Comment implémenter la communication entre les composants frères et sœurs dans Angular 2 ?

import {Injectable} from '@angular/core';

@Injectable()
export class SharedService {
  dataArray: string[] = [];

  insertData(data: string) {
    this.dataArray.unshift(data);
  }
}

import {Component} from '@angular/core';
import {SharedService} from './shared.service';
import {ChildComponent} from './child.component';
import {ChildSiblingComponent} from './child-sibling.component';

@Component({
  selector: 'parent-component',
  template: `<h1 >Parent</h1>
        <div>
            <child-component></child-component>
            <child-sibling-component></child-sibling-component>
        </div>`,
  providers: [SharedService],
  directives: [ChildComponent, ChildSiblingComponent],
})
export class ParentComponent {} 

import {Component, OnInit} from '@angular/core';
import {SharedService} from './shared.service';

@Component({
  selector: 'child-component',
  template: `<h1 >I am a child</h1>
        <div>
            <ul *ngFor="#data in data">
                <li>{{data}}</li>
            </ul>
        </div>`
})
export class ChildComponent implements OnInit {
  data: string[] = [];
  constructor(private _sharedService: SharedService) { }
  ngOnInit(): any { this.data = this._sharedService.dataArray; }
}

import {Component} from 'angular2/core';
import {SharedService} from './shared.service';

@Component({
  selector: 'child-sibling-component',
  template: `
          <h1 >I am a child</h1>
          <input type="text" [(ngModel)]="data"/>
          <button (click)="addData()"></button>`
})
export class ChildSiblingComponent {
  data: string = 'Testing data';
  constructor(private _sharedService: SharedService) {}
  addData() {
    this._sharedService.insertData(this.data);
    this.data = '';
  }
}