Flow-Based Service Selection forWeb Service Composition Supporting Multiple QoS Classes

TLDR

In service-oriented architectures, applications are composed of independently developed Web services, and because the same service may be offered by multiple providers with differing QoS attributes, a selection process is needed to identify the best constituent services for a given composite service. This paper studies a broker that offers a composite service with multiple QoS classes to several users, each generating a flow of requests over time. We propose a service selection scheme that optimizes the end-to-end aggregated QoS of all incoming request flows by solving a simple linear programming problem that scales with the number of users, request volumes, and services. Unlike most current proposals that may not scale well due to independent handling of requests or NP-hard selection problems, our approach scales efficiently as the number of users, request volumes, and services grows.

Abstract

In the service oriented paradigm applications are created as a composition of independently developed Web services. Since the same service may be offered by different providers with different non-functional Quality of Service (QoS) attributes, a selection process is needed to identify the constituent services for a given composite service that best meet the users QoS requirements. In this paper, we consider a broker that offers a composite service with multiple QoS classes to several users each generating a flow of requests over time. We propose a service selection scheme which optimizes the end-to-end aggregated QoS of all incoming flows of requests by means of a simple linear programming problem which scales as the number of users, request volumes and/or services grows. This approach differs from most of the current proposals which may not scale well since: a) requests, even from the same user, are handled independently from one another; and b) the selection process often requires the solution of an NP-hard problem.