In this paper, we show that, although P2P systems and DSM systems have been designed in rather different contexts, both can serve as major sources of inspiration for the design of a hybrid system, with intermediate hypotheses and properties. We propose the concept of data sharing service for grid computing, as a compromise between DSM systems and P2P systems. The main contribution of such a service is to decouple data management from grid computation, by providing location transparency as well as data persistence in a dynamic environment. To illustrate the proposed concept and validate its feasibility, we have implemented a software prototype: the JuxMem platform.