10. Models and Model Repositories
What Are Models and How Did They Come About?
A model is a symbolic or abstracted representation of something real or imagined. Building a model, such as a building or theme park, helps to visualize the design before the real thing is constructed. For a city architect, a computer simulation viewed from 1,000 feet above planned streets may reveal potential traffic and congestion areas.
It is in this manner that a data model helps visualize data structures to evaluate how completely and accurately they reflect the business problem. It is preferable to change a designed structure before any application system is built, since design changes generally cost significantly less than application code changes.
But just as important ...