A Survey of Evolutionary Computation for Web Service Composition: A Technical Perspective

Service oriented computing has emerged as a popular software development paradigm. In the era of Cloud computing, Big data, the Internet of Things (IoT) and Smart Cities, Web service composition has been extensively researched. Web service composition aims to find the best way of combining services, which accomplish simple tasks, into a more sophisticated composite application. Evolutionary computation lends itself to tackling the problem of Web service composition, since it allows for the optimisation of the overall Quality of Service attributes of the composite solution. In order to gain a better understanding of the different evolutionary computation-based approaches applied to this problem, a number of literature surveys have been written in this area. However, these surveys do not focus on the technical aspects of using evolutionary computation to this end, instead focusing on the general application of methods. Thus, the focus of this survey is on analysing existing works from a technical perspective, paying particular attention to the following key decisions when choosing an evolutionary computation-based approach for Web service composition: a) the representation of candidates, b) the fitness evaluation strategy, c) the handling of correctness constraints, d) the choice of evolutionary algorithms and operators. Based on these analyses, current trends, limitations, and future research paths are identified.

I. Introduction

Applications increasingly rely on the Web, and in particular Service-Oriented Computing (SOC), for their functioning [1]–[5]. The foundation of SOC is the concept of Web services, which provide functionality that is accessible over the network in a modular way [6]. This encourages the reuse of existing functionality as opposed to costly re-implementation, and gives rise to the idea of Web service composition [7], whereby multiple Web services that perform simpler tasks are combined into a more complex application. In order to produce a functional composite application, the inputs required by all service operations employed must be fulfilled, either by the user or by the outputs produced by operations of preceding services in the workflow. Languages such as WS-BPEL [8] are used to describe the composition, and the services in it are offered by a service provider and formally described according to standards such as WSDL [9].