Data-driven Active Rules for the Maintenance of Derived Data and Integrity Constraints in User Interfaces to Databases

It is presented an approach based on data-driven active rules for the maintenance of derived data (calculated data) and integrity constraints (data restrictions) in screen forms and other user interfaces to databases. The approach aims to improve the capabilities of current application development tools, by combining the power of active rules, as proposed in the context of active databases, with the simplicity and data-driven nature of spreadsheets. The proposed data-driven active rules define derived data items as functions of other data items, by explicitly reading and writing their values, conditionally or unconditionally. They are defined essentially as unordered action-only rules with implicit triggering events, and are executed essentially as ordered (prioritized) event-action (EA) rules, possibly in combination with other event-action (EA) or event-condition-action (ECA) rules originated from different sources. The specialized nature of the actions performed by these rules allows the automatic determination of the triggering events and priorities among rules, as well as the establishment of improved conditions on rule sets that guarantee termination and confluence (determinism) of rule execution. The maintenance of integrity constraints is essentially reduced to the maintenance of derived data. The approach presented is not tied to a particular rule definition language or data model. 1