Contents > B: List of Design Metrics > B.4 Interaction Metrics

B.4 Interaction Metrics

Metric: LifeLinesCategory: Size
The number of lifelines participating in the interaction.

Metric: MessagesCategory: Complexity
The number of messages sent within the interaction.

Metric: SelfMessagesCategory: not specified
The number of messages that objects in the interaction send to themselves.

The focus of sequence diagrams should be on object interactions. A sequence diagram with a large number of self messages may indicate that the modeler attempted to model object internal algorithms.

Metric: CombinedFragmentsCategory: Size
The number of combined fragments in the interaction.

Metric: OperandsCategory: Size
The number of interaction operands of the combined fragments in the interaction.

Metric: HeightCategory: not specified
The maximum number of messages on any of the lifelines of interaction.

Very long and busy lifelines with lots of messages attached to them may indicate objects that have too many responsibilities.

Metric: CombinedFragmentNestingCategory: not specified
The maximum nesting level of combined fragments in the interaction.

Excessive nesting of combined fragments makes sequence diagrams harder to read and understand. Consider extracting such combined fragments into sequence diagrams of their own.