Sequence diagrams

Question 1

What is interaction diagram?

Answer 1

A diagram that describes an interaction among a set of objects to produce some useful behaviours

Question 2

The difference between sequence diagrams and collaboration diagrams?

Answer 2

Both are interaction diagrams.

• Sequence diagram: emphasizes on time ordering of messages
• Collaboration diagram: emphasizes on collaboration relationships among the collaborating objects

Question 3

What is the purpose of sequence diagrams?

Answer 3

To show all the main sequence of actions in an interaction

Question 4

What are the main elements in sequence diagrams?

Answer 4

• Actor
• Objects
• Messages
• Lifeline
• Activation boxes
• Fragments

Question 5

What are the four kinds of messages in UML?

Answer 5

• Synchronous message
• Asynchronous message
• Creation message
• Reply message

Question 6

What is the difference between synchronous and asynchronous message?

Answer 6

• Synchronous message: the sender has to wait for the resulting action to be completed by the receiver before taking the next action
• Asynchronous message: the sender doesn’t have to wait, can take the next action immediately, if required