Efficient and fully abstract routing of futures in object network overlays

In distributed object systems, it is desirable to enable migration of objects between locations, e.g., in order to support efficient resource allocation. Existing approaches build complex routing infrastructures to handle object-to-object communication, typically on top of IP, using, e.g., message forwarding chains or centralized object location servers. These solutions are costly and problematic in terms of efficiency, overhead, and correctness. We show how location independent routing can be used to implement object overlays with complex messaging behavior in a sound, fully abstract, and efficient way, on top of an abstract network of processing nodes connected point-to-point by asynchronous channels. We consider a distributed object language with futures, essentially lazy return values. Futures are challenging in this context due to the global consistency requirements they impose. The key conclusion is that execution in a decentralized, asynchronous network can preserve the standard, network-oblivious behavior of objects with futures, in the sense of contextual equivalence. To the best of our knowledge, this is the first such result in the literature. We also believe the proposed execution model may be of interest in its own right in the context of large-scale distributed computing.