> You don't say which version of Tomcat you're using, but I guess 6.0 > from your paths.
Correct. I've tried both 6.0.16 and 6.0.20. > You should take a close look at > http://tomcat.apache.org/tomcat-6.0-doc/class-loader-howto.html . I read that page before posting to this list, along with other Tomcat docs, the Tomcat wiki, and the archives of this list. > So you ask for Class.forName("AudiBankImporter"). The webapp > classloader can't load this, so delegates to the common classloader. > The common classloader loads the class and tries to resolve the class' > references to other classes. It tries to resolve the reference to > TransactionImport; can't find it; delegates up the chain; still can't > find it; and fails with the error you see. Ah! Ok, that totally makes sense. Thank you for this clear interpretation! > If you really, really have to do it this way (and it seems like a > rather odd thing to do), you'll need to ensure that the common > classloader can resolve TransactionImport. This means that you then > should ensure TransactionImport is *not* loaded by your webapp > classloader - you need to move it out of your webapp to > CATALINA_HOME/lib. My idea was that TransactionImport is the interface (abstract class, actually) that the webapp authors define and use in webapp code, and plugin authors need only to implement TransactionImport, provide the fully-qualified class name of their implementation and put their compiled implementation somewhere that the Webapp can load. Ideally, this would be somewhere like $HOME/.mifos/plugins , I was just trying to simplify things during development by placing plugins in $CATALINA_HOME/lib for now. Any idea how I could load plugins from $HOME/.mifos/plugins ? Would it be possible to add jars or classes in this directory to the classpath at runtime? I could exclude TransactionImport from the webapp, but I think this would complicate deployment. I'd have to say something like "to deploy my webapp you must also place mifos-spi-1.0.jar in $CATALINA_HOME/lib". Maybe that's not too bad? Makes upgrading the webapp a bit more of a hassle (more than just dropping in a new war). Hmm, actually, maybe this will work! It appears I can import and mention TransactionImport even if it is only available during compilation (ie: not placed in WEB-INF/lib in the webapp). Ok, cool, this is looking like the best option so far until I can figure out how to load plugins from $HOME/.mifos/plugins . Yay! > Equally, you could put the jar containing > AudiBankImporter into your webapp, which seems like a simpler and more > isolated approach unless you're trying to solve a larger problem than > you've described! I want to release my webapp first, then allow plugin authors to write and load plugins at their leisure. Perhaps there's a way to automate copying a plugin into WEB-INF/lib such that it can be used by a webapp? I'm sure I'm going about this all wrong, but hopefully I'm getting closer to something that makes sense. I tried setting <Loader delegate="true"/> in context.xml (based on http://tinyurl.com/yk7f63k), and I *am* able to load AudiBankImporter if I include TransactionImport in the plugin jar. I don't know other implications of this change, and it seems like a weird thing to have to require to be able to deploy my webapp. I think I covered most of Pid's questions too, except: * yes, TransactionImport is in a package * I had been trying to include _and_ exclude TransactionImport in the plugin jar in $CATALINA_HOME/lib . The first gave me a class cast exception ("AudiBankImporter cannot be cast to TransactionImport"), and the second (which we've covered) runs into the ClassNotFoundException since TransactionImport can't be seen by the common classloader. Thank you both for your help so far, and sorry if this is drifting to non-Tomcat stuff. Finally, here's the code I've been experimenting with in case folks are curious. source for package defining TransactionImport abstract class: https://mifos.dev.java.net/source/browse/mifos/trunk/spi/ source for package implementing TransactionImport (AudiBankImporter): https://mifos.dev.java.net/source/browse/mifos/spikes/importPluginExample/ The plugin framework will eventually end up in the Mifos webapp ( https://mifos.dev.java.net/source/browse/mifos/trunk/application ), but I made a small webapp for testing purposes: http://adammonsen.com/tmp/smallappwithplugins.tgz --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
