An electrical computer system processing architecture for providing an indication of activity in the electrical computer system, the electrical computer system processing architecture comprising a plurality of client computers connected to at least one server by a computer network. Each of the client computers is configured to provide requests to the at least one server. The or each server comprises a store for storing requests provided by the plurality of client computers. The or each server is configured to match complementary requests from the plurality of client computers stored in the store. Following the matching of complementary requests, the or each server counts unmatched requests corresponding to one or other of the complementary requests in the store, and outputs the counted number of unmatched requests to provide the indication of activity in the computer system.