Data Architecture – Part of Information Systems Architecture
This post continues from the original article on IT Architecture Domains.
When we are talking about data, we need to understand at an organizational level what business entities exist and then demonstrate those entities in terms of data entities. The data entities would then need to model at a physical and logical level to ensure the database would support the business entities and their data associations.
Scenario: IPS Parcel Delivery Enterprise
In this scenario I will model the customer and order business process in terms of data architecture.
First we model the business entities to understand how the business works.
The model demonstrates two business entities:
By understanding the business we know that each customer will have one or more orders. Show the rule in the model.
The BE model also shows that the business customer must exist before he / she can place an order.
Diagram: Business Entity Relationship – CustomerOrder
With the logical model we now see some attributes added to each entity. Attributes gives more detail about an entity; it describe the entity. We still apply the BE rules as in the model above.
Do not add technology detail to the logical data entities, such as database Primary keys, data types etc.
Diagram: Logical Data Model – CustomerOrder
In the physical model we now see the technology side of matters. Again all the business rules apply as above.
The model now includes specific relational database management system (RDBMS) data types. Each table contain a unique key to identify each row – also known as a surrogate key to database people. The relationship between the entities is now linked via the unique table keys.
Now it is important to know how the data for each entity will look. You need to do some data analysis to understand the data and what data type will ensure data quality to the enterprise.
Diagram: Physical Data Model – CustomerOrder
The level of detail does not increase with the level of technical detail. From the BE level to the Physical level, all must contain as much detail as possible.
Note that this post is by no means justification of the domain, but only a high level glimpse.