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Behavior modeling and four diagrams

Short answer

Behavior modeling captures dynamic system interactions over time. Four key diagrams: use case diagram shows actor functions; sequence diagram shows time-ordered messages; state machine diagram shows object states and transitions; activity diagram shows process flow with decisions and parallelism.

What is behavior modeling in object-oriented analysis? Present any four sample diagrams that are based on behavior modeling.

Behavior modeling in OOA describes the dynamic side of the system: how objects interact, respond to events and change state over time, and how the system behaves from the user's point of view. It complements the static (structural) model of classes. The behaviour is captured in the sample diagrams below.

1. Use case diagram (functional behaviour)

Shows actors and the functions the system provides to them.

          +-------------------+
 [Customer]--( Withdraw Cash )|
          |-( Check Balance ) |
          +-------------------+

2. Sequence diagram (interaction in time order)

Shows messages exchanged between objects in a scenario.

 :Customer     :ATM       :Bank
     | enterPIN() |           |
     |----------->| verify()  |
     |            |---------->|
     |            |<- - - - - |
     |<- - - - - -|           |

3. State machine (state) diagram

Shows the states of one object and the events that cause transitions.

 (*)-->[ Idle ]--insertCard-->[ Verifying ]
          ^                       | pinOK
          +----- ejectCard ----[ Active ]

4. Activity diagram

Shows the flow of activities, decisions and parallel work in a process.

 (start)-->[Enter PIN]-->< valid? >--yes-->[Dispense]-->(end)
                            |no
                            +--->[Reject]-->(end)

A collaboration (communication) diagram is another behavioural diagram, showing the same interaction as a sequence diagram but organised by object links.

Use: behaviour models are used to find operations of classes, check use cases, and to design tests.

✓ Answer checked by Claude Opus 5.5 (high effort)

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