Benefits of N-Tier Architecture

Applying N-Tier Architecture and Example

Let’s now apply N-Tier Architecture to our shopping cart example. In this example, we will demonstrate how sales tax is calculated and displayed. The presentation tier calls the business logic tier to perform computations on the data in the shopping cart to calculate total price. The business logic tier communicates with a database (data tier) to extract the sales tax amount based on the total price.

The business logic tier is able to communicate with the data tier through the integration tier. Through encapsulation, the integration tier is able to conceal the complexities of communication. It also retrieves the right tax rate and returns it to the business logic tier. The business logic tier completes its calculations. The presentation tier formats the response through HTML and forwards it to the client or web browser, where it is displayed to the user.

Benefits of N-Tier Architecture

There are many business benefits to N-Tier Architecture. For example, a small business can begin running all tiers on a single machine. As traffic and business increases, each tier can be expanded and moved to its own machine and then clustered. This is just one example of how N-Tier Architecture improves scalability and supports cost-efficient application building.

N-Tier model also make applications more readable and reusable. It reduces the amount of spaghetti code. Custom tag libraries and EJBs are easier to port to readable applications in well-maintained templates. Reusability multiplies developer productivity and improves application maintainability. It is an important feature in web applications.

N-Tier Architectures make application more robust because there is no single point of failure. Tiers function with relative independence. For example, if a business changes database vendors, they just have to replace the data tier and adjust the integration tier to any changes that affect it. The business logic tier and the presentation tier remain unchanged. Likewise, if the presentation layer changes, this will not affect the integration or data layer. In 3-Tier Architecture all the layers exist in one and affect each other. A developer would have to pick through the entire application code to implement any changes. Again, well-designed modules allow for applications or pieces of applications to be customized and used across modules or even projects. Reusability is particularly important in web applications.

As demonstrated N-Tier Architecture offers innovations in the standard Client-Server technology that spawned the Internet itself. It is but one of many web application frameworks. These are used to develop dynamic web sites, web applications or web services. They provide database access libraries, templates, and, as previously stated code re-use. Most web application frameworks follow the Model View Controller (MVC) which separate the user interface, the business rules and the data model. They provide authentication and authorization to provide security. This allows the web server to restrict user access based on pre-determined criteria. Web application frameworks also provide a unified API (Application programming Interface). This allows web application to work with various databases without requiring any code change. These frameworks also maintain a web template system.

Finally, N-Tier Architecture helps developers build web applications because it allows developers to apply their specific skill to that part of the program that best suits their skill set. Graphic artists can focus on the presentation tier, while administrators can focus on the database tier.