Sharing Auth Observable value between components without executing it multiple times
<p>I have an <code>AuthService</code> that fetch an <code>Observable&lt;auth&gt;</code> data from Firebase and put it in a public variable <code>auth$</code>.</p>

<p>Somewhere in my app, I need multiple components to access this <code>auth$</code> value to check its content.</p>

<p>I'm currently just doing <code>this.authService.auth$.subscribe(auth =&gt; this.auth = auth)</code> in components.</p>

<ol>
<li><p><strong>Does it mean that I'm executing the <code>fetch data from Firebase</code> multiple times?</strong></p></li>
<li><p><strong>If yes, should I define auth$ as a Subject/BehaviorSubject, subscribe in the service and push data with <code>.next</code>?</strong></p></li>
</ol>