The Resource Service

Abstract

A workflow comprises three main perspectives: control-flow, data, and resources. The resource perspective is particularly important because, for the most part, workflow tasks are designed to be performed by people, and so a workflow environment should support efficient and flexible ways to associate work with the people who have the required skills and authorizations to carry it out. Thus, the resource perspective is primarily responsible for modeling an organizational structure, and the people who populate it, in a computational form, so that a person may be coupled with tasks and data emanating from the control-flow and data perspectives. While control-flow and data-flow are necessarily tightly coupled within a workflow enactment engine, in the YAWL environment the resource perspective is supported by a discrete Custom Service called the Resource Service, in line with YAWL’s Service Oriented Architecture. Consequently, the Engine is oblivious to the assignment of resources to tasks (i.e., it is said to be agnostic with regards to resourcing). The YAWL Resource Service provides full support for 37 of the 43 identified resource patterns (the remaining six being particular to the case-handling paradigm) and so may be considered the preeminent implementer of workflow resource pattern support.