Creating a class that can be used by workflow is a little more time consuming than creating a copy of a standard SAP Business Object and delegating your new object, but once you have done it a few times it is rather simple and allows you to utilize ABAP OO.
workflows
SAP Business Workflow was built on an approximation of object orientated programming called the Business Object Repository or BOR. It uses object oriented techniques which allowed developers the ability to create copies of standard BOR objects, modify them and through inheritance allow them to be used in place of the standard.