This chapter describes a GridService demonstrator built around the Unicore Grid environment, its architectural design and implementation [1]. It then examines some lessons learned from the process of developing an implementation of a family of GridServices that conforms to the Open Grid Services Architecture (OGSA) [2] and the Grid Service Specification [3]. The goals of this project were two fold. Primarily, it is only through implementation that complexities such as those that arise in OGSA can be fully understood and analyzed | 29 Unicore and the Open Grid Services Architecture David Snelling Fujitsu Laboratories of Europe Hayes Middlesex United Kingdom INTRODUCTION This chapter describes a GridService demonstrator built around the Unicore Grid environment its architectural design and implementation 1 . It then examines some lessons learned from the process of developing an implementation of a family of GridServices that conforms to the Open Grid Services Architecture OGSA 2 and the Grid Service Specification 3 . The goals of this project were two fold. Primarily it is only through implementation that complexities such as those that arise in OGSA can be fully understood and analyzed. Secondly Unicore is a complete production Grid environment that seemed to conform extremely well to the OGSA. The author wanted to test this hypothesis and see how difficult it would be to construct an OGSA-hosting environment on top of the Unicore infrastructure. By way of a brief summary both goals were met easily and with satisfaction. The OGSA model is remarkably clean and the abstractions well matched to what is needed at the implementation level. The lessons learned reveal where cracks exist and in many Grid Computing - Making the Global Infrastructure a Reality. Edited by F. Berman A. Hey and G. Fox 2003 John Wiley Sons Ltd ISBN 0-470-85319-0 702 DAVID SNELLING cases support the changes currently under discussion in the Open Grid Services Infrastructure OGSI working group of the Global Grid Forum GGF . The reader should note that this chapter and the implementation on which it is based are targeted at the first draft 2 15 2002 of the Grid service specification 3 . By the time of going to the press many of the issues discussed here and elsewhere will have become part of the next version. With respect to the second goal the implementation of a complete OGSA GridService environment that could be used to deploy task specific GridServices was significantly easier than expected .
