The data derivation model: a program specification technique that improves reusability

Commonly used procedures for database retrievals and computational functions arc frequently required for the specification of data-intensive business programs. Existing program specification techniques use mostly procedural approaches which are tedious and highly repetitive for specifying validations. Tremendous efforts are still spent for re-specifying same procedures and computational functions in the process of specifying business programs. In this paper, we propose a program specification technique called the data derivation (DD) model to address the abovementioned problems. In this technique, we further enhance the reusability idea provided in fou* generation languages for the specification of business programs. We also adapt a declarative approach for the specification of validations to remove the repeated efforts inherited from procedural approaches. The data derivation (DD) model specifies a program through representing its data flows and their relationships with output operations attached to data flows. A DD model is formed by a composition of instances of generic components drawn from the set of formally defined generic components, with the incorporation of specification of output operations and constmints into the composition. It consist-s of an ER-like diagmm, called a data derivation (DD) diagram, and a specification of pammetera, attributes, output opcmtions and constraints involvd. The control structure of the DD model is defined by a set of rules. Whh the formats of its screens and reports defined separately, a DD model is executable and is sufficient for specifying progmms.