An App Interface (Application Interface) is an interface definition used to describe the communication that may exist between applications.
An Exposed Interface is an instance of an interface that is attached to a specific component. It is a short-cut for drawing a realization from a component to an interface and provides additional modeling functionality. Exposed Interfaces come in two styles, ProvidedInterfaces and RequiredInterfaces. The former indicates that the component provides the features defined by the interface while the latter indicates that the component requires the features as provided by some other component.
(EA)<sup>2</sup> employs two categories of interfaces, App Interfaces and DB Interfaces. The (EA)<sup>2</sup> Application Architecture Toolbox, (EA)<sup>2</sup> Application Component Toolbox, supply ProvidedInterfaces and Required Interfaces for the App Interfaces you design.
Modeling App Interfaces
You create App Interfaces using the toolbox element of the same name, which provides a UML Interface with (EA)<sup>2</sup> tagged values. You may add attributes and operations to the App Interface to build up the signature of the interface. Typically, the App Interfaces are kept with the application that provides the interface unless you are creating an interface that may be provided by numerous components. In this case, you can put them in a package at the enterprise or domain level.
