Sharing complex objects in a distributed PEER environment

For distributed computing environments, required for computer integrated manufacturing and other engineering applications, it is most important to support the sharing and exchange of complex objects among cooperating sites, while preserving their autonomy. Specification of complex objects and their object boundaries in a federated database are described. Each database, as well as the entire federation, is modeled as a collection of related objects. Complex objects are defined as subgraphs of the entire object base and are specified by a root object and a collection of paths. A complex object can be distributed over several sites. A method is described that ensures referential integrity while maintaining the autonomy of each database. Different linearization techniques of complex objects are supported to enable applications to retrieve complex objects as single entities. This model is implemented in PEER, a federated, object-oriented database system developed for engineering applications