OneData provides a rules engine that you can use to create validation or action rules to validate data. When data is updated or inserted, the rules engine invokes a post-command hook to validate data or perform an action. Hooks are command-line commands that invoke external programs (including stored procedures and shell scripts) at a specific data manipulation event. The post-command hooks of the rules engine run behind the scenes. For more information about hooks, see Developing for webMethods OneData.

The rules engine only evaluates inserts and updates. The rules engine does not support rules comparing columns from different tables.