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Possible Duplicate:
A modern n-layer asp.net web application sample?

I'm having a hard time trying to design a solid N-Tier framework in ASP.Net. I know the basic fundementals: BLL, DAL, and Business Objects, etc. What I can't understand is the actual flow of the application and what the return types in the BLL and DAL should be.

Most articles I've read have suggested that the BLL and DAL communicate via Business Objects. However I don't see the real benefit if I have to instantiate the Business Object twice during each pass.

Does anyone have any links to good tutorials/sample applications that could guide me in the right direction?

Thanks

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robert
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  • Are you talking about tiers (physical tiers) or layers (programming Paradigms)?? I ask because n-tier has nothing to do with data access layer or business logic layer.. – Jamie Dixon Jul 05 '11 at 22:40
  • I'm looking at ASP.net web forms, and I'm interested in the effectively programming the layers. – robert Jul 05 '11 at 22:42
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    This is a duplicte of another question: http://stackoverflow.com/questions/3277257/a-modern-n-layer-asp-net-web-application-sample – George Stocker Jul 05 '11 at 22:47

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First, you must understand that tiers and layers are different things, although they are often confused. A layer is a software abstraction. the L in DAL stands for Layer. The last L in BLL stands for Layer.

A tier is a physical seperation of some type. At the loosest definition, merely putting you DAL in a seperate assembly is considered a Tier, although I am a bit more narrow in my definition. I consider a tier to be a physically seperated component that does not require being run on the same computer (although it may run on it, it doesn't need to).

To answer your question, though. Yes, Business Objects are typically used to transfer data (also called Data Transfer Objects, or DTO's). I'm not sure what you mean by having to instantiate the object twice. Can you be more specific?

Erik Funkenbusch
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Don't know if you've already run into this article on msdn. If not it could be worth reading as they discuss designing tiers in general and DAL in particular, differences, pros and cons of different approaches. I think they use the same terminology as you do. Designing Data Tier Components and Passing Data Through Tiers

You could be also interested in answers to the similar question here.

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Kirill
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