Tomcat has been a very popular alternative to other application servers like JBoss, WebLogic and WebSphere. People preferred it for its simplicity. I am writing this article to point out how Java EE 6 changes things and why using tomcat could be downright harmful.
Let’s have a quick summary of what makes Java EE 6 so great:
- Contexts and Dependency Injection (CDI).
- Java Server Faces (JSF) 2.0.
- No interface EJB and ability to create EJB in a web module.
- RESTful Web Service using JAX-RS.
There is the problem with Tomcat right there. None of the above technologies are supported by Tomcat out of the box. Surely, you can add enough JAR files to your web project to get CDI, JSF and JAX-RS. After you are done doing that, you have pretty much created a JBoss look alike. Even then, CDI will be semi-functional. CDI really needs a proper Java EE web and EJB container.
Finally, lack of EJB remains a huge elephant in the room. Sure, EJB was complicated and over engineered. There were good reasons to shun it. That’s not the case any more. EJB has been simplified to the extent it is downright criminal not to use session EJB as your façade to the model layer.
EJB buys you several valuable architecture attributes:
- You get automated transaction management.
- You get role based security.
- Doing audit logging from the model layer becomes a breeze (since you know the user Principal).
- @Startup and @Singleton classes for better application initialization.
- Stateless session EJBs can be directly exposed as RESTful Web Services, there by creating a fully transactional and secure interface. With JAX-RS, you can secure a POJOs resource but don’t get transaction support.
All it takes is one extra line to create an EJB:
public class OrderManager {
}
You can even create these EJBs right within your web module. There is no excuse not to use them.
Edited: Apache TomEE project has assembled these missing pieces and integrated them with Tomcat. This is the correct direction for the Tomcat project. My problem with Tomcat is that most shops that will use it will shy away from what is so great about Java EE 6. Don’t do that to yourself. Switch to JBoss, Glassfish or TomEE.
