| Active database systems typically use ECA (even-condition-action) rules for specifying events of interest, conditions to be checked, and action to be performed. Though triggers provide active capability in commercial RDBMSs, they provide only a limited specification of events (e.g., insert/delete/modify) and do not allow combination of events. Triggers also do not support parameter contexts, coupling modes and priority.; In this thesis, we use a mediator-based approach to provide full ECA functionality to a commercial RDBMS without changing the underlying system. IBM DB2 6.1 is used as the test RDBMS. Triggers can be created on primitive events (insert/delete/modify) and composite events (combination of events) and support parameter contexts, coupling modes and priority. Though the approach used in this thesis is a generalized approach that can be used for other RDBMSs, the Mediator implementation is unique in certain respects as it is based on the underlying trigger support specific to DB2. |
