Ok, here is what happend:
The deployed version of the filter class contained a field that no longer existed in the client jars. During unmarshalling the glassfish gets confused with the filter and seems to try to contact the client issuing the request. This issuing fails if the client set up the initial context with the glassfish hostname rather than its ip address.
Once i switched to the IP i received the error message that a required field was not set. This field is one of the last in the class, so i guess the unmarshalling tried to map into the field that does only exist in the server jars, but is no longer in the client classes. This the field was empty.
Unfortunatly glassfish error messages did not help :-(
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