13-06-2009, 04:58 PM
Model-view-controller (MVC) is a software architecture that separates an application s data model, user interface, and control logic into three distinct components so that modifications to one component can be made with minimal impact to the others.
MVC is often thought of as a software design pattern. However, MVC encompasses more of the architecture of an application than is typical for a design pattern. Hence the term architectural pattern may be useful (Buschmann, et al 1996), or perhaps an aggregate design pattern.
In broad terms, constructing an application using an MVC architecture involves defining three classes of modules.
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Model: The domain-specific representation of the information on which the application operates. The model is another name for the domain layer. Domain logic adds meaning to raw data (e.g. calculating if today is the user s birthday, or the totals, taxes and shipping charges for shopping cart items).
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View: Renders the model into a form suitable for interaction, typically a user interface element. MVC is often seen in web applications, where the view is the HTML page and the code which gathers dynamic data for the page.
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Controller: Responds to events, typically user actions, and invokes changes on the model and perhaps the view.
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Many applications use a persistent storage mechanism (such as a database) to store data. MVC does not specifically mention this data access layer, because it is understood to be underneath or encapsulated by the Model.
