Unhandled exception updating material

This brings many advantages, including cleaner code, increased maintainability and the ability to spread your application's load over multiple servers.

In the discussion of layered design, you often see both the terms .

Similarly, you should be able to remove a SQL Server specific DAL and replace it with an Oracle or Microsoft Access version without the Presentation layer even noticing the difference.

In the diagram in figure 1 you see a process go around in a counter clockwise direction.

The process goes through the following 6 steps: I'll revisit this diagram at the end of the article and add more detail to it. NET 1.0, layered development was brought to web applications on the Microsoft platform.

While previous versions of ASP (now referred to as "classic ASP") allowed for some separation in the form of COM components or ASP classes, this usually wasn't done as it was quite cumbersome and hard to maintain. NET it's much easier to create reusable, object oriented classes that can be consumed by web applications and other types of applications.

However, it's a design that has worked for me in the past and still works today.

Then in the middle, you find the Business Logic Layer, or the BLL that is the bridge between the Presentation layer and the next layer: the Data Access Layer or the DAL.

- I have written a new series on N-Layer design targeting ASP. What's important to realize is that this is *my* take at layered design for web applications.

It builds on the foundation created in this first series, but digs much deeper into concepts like Validation, Sorting, Paging, Concurrency and Security. It doesn't feature all the necessary functionality your application needs, but instead focuses on the underlying concepts.

What should these objects be capable of and how do they look?

How do these business objects interact with other parts of the system?

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