Semantically-Guided Workflow Construction in Taverna: The SADI and BioMoby Plug-Ins

In the Taverna workflow design and enactment tool, users often find it difficult to both manually discover a service or workflow fragment that executes a desired operation on a piece of data (both semantically and syntactically), and correctly connect that service into the workflow such that appropriate connections are made between input and output data elements. The BioMoby project, and its successor the SADI project, embed semantics into their data-structures in an attempt to make the purpose and functionality of a Web Service more computable, and thereby facilitate service discovery during workflow construction. In this article, we compare and contrast the functionality of the BioMoby and SADI plug-ins to Taverna, with a particular focus on how they attempt to simplify workflow synthesis by end-users. We then compare these functionalities with other workflow-like clients we (and others) have created for the BioMoby and SADI systems, discuss the limitations to manual workflow synthesis, and contrast these with the opportunities we have found for fully automated workflow synthesis using the semantics of SADI.