We've been using Restlet and OSGi, and recently we've begin using Spring DM (Dynamic Modules) in our stack, which is a way to integrate Spring's dependency injection and other tools with an OSGi server environment.
We maintain our own build of Restlet, based on the trunk, with local changes to fix show-stopper bugs, and one change we had to make in order to work with Spring DM is in Engine.getClassLoader(). I figured I should mention it here. :-) Engine.getClassLoader() is used by the Engine class's constructor to find helper classes, like external connector implementations. It's implementation checks first for the Thread context classloader, which it will use in preference to it's own Engine.class.getClassLoader(). The problem with this is that if any other library happens to use the Thread context classloader, even if that use is intended to be independent of Restlet, then the wrong classloader is searched for Restlet helper connectors. This is the case with Spring DM, which sets the thread classloader to be the one used in configuring it's bean contexts. Since this classloader doesn't know anything at all about the location of restlet connector extension libraries, Restlet is unable to load any ext connectors. The change we made locally was to remove this usage of the ContextClassLoader. We also removed the usage of the System classloader, since that code is basically unreachable (only executes if Engine.class.getClassLoader() returns null, which is impossible). Now, it's possible that some people are relying on the existing behavior of checking the thread context classloader first. (My guess is that anyone relying on this probably wishes they didn't have to). If it's important to maintain the current behavior, then I suggest that the helper/extension finding code be changed to look in _multiple_ classloaders for potential helper classes, and not just the first one that happens to be found. This would not disrupt people relying on the current code, and would enable much better behavior for osgi and other environments which don't have one big central classloader. -Dave Fogel ------------------------------------------------------ http://restlet.tigris.org/ds/viewMessage.do?dsForumId=4447&dsMessageId=2335380
