User-1088661752 posted
Hi,
The traditional three tiered architecture is as you described in the latter. I've seen this called both n-Tier and Layered architecture.
Your Presentation Layer is responsible for calling the Business Logic Layer. Your Business Logic Layer calls your Data Access Layer. Your Data Access Layer returns information back to your Business Logic Layer, which implements business
rules (logic). Once your Business Logic layer has finished processing the data, it returns it to the Presentation Layer. So you can see it goes in a big circle.
The layers are important, because they seperate concerns of the application. The Presentation layer does not care what the Business Logic Layer does, it just wants data formatted in a specific way. The Business Layer doesnt know what tables the DAL
is accessing, it also just expects something in particular back.
If implemented correctly, you can change each layer independently without really affecting the other layers. Thats why this design is so popular.
You can move each layer to a different machine, or even multiple machines and distribute the load. This is a bit involved, so here is a quick search result I found that may help you:
http://www.exforsys.com/tutorials/csharp/building-web-based-n-tier-applications-using-csharp.html
