Multi-Tier Network Architecture: 3 tier Architecture

Earlier Articles: Multi-Tier Network Architecture: Single Tier Architecture and Multi-Tier Network Architecture: Two-Tier Architecture

This is where things get serious. Three tier architecture is the most advanced form of this network architecture. Now a days, n-tier architecture has come to mean the 3-tier architecture.

To summarize, n-Tier Architecture is a client–server architecture in which presentation, application processing, and data management functions are logically separated. By segregating an application into tiers, developers acquire the option of modifying or adding a specific layer, instead of reworking the entire application.

For example, an application that uses middle-ware to service data requests between a user and a database employs multi-tier architecture.

Needless to say though, the most widespread use of multi-tier architecture is the Three-tier architecture.

Three Tier Architecture

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 well-established software architecture. Its three tiers are the presentation tier, application tier and data tier.

The three tier architecture is used when an effective distributed client/server design is needed that provides (when compared to the two-tier) increased performance, flexibility, maintainability, reusability and scalability, while holding the complexity of distributed processing from the user.

Image source: Wikipedia

As shown in the Figure above, the three tiers in three-tier architecture are as follows:

i. Presentation Tier:

This tier occupies the top level and displays information related to services available on a website. This tier communicates with other tiers by sending results to the browser and other tiers in the network.

ii. Application Tier:

Also called the middle tier, logic tier, business logic or logic tier, this tier is pulled from the presentation tier. It controls application functionality by performing detailed processing.

iii. Database Tier:

This tier houses the database servers where information is stored and retrieved. Data in this tier is kept independent of application servers or business Logic.

Now let's move on to the advantages and disadvantages of this architecture.

The following are the advantages of Three-Tier systems:

• Clear separation of user-interface-control and data presentation from application-logic:

Through this separation more clients are able to have access to a wide variety of server applications. The two main advantages for client applications are quicker development through the reuse of pre-built business-logic components and a shorter test phase.

• Dynamic load balancing:

If bottlenecks in terms of performance occur, the server process can be moved to other servers at run time.

• Change management:

It is easy and faster to exchange a component on the server than to furnish numerous PCs with new program versions.

And the disadvantages of Three-Tier systems are as below:

• It creates an increased need for network traffic management, server load balancing, and fault tolerance.

• Current tools are relatively immature and are more complex.

• Maintenance tools are currently inadequate for maintaining server libraries. This is a potential obstacle for simplifying maintenance and promoting code reuse throughout the organization.

Well, that's all on 3 tier architecture. We will discuss Virtual Private Networks in the next article. Stay tuned for that.

And like always, if you have any concerns, doubts or suggestions just click on ask questions at the left panel of your screen.

Thank You.