OWLS-SLR is the prototype implementation of our semantic Web service discovery framework that adopts a conceptual model, following the WSMO Discovery Framework and using descriptions that are expressed as instances of the Profile concept of the Service Profile of the OWL-S 1.1 ontology. Some of its main features include:

• Taxonomy-based matchmaking. OWLS-SLR allows the existence of a Profile Taxonomy, that is, a subclass hierarchy of the OWL-S Profile concept. This is feasible by performing complete ABox DL reasoning on OWL-S advertisements and queries that are both represented as direct or indirect Profile ontology instances. OWLS-SLR has been defined on top of the Pellet DL reasoner.
• Structural ontological  knowledge. OWLS-SLR implements two concept distance measures, namely the edge distance and the upwards cotopic distance. The former computes the distance of two concepts based on the number of edges found on the shortest path between them. The latter determines the similarity of two ontology concepts taking into account the ratio of the common superclasses of the two concepts. In that way, we are able to match concepts not based only on logic-based reasoning, but also on the structural knowledge that the ontology provides, returning useful matchmaking results.
• Role-oriented matchmaking. OWLS-SLR allows the annotation of the input and output parameters of the Profile concept with ontology roles. This is achieved by extending the Input and Output OWL-S concepts and exploiting the excellent classification capabilities of DL reasoning that is based on anonymous concept definitions. The rationale behind this direction is to allow the ontology roles to play an important role during matchmaking, since they encapsulate important domain knowledge.
• Filtering: The functionality of OWLS-SLR is characterized by a number of filters that allow users to control the matchmaking results according to the application domain and their preferences.