What do ContextLoaderListener and RequestContextListener do?
<p>I have an application, where i am using Spring.
And in my web.xml i use lines below </p>

<pre><code>&lt;web-app&gt;
     ....
     &lt;listener&gt;
          &lt;listener-class&gt;
             org.springframework.web.context.ContextLoaderListener
          &lt;/listener-class&gt;
       &lt;/listener&gt;
       &lt;listener&gt;
          &lt;listener-class&gt;
             org.springframework.web.context.request.RequestContextListener
          &lt;/listener-class&gt;
       &lt;/listener&gt;
       ....
&lt;/web-app&gt;
</code></pre>

<p>What are they ?
Are they mandatory ?</p>