Object Migration in Non-Monolithic Distributed Applications

Object migration is usually applied to optimize distributed monolithic systems. In this paper, the authors investigate whether object migration can also be utilized in cooperative systems which consist of autonomous components. We show that object migration policies will not always optimize system performance. Rather they can reduce it drastically if di erent components apply these policies concurrently. Conventional run-time support for linguistic primitives which are usually used to express migration policies is adapted to cooperative systems. We show that two novel approaches, place-policy and reduction of attachment-transitiveness, can counter the degradation caused by con icting policies. In order to restrict attachment-transitiveness we introduce dynamic relationships called alliances between objects which explicitly de ne cooperation contexts. The e ects of these modi cations are evaluated by simulation. 1