QoS aggregation for Web service composition using workflow patterns

TLDR

Web service composition depends on matching semantic descriptions and quality of service attributes. The study introduces a mechanism that aggregates individual service QoS dimensions to determine composition QoS and defines composition patterns based on workflow patterns. The aggregation relies on abstract composition patterns—sequence, loop, parallel—derived from Van der Aalst’s workflow patterns within workflow management environments. The resulting aggregation schema verifies that selected services satisfy overall QoS requirements, supports workflow structural elements, and enables aggregation of multiple QoS dimensions.

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.