Timing Diagrams

Timing diagrams are UML
interaction diagrams
used to show interactions when a primary purpose of the diagram is to reason about time.
Timing diagrams focus on conditions changing within and among lifelines along a linear time axis.
Timing diagrams describe behavior of both
individual classifiers
and interactions of classifiers, focusing attention on time of events causing changes in the modeled
conditions of the lifelines.

Major elements of timing UML diagram –
lifeline,
timeline,
state or condition, message,
duration constraint,
timing ruler.

You can find some
timing diagram examples here:

Lifeline

Lifeline is a
named element
which represents an individual participant in the interaction.
While parts
and structural features may have multiplicity greater than 1, lifelines represent only one
interacting entity.
See lifeline
from sequence diagrams for details.

Lifeline on the timing diagrams is represented by the name of classifier or the instance
it represents. It could be placed inside diagram frame or a “swimlane”.

Lifelines representing instances of System and Virus

State or Condition Timeline

Timing diagram could show states of the
participating classifier
or attribute, or some testable conditions, such as a discrete or enumerable value
of an attribute.

Timeline shows Virus changing its state between Dormant, Propagation, Triggering and Execution state

UML also allows the state/condition dimension be continuous.
It could be used in scenarios where entities undergo continuous state changes, such as temperature or density.

Duration Constraint

Duration constraint is an
interval constraint
that refers to a duration interval.
The duration interval is duration used to determine whether the constraint is satisfied.

The semantics of a duration constraint is inherited from constraints.
If constraints are violated, traces become negative which means that system is considered as failed.

Duration constraint is shown as some graphical association between a duration interval
and the constructs that it constrains.

Ice should melt into water in 1 to 6 minutes

Time Constraint

Time constraint is an
interval constraint
that refers to a time interval.
The time interval is time expression used to determine whether the constraint is satisfied.

The semantics of a time constraint is inherited from constraints.
All traces where the constraints are violated are negative traces, i.e., if they occur, the system is considered
as failed.

Time constraint is shown as graphical association between a time interval and the construct that it constrains.
Typically this graphical association is a small line,
e.g., between an occurrence specification and a time interval.

Person should wake up between 5:40 am and 6 am

Destruction Occurrence

Destruction occurrence is
a message occurrence
which represents the destruction of the instance described by
the lifeline.
It may result in the subsequent destruction of other objects that this object owns by
composition.
No other occurrence may appear after the destruction event on a given lifeline.

Notation

The destruction event is depicted by a cross in the form of an X at the end of a timeline.

Virus lifeline is terminated

History

Complete UML name of the occurrence is destruction occurrence specification.
Until UML 2.4 it was called destruction event, and earlier – stop.