Heuristics for QoS-aware Web Service Composition

Abstract

This paper discusses the Quality of Service (QoS)-aware composition of Web Services. The work is based on the assumption that for each task in a workflow a set of alternative Web Services with similar functionality is available and that these Web Services have different QoS parameters and costs. This leads to the general optimization problem of how to select Web Services for each task so that the overall QoS and cost requirements of the composition are satisfied.Current proposals use exact algorithms or complex heuristics (e.g. genetic algorithms) to solve this problem. An actual implementation of a workflow engine (like our WSQoSX architecture), however, has to be able to solve these optimization problems in real-time and under heavy load. Therefore, we present a heuristic that performs extremely well while providing excellent (almost optimal) solutions. Using simulations, we show that in most cases our heuristic is able to calculate solutions that come as close as 99% to the optimal solution while taking less than 2% of the time of a standard exact algorithm. Further, we also investigate how much and under which circumstances the solution obtained by our heuristic can be further improved by other heuristics.

Cost-Based Optimization of Service Compositions

“…This bears a natural resemblance to the idea of QoS optimization for service compositions, as prominently described in [25]. Later approaches tried to improve on this concept by using more efficient heuristic algorithms, e.g., H1 RELAX IP [26] (a heuristic relaxation of integer programming), WFlow [27] (based on stochastic workflow reduction) or the immune algorithm [28]. Different authors approached the problem by combining global optimization and local selection (which can be done much more efficient than global optimization).…”

Quality-of-Service-Aware Service Selection: A Novel Approach Considering Potential Service Failures and Nondeterministic Service Values

“…Ardagna and Pernici 2007;Cui et al 2011;Huang et al 2009;Yu et al 2007;Zeng et al 2004) and heuristic approaches (cf. Alrifai et al 2012;Ardagna and Mirandola 2010;Berbner et al 2006;Canfora and Di Penta et al 2005;Canfora et al 2008;Jaeger and Muehl 2007;Li and Yan-xiang 2012;Maolin and Ai 2010;Menascé et al 2008;Yang et al 2010;Yu et al 2007;Zheng and Xiong 2012)0 F 2 . The QoS-aware ex-ante service selection is realized either by a local or a global optimization.…”

On Guaranteeing Global Dependability Properties in Collaborative Business Process Management

“…Several existing methodologies only consider implementations consisting of a single service provided by some CBP participant ( [5,10,12,35,46,47]). In this case, the set of possible implementations for a given task corresponds to the set of functionally equivalent services implementing that task, provided by the (candidate) CBP participants.…”

“…Methodologies to assess the QoS of a SOA system and to drive its selfconfiguration have been already presented. Some of them specifically focus on the fulfillment of dependability requirements (e.g., [22,49]), while others consider multiple QoS attributes including dependability (e.g., [5,10,12,15,14,35,46,47]). Most of these methodologies base the selfconfiguration on the runtime selection for each CBP task of a single service that implements it, to which that task will be dynamically bound.…”