4. Quantitative real-time characteristics

The previous paragraphs were dedicated to modeling the qualitative aspects of real-time applications: competition, communication, behavior and actions. We will now focus on the quantitative aspects of real-time specification in UML.

UML defines two types of time-related data, Time and TimeExpression :

• Time defines a value representing an absolute or relative moment in time;

• TimeExpression lets you specify expressions whose evaluation gives a Time value.

In particular, this data can be used in two types of diagrams: state diagrams and sequence diagrams.