From its inception, EGEE had considerable advantages in the area of middleware. EGEE is in many ways the successor to the European DataGrid project,⁷ which had previously developed a well built middleware solution, the EDG middleware. This stack had already been further developed by the LCG project into the LCG-2 middleware, providing EGEE with a working middleware stack to deploy from day one. In parallel, EGEE has also developed a new middleware solution, gLite,⁸ tailored to the multi-science user communities it supports. Rather than starting from scratch, gLite takes components from a large number of software sources, re-engineering some of them and integrating them into a modern, lightweight, service-orientated middleware solution. The resulting software stack provides a full set of Grid foundation services, as well as a range of higher level services.

This modular approach, combines best-of-breed elements from other middleware sources, allowing outside projects interested in the middleware to install only the elements of gLite relevant to them, developing their own specialist, high-level services on top of it. The gLite stack also contains the foundations necessary for interoperability with other Grid systems, in particular in the area of security frameworks, and its development team actively participates in security working groups through the Global Grid Forum⁹ and other such bodies. The gLite stack is released under a permissive, business-friendly open source license, which facilitates and encourages its use by outside groups. With gLite in use within the project, outside groups such as the DILIGENT digital library project are already making use of gLite on their own Grid infrastructure, and it is hoped that more groups, and eventually industry, will join them in the future.