title: Symfony2 event listener
body: <p>So, I'm trying to figure out these listeners but I'm having issues finding any information on the symfony site regarding them..</p>
  
  <p>Initially, I wanted to create a listener that would trigger on every page load...  I figured that could be detrimental to the overall system performance so i then thought of having it trigger only on: / and /otherpage</p>
  
  <p>But again, i'm having issues finding any information on where to get started with the listener.  Any help appreciated..  All this listener will be doing, is using Doctrine to check the database and setting a session based on what it finds..</p>
  
  <p>Again, any help or suggestions appreciated.  Thanks.</p>