Efficient discovery of services is a central task in the field of Service Oriented Architectures (SOA). Service discovery techniques enable users, e.g., end users and developers of a service-oriented system, to find appropriate services for their needs by matching user’s goals against available descriptions of services. The more formal the service descriptions are, the more automation of discovery can be achieved while still ensuring comprehensibility of a discovery technique.
Currently, only invocation related information of Web services is described with the W3C standard WSDL while the functionality of a service, i.e., what a service actually does, is described in form of natural language documents. In suprime, we use the pi-calculus based service and process description formalism. However, there are still a lot of Web services that are not annotated formally.
We have developed discovery techniques in order to provide users, e.g., end users, developers, and annotators, with a discovery component that is capable to consider semantic descriptions of Web services. Traditional non-semantic descriptions are not used for a full text based discovery, which makes use of the Web service descriptions provided by the WSDL service description files, the Web pages describing REST-ful Web services, and related documents found by a crawler.
The semantic discovery mechanism considers functionalities of services formally described with pre-conditions and effects. This discovery component enables users to enter a more structured goal (service classification, pre-conditions, and effects), then finds the available descriptions from the repository that match the goal by using the reasoning facilities. While keyword based search mechanisms may scale well, reasoning over logical expressions is computationally expensive. We therefore also develop an approach that on one side considers the functionalities of Web services, on the other side has the potential of scaling to a large number of Web service descriptions.