The purpose of the SLA4D-Grid Project is to design and realise a Service Level Agreement layer (SLA layer) for D-Grid. This layer is situated, as shown in the illustration, between the D-Grid middleware (which features the gLite, Globus, and UNICORE middlewares) and the D-Grid user layer and integrates with the existing D-Grid infrastructure (e.g. through connections to core D-Grid services). Communities may either use the SLA layer via SLA-enabled clients or through direct interfaces. The SLA layer is a value-added service and does not interfere with the present use of the D-Grid, nor does it require changes in communities that do not yet have a need for SLAs

The Service Level Agreement layer offers individual users, whole D-Grid communities, and the providers of D-Grid resources service usage under given guarantees, quality-of-service requirements and pre-defined business conditions. For this purpose, service level requests and the corresponding offers are linked by binding Service Level Agreements. By means of the SLA layer and with the assistance of other D-Grid services, such as monitoring and accounting, SLAs can be automatically created, negotiated and their observance monitored, so that the D-Grid can be used by academic and industrial users in an economically efficient manner, in accordance with their respective business models.