15.1 Interchanging Incomplete Models

In practice, it is common for models to be interchanged before they are complete. This occurs frequently when doing iterative modeling, where one user (such as a subject matter expert or business person) first defines a high-level model, and then passes it on to another user to be completed and refined.

Such “incomplete” models are ones in which all of the mandatory attributes have not yet been filled in, or the cardinality lowerbound of attributes and associations has not been satisfied.

XMI allows for the interchange of such incomplete models. In BPMN, we extend this capability to interchange of XML files based on the BPMN XSD. In such XML files, implementers are expected to support this interchange by:

•Disregarding missing attributes that are marked as ‘required’ in the XSD.

•Reducing the lower bound of elements with ‘minOccurs’ greater than 0.