I did a post some time ago about some classloading issues with JBoss. I wanted to follow up with some additional information, particularly I wanted to mention some simple things that you can do as a developer to avoid any of those verify or linkage errors that vex us.
- Avoid any classloader conflicts by putting every web application into an ear file. If you have just one single war file with no other resources do it anyway. It will save you from heartache.
- At times you will encounter a message like the following :java.lang.LinkageError: loader constraints violated when linking com/xyzcorp/something/Something.class. One of the things to look out for is that you do not have a jar file in the /WEB-INF/lib folder of your web application AND in the as a <java><module>library in your ear file. The contents of your ear are loaded separately from the contents of war, and this can cause your linkage error. Check for other duplicates among all your jars, wars, and hars (hibernate archives).
If you are still having some problems, I'd like to know about them. You can also check out information about classloading at JBoss' wiki
Mon, 14 Aug 2006 10:10 AM GMT
I had some XML (SAX) API and implementation in WEB-INF/lib. Got Linkage Error for ...Parser. Removing that from lib worked. xmljar was removed Can you enlighten me on what happened that it worked.