The language that enables communication between the front-end and back-end is the RECAST API (application programming interface). It will:
- define the format of requests sent to a collaboration,
- define the format of results obtained by a collaboration, and
- establish a communication protocol between the front-end and back-end.
A well-defined API is the key to enabling multiple back-ends to communicate effectively with the front-end. It is analogous to the Les Houches interfaces which enable interop- erability between the various event generators. Web-based APIs are also at the heart of the GRID tools that coordinate the full-chain of generation, simulation, and event reconstruction.