A Graphical Approach to Allocating Class Fragments in Distributed Objectbase Systems

Abstract

This paper contributes by providing an allocation taxonomy to analyze DOBS models and identify the primary characteristics of a DOBS allocation. A graphical optimization technique, based on the work by Kernighan and Lin (The Bell System, Technical Journal, pp. 291–307, 1970), is basis of our approach. The algorithm attempts to arrive at a “near optimal” distribution of fragments by exchanging and/or moving fragments between every pair of sites. The algorithms are implemented and are tested with carefully generated test data to obtain an analysis of the performance. The design, implementation and analysis of the allocation algorithms form the most significant contribution of this paper. Several significant insights are derived from the analysis of the results obtained that can be usefully applied to any real life DOBS allocation design. The applicability of the allocation algorithms for the DOBS model of interest may be verified by a cost benefit analysis based on their efficiency. The optimization of the initial allocation is meaningful only if the improvement obtained by optimization justifies the additional overhead. If significant improvement is not obtainable by optimization then our efficient initial allocation scheme alone may serve the purpose.