Service Oriented Architecture (SOA) is a flexible software design paradigm for enterprises. The workflows of a company are implemented as services which can be arranged, updated and managed at runtime without interfering with ongoing business. Service management aims at providing undisturbed access to services. Its efficiency strongly depends on a fast response time in the case of a failure. This is hard to achieve since the relations between applications and services require comprehensive knowledge and lack transparency for administrators. Self-organizing approaches promise a solution by automating service discovery. In this paper we present a service discovery system which enables service compositions from semantic descriptions stored in a knowledge base. Therefore, it utilizes multiple composition algorithms from which the most appropriate set is selected and applied according to the size of the knowledge base and the available processors. The functionality of our system is made available through a Web Service interface itself. It is thus applicable in self-organizing service management systems with any number of services and ontologies.