Hello! I'm integrating JForum into our webapp now and ran over the serious (at least for me) issue.
I'm using JForum 2.1.7 on JBoss 4. I'm required to manage JForum entites from a separate webapp, so I start up separate copy of ForumRepository and friends in it. Because I need repositories (of my & JForum's webapps) to be synchronized, I wrote MBeanTreeCacheEngine that uses tree cache deployed as JBoss service. So I faced the fact that entites from different webapps are loaded by different classloaders. To solve it, I serialize entities before putting them in cache.
Then I encountered terrible bugs when some things just dissapear from forum. I debugged this to reason that when you serialize entitiy with non-serializable fields (other entities), serialization engine just silently skips them!
So I suggest to make all classes in net.jforum.entities serializable to make them really cacheable - you do require it for stand-alone (not embedded) cache (there are other ways, like in Hibernate, but they are way more complicated). Note that for now many of them already are serializable, but some are not. [originally posted on jforum.net by skoptelov]