Creating ASP.net Applications With N-Tier Architecture - CodeProject

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About Article

This article describes how

to build ASP.NET

applications using n-tier

architecture.

Type Article

Licence CPOL

First Posted 13 Aug 2012

Views 48,115

Downloads 4,845

Bookmarked 79 times

C# ASP.NET Beginner

N-Tier

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Creating ASP.NET Applications with N-Tier

ArchitectureBy Rahul Rajat Singh, 20 Aug 2012

Download demo - 760.7 KB

Introduction

This article describes how to build ASP.NET applications using n-tier architecture. The benefits of

having n-tier architecture is that all the modules having dedicated functionality will be

independent of each other. Changing one tier will not effect other tiers and there is no single

point of failure even if some tier is not working.

Background

In a typical n-tier application there will be 4 Layers. The bottom most layer is the Data layer which

contains the tables and stored procedures, scaler function, table values function. This Data layer

is typically the database engine itself. We will be using as the data layer in our

example.

On top of Data Layer, we have a Data Access Layer (DAL). This layer is responsible for handling

Database related tasks i.e. only data access. This is created as a separate

solution so that the changes in only need the recompilation of DAL and not the complete

website. The benefit of having this layer as a separate solution is that in case the database engine

is changes we only need to change the and the other areas of the website need not be

changed and recompiled. Also the changes in other areas outside this solution will not demand

for recompilation.

On top of DAL, we have our . contains all the calculations

and Business Rule validations that are required in the application. It is also in a separate solution

for the reason that if the Business rules change or the calculations change we only need to

recompile the and the other layers of the application will remain unaffected.

Finally on top of we have our Presentation Layer. The Presentation layer for an ASP.NET web

forms application is all the Forms (pages and their code behinds) and the classes

contained in the App_Code folder. The Presentation layer is responsible for taking the user input,

showing the data to the user and mainly performing input data validation.

Note: Input data filtration and validation is typically done at the Presentation Layer(Both client

side and server side). The business Rule validation will be done at the .

So to visualize the above mentioned architecture:

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Note: The Data Access Layer in this article was written using classic , due to which the

amount of code in is little too much. Nowadays using ORMs like

!" to

generate the is recommended. The code will be generated by ORM itself.

Using the code

Let us develop a small Toy # application that will use n-tier architecture. We will develop

a small Employee Management application for the $%&Database. (For simplicity, I have

removed all other tables from the DB and some columns from the Employee table). This

application should be able to perform the basic CRUD operations on the DB.

The solution for this application will contain separate projects for and . The Data Layer

will be . The Presentation Layer is an ASP.NET website running on top of these

projects.

The Data Layer

The data layer in this example contain only one table called Employee. The data layer also

contains the stored procedures for all the basic operations on the Employee table. So let us look

at the table and all the stored Procedures we have in our Data Layer.


2 of 12 12-02-2013 09:17

Now we will create a set of stored procedures to perform the operations on the Employees Table.

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The Data Access Layer

Now we will go ahead and create a Data Access Layer for our application. The data access layer

will contain 2 main type of classes. A set of classes that will represent the Table entities. And

classes to perform the '()operations on the database.

The class in the above diagram is the Entity that will represent the table.

This class has been created so that the Layers above the will use this class to perform

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generate all the DAL code.

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and Contexts.

The Business Logic Layer

The business logic layer will have a reference to the DAL and will mainly perform Business rule

validation and business logic specific calculations. In out example, I will write a simple that

will govern the IO between the and Presentation layer. In real applications the will

contain more logic and code.


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The Presentation Layer

The presentation layer now contains only a set of pages and code behinds and it will use the

and the the Employee class to perform all the operations. The add Operation can be seen as an

example how the is being used to perform an operation.


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Creating ASP.net Applications With N-Tier Architecture - CodeProject