Describe System Behavior Using Sequence Diagrams

A sequence diagram represents the expected interaction between structural elements of an architecture as a sequence of message exchanges.

Use sequence diagrams to describe how the parts of a system interact.

Sequence diagrams are integrated with architecture models in System Composer™.

• Author Sequence Diagram for Traffic Light Example: Interactively create and edit a sequence diagram and learn terminology.

• Author Sequence Diagram Fragments: Learn how to implement fragments and more about fragment semantics.

• Use Sequence Diagrams with Architecture Models: Create and use sequence diagrams with architecture models.

• Synchronize Sequence Diagrams and Architecture Models: Learn how to synchronize sequence diagrams with architecture models.

A lifeline is represented by a head and a timeline that proceeds down a vertical dotted line.

The head of a lifeline represents a component in an architecture model.

A message sends information from one lifeline to another. Messages are specified with a message label.

A message label has a trigger and a constraint. A trigger determines whether the message occurs. A constraint determines whether the message is valid.

An annotation describes the elements of a sequence diagram.

Use annotations to provide detailed explanations of elements or workflows captured by sequence diagrams.

A fragment indicates how a group of messages within it execute or interact.

A fragment is used to model complex sequences, such as alternatives, in a sequence diagram.

An operand is a region in a fragment. Fragments have one or more operands depending on the kind of fragment. Operands can contain messages and additional fragments.

Each operand can include a constraint to specify whether the messages inside the operand execute. You can express the precondition of an operand as a MATLAB^® Boolean expression using the input signal of any lifeline.

Related Topics

• Simulate Sequence Diagrams for Traffic Light Example
• Compose Architectures Visually
• Implement Component Behavior Using Simulink
• Implement Component Behavior Using Stateflow Charts