LoadTimeWeaver for WebSphere [SPR-4331]

[spring-projects-issues]

David J. M. Karlsen opened SPR-4331 and commented

Implement a suitable LoadTimeWeaver for use on WebSphere Application Server.
I guess this is important since spring is certified on WebSphere: http://blog.interface21.com/main/2007/06/21/spring-framework-certified-on-websphere/
Being able to use LTW without having to specify any javaagent would ease deployment.

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Affects: 2.5.1

Referenced from: commits 9c071e5, f191be5

10 votes, 10 watchers

[spring-projects-issues]

Juergen Hoeller commented

As far as we are aware, WebSphere does not provide an API for ClassLoader-specific instrumentation at this point. We'll revisit this for Spring 3.0, using whatever WebSphere 7.0 will be introducing for its full JPA support (which requires weaving as well).

So for the time being, InstrumentationLoadTimeWeaver seems to be the best supported option on WebSphere.

Juergen

[spring-projects-issues]

David J. M. Karlsen commented

Maybe it's possible to use something of this:
http://rbodkin.blogs.com/ron_bodkins_blog/2005/10/websphere_loadt.html

[spring-projects-issues]

Juergen Hoeller commented

As far as I understand, Ron's plugin is just a replacement for a Java agent - available for JDK 1.4. Any such plugin still needs to be specified in the global server configuration, not applying on a per-application basis...

The JPA SPI contract requires load-time weaving with application-specific ClassFileTransformers too, so any fully Java EE 5 compliant server needs to have ClassLoaders that support this. Spring can use the same "addTransformer" style API for a LoadTimeWeaver then. So with WebSphere 7 at the latest, we should have the runtime facility that we need for supporting a LoadTimeWeaver.

Unfortunately, JPA previews - such as the one in JBoss 4.2 or in the WebSphere 6.1 feature pack - usually do not support pluggability of JPA providers yet (for which they'd need to support application-specific ClassFileTransformers). For that reason, our options for general load-time weaving are limited on those platforms. Using the general spring-agent.jar is effectively the sole option there.

Juergen

[spring-projects-issues]

Michael Vorburger commented

Any plans to do this at least for WAS 7.x? (PS: Could this http://rbodkin.blogs.com/ron_bodkins_blog/2005/10/websphere_loadt.html be of any interest?)

[spring-projects-issues]

Paul Benedict commented

Could it be hacked together using AspectJ?

[spring-projects-issues]

Costin Leau commented

Hi guys,

The LTW for WebSphere 7 is not available in trunk. I have tested it on WebSphere 7.0.0.9 and 7.0.0.13 (that is fix pack 9 and 13) with and without AspectJ.Not sure if you guys are following this but feedback is definitely welcomed especially regarding the various classoading configuration scenarios available.

The LTW is already hooked into the auto-detection process so there's nothing special you need to do except the context:load-time-weaver/ declaration (see the docs for more information).

Note that it's impossible to support a LTW on WebSphere 6 (which ironically delayed this feature as we had no expectations that something has really changed) at least out of the box. I'm not sure whether there are any packs or fixes that address this but with WebSphere 7 available for a while, I think this gives us a good start.