Directory Support for Large-Scale, Automated Service Composition

In an open environment populated by large numbers of services, automated service composition is a major challenge. In such a setting the efficient interaction of directory-based service discovery with different service composition algorithms is crucial. In this paper we present a directory with dedicated features for service composition. In order to optimize the interaction of the directory with different service composition algorithms exploiting application-specific heuristics, the directory supports user-defined selection and ranking functions written in a declarative query language. Inside the directory queries are transformed in order to enable a best-first search for matching directory entries, efficiently pruning the search space.