Breve descrizione dei contenuti: Service-oriented computing and Web services are becoming more popular, enabling organizations to use the Web as a market for selling their own services and consuming existing services from others. Nevertheless, the more services are available, the more difficult it becomes to find the most appropriate service for a specific application. Existing approaches to Web service discovery tend to address different information-processing styles. However, Web services have functional and nonfunctional characteristics that can be difficult to present and control. Service behavior and quality-of-service (QoS) parameters can vary over time, and new services can emerge in certain business areas.