Class Roster Professor 5. Grade Submission Professor Grade Report 6. An event is an occurrence which takes place at a specific time and initiates or triggers a predetermined response from the system. An external event is an event which occurs outside the system boundary. For example, when a customer makes a deposit to a bank account.
External events are clearly the most common types of events that occur in business systems.
An internal event is an event which occurs inside the system boundary. An example of an internal event is the falling of the quantity of an item of inventory below the reorder point. Internal events are important in real-time systems as well as to coordinate the dynamic behavior of objects in a system. However, internal events are not covered in this book, as they are relatively rare in most business systems. A temporal event is an event which occurs at a pre-specified time.