Web Service Grids: an evolutionary approach

Abstract

SUMMARYThe 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.

Special Issue: Grids and Web Services for e‐Science

“…However, it is an unfortunate fact that, although the Web Services movement is supported by all of the IT companies, even at the end of 2004, this 'grand project' is still very much 'work in progress'. The presently accepted Web Services certainly do not constitute a satisfactory basis to construct a robust, international Cyberinfrastructure on which to build novel and demanding e-Science and business applications [3,4].…”

“…Web Services are the distributed computing technology that the IT industry is trying to define to be the building blocks for building loosely-coupled, distributed applications, based on service-oriented architecture principles [3]. Web Services interact by exchanging messages in SOAP format, while the contracts for the message exchanges that implement those interactions are described via WSDL and other metadata formats.…”

“…There are over 60 proposed specifications presently in discussion at the different standards bodies and until the dust settles it is not clear which specifications will survive and in what precise form. The Web Service Grids paper [3] introduces a minimal set of specifications that appear necessary for Grid systems. The authors term this choice WS-I+ as it builds on Web Service profiles built by the Web Service Interoperability organization [8] that has broad industry support.…”

Interoperability and eServices

“…Grid developers can thus exploit the experience of the WS community and concentrate on building the higher-level services that are specific to the Grid application domain. There is a need, however, for WS specifications that could safely be used for building interoperable Web Service Grids, and for this reason a WS specification profile WS-I+ has been proposed in [1]. Another proposal on how Grid applications could be built using existing WS specifications is found in [17].…”

Best practices for describing, consuming, and discovering web services: a comprehensive toolset

“…Furthermore, SOC systems might interconnect different organization systems. Finally, SOC usage eventually spread to gave birth to a wave of contemporary infrastructures and notions including Service-Oriented Grids [3] and Software-As-A-Service [4].…”