Explorative UML modeling - Comparing the usability of UML tools

UML tools are used in three main ways: (1) to exploratively sketch key system components during initial project stages; (2) to manage large software systems by keeping design and implementation synchronized; and (3) to extensively document a system after implementation. Professional tools cover (3) to some extent, and attempt to cover (2), but the vast number of languages, frameworks and deployment procedures makes those tasks all but impossible. By aiming at these two goals, tools must enforce formal UML language constructs more rigorously and thus become more complicated. They can become unsuitable for (1). This paper looks at explorative modeling with the leading UML tool Rational Rose and the open-source sketching tool UMLet. We define usability measures, assess both tools' performance for common UML design tasks, and comment on the consequences for the application of UML tools.