GridRPC is an international standard of the Open Grid Forum defining an API designed to allow applications to be submitted in a seamless way on large scale, heterogeneous and geographically distributed computing platforms. First versions of the standard did not take into account any data management feature. Data were parameters of the Remote Procedure calls, without any possibility to prefetch them, to use persistence, replication, external sources, etc. , and making GridRPC codes middleware dependent. The data extension of the standard introduced a short set of functions and data structures to complete the API with simple but powerful data management features. In this paper, we present a modular and extensible implementation of both APIs, which needs only a few developments to be usable with any middleware relying on RPC, and which provides access to numerous and easy to extend protocols and data middleware to access data. Gaining data management functions, it introduces interesting potentiality for optimization that such an approach would provide to large scale applications.