Contents
What is the purpose of a lifeline on a sequence diagram?
A lifeline represents an individual participant in a sequence diagram. A lifeline will usually have a rectangle containing its object name. If its name is “self”, that indicates that the lifeline represents the classifier which owns the sequence diagram.
What are lifelines in sequence diagram?
In UML diagrams, such as sequence or communication diagrams, lifelines represent the objects that participate in an interaction. For example, in a banking scenario, lifelines can represent objects such as a bank system or customer. Each instance in an interaction is represented by a lifeline.
Which of the following does a lifeline represent in a UML sequence diagram?
Lifeline: is used to denoted the life of the object during the sequence. The messages are written above the arrows from the object to another object. The arrow shows the direction of the message that is being passed. The sent message is represented with a solid line and the received message with a dotted line.
How does a sequence diagram work?
A sequence diagram simply depicts interaction between objects in a sequential order i.e. the order in which these interactions take place. We can also use the terms event diagrams or event scenarios to refer to a sequence diagram. Sequence diagrams describe how and in what order the objects in a system function.
What are the elements of a sequence diagram?
Basic Sequence Diagram Notations
- Class Roles or Participants. Class roles describe the way an object will behave in context.
- Activation or Execution Occurrence.
- Messages.
- Lifelines.
- Synchronous Message.
- Asynchronous Message.
- Reply or Return Message.
- Self Message.
What is in a sequence diagram?
A sequence diagram consists of a group of objects that are represented by lifelines, and the messages that they exchange over time during the interaction. A sequence diagram shows the sequence of messages passed between objects. Sequence diagrams can also show the control structures between objects.
How are lifelines represented in a sequence diagram?
Each instance in an interaction is represented by a lifeline. As the following figure illustrates, a lifeline in a sequence diagram is displayed with its name and type in a rectangle, which is called the head. The head is located on top of a vertical dashed line, called the stem, which represents the timeline for the instance of the object.
Can you have multiple actors in a sequence diagram?
We can have multiple actors in a sequence diagram. For example – Here the user in seat reservation system is shown as an actor where it exists outside the system and is not a part of the system. Lifelines – A lifeline is a named element which depicts an individual participant in a sequence diagram.
When to use sequence diagram or interaction diagram?
A sequence diagram is the most commonly used interaction diagram. An interaction diagram is used to show the interactive behavior of a system. Since visualizing the interactions in a system can be a cumbersome task, we use different types of interaction diagrams to capture various features and aspects of interaction in a system.
What are the use of sequence diagrams in UML?
Uses of sequence diagrams – 1 Used to model and visualise the logic behind a sophisticated function, operation or procedure. 2 They are also used to show details of UML use case diagrams. 3 Used to understand the detailed functionality of current or future systems. 4 Visualise how messages and tasks move between objects or components in a system.