‘Things of Interest’ to a business means a business wants to remember what it knows about those things. In a business model (the next row down in Zachman), this means defining what data about things that the business needs to capture and use, leading to definitions of files and databases in the subsequent System Model.

 The most common format used to capture data requirements is the Entity-Relationship Diagram, which like Architecture, was most popularized by the Information Engineering Methodology. The main component is the Data Entity, a subject of interest to the Business, associated by the business relationships between them. Each entity contains data items/attributes that relate to or describe the Entity. Each attribute belongs only to one Entity, so duplication of data is reduced.

 There are levels of data models that lend themselves to specific purposes. For a Business Model, the usual level is known as “Conceptual”, so we get a Conceptual Data Model. This type of model is all about describing the business, and does not need to be formally normalized as per Codd’s rules to do so. The next level down is the “Logical Data Model” where normalization is applied, and it is key to the System Model row of Zachman. It can be transformed in straightforward way to produce a “Physical Data Model”, and the latter can be used to create actual databases.  
There are other uses for Data Models, such as specialized models for data warehousing (the decidedly de-normalized star schema), and Class Diagrams in object oriented methods do encapsulate data in a Class/Object, but that is for design. For me, the Conceptual Model using an ER Diagram is still the best method for describing the “What” of business architecture.
Next time – “how”


Excerpted from “Cascade: Better practices for effective delivery of information systems in a multi-project environment”, see more at http://www.amazon.com/-/e/B007YLUL7K#

…and more about me at www.about.me/dwwright99

David Wright


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