Mobile Java']Java objects

In this paper we discuss the engineering requirements for adding object mobility to the Java programming language, and give an overview of the design and implementation of our mobile object system. We show that it is helpful to cluster objects for mobility, and that if these clusters represent untrusted pieces of code (for example Agents) then they must be encapsulated both to control their access and to control access to them. We show that managing large numbers of mobile objects in an open environment is a difficult problem, but has its roots in the management of large distributed name spaces. We propose an architecture for relocating moved objects that is both scaleable and tuneable. The mobile object system we describe has been implemented, and is currently in use as part of an ESPRIT agent project. We are currently evolving the design and implementation to provide additional security and distribution facilities.