Server:
    char request[RequestSize];
    char reply[ReplySize];
    FileDescriptor clientInput[NumClients];
    FileDescriptor clientOutput[NumClients];

    // Loop waiting for a request from any client.
    while (fd = select(clientInput, NumClients) {

        // Read incoming command from a specific client.
        read(clientInput[fd], request, RequestSize);
	
        // Do operation.

        // Send result.
        write(clientOutput[fd], reply, ReplySize);
    }