Business Abstraction defines four “Levels of Abstraction”, which are defined in terms of the audience that can understand information in a particular Layer:
- Strategic Layer contains information for senior executives. It is free from technical details, but also from specific business details. It is the information your CEO or Department Secretary has time for.
- Business Layer is strictly computation-independent, however can go into details. For example, Business Layer for the Medici Bank in 1397 would be surprisingly similar to a late 20th Century retail bank. Business Layer can be split vertically into the Enterprise Business Layer, that talks about how the business works, and the Customer Layer that looks at the Customer needs and circumstances in the relation the the business in hand. The audience for Business Layer are Business executives and Domain Experts involved in day to day running of the enterprise, Business Process Analysts, User Analysts. They are happy to get into details, and review individual cases, however would not necessarily know how to operate specific software system.
- Functional Layer deals with behaviour of software systems, without looking into how the system is built. It is the domain of traditional Business Analysts, and usually of the less technical Architects.
- Technical Layer is the domain of Software Engineers, Database Administrators, and other technical staff.
The first two Layers, Strategic Layer and Business Layer, can be together described as the Computation-Independent Layers. No computer systems are mentioned. If you replace software systems with a lot of clerks making records on cards, and AI with psychics, they should not change. Well, some Objectives on the Strategic Layer would become utterly unrealistic.
Such separation of layers ensures that the models can be used and commented on by the target audience.