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H. F. Wedde, S. Böhm und W. Freund
Real-Time Transactions Need Their Constituting Tasks
IFAC Conference on New Technologies in Computer Control 2001 (NTCC’01), Hong Kong, ROC, 2001-11


Transaction handling in real-time applications has been studied since quite a number of years, pursuing a variety of research topics. Considering concurrency control, in particular for replicated objects, the algorithms suggested have been moderate modifications of algorithms originally defined for non-real-time database applications. This resulted, for some of them (OQPL and OCC), in a considerable performance improvement (total deadline failure rate) compared to the original versions. As their specific time-sensitive parameter these real-time versions were designed to work on a transaction deadline. While transaction deadlines are to be chosen in accordance with the deadlines of the tasks constituting the transactions no attention has been paid to the latter ones. Taking the perspective of object or task/ transaction similarity we experimentally demonstrate that it is highly advantageous (if not indispensable) for the real-time performance to fully utilize the task level and structure of transactions, in particular for safety-critical applications. Keywords: Distributed operating systems, real-time systems, safety-critical systems, adaptive transaction management, adaptive concurrency control.