An execution model for distributed database transactions and its implementation in VPL

Abstract

We present an execution model for distributed transactions that can be employed for multidatabase systems. We use the Flex Transaction model that has been proposed as a highly general and flexible tool for the specification of distributed transactions and extend it by allowing nested and possibly recursive transaction specifications. We show how a given transaction specification and its execution model can be mapped into a representation in a new concurrent Prolog language, the VPL (Vienna Parallel Logic) language. The representation in VPL can be considered as an executable specification. We show some optimizations concerning this mapping and define a significant subclass of Flex Transactions with a declarative representation in VPL that can be modeled by AND/OR structures. We argue that it is more advantageous to use VPL directly for the transaction specification because it provides more flexibility and more control aspects than the Flex Transaction model.

The work is supported by the Austrian FWF (Fonds zur Förderung der Wissenschaftlichen Forschung), project “Interoperability of Autonomous Databases”, contract number P7773-PHY.