API (Application and Programmation Interface): An API is an interface presenting functions and/or objects allowing the utilisation of libraires.

Resource: a computing resource can be of several types: server, processor, memory, storage disk...

Cluster: a set of computing servers.

Grid: set of clusters (also called cluster of clusters).

Middleware: set of software tools being the intermediary between several applications for communications and data transfers.

SYSFERA-DS: middleware providing transparent and intelligent access to distributed resources.

ASP (Application Service Provider): provides access to distant applications seen as services.

Request: request for executing a service (also called task).

GENCI: Grand Equipement National de Calcul Intensif, is a legal entity taking the form of a «société civile» under French law, owned for 49 % by the French State represented by the Ministry for Higher Education and Research, for 20 % by CEA, 20 % by CNRS, 10 % by the Universities and 1% by INRIA. Created in january 2007, GENCI has the following mission:

• promote the use of modelling, simulation and high performance computing in fundamental and industrial research;
• promote the organisation of European high performance computing and participate to its actions;
• set in place and coordinating the major computer equipment for the French computer centers for civilian research, by providing for their financing and assuming their ownership;
• perform all research required for developping and optimising the utilisation of computing equipment
• open its facilities to all interested scientific communities, academic or industrial, national, European or international.

Some of these definitions are extracted from Wikipedia (http://en.wikipedia.org), from GENCI website (http://www.genci.fr) and from CCRT website (http://www-ccrt.cea.fr).