Preprocessor transformations and adaptation operations for improving QoS delivered by WS-BPEL scenario adaptation through service execution parallelization
Technical report SDBS-TR-15002
In this technical report, we present the preprocessor transformations and adaptation operations for improving QoS delivered by WS-BPEL scenario adaptation through service execution parallelization. The preprocessor transformations aim at restructuring the parallelizable operations to be executed in parallel, even though the WS-BPEL scenario designer has specified sequential execution. Exploitation of parallelism can serve as an aid to the adaptation process by broadening the set of alternatives available to the adaptation mechanism: since parallelism reduces the overall execution time, in the parallelized scenario it is possible to choose operations with higher response times but better values in other QoS dimensions (e.g. cost), with the composition respecting the overall WS-BPEL scenario execution time limits, but scoring higher in the other dimensions (e.g. having lower costs).
The preprocessor also caters for making the scenario adaptation ready, i.e. inserting appropriate code to pass the data required to perform the adaptation to a newly introduced adaptation layer and redirect service invocations to this layer.