Interaction Diagrams

Interaction Diagrams:

   Terms and Concepts:

              An interaction is a behavior that comprises a set of messages exchanged among a set of Objects within a context to accomplish a purpose.

              A message is a specification of a communication between objects that conveys information with the expectation that activity will ensue.

              A sequence diagram is an interaction diagram that emphasizes the time ordering of messages.

              A collaboration diagram is an interaction diagram that emphasizes the structural organization of the objects that send and receive messages.

    

 Interaction diagrams commonly contain

·                     Objects

·                     Links

·                     Messages

 Interaction diagrams are used in two ways:

·                     Modeling a Flow of Control

·                     Modeling Flows of Control by Time Ordering

 To model a flow of control,

·                     Set the context for the interaction, whether it is the system as a whole, a class, or an individual operation.

·                     Set the stage for the interaction by identifying which objects play a role; set their initial properties, including their attribute values, state, and role.

·                     If your model emphasizes the structural organization of these objects, identify the links that connect them, relevant to the paths of communication that take place in this interaction. Specify the nature of the links using the UML's standard stereotypes and constraints, as necessary.

·                     In time order, specify the messages that pass from object to object. As necessary, distinguish the different kinds of messages; include parameters and return values to convey the necessary detail of this interaction.

Also to convey the necessary detail of this interaction, adorn each object at every moment in time with its state and role.