Hi all, As you might know, I've been experimenting with dynamic loading of optional modules lately, and I've come up with a solution that seems to work ok. I'd like to know what I'll explain how it works.
There is a new xdoclet.loader package which contains all the logic for handling dynamic loading. Some of the classes in this package (ModuleFinder/XDocletXmlParser) introspect jar files located in the same directory as xdoclet.jar and look for a META-INF/xdoclet.xml "deployment descriptor" in each of the jars it finds. If an xdoclet.xml file is found, XDocletXmlParser looks for the following information: -what subtasks the module contains, and what parent task they belong to. -what tag handler the module contains, and the namespace they map to. Everything is orchestrated by the Bootstrapper class (which is a task and will replace <taskdef> for xdoclet tasks), and as the jars are introspected it registers the classes (XDoclet core tasks like EjbDocletTask and WebDocletTask) with the BootstrapClassLoader. This class loader is used as a parent for an AntClassLoader, which will be used to load XDoclet classes. Whenever BootstrapperClassLoader is asked to loadClass a class, it will check if the requested class is one of the parent tasks that should be instrumented to add createBlaBla methods. The BootstrapperClassLoader uses BCEL (Jakarta's fantastic Byte Code Engineering Library) to instrument the parent task classes during loading. All it does is to dynamically insert createBlaBla methods so that Ant will accept <blabla> sub elements to parent tasks (like <ejbdoclet>). So far so good for optional subtasks. The other part is to register tag handlers contained within the optional modules. Since XDoclet can be invoked in a different VM, the tag handlers must be registered in the DocletMain class. The registered subtasks "survive" the intra-vm transfer because the subtasks are serialised in DocletContext. In XDocletMain's start method the ModuleFinder.findModules() is called again, and this will register the tag handlers. The actual registration is done inside XDocletModule, which receives callbacks from XDocletXmlParser. XDoclet and Ant are now ready fit for fight. All the resources (dtds, templates and Message.properties) are located in a resources folder beneath the classes. I suggest we put tag handlers and subtasks in the same package (as done with WebLogic stuff). The best argument I can think of for doing it this way is to keep related stuff close together on the file system. I don't like to browse too much around for related stuff. I don't know if I have succeeded in describing how it works. It isn't as complicated as it sounds. Take a peek under xdoclet.loader and the sample weblogic module implementation, as well as the samples/build.xml arounf the <ejbdoclet> task. It should give a fair picture for those of you who understand code better than prose. As ususal, I have been ego. Some of the other developers have made me aware that I should share my thoughts and doings more with you guys. Therefore, consider it all a fictual idea. Just let me know what you think. Peace, Aslak _______________________________________________ Xdoclet-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/xdoclet-devel
