The DEAT Business Rule Pattern Language

Russell R. Hurlbut, Ph.D.

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Rule Pattern 15: Temporal Aggregation

Problem Describing a Temporal Aggregate Property of an Entity

The historical state or performance of an entity may reveal trends. Once identified, these trends may be used to take corrective actions. Performance requirements are often stated in terms of such aggregate properties.

Solution

Historical trends of an entity can be expressed though definitions of a temporal aggregate type (e.g. rates or counts). The history of the entity is considered a collection of prior states. A derived meta-attribute may then be defined at the collection level that aggregates one or more attributes of the collection over a specified period of time. The type of aggregate function and a threshold are defined in order to detect a condition in which action should be taken.

Example Pension Estimate

A company policy restricts an employee to a maximum of four requests for pension estimates in a calendar year.
Pension Estimate Parameters
Attribute Type sum
Unit of measure pension estimate requests
Period calendar year
Threshold 4

Example Sales Volume

A franchiser requires that a dealer must maintain an average monthly sales volume of over $20,000. If the average for any three-month period drops below $20,000, the dealer is placed on probation.

Sales Volume Parameters
Aggregate Type average
Unit of measure sales volume
Threshold $20,000
Period 3 months

UML Representation and Related Patterns

The Temporal Aggregation business rule pattern is modeled in the UML as a derived attribute of a model element that contains a collection of its own states. It shares an affinity with the Aggregation business rule pattern in this respect.

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