Guidelines: Interfaces for J2EE Applications
Topics
Introduction
A Java Interface, as defined in the Java language syntax, is not limited to having operations-it can have Java Field, Class, or Interface members. For this reason, Java Interfaces are modeled as classes stereotyped <<JavaInterface>>.
The UML interface has no direct mapping to a language construct in Java or J2EE development.
Interfaces in Java Design
Even though UML interfaces do not map to a language construct in Java or J2EE, there are situations where the designer might want to use them. Some possible reasons are:
- to potentially target other languages and technologies
- to express the idea of an interface without initially deciding if a Java Interface, or some kind of delegate or access class, will be used
If the implementation language is Java, you might decide to use <<JavaInterface>> stereotyped classes in the Design Model in place of UML interfaces. This allows the Design Model to evolve more easily and remain consistent with the Implementation Model (see Concepts: Mapping from Design to Code).
Note that <<JavaInterface>> stereotyped classes cannot be represented as lollipops on the outside of UML subsystems or components. Instead, the exposed interfaces are shown as publicly visible elements owned by a subsystem or as publicly visible elements residing on a UML component.
Interfaces in EJB Design
EJB interfaces are specializations of Java interfaces. Their stereotypes are described in Guidelines: Identifying Enterprise JavaBeans.
The designer might use UML interfaces, <<JavaInterface>> stereotyped classes, or EJB-specific stereotyped classes to model interfaces depending on how closely the designer wants to map to a particular implementation.
