Derive Dependency   A derive dependency is an abstraction dependency that indicates that the client (tail end) can always be calculated from the supplier (arrowhead). This implies that the client is strictly redundant, and may be modeled for performance reasons or ease of use.

Explanation

It is important that this dependency is modeled and the derivation made explicit, as it can be a point of weakness in a model. While the derived element could be calculated (or computed) from the information provided in the supplier, a decision has been made not to do this. This is often done to increase performance or the speed of the executing system. This redundancy adds a point of structural weakness to the model because if a change is made to the supplier it is often necessary to make an equivalent change to the client. Modeling the relationship with a derive dependency increases the likelihood that the change to the client will not be overlooked. Significantly the parts of the system that are made redundant are frequently the most used parts (hot spots) of a system, so overlooking a change can have far reaching and obvious effects on the executing system.

Related Entries

Dependency  Type of A dependency is a related element because it is the base element for the abstraction relationship. The derive abstraction is a stereotyped abstraction which is a type of dependency. The abstraction stereotyped as derive adds more precision to the less specific or standard dependency relationship.

Abstraction  Base Type An abstraction is a related element because it is the base element for the derive abstraction which is a stereotyped abstraction and a type of dependency. The derive stereotype adds more precision to the less specific or standard abstraction relationship.