An Adaptive Object-Oriented Approach to Integration and Access ofHeterogeneous Information Sources

Abstract

A large-scale interoperable database system operating in a dynamic environment should provide Uniform access to heterogeneous information sources, Scalability to the growing number of information sources, Evolution and Composability of software and information sources, and Autonomy of participants, both information consumers and information producers. We refer to these set of properties as the USECA properties [29]. To address the research issues presented by such systems in a systematic manner, we introduce the Distributed Interoperable Object Model (DIOM). DIOM promotes an adaptive approach to interoperation via intelligent mediation [46, 47], aimed at enhancing the robustness and scalability of the services provided for integrating and accessing heterogeneous information sources. DIOM‘s main features include (1) the recursive construction and organization of information access through a network of application-specific mediators, (2) the explicit use of interface composition meta operations (such as specialization, generalization, aggregation, import and hide) to support the incremental design and construction of consumer‘s domain query model, (3) the deferment of semantic heterogeneity resolution to the query result assembly time instead of before or at the time of query formulation, and (4) the systematic development of the query mediation framework and the procedure of each query processing step from query routing, query decomposition, parallel access planning, query translation to query result assembly. To make DIOM concrete, we outline the DIOM-based information mediation architecture, which includes important auxiliary services such as domain-specific metadata library and catalog functions, object linking databases, and associated query services. Several practical examples and application scenarios illustrate the flavor of DIOM query mediation framework and the usefulness of DIOM in multi-database query processing.