THE WEB SERVICE CHALLENGE 2009, PARTICIPATION AND LESSONS LEARNED.

During the academic year of 2008- 2009 I participated in the Web Services Challenge (WSC) 2009 as part of the team from the Rijksuniversiteit Groningen (RuG). The goal of the WSC is to create an algorithm that can solve the web service composition problem in a fast and efficient way. The web service composition problem consist of creating a chain of services, regarded as black boxes with specified input and output, that will satisfy a requested set of output concepts with given input concepts. When no single service exists that can satisfy such a request, services will have to composed so that the output of one or more services serves as the input of a next service. This chaining of services is called composing and the challenge of the WSC is to solve this NP-hard problem in an as short amount of time as possible. In this thesis the RuGQoS system, the entry of the RuG in this year’s WSC, is described in detail. It uses a priority queue and adds a single service in every iteration while searching for the optimal solution of any given challenge. Algorithms presented by the other participating teams are analyzed and four general approaches for solving the web service composition problem are derived. Using the results from the WSC 2009 guidelines for future web service composition software and recommendations for future Web Service Challenges are proposed. 1