Web Services Discovery with DAML-QoS Ontology

As more and more Web services are deployed, Web service’s discovery mechanisms become essential. Similar services from different sources often exhibit quite different Quality of Service (QoS) levels. For service selection and management purpose, it is necessary to explicitly, precisely, and flexibly specify various constraints and QoS metrics for Web services descriptions. This paper provides a novel ontology as a complement to DARPA Agent Markup Language—Service (DAML-S) Ontology to provide a better QoS metrics model. Three layers are defined, together with clear role descriptions for development. Cardinality constraints are utilized to describe the QoS property constraints. A matchmaking algorithm with multiple matching degrees is provided accordingly. When incorporated with DAML-S, the multiple service level objectives can be described by assigning multiple QoS profiles to one service profile. A prototype system was developed, which demonstrates the feasibility for small to medium-sized service advertisement repository.