If you wish process instances to execute in a certain order, you can use Wait and Notify activities to accomplish this. This requires using some portion of the incoming event to determine the order.
For example, an application may assign a priority number to incoming orders. This may be important when accepting requests for a limited resource, for example, airplane seats or available space in a university class. The orders must be processed in order of priority to ensure that orders with the highest priority number have access to the resource first. Figure 41 illustrates an example process definition that orders incoming events.