Data base communication in a heterogeneous data base management system network

摘要

An architectural approach is outlined toward the long range goal of a far-reaching data base communication system capable of supporting a network in which any user in any network node can be given an integrated and tailored view or schema (e.g. hierarchical, relational), while in reality the data may reside in one single data base or in physically separated data bases, managed individually by the same type of GDBMS (e.g. CODASYL, IMS, relational) or by different GDBMS. A series of data base model layers and mappings or translations between these layers are proposed. The entity-relationships model is fundamentally used for the highly logical model layers of the integrated system and a modified DIAM is used for the physical distribution and access path oriented layers. A comprehensive example of an integrated network of heterogeneous data bases is outlined, showing for a set of queries their formulation through different layers of the system from the virtual user realm to the physical data bases. Major challenges and issues are discussed.