Release 10.1A: OpenEdge Getting Started:
OpenEdge Reference Architecture

> ## Components of the Presentation Layer

> In order to effectively design a Presentation Layer, you need to understand the types of components that comprise the layer, their capabilities, and proper uses.

> The three types of components in the Presentation Layer are shown in Table 4–1.

> Table 4–1: Presentation Layer components
> Component type | Role
> --- | ---
> Model | Manages data and communicates data to View components.
> View | Contains all the elements (menus, buttons, dialog boxes, etc.) that allow the user to interact with the application. Also displays data.
> Controller | Enables communication between the Model and View components. Also processes user input and events.

> These types of components are borrowed from the Model-View-Control (MVC) design pattern, which is an object-oriented coding practice. A design pattern is a high-level description of a type of design that typically repeats itself in application architectures. Design patterns are not language or technology specific; instead, they are indicative of application architectures as a whole, and represent repeatable processes that an application architect encounters when designing an application.

> Note, however, that the OpenEdge RA is not limited to the MVC design pattern, or object-oriented coding. MVC is used for illustration purposes and because it is a convenient way to categorize the functionality found in the Presentation Layer.

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