What is the use of system sequence diagram?
Sequence diagrams are used to express interactions of external elements with the system realizing a use case, interesting specific interactions among elements within the system design, or specify test cases using the UML Testing Profile [2].
What is ref in sequence diagram?
ref Reference: refers to an interaction defined on another diagram. The frame is drawn to cover the lifelines involved in the interaction. You can define parameters and a return value.
What is break in sequence diagram?
Breaks are most commonly used to model exception handling. This sequence diagram example uses a break combination fragment because it treats the balance < amount condition as an exception instead of as an alternative flow. To read this example, we start at the top left corner of the sequence and read down.
How do you describe a sequence diagram?
A sequence diagram or system sequence diagram (SSD) shows object interactions arranged in time sequence in the field of software engineering. It depicts the objects involved in the scenario and the sequence of messages exchanged between the objects needed to carry out the functionality of scenario.
What is the main objective of the sequence diagram?
The basics. The main purpose of a sequence diagram is to define event sequences that result in some desired outcome.
What is ref in UML?
To reference other interactions in a UML sequence diagram, interaction uses can be used. It is shown in the sequence diagram as a fragment with the operator ref to indicate the reference to another interaction.
What is ALT in UML?
alt is used to describe alternative scenarios of a workflow. Only one of the options will be executed. opt is used to describe optional step in workflow. For example, for online shop purchase sequence diagram you may use opt to describe how user can add gift wrapping if she wishes.
What is a lifeline OOSE?
Explanation: Lifeline is a rectangle containing an identifier with a dashed line extending below the rectangle. Explanation: All communications from one object to another are called messages and are represented by message arrows in sequence diagrams.
How does a sequence diagram work?
A sequence diagram is structured in such a way that it represents a timeline which begins at the top and descends gradually to mark the sequence of interactions. Each object has a column and the messages exchanged between them are represented by arrows.