Decoupling Constraint Validation from Business Activities to Improve Dependability in Distributed Object Systems

Integrity constraints are an important means to discover and specify application requirements. Although they are explicitly available and discussed during the system analysis and design phases, the constraint validation functionality is generally still tangled with other implementation code, e.g., the business logic, in today´s systems. We contribute with an approach to decouple the integrity constraints from the business logic as well as the setpoints of constraint validation from the business activities. This allows us to balance dependability with respect to node and link failures by temporarily relaxing constraint consistency. Our prototype implementation indicates that this approach is typically worth its effort in systems where availability is of higher priority than strict consistency and a roll-forward approach to system repair, e.g., through compensating actions, is preferred over generic rollback-based solutions