N-Tier Architecture

 

N-tier architecture is also called multi-tier architecture because the software is engineered to have the processing, data management, and presentation functions physically and logically separated.  That means that these different functions are hosted on several machines or clusters, ensuring that services are provided without resources being shared and, as such, these services are delivered at top capacity.  The “N” in the name n-tier architecture refers to any number

There are following :-

1- Business Object

2- Data Layer

3- Business Layer

4- Presentation Layer

How It Works and Examples of N-Tier Architecture

When it comes to n-tier architecture, a three-tier architecture is fairly common.  In this setup, you have the presentation or GUI tier, the data layer, and the application logic tier.

The application logic tier.  The application logic tier is where all the “thinking” happens, and it knows what is allowed by your application and what is possible, and it makes other decisions.  This logic tier is also the one that writes and reads data into the data tier.

The data tier. The data tier is where all the data used in your application are stored.  You can securely store data on this tier, do transaction, and even search through volumes and volumes of data in a matter of seconds.

The presentation tier.  The presentation tier is the user interface.  This is what the software user sees and interacts with.  This is where they enter the needed information.  This tier also acts as a go-between for the data tier and the user, passing on the user’s different actions to the logic tier.

Just imagine surfing on your favorite website.  The presentation tier is the Web application that you see.  It is shown on a Web browser you access from your computer, and it has the CSS, JavaScript, and HTML codes that allow you to make sense of the Web application.  If you need to log in, the presentation tier will show you boxes for username, password, and the submit button.  After filling out and then submitting the form, all that will be passed on to the logic tier.  The logic tier will have the JSP, Java Servlets, Ruby, PHP and other programs.  The logic tier would be run on a Web server.  And in this example, the data tier would be some sort of database, such as a MySQL, NoSQL, or PostgreSQL database.  All of these are run on a separate database server.  Rich Internet applications and mobile apps also follow the same three-tier architecture.

And there are n-tier architecture models that have more than three tiers.  Examples are applications that have these tiers:

• Services – such as print, directory, or database services
• Business domain – the tier that would host Java, DCOM, CORBA, and other application server object.
• Presentation tier
• Client tier – or the thin clients

One good instance is when you have an enterprise service-oriented architecture.  The enterprise service bus or ESB would be there as a separate tier to facilitate the communication of the basic service tier and the business domain tier.