Multitier Architecture

Multitier Architecture

In software engineering, multi-tier architecture (often referred to as n-tier architecture) is a client–server architecture in which presentation, application processing, and data management functions are logically separated. For example, an application that uses middleware to service data requests between a user and a database employs multi-tier architecture. The most widespread use of multi-tier architecture is the three-tier architecture.

N-tier application architecture provides a model by which developers can create flexible and reusable applications. By segregating an application into tiers, developers acquire the option of modifying or adding a specific layer, instead of reworking the entire application. Three-tier architectures typically comprise a presentation tier, a business or data access tier, and a data tier.

While the concepts of layer and tier are often used interchangeably, one fairly common point of view is that there is indeed a difference. This view holds that a layer is a logical structuring mechanism for the elements that make up the software solution, while a tier is a physical structuring mechanism for the system infrastructure.

There have been growing concerns in recent years that many organizations are facing an excessive number of layers in their multi-layered architecture. These concerns stem from sprawling application architectures that are not well designed or managed, in which development teams create an ever-growing number of "wrapper" layers that compromise maintainability. The resulting architecture resembles a Rube Goldberg Machine that scares organizations from solving the root cause of the sprawling layers, resulting in the creation of more layers.