A Flexible Operation Execution

Many parallel and distributed programming models are based on some form of shared objects, which may be represented in various ways (e.g., single-copy, replicated, and partitioned objects). Also, many diierent operation execution strategies have been designed for each representation. In programming systems that use multiple representations integrated in a single object model, one way to provide multiple execution strategies is to implement each strategy independently from the others. However, this leads to rigid systems and provides little opportunity for code reuse. Instead , we propose a exible operation execution model that allows the implementation of many diierent strategies, which can even be changed at runtime. We present the model and a distributed implementation of it. Also, we describe how various execution strategies can be expressed using the model, and we look at applications that ben-eet from its exibility.