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Pitchfork: EJB 3 Interception & Injection to WebLogic using Spring

by Floyd Marinescu on May 23, 2006 |
Last week it was announced that the EJB 3 implementation in the BEA WebLogic EJB 3 Tech Preview was being built with Spring, using a joint project called Pitchfork, led by Spring framework founder Rod Johnson and WebLogic core engineer Michael Chen. The use of Spring to do injection and interception, as well as the integration with Kodo allowed BEA to get its Tech Preview out faster. Pitchfork can also be re-used by other appserver vendors or open source projects that want to offer EJB 3 interception and dependency injection.

Pitchfork will be released under Apache license and is available for download. InfoQ spoke with Rod Johnson recently about the project and got more details about the project's internals and what it might mean for the community.

The project builds on the Spring IOC container to deliver the @Resource style injection in JSR 250 as well as lifecycle implementations. It also provides EJB-style interception, done with Spring AOP.  In the solution, every EJB corresponds to a Spring bean definition which is extended with a new JSR 250 metadata object.  The role of the WLS container when it starts up is to create a Spring container with the additional metadata. Then when it wants to get an EJB instance it asks the Spring container which injects the EJB with the metadata it needs as well as sets up any interception required. 

According to Rod:
Spring effectively delivers the delta between EJB 2 and EJB 3 (other than the persistence). All the existing stuff that was in EJB 2 such as transaction management, etc, BEA is doing using WebLogic code.  But the actual bean instance benefits from Spring backed services. The WebLogic EJB container thus internally uses the Spring container internally to do its injection and interception.
An important side benefit for BEA WebLogic users will be the ability to go beyond the EJB spec with extensions provided by Spring, such as full use of Spring AOP and AspectJ integration, and more advanced DI capabilities, all while maintaining portability of your code, as  demonstrated by Christian Dupuis.

Pitchfork is not specifically tied to WebLogic, and could also be used with a JPA provider on Tomcat to get much of the EJB 3 complete programming model.  However, according to Rod, such an integration wouldn’t be compliant, Pitchfork is meant to be used in the context of an application server.  

It is likely that other appserver vendors or open source containers such as OpenEJB (used by Geronimo) will also be looking at using Spring to speed up their own EJB 3 support.

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Good stuff... keep it coming by Rick Hightower

There is a good thread on this on Matt's blog by Rick Hightower

There is now a really good FAQ on the Spring site on project PitchFork... by Rick Hightower

The FAQ has things that are no where else. I shed a lot of light on project PitchFork for me.

www.interface21.com/pitchfork/pitchfork-faq.html

"We have not changed our views, for example, on the EJB 3 interception model, which fails to achieve any of the goals of true AOP and is, in our opinion actively bad, as it is both invasive and weak."

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"We believe that any statements to the effect that "EJB 3 can substitute for Spring" are a false play. A cosmetic revision of the EJB spec, which fails to address many fundamental issues in that spec, discussed in numerous places, does not invalidate the world's most popular application programming framework, which is arguably used today much more widely than EJB."

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Rick Hightower (linked in),blog
JSF, Spring, and Hibernate training and consulting

Re: There is now a really good FAQ on the Spring site on project PitchFork. by Rick Hightower

When I wrote: I shed a lot of light on project PitchFork for me.

I meant: It shed a lot of light on project PitchFork for me.

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