('server') private server) {
    console.log('Hello SocketProvider Provider');
    let wsAddr = this.server.webSocketUrl();
    this.message = <Subject<Message>>socket
    .connect(wsAddr)
    .map((response: MessageEvent): Message => {
        let data = JSON.parse(response.data);
        return data;
    })
  }

  }


private subject: Rx.Subject<MessageEvent>;

public connect(url): Rx.Subject<MessageEvent> {
  if (!this.subject) {
    this.subject = this.create(url);
    //console.log('successfully Connnect: ' + url);
  }
  return this.subject;
}

public create(url): Rx.Subject<MessageEvent> {
let ws = new WebSocket(url);

let observable = Rx.Observable.create(
  (obs: Rx.Observer<MessageEvent>) => {
    ws.onmessage = obs.next.bind(obs);
    ws.onerror = obs.error.bind(obs);
    ws.onclose = obs.complete.bind(obs);
    return ws.close.bind(ws);
  }
)

let observer = {
  next: (data: Object) => {
    if (ws.readyState === WebSocket.OPEN) {
      ws.send(JSON.stringify(data));
    }
  }
}

return Rx.Subject.create(observer, observable);
}
}

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