These are components of the deployment. e.g. a sar contains many mbeans an ejb-jar contains many ejbs The idea is that you can write a deployer that deals with one component at a time rather than having to do the complicated error handling (of rolling back previous components) if it fails part way through in every deployer. In the JBoss4 deployers, this is mostly broken and where it even exists it is often inconsistent and contains different bugs in different deployers. Depending on what you want to process there is an isTopLevel() and isComponent() available on the DeploymentContext which need to be exposed as part of the strucure query stuff that needs adding for the DeploymentUnit. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3976255#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...