Invoke remote EJB3 from JVM 1.4 client

[bmaras]

I managed to call remote EJB3 from a JVM 1.4 client.
I would be glad to have some feedback on the way I dit it : is it safe? Should I open a JIRA to publish a patch?

I use JBoss 4.0.3SP1 with EJB3 RC6. A JDK 1.5 is needed for the EJB3.
I need to remotely call some of these EJB from a client that runs on JDK 1.4.

It doesn't work natively, because the jboss-ejb3.jar bundled with EJB3 RC6 is compiled with JDK 1.5. It gives errors on major/minor version.

So I used JBossRetro (http://labs.jboss.com/jbossretro/) to convert this jar in jdk 1.4 compatible format.
That gave me a jar that works in my jdk 1.4 client.

I also needed to create a client jar for my EJBs, compiled with a 1.4 target.
I had to include the EJB interfaces in it, but they don't compile by default because of the annotations @Local and/or @Remote, so I needed to remove these annotations when I compile the client jar.

Thus, I can call my EJB 3 Session Stateless Beans. I need on my client :
- the client jar for my EJBs, compiled as explained above
- the generated jboss-ejb3-client14.jar
- jbossretro-rt.jar
- jboss-backport-concurrent.jar
- javassist.jar

I tested that on JBoss 4.0.3SP1+EJB3 RC6, with Session Stateless Beans only.

I have a patch for the current version of ejb3/build.xml. I could not test the generated jar from this script, because I only use JBoss 4.0.3SP1 that doesn't support the latest version of EJB3 jars.
I generated my jboss-ejb3-client14.jar with another ant script, that does this :
- uncompress the file jboss-ejb3.jar bundled with EJB3 RC6
- delete all files that are not included in jboss-ejb3-client.jar (based on the list of current ejb3/build.xml)
- run jbossretro on the classes, using the jboss 4.0.3SP1 libraries on the classpath
- recompress the jar

Should I create a JIRA for that ?
I would be glad to have some feedback on all that.

[bmaras]

I opened a patch proposal for this feature :
http://jira.jboss.com/jira/browse/EJBTHREE-1029

It also contains the files mentioned above.

[bdecoste]

The problem is that the final version of the EJB3 API is dependent on Java 5 constructs. For example, javax.ejb.SessionContext.getBusinessObject() returns a Generic. So we cannot compile some client classes using JDK1.4. The earlier versions of the specification were not dependent on Java 5 constructs, so we were able to support JDK1.4 clients in our earlier release (e.g. EJB3 RC6).

[bmaras]

All right, thanks for this feedback.

So you confirm that this method should work on version RC6 of EJB3? (we only use Session Stateless EJB3s)

Do you know on which version of EJB3 the specification became Java 5 dependent? Is it RC7, or higher?

Thanks