Much has been written on the promise of Web service discovery and (semi-) automated composition. In this discussion, the value to practitioners of discovering and reusing existing service compositions, captured in workflows, is mostly ignored. We present the case for workflows and workflow discovery in science and develop one discovery solution. Through a survey with 21 scientists and developers from the myGrid/Taverna workflow environment, workflow discovery requirements are elicited. Through a user experiment with 13 scientists, an attempt is made to build a benchmark for workflow ranking. Through the design and implementation of a workflow discovery tool, a mechanism for ranking workflow fragments is provided based on graph sub-isomorphism detection. The tool evaluation, drawing on a corpus of 89 public workflows and the results of the user experiment, finds that, for a simple showcase, the average human ranking can largely be reproduced.
Haiku - a Scala Combinator Toolkit for Semi-automated Composition of Metaheuristics