title: Which use case scenarios are the most appropriate for the publish/subscribe pattern?
body: <p>I am currently working on a social networking application that needs to be highly scalable. </p>
  
  <p>I have been reading about the publish/subscribe pattern(message bus) and am struggling with understanding proper use case scenarios - <strong>when this would be appropriate and when this would be overkill?</strong></p>
  
  <p>For example:</p>
  
  <ul>
  <li>There are several areas of the site where users enter information on a form that needs to be saved to the database; </li>
  <li>When the database saving occurs and an email notification(s) must be made to one or more users.  </li>
  </ul>
  
  <p>Also, for the save scenarios, I would like to give the user friendly messages letting them know their data is saved on the form after saving process completes, if I were to go pub/sub 
  approach.<BR>
  <strong>How would I return success/fail messages back to the UI after a specific task completed?</strong> </p>
  
  <p>Which scenarios are ideal candidates for pub/sub pattern?  It seems to be overkill for basic form database saving.</p>