title: OSGi and application servers
body: <p>I'm having trouble undrstanding the difference about both platforms?
  Both seem to offer an environment for deploying and managing applications.
  First I thought app servers use OSGi under the hood, I don't think so now but I see large AS (jboss, glassfish, websphere, etc) use OSGi.
  What's the big picture?</p>
  
  <p>Thank you</p>