A Penalty-Based Genetic Algorithm for QoS-Aware Web Service Composition with Inter-service Dependencies and Conflicts.
ABSTRACT In Web service based systems, new value-added Web services can be constructed by integrating existing Web services. A Web service may have many implementations, which are functionally identical, but have different quality of service (QoS) attributes, such as response time, price, reputation, reliability, availability and so on. Thus, a significant research problem in Web service composition is how to select an implementation for each of the component Web services so that the overall QoS of the composite Web service is optimal. This is so called QoS-aware Web service composition problem. In some composite Web services there are some dependencies and conflicts between the Web service implementations. However, existing approaches cannot handle the constraints. This paper tackles the QoS-aware Web service composition problem with inter-service dependencies and conflicts using a penalty-based genetic algorithm (GA). Experimental results demonstrate the effectiveness and the scalability of the penalty-based GA.
Conference Proceeding: QoS-Driven Web Service Composition with Inter Service Conflicts.[show abstract] [hide abstract]
ABSTRACT: Web service composition provides a way to build value-added services and web applications by integrating and composing existing web services. In a two-stage approach for web service composition, an abstract specification is synthesized in the first phase and an executable composition process is generated in the second phase by selecting and binding a concrete web service for each abstract task. However, the selection of a web service for one task is not a stand-alone operation, as there may be compatibility conflicts between this service and services chosen for other tasks. This paper gives a method for dynamic web service selection in the presence of inter service dependencies and conflicts. Firstly, a method based on Integer Programming is discussed to implement the process of dynamic service selection. Then, inter service conflicts are explored and expressed formally, which are accommodated into the IP-based method. By combing domain specific service conflicts into a two-stage approach, the method in this paper provides a united approach for dynamic service selection that can integrate both QoS constraints and other domain specific constraints. Experiments show that this method is effective and efficient.Frontiers of WWW Research and Development - APWeb 2006, 8th Asia-Pacific Web Conference, Harbin, China, January 16-18, 2006, Proceedings; 01/2006
Conference Proceeding: QoS Aggregation for Web Service Composition using Workflow Patterns.[show abstract] [hide abstract]
ABSTRACT: Contributions in the field of Web services have identified that (a) finding matches between semantic descriptions of advertised and requested services and (b) nonfunctional characteristics - the quality of service (QoS) - are the most crucial criteria for composition of Web services. A mechanism is introduced that determines the QoS of a Web service composition by aggregating the QoS dimensions of the individual services. This allows to verify whether a set of services selected for composition satisfies the QoS requirements for the whole composition. The aggregation performed builds upon abstract composition patterns, which represent basic structural elements of a composition, like sequence, loop, or parallel execution. This work focusses on workflow management environments. We define composition patterns that are derived from Van der Aalst's et al. comprehensive collection of workflow patterns. The resulting aggregation schema supports the same structural elements as found in workflows. Furthermore, the aggregation of several QoS dimensions is discussed.8th International Enterprise Distributed Object Computing Conference (EDOC 2004), 20-24 September 2004, Monterey, California, USA, Proceedings; 01/2004
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ABSTRACT: Current business process flow representation languages such as BPEL4WS are prescriptive and operate at the execution level. They do not accommodate abstract specifications of business activities and dynamic binding of Web Services at run time. Moreover, dynamic selection of Web services for a process is, often, not a stand-alone operation. There may be many interservice dependencies and domain constraints that need consideration in selecting legal and meaningful services for realizing an abstract flow. In this paper, we present a prototype for dynamic binding of Web Services for abstract specifications of business integration flows using a constraint-based semanticdiscovery mechanism. Building on prior work in this area (Mandel and McIlraith 2002), we provide a way of modeling and accommodating scoped constraints and inter-service dependencies within a process flow while dynamically binding services. The result is a system that allows people to focus on creating appropriate high-level flows, while providing a robust and adaptable runtime.02/2004;