A survey of QoS-aware web service composition techniques

Web service composition can be briefly described as the process of aggregating services with disparate functionalities into a new composite service in order to meet increasingly complex needs of users. Service composition process has been accurate on dealing with services having disparate functionalities, however, over the years the number of web services in particular that exhibit similar functionalities and varying Quality of Service (QoS) has significantly increased. As such, the problem becomes how to select appropriate web services such that the QoS of the resulting composite service is maximized or, in some cases, minimized. This constitutes an NP-hard problem as it is complicated and difficult to solve. In this paper, a discussion of concepts of web service composition and a holistic review of current service composition techniques proposed in literature is presented. Our review spans several publications in the field that can serve as a road map for future research

QoS-Aware Middleware for Web Services Composition

The paradigmatic shift from a Web of manual interactions to a Web of programmatic interactions driven by Web services is creating unprecedented opportunities for the formation of online Business-to-Business (B2B) collaborations. In particular, the creation of value-added services by composition of existing ones is gaining a significant momentum. Since many available Web services provide overlapping or identical functionality, albeit with different Quality of Service (QoS), a choice needs to be made to determine which services are to participate in a given composite service. This paper presents a middleware platform which addresses the issue of selecting Web services for the purpose of their composition in a way that maximizes user satisfaction expressed as utility functions over QoS attributes, while satisfying the constraints set by the user and by the structure of the composite service. Two selection approaches are described and compared: one based on local (task-level) selection of services and the other based on global allocation of tasks to services using integer programming

Using Domain Ontology for Service Replacement Tasks: An Empirical Evaluation

Organizations increasingly use information technology (IT) to integrate their business processes into the processes of their suppliers, customers, and other third parties. An important IT approach is the realization of composite services that organize elementary software services under a shared workflow. Any failure of an elementary service can severely impact the process. The failed service must be examined and, ultimately, be replaced. In solving that task, the process designer must consider the quality-of-service (QoS) of the process. However, the heterogeneity of service descriptions puts the burden on the designer. This research empirically evaluates how designers can use a domain ontology, namely the QoS aggregation ontology, for the replacement task. We report on a laboratory experiment to compare the effectiveness and efficiency of using the ontology vis-à-vis an aggregation table. The results provide evidence for the usefulness of the domain ontology that specifies problem-solving knowledge required for a time-critical task