Check if another user is logged in for messaging
<p>Is it possible to find out if another user is logged in on a website using ASP.NET Forms Authentication?</p>

<ul>
<li>User A sends User B a message.</li>
<li>if User B is logged on to the website, a popup should occur.</li>
<li>if not, it will go to the usual notification page. </li>
</ul>

<p>How can I go about implementing this scenario?</p>
