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SDD-1, A System for Distributed Databases, is a distributed database system being developed by Computer Corporation of America (CCA), Cambridge, MA. SDD-1 permits data to be stored redundantly at several database sites in order to enhance the reliability and responsiveness of the system and to facilitate upward scaling of system capacity. This paper describes the method used by SDD-1 for updating data that are stored redundantly. Redundant updating can be costly because it may potentially involve extensive intercomputer communication overhead in order to lock all copies of data being updated. The method described here avoids this overhead by identifying cases in which it is not necessary to perform this global database locking. The identification of transactions that do not require global locking is based on a predefinition of transaction classes performed by the database administrator using an analysis technique described herein. The classes defined are used at run time to decide what level of synchronization is needed for a given transaction. It is important to note that this predefinition activity in no way limits the transactions that the system can accept; it merely permits more efficient execution of those types of transactions that were anticipated. [ABSTRACT FROM AUTHOR]

The article presents an introduction to the special section related to International Conference on Software Engineering (ICSE'97), published in the August 1998 issue of the journal "IEEE Transactions on Software Engineering." Authors say that ICSE was held in Boston Massachusetts, in the week of May 17-23, 1997. The main goal of the conference was to meet needs and expectations of a large variety of attendees. The program committee of the conference was involved in a comprehensive reviewing process of papers submitted. At the end of this process, three papers were selected for publication. In the first paper, "Evaluating Testing Methods by Delivered Reliability," researchers discuss a method for evaluating the effectiveness of testing, based on a measure of the program reliability after testing. The second paper "Analyzing Partially Implemented Real-Time System," presents a technique for analyzing partially-implemented real-time systems. The third paper "Communication Metrics for Software Development," discusses results of comprehensive experiment whose goal was to evaluate the effectiveness of a set of communication metrics.