what is 3-Tier,n-tier &difference Between Tier and layer

1-Tier Architecture is the simplest, single tier on single user, and is the equivalent of running an application on a personal computer. All the required component to run the application are located within it. User interface, business logic, and data storage are all located on the same machine. They are the easiest to design, but the least scalable. Because they are not part of a network, they are useless for designing web applications.

 

3-Tier Architecture is most commonly used to build web applications. In this model, the browser acts like a client, middleware or an application server contains the business logic, and database servers handle data functions. This approach separates business logic from display and data.

So the 3 layers commonly known as:

1) Presentation layer is deployed on client machines

2) Business layer is deployed to an application server

3) Data access layer is deployed to an database server

 

Here the main goal is isolation of the code so as to achieve scalability.

 

In n tier architecture there will be minimum 3 logical layers and maximum can be N(any number) . These logical parts will be deployed to separate physical servers so that any code change can be tracked and implemented easily with the least dependancy on other servers .Also, what each layer does internally is completely hidden to other layers and this makes it possible to change or update one layer without recompiling or modifying other layers.

 

One example of n tier architecture is :

 

 

difference bw tier & layer 

 Layers are logical entities like different classes/modules .Logical layers are merely a way of organizing your code. Typical layers include Presentation, Business and Data – the same as the traditional 3-tier model. But when we’re talking about layers, we’re only talking about logical organization of code. In no way is it implied that these layers might run on different computers or in different processes on a single computer or even in a single process on a single computer. 

Priyan

 

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