Question

In web programming, what is the three tier architecture?

Answer 1

A 3-tier application architecture consists of a presentation tier, an application tier and a data tier.

Presentation tier - This tier is what is shown to user which is the front end layer in the 3-tier system and called the user interface. This is built using web technologies like HTML5, cascading style sheets (CSS) and JavaScript. This GUI(Graphical user interface) is accessible using device through a web browser or a web-based application. This tier communicates with the other tiers through application program interface (API) calls.

Application tier - The application tier is not directly shown to the user and works at the back end.which contains the functional business logic. It is built using programming languages like Java, .NET, C#, Python, C++ and contains the business logic that supports the application’s core functions by performing detailed processing. The application tier can run either on distributed servers in the cloud or on a dedicated in-house server.

Data tier - The data tier comprises of the database/data storage system and data access layer which contains database servers where information is stored and retrieved. Data in this tier is kept independent of application servers or business logic.For example, MySQL, Oracle, MongoDB, etc. The data tier consists of a database and a program for managing read and write access to a database. Application layer accesses data via API calls.

With three tiers, different team of developers can work on each tier parallely without effecting each other. Independency of one module over other also makes modification easy.