Exploiting Object Locality in JavaParty, a Distributed Computing Environment for Workstation Clusters

In a distributed programming environment with location transparency, fast access to remote resources is absolutely critical for eÆcient program execution but it is not suÆcient. Locality optimization will try to group objects according to their communication patterns and replace remote access by local access whenever possible. Locality optimization is based on the assumption that local access always is much faster than remote access. Using conventional communication packages like RMI, this assumption is void. A remote object always needs an access layer around it to allow access to the object by means other than direct reference. Transparent access to a remote object also needs to overcome this access layer, even in a local access. Direct reference access can not be used, because of di erent parameter passing semantics. In this paper we present techniques to provide transparent local access to potentially remote objects in the same magnitude as direct Java access.