UML timing diagrams

Communication diagrams, sequence diagrams and timing diagrams are different views of the interaction. Timing diagrams focus on the timing or duration of the message or conditions in change along a timeline in the diagram.

You create timing diagrams to represent a part of the timing of a system. You can use timing diagrams to examine and further model time constraints and duration. You can create multiple timing diagrams that each focus on a different lifeline or view of the interaction. The elements that you add to a sequence diagram are not added to the corresponding timing diagram. However, the elements that you add to a timing diagram are added to the corresponding sequence diagram. You can add elements to the timing diagram by creating new elements or by selecting existing elements. Timing diagrams are not canonical and sequence diagrams are canonical. The timing diagram represents only a partial view of the interaction and therefore does not contain all the elements of a sequence diagram.

States and conditions

Timing diagrams contain states or conditions. Sequence diagrams have state invariants that closely resemble a state or condition. A state invariant in a timing diagram is interpreted as the time, or duration, that the particular state invariant lifeline is in a specified state.

The following example shows a timing diagram that contains two lifelines, state invariants, messages, duration observations and constraints and time observations and constraints.