How to call component method from service? (angular2)

Question

I want to create service, which can interact with one component. All another components in my app, should be able to call this service, and this service should interact with

Answer 1

as this post is a bit old, I actualize the response of Tudor the stackblitz

the service

private customSubject = new Subject();
  customObservable = this.customSubject.asObservable();

  // Service message commands
  callComponentMethod(value:any) {
    this.customSubject.next(value);
  }

the main-component

constructor(private communicationService:CommunicationService){}
  ngOnInit()
  {
    this.communicationService.customObservable.subscribe((res) => {
          this.myFunction(res)
        }
      );
  }
  myFunction(res:any)
  {
    alert(res)
  }

Another component that call to the method of the service

constructor( private communicationService: CommunicationService  ) { }

  click() {
    this.communicationService.callComponentMethod("hello word");
  }