Implementation of Multi-Merge pattern Parallel Split Sample Clauses

Implementation of Multi-Merge pattern Parallel Split. + Discriminator (PSD) In a Discriminator pattern, the service succeeding the mergence waits for the first completed incoming branch and ignores the rest. In other words, the succeeding service will be activated once one of the incoming branches is firstly completed. We now discuss how to adapt the parallel services when SLA violations occur. In this pattern combination the fastest branch (the one with the shortest execution time) determines the start time of the service succeeding the mergence. Once the succeeding service is activated, the uncompleted branches will be ignored. In fact, the Discriminator pattern is not found often in business processes where SLA is enabled because generally the execution time of the services will be specified in the SLAs and hence it can be estimated that which branch is likely to complete first and which branches will be ignored. However, there is one exception – the service consumer wants to hedge the risk of delay caused by SLA violations. In this case, by employing the Discriminator pattern, when a branch is broken, other branches can still deliver expected results in a relatively tolerant period of time. Intuitively, the most effective way to hedge the risk is to allocate low execution time for individual branches while obtaining a high successful global execution rate of the branches. It is also the major objective of the adaptation of the services when SLA violations occur. Since the services on different branches are functionally equivalent, they share a group of candidate service providers and a utility function. For the demonstration purpose, we use the example in Figure 5.3.