See http://www.awl.com/cseng/titles/0-201-89542-0/techniques/interactions.htm (ISBN 0201895420) [see also AnalysisPatterns]

UnifiedModelingLanguage (UML) diagrams that show the interaction of object instances over time.
Two forms for the same data:
	1. SequenceDiagram (Wiki MessageSequenceChart) -- emphasizes the flow of time; what messages are sent in what sequence.
	2. CollaborationDiagram -- emphasizes the relationships between objects.  Clusters of arrows show heavy communication between instances.  Shows "spatial" relationships between objects, much like a class diagram.
''(Both shown at the URL on the top of this page.)''

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JeffGrigg last updated this almost 4 years ago and we are in 2004Q4. Do people still think this type of ClassDiagram''''''s is a cost effective way to communicate with other developers with no prior application knowledge, and have to maintain work done by long gone gurus? -- DavidLiu