Some details Loaders A lot of the code is based on Loaders, well really DelegateLoaders. https://svn.jboss.org/repos/jbossas/projects/microcontainer/trunk/classlo... which do what you might expect. Although I can support raw Loaders in some places (e.g. as parents of a Domain), most places need DelegateLoaders. That is a Loader associated with a ClassLoaderPolicy and transitively a ClassLoader. DelegateLoaders The DelegateLoaders are Loaders associated with a Policy. https://svn.jboss.org/repos/jbossas/projects/microcontainer/trunk/classlo... They can also implement additional rules. e.g. for handling imports or exports you can add a filter. https://svn.jboss.org/repos/jbossas/projects/microcontainer/trunk/classlo... ClassFilter ClassFilters let you decide what parts of a delegate classloader you are going to import or export. https://svn.jboss.org/repos/jbossas/projects/microcontainer/trunk/classlo... There are some standard ones defined like EVERYTHING and NOTHING in that class. Examples. A DelegateLoader that imports only a certain package | new FilteredDelegateLoader(policy, new PackageClassFilter(new String[] { "com.acme" }); | Only importing java.* and javax.* from the parent of your domain | ClassLoadingSystem system = ClassLoadingSystem.getInstance(); | system.createAndRegisterDomain("MyDomain", ParentPolicy.BEFORE_BUT_ONLY_JAVA); | See https://svn.jboss.org/repos/jbossas/projects/microcontainer/trunk/classlo... for more on the parent policy. Domains allow multiple hierarchies and not just delegation to another domain. | Loader parent = ...; | system.createAndRegisterDomain("MyDomain", ParentPolicy.BEFORE, parent); | this works because ClassLoadingDomains are also Loaders. If you don't specify a parent then it uses the ClassLoader that defines the org.jboss.classloader classes as the parent, via an adapter https://svn.jboss.org/repos/jbossas/projects/microcontainer/trunk/classlo... View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4041344#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...