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.