Integrity Checking for Nested Transactions

In this paper, we present a mechanism to specify and to validate consistency constraints in object oriented databases. Constraints are speciied using pre and post-conditions associated with an exception handling mechanism. During transaction run-time, we treat exceptions corresponding to errors (in this case, we use immediate exceptions which are processed immediately) or presumption of errors (in this case, we use deferred exceptions which are processed at the end of the transaction), in order to insure validation. To re-ne our mechanism, we enlarge it to nested transactions. Deferred exceptions can be processed at each node of the transaction tree. Using a predeened exception , we propagate an abort of a sub-transaction to its parent transaction. Thus, the parent transaction can choose among diierent policies for processing the sub-transaction abort.