A Generalized Constraint and Exception handler for an Object-Oriented CAD-DBMS

A generalized constraint and exception handler for object-oriented CAD databases is presented. The main features of the constraint and exception handler are: dynamic definition of new constraints without recompilation of the schema, deferred constraint checking, and homogeneous handling of constraints and their exceptions. In the paper we analyze first the constraints typically encountered in a CAD environment, discuss the problems of dynamic constraint definition and deferred evaluation and, based on that discussion, present design and implementation issues of the constraint handler which is currently being implemented.