Multi-Object Cooperation in Distributed Object Bases

Abstract

It is an emerging trend to build large information systems in a component-based fashion where the components follow the concept of object. Applications are constructed by organizing pre-built objects such that they cooperate with each other to perform some task. However, considerable programming effort is required to express multi-object constraints in terms of the traditional message-passing mechanism. This observation lead many authors to suggest communication abstractions in object models. One promising approach is to separate multi-object constraints from the objects and collect them into a separate construct. We call this construct an alliance. Unlike other approaches we allow alliances to involve large sets of long-lived objects which may dynamically vary during the --- also potentially long --- life-time of the alliance. Alliances are not only visible at the specification level but are also computational entities which enforce multi-object constraints at run-time. They do so in..