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Three-Tier Architecture

Reviewed by Juliano RabeloCheckmark | Last updated: January 15, 2021

What Does Three-Tier Architecture Mean?

A three-tier architecture is a client-server architecture in which the functional process logic, data access, computer data storage and user interface are developed and maintained as independent modules on separate platforms.

Three-tier architecture is a software design pattern and a well-established software architecture.


Techopedia Explains Three-Tier Architecture

Three-tier architecture allows any one of the three tiers to be upgraded or replaced independently.

The user interface is implemented on any platform such as a desktop PC, smartphone or tablet as a native application, web app, mobile app, voice interface, etc. It uses a standard graphical user interface with different modules running on the application server.

The relational database management system on the database server contains the computer data storage logic.

The middle tiers are usually multitiered.

Since the three are not physical but logical in nature, they may run in different servers both in on-premises based solutions, as well as in software-as-a-service (SaaS).

What's the Main Benefit of a Three-Tier Architecture?

it provides great freedom to development teams who can independently update or replace only specific parts of the application without affecting the product as a whole.

The application can be scaled up and out rather easily by detaching the front-end application from the databases that are selected according to the individual needs of the customer.

New hardware, such as new servers, can also be added at a later time to deal with massive amounts of data or particularly demanding services.

A three-tier-architecture also provides a higher degree of flexibility to enterprises who may want to adopt a new technology as soon as it becomes available.

Critical components of the application can be encapsulated and retained while the whole system keeps evolving organically.

Development cycle or upgrade times are significantly improved ensuring minimal disruption in customer’s experience.

Different teams can work on different sections of the application rather than on the full stack according to their areas of expertise, improving their efficiency and speed.

The Three Tiers in a Three-Tier Architecture

Presentation Tier

Occupies the top level and displays information related to services commonly available on a web browser or web-based application in the form of a graphical user interface (GUI).

It constitutes the front-end layer of the application and the interface with which end-users will interact directly.

This tier is usually built on web development frameworks, such as CSS or JavaScript, and communicates with other tiers by sending results to the browser and other tiers in the network through API calls.

Application Tier

This tier — also called the middle tier, logic tier, business logic or logic tier — is pulled from the presentation tier.

It controls the application’s core functionality by performing detailed processing and is usually coded in programming languages, such as Python, Java, C++, .NET, etc.

Data Tier

Houses database servers where information is stored and retrieved.

Data in this tier is kept independent of application servers or business logic, and is managed and accessed with programs, such as MongoDB, Oracle, MySQL, and Microsoft SQL Server.


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