Ranked Matching for OWL-S Process Model Discovery

One of the key tasks in the service oriented architecture that semantic web services aim to automate is the discovery of services that can fulfill the application or user needs. OWL-S is one of the proposals for describing semantic metadata about web services, which is based on the OWL ontology language. The OWL-S ontology is organized in three modules: the Service Profile module describes the functionality of the service; the Process Model module describes how it does it; and the Service Grounding module describes how to access the service. Majority of current approaches for matching OWL-S processes take into account only the input/output service profile. In this paper we argue that, in many situations, the service matchmaking should take into account also the process model. When searching services for integrating in a given application, the process model specifying how to interact with the provider has to be taken into account in the discovery process. Other application example is scientific workflow discovery, where scientists look in a workflow repository for existing workflows that could support their research. We propose to develop matching techniques that operate on OWL-S process models and allow to retrieve in a given repository, the processes most similar to the request. To do so, we reduce the problem of process matching to a graph matching problem and we adapt existing algorithms for this purpose. We propose a similarity measure that will be used to rank the discovered services. This measure captures differences in process structure and semantic differences between input/outputs used in the process.