Excerpt from Enterprise Architecture Fundamentals, available on:
At the system level, Use cases seem to be the tool of choice for a continuous and consistent integration of heterogeneous requirements into engineering processes. What is missing at the enterprise level is a mapping of architectural changes to business objectives, policies, and strategies.
Since these mappings are shared by executives and stakeholders across organiza- tions and over time, they are generally formulated in terms of abstractions set across a range of diverse dimensions: unspecific scales (e.g., general, detailed, more detailed), data modeling (conceptual, logical, physical), decision-making (strategic, tactical, op- erational), etc. For enterprise architects, the challenge is to define actionable junctures between business expectations and their realization through EA engineering.
Extending the semantics of Use cases provides a way to identify and manage business shifts that emerge bottom-up from environments, and to integrate them with business policies and strategies that are planned top-down.
Taking a cue from Alistair Cockburn’s seminal work (cf. bibliography), Use cases can be characterized with regard to execution and modeling level (figure 13-15):
Figure 13-15. Typical Cases
- Business cases (green background) are meant to fulfill broadly defined objectives. As such, they are not supposed to be executed and are not limited to information models (descriptive or predictive), but can rely on knowledge (thesauruses, Knowledge graphs, and/or predictive models); e.g., Complaints Policy.
- Use cases (orange background) are meant to describe what happens between en- terprises and business environments. As such, they are supposed to be executed, and thus should only reference information models (descriptive or prescriptive); e.g., Manage Complaints.
- System cases (orange background, slashed ellipse) are the parts of Use cases directly supported by systems; therefore, they should only rely on prescriptive or technical models. Some system cases correspond only to symbolic activities (e.g., Check Account), whereas others are also tied to physical ones (e.g., Check Identity).