"manik.surtani(a)jboss.com" wrote : Agreed that some exceptions may get serialised as return values, but as you pointed out, this is not in the list of errors. | | As for other JGroups classes, those that are transported across the wire are marshalled using the TreeCacheMarshaller in 1.4.0, so this is not a problem when talking to 1.4.x. So, if I got it right this means that it is safe to exclude all jgroups classes excepth "*Exception" when testing agains 1.4.0 GA ? "manik.surtani(a)jboss.com" wrote : | This does break down in one scenario though; and this is when we use region-based marshalling (JBC 1.2.x/1.3.x) which forces Java serialization on the payload, including JGroups classes. (When not using region-based marshalling, JGroups Streamable interface is used, which does not make use of Java seriaization) Does 1.4.x support region-based marshalling i.e. for backward compatibility with older versions i.e. is it possible to run 1.4.x with 1.3.x so that they'll exchange java serialized objects ? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3997561#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...