constructor() {
		let eventManager = EventManager.getInstance();

		eventManager.subscribe("authenticationStateChange", (event: Array<any>) => {
			this.message = event[1];
		});

		eventManager.subscribe("tasksResult", (event: Array<any>) => {
			this.message = event[1];
		});
	}

 constructor(public authenticationService: AuthenticationService) {
     this.eventManager = EventManager.getInstance(); // singleton, do not use DI
 }

 this.authenticationService.getNewToken(username, password).then((data) => {
     if (data != null && data.split(".").length === 3) {
         this.authenticationService.logIn(data);
         let expires = this.authenticationService.getExpireTimestamp(data);
         this.eventManager.publish("authenticationStateChange", [true, "Logged in to the system until " + new Date(expires)]);
         setInterval(
             (_) => this.checkLoggedInStatus(),
             1000 * 60 * 5
         );
     } else {
         this.authenticationService.logOut();
         this.eventManager.publish("authenticationStateChange", [false, "server did not send correct token"]);
     }
 })

 private checkLoggedInStatus() {
     if (!this.authenticationService.isLoggedIn()) {
         this.authenticationService.logOut();
         this.eventManager.publish("authenticationStateChange", [false, "Your session expired. Please log in"]);
     }
 }

 .catch((error) => {
     console.log(error.message);
     this.eventManager.publish("authenticationStateChange", [false, error.message]);
 });