Solving a problem

Assuming that the architecture described in Section 1.1 includes several servers able to solve the same problem, the algorithm presented below lets an MA select a server for the computation among those available. This decision is made in four steps.

• The MA propagates the client request through its subtrees down to the capable servers; actually, the agents only forward the request on those subtrees offering the service.
• Each server that can satisfy the request can send his performance and hardware information or an estimation of the computation time necessary to process the request to its “parent” (an LA) (via performance prediction tools: see Chapter 10).
• Each LA that receives one or more positive responses from its children sorts the servers and forwards the best responses to the MA through the hierarchy.
• Once the MA has collected all the responses from its direct children, it chooses a pool of “better” servers and sends their references to the client.