State Machine Diagrams

State machine diagrams model the dynamic behavior of a system by showing how objects change state in response to events. They are particularly useful for modeling reactive systems, user interfaces, and protocol specifications.

Palette

The palette contains elements for creating your state machine diagram:

  • State (empty)

  • State with Body

  • State with Body and Fallback Body

  • Initial State Node

  • Final State Node

  • Code Block

Transitions are created by connecting states directly on the canvas (they are not palette elements).

Getting Started

States

To add a state:

  1. Drag and drop the state element from the left panel.

  2. Double-click the shape to edit properties.

State Properties

  • Name: The name of the state.

  • Body: Define the behavior (actions) of the state.

  • Fallback Body: An optional action executed if the state is entered without a specific trigger.

Transitions

To create a transition:

  1. Click the source state.

  2. Drag from a blue connection point to the target state.

  3. Double-click the transition arrow to edit its Name and Parameters.

Transition Properties

Initial and Final States

Every state machine should have an Initial State (the entry point) and optionally one or more Final States (termination points).

  • Drag the Initial State element from the palette. Connect it to the first meaningful state with a transition.

  • Drag a Final State element to indicate where the machine terminates.

Code Blocks

Code blocks allow you to define custom behavior within states using Python code. Drag a Code Block element onto the canvas and double-click to open the code editor.

The code receives a session parameter for accessing state machine context.

Code Generation

State machine diagrams do not support direct code generation. They are used as method implementations within Class Diagrams. To generate code that includes state machine behavior, generate from the Class Diagram that references the state machine.