A computer network connects to a first computer, a second computer, other multiple computers, and a job category database A service to be executed by any of the other multiple computers is divided into multiple jobs; the job category is associated with each of the divided jobs; a region code and an instruction to execute the service are received from the first computer; and for each of the multiple jobs, the job category database is searched with the received region code and the associated job category as keys to acquire the operation identifier list corresponding to the job; the operation identifier list is transmitted to at least one of the other multiple computers; and a combination of the job, the identifier of that other computer and the identifier list are transmitted to the first computer.