The model-assisted global query system for multiple databases in distributed enterprises

Today's enterprises typically employ multiple information systems, which are independently developed, locally administered, and different in logical or physical designs. Therefore, a fundamental challenge in enterprise information management is the sharing of information for enterprise users across organizational boundaries; this requires a global query system capable of providing on-line intelligent assistance to users. Conventional technologies, such as schema-based query languages and hard-coded schema integration, are not sufficient to solve this problem. This article develops a new approach, a ''model-assisted global query system,'' that utilizes an on-line repository of enterprise metadata-the Metadatabase-to facilitate global query formulation and processing with certain desirable properties such as adaptiveness and open-systems architecture. A definitional model characterizing the various classes and roles of the required metadata as knowledge for the system is presented. The significance of possessing this knowledge (via a Metadatabase) toward improving the global query capabilities available previously is analyzed. On this basis, a direct method using model traversal and a query language using global model constructs are developed along with other new methods required for this approach. It is then tested through a prototype system in a computer-integrated manufacturing (CIM) setting.