See the Big Picture, Plan for Change
Most experienced developers have at some point felt frustrated because the applications they are maintaining or having to extract data from have not been designed for change. They have probably also experienced this frustration from the other side-frustration that they are not provided with the time or resources to develop a system that provides a flexible but sound foundation for future work.
Data from one application is often reused in multiple applications. The second and subsequent uses are often unanticipated, resulting in a range of problems. For example, data quality might be poor or new databases with gross data transformations between the new and the old databases might be required. (See Figure 15-6 for examples of bad and good data management planning.) The problems arise because the original application was not designed in the context of a corporate long-term view. Without a forward-looking view, some data is not captured and overoptimized structures are used. A business architecture provides a logical view of function and data and attempts to anticipate future needs. To design an application successfully (where success is viewed over the lifetime of the application), you must take the bigger picture into account. A well-planned application can grow organically as new requirements emerge. To plan and design solely for the current application creates problems for the future. For example, databases might not be structured flexibly to support future queries; designs might be highly optimized for a particular application but prove to be inadequate for a subsequent application or after maintenance. Producing reusable business rules and generic code tends to take a low priority if the focus is only on the current project. Designing logically, based on a high-level view of core business operations, tends to produce a reusable design that will support multiple applications at the database and code levels.
Figure 15-6 Design for the future