A protocol for fast co-allocation of shared web services

Abstract

The emerging Web services are building blocks for creating highly distributed e-Business applications, allowing any services to be integrated as long as they are Web-enabled. This interoperability allows businesses to dynamically discover and aggregate a range of component services to more easily create value-added composite services. One of the problems underlying the deployment of such composite services on the Web is service co-allocation that arises when a composite service needs to ensure all the required component services to be available for execution at the same time. This paper presents a protocol, named WSCP (Web Service Co-allocation Protocol), that supports fast co-allocation of distributed Web services when they are shared by multiple independent composite Web services. Our objective is to minimize the waiting time incurred on a composite service before it successfully co-allocates its components. WSCP is inspired by two seemingly unrelated ideas in distributed computing, namely the tentative hold protocol and the backoff protocol. By efficiently combining and taking advantage of these two protocols, WSCP is able to achieve a significant improvement over existing protocols while effectively minimizing livelock.