Angular 2试图在服务中实现Observable

Question

我试图使用observable将数据从一个组件发送到另一个组件.在这里,我正在实现像这样的服务中的可观察性......

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/RX'

@Injectable()
export class SelectedItemService {
    stream1$:Observable<any>;
    selectedItem:JSON;

    stream1$= new Observable(observer=> setTimeout(() => {
              observer.next(this.selectedItem);
          }, 3000);)

}

我的父组件正在将数据初始化为onselect()中的服务,如下所示:

import { Component } from '@angular/core';
import {Http, Headers,Response } from '@angular/http';
import {Observable} from 'rxjs/Rx';
import 'rxjs/add/operator/map';
import {SelectedItemService} from './selecteditem.service'

@Component({
    selector: 'newcomponent',
    template:`<p>

    </p>
    <h2>Your Title: {{nameValue}}</h2>
    <ul><li *ngFor="let list of lists">Hello {{ list }}</li></ul> 
    <form class="ui large form segment"> 
    <h3>Add a Link</h3> <div> 
     <label for="title">Title:</label>  
      <input [(ngModel)]="nameValue" placeholder="title" name="Title" >
      </div>   
      <label for="link">Link:</label>  <input name="link"></form>
      <div class=container *ngFor="let data of dataServer"
           [class.selected]="data === selectedItem"
           (click)="onSelect(data)"> 
         <div id="myimages">
             <a routerLink="/SecondNewCom">
                 <img src="myBaseurl/{{data.images.image3}}">
             </a>
             <router-outlet></router-outlet>
         </div>
         <div class=caption>       {{data.productName}} </div>
    </div>`,
    styleUrls: [`./app/mydoc.css`]  
})
export class NewComponent {
    nameValue: string;
    lists: string[];
    url:string;
    dataServer:JSON[];
    length:number;
    selectedItem:JSON;


    constructor(private http:Http, public myservice:SelectedItemService) {
        this.myservice=myservice;
        this.nameValue = "declaredName";
        this.url="myBaseurl";
        this.lists = ['abc', 'xyz', 'lol'];
this.http.get(this.url).map((res:Response) => res.json())
      .subscribe(
        data => { this.dataServer = data
            this.length=Object.keys(this.dataServer).length},
        err => console.error(err),
        () => console.log('done')
      );}

      onSelect(data:JSON):void{
            this.selectedItem=data;
            this.myservice.selectedItem=data;
      }
}

和子组件正在接收来自订户的数据......但显示的数据未定义,我看到空白屏幕..我在哪里做错了...

import {Component,Input} from '@angular/core';
import {SelectedItemService} from './selecteditem.service'

@Component({
    selector:'secondcomponent',
    template:`<h1> This is second new Component</h1>
    <h1>{{UiSelectedItem}}</h1>
   `

})
export class SecondComponent{
     UiSelectedItem:JSON;

     constructor(public mservice:SelectedItemService) {
        this.mservice=mservice;
        mservice.stream1$.subscribe(value=>this.UiSelectedItem=value);
    }    
}