A New Semantics for the Inclusive Converging Gateway in Safe Processes

We propose a new semantics for the inclusive converging gateway (also known as Or-join). The new semantics coincides with the intuitive, widely agreed semantics for Or-joins on sound acyclic workflow graphs which is implied, for example, by dead path elimination on BPEL flows. The new semantics also coincides with the block-based semantics as used in BPEL on cyclic graphs that can be composed from sound acyclic graphs, repeat- and while-loops. Furthermore, we display several examples for unstructured workflow graphs for which Or-joins get the desired intuitive semantics. A key insight is that not all situations where two or more Or-joins seem to be mutually dependent (known as ‘vicious circles’) are necessarily symmetric. Many such situations are asymmetric and can be resolved naturally in favor of one of the Or-joins. Still symmetric or almost symmetric situations exist, for which it is not clear what semantics is desirable and which result in a deadlock in our semantics. We show that enabledness of an Or-join in our semantics can be decided in linear time in the size of the workflow graph.
Keywords: Volzer, Voelzer

A shortened version of this report appears in:"Business Process Management" Proc. 8th Int'l Conf. on Business Process Management "BPM 2010", Hoboken, NJ, Lecture Notes in Computer Science, Vol. 6336, (Springer-Verlag Berlin Heidelberg, September 2010), pp. 294-309

By: H. Völzer

Published in: RZ3791 in 2010


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