Retrieval of Service Descriptions using Structured Service Models

The Application Service Provider (ASP) market leads to rapidly increasing numbers of sites that offer software as an online service, rather than for download and installation. This creates a demand for intelligent solutions to retrieve the best service to resolve the user''s problem. This paper introduces Structured Service Models to represent software services and explores a retrieval mechanism on repositories of structured service models. The mechanism is based on computing graph similarity on a special class of directed acyclic graphs. Finding most similar models is NP-complete, however the special structure of the graphs can be exploited for exact and heuristic algorithms. The paper also presents a prototype system designed as a three-tier client-server application where the client is implemented in Java. The system provides facilities for stating queries on a remote repository by drawing a structured service model in a Java applet. The paper concludes with an initial evaluation of the system.