Designing the System Structure › How to Analyze User Tasks › Identify Events

Identify Events

Since events require a response, they are useful pointers to the tasks that might be performed in order to respond.

The following list details the types of events:

• External-An external event is something that happens outside the system being designed. Mail arriving is an example of an external event.
• Temporal-A temporal event is the arrival of a time point of interest to the system, for example, end of month.
• Internal-An internal event is something that occurs within the business activities that are included in the scope of the development project. They often arise as the result of human activities that are not specified as part of formal procedures. For example, making a decision or initiating an analysis of data is an internal event.

The event analysis technique defines external and temporal events, and the planned responses by business processes. This technique is described in the Analysis Guide. Analysts should have recorded the frequency of event, and possibly the required response time. This detail is useful for assessing the performance requirements of user tasks and system procedures.

External and temporal events can cause user roles to initiate a system procedure in order to respond. A batch procedure may be initiated by some automatic mechanism, such as the arrival of a time of day, or the existence of data that has been transmitted through a network.

Internal events are now of interest to you because they may indicate the need for additional procedures (such as reporting or browsing data), as well as providing an additional reason for executing formal, process-implementing procedures.