Working with Data in ASP.NET 2.0 Handling BLL and DAL Level Exceptions in an ASP.NET Page
Working with data from an ASP.NET web application using a tiered application architecture involves the following three general steps:
1. Determine what method of the Business Logic Layer needs to be invoked and what parameter values to pass it. The parameter values can be hard coded, programmatically assigned, or inputs entered by the user.
2. Invoke the method.
3. Process the results. When calling a BLL method that returns data, this may involve binding the data to a data Web control. For BLL methods that modify data, this may include performing some action based on a return value or gracefully handling any exception that arose in Step 2.
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Working with Data in ASP.NET 2.0 - Querying Data with the SqlDataSource Control
All of the tutorials we’ve examined so far have used a tiered architecture consisting of presentation, Business Logic, and Data Access layers. The Data Access Layer (DAL) was crafted in the first tutorial (Creating a Data Access Layer) and the Business Logic Layer in the second (Creating a Business Logic Layer). Starting with the Displaying Data With the ObjectDataSource tutorial, we saw how to use ASP.NET 2.0’s new ObjectDataSource control to declaratively interface with the architecture from the presentation layer. While all of the tutorials so far have used the architecture to work with data, it is also possible to access, insert, update, and delete database data directly from an ASP.NET page, bypassing the architecture. Doing so places the specific database queries and business logic directly in the web page. For sufficiently large or complex applications, designing, implementing, and using a tiered architecture is vitally important for the success, updatability, and maintainability of the application. Developing a robust architecture, however, can be overkill when creating exceedingly simple, oneoff applications.
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