Designing active objects in DEGAS
This report discusses application design for active databases, in particular for the active object-based database programming language DEGAS. In DEGAS one modularisation principle, the object, is applied to all elements of the application, including rules. We discuss a design process consisting of four phases, corresponding with the four kinds of capabilities in a DEGAS object, attributes, methods, rules, lifecycles. The elements of this design process are similar to those found in a design methodology such as OMT. To illustrate the design process we use the example of workflow management. In addition, it shows that the application of one modularisation to all elements of an active database leads to a clear modularisation of the workflow application, Furthermore, this modularisation facilitates all important workflow evolutions.