what is the difference between 3 tier architecture and a mvc?

Question

Comparison with the MVC architecture

At first glance, the three tiers may seem similar to the model-view-controller (MVC) concept; however, topologically they are different. A fundamental rule in a three tier architecture is the client tier never communicates directly with the data tier; in a three-tier model all communication must pass through the middle tier. Conceptually the three-tier architecture is linear. However, the [model-view-controller] MVC architecture is triangular: the view sends updates to the controller, the controller updates the model, and the view gets updated directly from the model.

Source: http://en.wikipedia.org/wiki/Multitier_architecture#Three-tier_architecture

MVC is a pattern used to make UI code easier to maintain and test. When the MVC pattern is used a larger portion of the UI code can be unit tested.

Here is a good article which describes the MVC pattern in more detail: http://martinfowler.com/eaaDev/uiArchs.html

3 tier architecture is a pattern used for a completely different reason. It separates the entire application into meaningful "groups": UI, Business Logic, Data Storage.

So 3 tier application refers to all code in the application. The MVC pattern is a pattern used in the UI tier.

Here is a good article on the 3 tier architecture: http://dotnetslackers.com/articles/net/IntroductionTo3TierArchitecture.aspx

For further information you can search the internet and find a gazzilion articles on both subjects.

In MVC : MVC architecture is triangular: the view sends updates to the controller, the controller updates the model, and the view gets updated directly from the model

In Three Tier : A three tier architecture is the client tier never communicates directly with the data tier In a Three-tier model all communication must pass through the middle tier

Their are similar in a way, like:

• 3 tier divides the whole app in: UI, logic and data
• MVC divides the UI part in: view (kind of UI of the UI), model (data) and controller (logic)

But the difference comes from how the tiers communicate with each other:

• 3-tier: anything goes through the logic tier (a->b, b->c and c->b, b->a)
• MVC: they communicate 2 by 2, in a triangular way. (a->b, b->c, c->a)

http://en.wikipedia.org/wiki/Multitier_architecture Briefly, in 3-tier architecture, presentation tier never communicates directly with data tier. In MVC, the relation among model, view, and controller is triangular. Two of three can communicate each other

In three tier solution the UI is separated from the business tier to make sure that the UI designer who is concerned with the look and feel is not confused with the heavy programming which is left to the programming professions.

This architecture (three tier) is essential when a large number of people are involved in producing a large application.

The MVC architectural style is nonhierarchical (triangular):

• View subsystem sends updates to the Controller subsystem
• Controller subsystem updates the Model subsystem
• View subsystem is updated directly from the Model subsystem

The 3-tier architectural style is hierarchical (linear):

• The presentation layer never communicates directly with the data layer (opaque architecture)

• All communication must pass through the middleware layer