Hi Klaus, You want the compressing marshaller and unmarshaller to work on both sides of the connection, of course, which means you want to tell the client about them, which you do by way of InvokerLocator parameters. When use use the Configuration attribute, only the "subattributes" labeled with isParam="true" get added to the InvokerLocator. Your marshaller and unmarshaller attributes don't have this label, so the client doesn't know about them. This is confusing to me, though, since the client and server shouldn't be able to communicate if they're using different marshaller/unmarshallers. Still, it's a place to start. I should mention that some people have reported problems with the compression marshaller, particularly in the context of EJBs. See JBREM-677 "Compression marshalling fails intermittently." (http://jira.jboss.com/jira/browse/JBREM-677). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4093751#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...