Live from JavaOne: EJB 3.1 New Features

I’m blogging live from the floor of the Sun JavaOne Conference in San Francisco today, currently attending a session about the new features of EJB 3.1. This article highlights some of the much-needed features added to the EJB 3.1 specification.

1. EJB Singletons (finally!)
The EJB 3.1 specification will support shared session bean instances without using a Java static object. Singleton session beans are added with the @Singleton annotation and are created per application, per JVM. The new features of a singleton object require a number of concurrency enhancements, referred to as bean-managed concurrency and container managed concurrency, which essentially supports read/write locks for the singleton object, helping to ensure proper access from multiple concurrent clients.

2. Dynamic/Portable JNDI names
When EJB modules are deployed, JNDI names are auto-created for each bean as follows:

  • Global: java:global/[<app-name>]/<module-name>/<ejb-name>
  • Same App: java:app/[<module-name>]/<ejb-name>
  • Module: java:module/<ejb-name>

3. EJB Timers
Added cron-like support for EJB timers. Seems identical to Java Quartz, but I’d have to see the lower level details to see if they are related. Timers can be created via annotations or explicitly in Java code and seem to have a much larger expressive language for creating schedules.

4. EJB Lite
Subset of the EJB implementation allowing vendors to create and support EJB environments with a much smaller overhead. Not sure how helpful this will be in practice since most vendors are currently used to creating full EJB implementations and creating a new, smaller subset will require some amount of non-trivial work.

5. Asynchronous Session Bean Invocations
Add asynchronous support for remote/local enterprise bean. “Fire and forget” with results available from Java concurrent Future API. Example:

@Stateless
public class HelloBean {
...
@Asynchronous public Future<int> getHelloValue() {...}
}

More to come
There were other things discussed in EJB 3.1 specification such as interface-less local beans, testing EJBs, startup/shutdown callbacks, and JAX-RS integration, but I’ve covered the ones I find most exciting. Overall, the Singleton aspect has to be one of the most needed features of EJB. More to come from the JavaOne conference this week!

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