Efficient Delivery of Web Services

This dissertation addresses issues for the efficient access to Web databases and services. We propose a distributed ontology for a meaningful organization of and efficient access to Web databases. Next, we dedicate most of our work on presenting a comprehensive query infrastructure for the emerging concept of Web services. The core of this query infrastructure is to enable the efficient delivery of Web services based on the concept of Quality of Web Service. Treating Web services as first class objects is a fundamental step towards achieving the envisioned Semantic Web. Semantics-aware processing of information requires intensive use of Web services. In our research, we propose a new query model where queries are resolved by combining Web service invocations. To efficiently deploy such scheme, we propose an optimization strategy based on aggregating Quality of Web service (QoWS) of different Web services. QoWS is adjusted through a dynamic rating scheme and multilevel matching. Web service rating provides an assessment of their behavior. The multilevel matching allows a larger solution space by enabling similar and partial answers.