Distributed Shared Memory with Versioned Objects

Distributed Object Memory (DOM) is an abstraction that represents a distributed-memory system as a single shared container of language-level objects. The goal of DOM is to simplify programming of parallel applications for such systems. All accesses to shared memory are made relative to objects that reside in one or more node-local memories. For example, in Amber, a DOM system for a network of workstations, remote references are transparent at the language level and are implemented using either remote procedure call or object replication and migration. While DOM can greatly simplify distribution for many application classes, it is not well suited for all domains (parallel-scientific codes, in particular). To address the shortcomings of DOM for such domains, we introduce Versioned DOM (VDOM). In VDOM a version number is associated with each object. Multiple versions of objects can coexist and may be cached in local memories as needed to in- This work was supported in part by the Nationa..