4.2 Workflow Specification

Background & Motivation. The problem of workflow specification is to specify the in situ discovery process as a composition of different tools and applications (tasks): What are the inputs and outputs of each task? When and where should a task execute? What resources are needed by each task?The style of the specification (procedural, declarative), level of detail required (detailed, abstract), degree of problem domain specificity (domain-specific, generic), and the modification of the individual tasks (level of intrusion) are aspects of all of the above questions. Workflow specification is closely tied to workflow execution because the specification also implies the functions needed to be carried out by the workflow runtime engine to execute the workflow. Here, we focus on the specification from the end-user’s and developer’s perspective: how humans describe the workflow to the runtime and instrument (modify) tasks to operate within the workflow.