Figure 2. Adapt to Changes. This figure illustrates what happens when you have to accommodate minor changes in an SO-based application. The increased volume of customer activity has been accommodated by fronting the Help Desk service with a Routing service that distributes traffic among multiple instances of the Help Desk service. An Approval service has been inserted between the Dispatch service and the Parts service to approve or decline parts orders, with the same interface as the Parts service. The Parts service now works with a wider selection of vendors.