Web Service Grids: An Evolutionary Approach

Abstract

The U.K. e‐Science Programme is a £250 million, five‐year initiative which has funded over 100 projects. These application‐led projects are underpinned by an emerging set of core middleware services that allow the coordinated, collaborative use of distributed resources. This set of middleware services runs on top of the research network and beneath the applications we call the ‘Grid’. Grid middleware is currently in transition from pre‐Web Service versions to a new version based on Web Services. Unfortunately, only a very basic set of Web Services embodied in the Web Services Interoperability proposal, WS‐I, are agreed by most IT companies. IBM and others have submitted proposals for Web Services for Grids—the Web Services ResourceFramework and Web Services Notification specifications—to the OASIS organization for standardization. This process could take up to 12 months from March 2004 and the specifications are subject to debate and potentially significant changes. Since several significant U.K. e‐Science projects come to an end before the end of this process, the U.K. needs to develop a strategy that will protect the U.K.’s investment in Grid middleware by informing the Open Middleware Infrastructure Institute’s (OMII) roadmap and U.K. middleware repository in Southampton. This paper sets out an evolutionary roadmap that will allow us to capture generic middleware components from projects in a form that will facilitate migration or interoperability with the emerging Grid Web Services standards and with ongoing OGSA developments. In this paper we therefore define a set of Web Services specifications, which we call ‘WS‐I+’ to reflect the fact that this is a larger set than currently accepted by WS‐I, that we believe will enable us to achieve the twin goals of capturing these components and facilitating migration to future standards. We believe that the extra Web Services specifications we have included in WS‐I+ are both helpful in building e‐Science Grids and likely to be widely accepted.