The grid middleware used for the LCG/EGEE grid includes components that have been developed by a number of projects and organisations. The major components and contributors are listed below. The agreed set of components is integrated by the Grid Deployment Area (GDA) of the project, which tests and certifies releases of the complete toolkit, which are then made available to all sites for installation. The GDA provides first level support for certified releases, and negotiates agreements for in-depth support from the suppliers and developers of the various components.

The principal components of the middleware package are:

• The Globus Toolkit (GT2) developed by the Globus Project

• The Condor system developed at the University of Wisconsin, Madison

• The Globus and Condor components and some other tools from US projects are integrated and packaged as the Virtual Data Toolkit by the VDT project at the Univeristy of Wisconsin, Madison. VDT provides support for this package to LCG/EGEE.

• Tools developed by the DataGrid Project (EDG). The EU-funded DataGrid project ended in 2004, but the institutes that had developed the tools needed for the LCG/EGEE grid continue to support them until they are replaced by improved software.

• New middleware components developed as part of the gLite toolkit by the EGEE project. The first release of gLite will provide improved tools for workload scheduling, grid catalog, and a monitoring infrastructure. Future releases will add additional functionality and provide re-engineered components with the aim of  satisfying the requirements of the main EGEE application domains: high energy physics, biology and medicine. This middleware activity of EGEE works very closely with the LCG project, and has a formal place in the management of LCG.

As the gLite middleware becomes available it is certified by the deployment team, and installed first on the pre-production service, where it is further tested by applications groups before being more widely distributed. As far as possible the new components should be able to co-exist on the same grid system with the current middleware, enabling a progressive deployment strategy to be adopted. This is an essential feature for new middleware to be introduced into a large operational grid.

The current middleware package is called LCG-2. It is planned to phase out LCG-2 as soon as practicable after the gLite package has been adopted by the major applications.