Tomcat - Application Server?

• The definition of 'Application Server' is not 'Full JEE Server'.
• Tomcat is a server which executes applications with extensive support for web applications.
• Tomcat is a servlet container/engine, which is more than adequate to run many applications.
• It's a LOT more than just a web server, but it doesn't have full EJB support. It may well be enough of an application server (in the more general definition of application) for what you need.
• Look at JBoss if you need full EJB support. Keep in mind that servlets and standard java code can do an awful lot, so you may not need full EJB support.
• Tomcat is not a full JEE server.
• Call Tomcat an App server since it "processes server-side business logic" (i.e. you don't need EJBs to process business logic and it's sometimes a bad idea anyway.)
• You can use a third-party transaction manager like Bitronix or Atomikos if you need distributed transaction support.
• You can use a third-party JMS provider like ActiveMQ if you need this support.

http://tomcat.10.n6.nabble.com/Tomcat-as-Application-Server-td4480636.html