Events

An event describes a cause or reason, which may activate an action (rule). There is a difference between individual and general events. An individual event is something that had really happened, while a general event is an event that may happen. TM mainly considers general events.

Usually, general events are referenced from within causalities. The same general event might be referred to from within different causalities, in which case all related actions are called, when an individual event happens.

General events are features describing relevant state transitions. Depending on different categories of state transitions, three categories of events may be defined:

• Instance events - are defined as relevant instance state transitions that may cause a reaction (activating a rule), e.g. when a person has married (cause) this has to be registered (action).

• Time events - are defined as relevant time state transitions (e.g. a person's birthday) that require appropriate actions (as sending a mail). This does not differ in principle from object state transitions, but time plays a special role and thus, it becomes useful to consider time-dependent reactions separately.

• Process events - are events defined by a process (e.g. the database system or GUI frame work). Process events reflect process states rather than instance states. Typical process events are events as an instance has been updated, created or deleted.

Instance and time events are those, which are typically defined by subject area experts in the terminology model. Process events are a more technical issue and are, usually, managed by IT experts.

Event feature relations may refer to rules as pre- and post-condition, which is one way of defining relevant state transitions [UDT]. In this case, an event happens, when both, pre- and post-condition become true.