Object Orientation in Multidatabase Systems

Using object-oriented techniques to build heterogeneous databases is a promising approach. Objects provide a natural model of a heterogeneous environment. Modeling resources as objects and their services as methods hides the heterogeneity of their implementation and respects their autonomy. At a lower level, providing an object-oriented model for the data in the heterogeneous database facilitates the expression of relations and the resolution of conflicts that exist between entities at different component database systems. Finally, object technology offers an efficient method for modeling and implementing heterogeneous transaction management and for supporting the use of semantic information to allow more concurrency. Unfortunately, the abundance of models and techniques makes the study and evaluation of object-oriented approaches intricately difficult. In this paper we have presented a unifying analysis of the process of building object-oriented heterogeneous database systems. Various methods have been examined, and a number of real-life systems have been compared. We believe that this comprehensive review will enhance our understanding of these issues, substantiate the use of object-oriented techniques, and help put into perspective existing and future projects.