Special Edition Using Microsoft® Visual Basic® .NET

Building a Reusable Data Access Layer

The layers of a multi-tier application are usually specific to the application’s domain. The data layer, for example, contains code to execute only the stored procedures used by that particular application. Layers can be reusable in other applications if the functions they perform are needed elsewhere. For example, the business tier in an Accounts Payable application could talk to the business tier in Personnel to validate employee names on expense reports. This type of reusability is one of the main advantages of object-oriented programming. However, across all your applications there will likely be some common data-layer functions. For example, you need code to connect to a database, execute a stored procedure ...