The availability of many independent services on an open network opens the opportunity of composing individual instances to achieve complex functionality. Most often there are several possible compositions to achieve the same highlevel functionality; the advantage of choosing one composition instead of another one may lie in the different quality of the composition, e.g., one might be cheaper, faster, or more reliable. In this paper, we focus on services described with XML documents and accessed via XML Protocols, known as Web services, and enriched with semantic and Quality of Service (QoS) annotations. We propose an algorithm that, given a desired functionality, returns a composition of services from a repository with the optimal response time or throughput. Services are composed taking into account an ontology of operation names expressed in OWL. RuGQoS is the related implementation.

No abstract

Abstract-Service-Oriented Computing (SOC) is becoming the mainstream development paradigm of applications over the Internet, taking advantage of remote independent functionalities. The cornerstone of SOC's success lies in the potential advantage of composing services on the fly. When the control over the communication and the elements of the information system is low, developing solid systems is challenging. In particular, developing reliable web service compositions usually requires the integration of both composition languages, such as the Business Process Execution Language (BPEL), and of coordination protocols, such as WSAtomicTransaction and WS-BusinessActivity. Unfortunately, the composition and coordination of web services currently have separate languages and specifications. The goal of this paper is twofold. First, we identify the major requirements of transaction management in Service-oriented systems and survey the relevant standards. Second, we propose a semiautomatic approach to integrate BPEL specifications and web service coordination protocols, that is, implementing transaction management within service composition processes, and thus overcoming the limitations of current technologies.