Managing references upon object migration: applying separation of concerns

Java mobile object systems generally rely on Java RMI (Remote Method Invocation) to transmit objects between remote sites. As a consequence, the semantics of parameter passing and value returning is restricted to the choices made by, the designers of RMI. Nevertheless, some applications require more adaptability in this regard. Resources (i.e., passive objects) may need to be transferred using a particular strategy depending not only on their type (like RMI statically permits), but also possibly on application-specific criteria, such as instance-based (e.g, the expected size of an instance) or environment-based (e.g., the state of the net-work). Indeed, the strategy adopted to transmit an object can be seen as a nonfunctional aspect, and therefore should possibly be specified separately from the application object code, and its use should be transparent. We present how a suitable reflective extension of Java can easily be applied to elegantly solve this issue, achieving a clean separation of concerns. We illustrate our approach by showing the implementation of a metaobject for the rebinding policy, and a concrete example of use. We also briefly explain our solution for the remote reference policy