The separation of duties and retain familiar constraints are to be considered core . The piled execution is to be considered non-core . Piled execution is an alternative to the interaction point behaviour described to date. It’s exclusion will deny pattern support, but it can be added into a system once the base interaction point behaviour has been established. REQ-012 : Workflow designer to choose System-Initiated Allocation mechanism. If the set of participants offered a work item contains only a single participant, the running workflow system does not need to choose between alternatives, and may allocate the work item directly when system-initiated allocation is being used. However, no guarantee can be made at design-time that an offer will be limited to a single participant at runtime. A design-time choice needs to be made to tell the YAWL system how it must choose a single participant from a number of possible alternatives for allocation. Ultimately, so long as an algorithm takes a participant set, and returns only one of those participants, it could be considered a valid automated allocation mechanism. Initially, three mechanisms will be constructed. A workflow designer may chose from these three mechanisms: Round-Robin: From the identified participants, choose the one who recently completed a work item for the task. In the event that several users are recorded as being equally least-recent, choose one of these randomly. Shortest-Queue: From the identified participants, choose the one whose sum of allocated and started work item queue numbers is shortest. This will be used as the default choice. Page 84 of 100
Random: Choose a participant from the collection identified randomly. The mechanisms will be registered with the workflow engine and communicated to the workflow designer when they come to choose an appropriate mechanism for system-initiated allocation. As new mechanisms are programmed and registered with a running engine, they will be subsequently made available to the workflow designer to choose from as well. This requirement will need a workflow specification passed from the workflow designer to a newYAWL engine to be sufficiently flexible to allow new mechanisms to be identified within the workflow specification without requiring changes to the specification structure. This requirement is classified as core . REQ-013 : Resourcing Decisions made must be encoded within the task definition of a YAWL specification. The specification generated by a workflow design tool for consumption by a newYAWL resourcing-enabled system must encode the resourcing-required choices made by a workflow designer that have been described in this section. The requirements listed below require special effort to ensure that as new options are made available by an engine for key decisions, the specification does not require structural changes in order to have them identified: • Workflow Designer to be able to specify filters for a base distribution set of participants using organi- sation, capability and historical data.
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- Spring '17