Sequence Diagram Loop

Help|Tutorials|UML|Diagramming| 27 June 2024 | Dusan Rodina - softwareideas.net
When working with UML sequence diagrams, representing loops is essential to accurately model the repetitive behavior of software algorithms. This article will guide you through the process of using loop fragments in UML sequence diagrams, with a focus on the tools and methods available in Software Ideas Modeler.

Using Loop Fragments in UML Sequence Diagrams

In UML sequence diagrams, a loop is represented using the UML Combined Fragment element with a loop interaction operator and a single interaction operand. It is important to note that the loop operation cannot have more than one operand.

By utilizing the loop fragment, you can effectively represent various types of loops from your software algorithms, such as foreach loops and do-while loops.

Loop Condition

The condition for a loop is specified within the brackets of the operand guard parameter. For instance, a simple condition could be i < 10, where i is the loop variable and the loop continues as long as the condition evaluates to true.

Sequence Diagram Loop
Sequence Diagram Loop

Loop Break

Within a loop fragment, you can include a Break fragment. This fragment is placed around a message that, when it returns true, will break the entire loop. Consequently, the process will continue with the messages that follow the loop fragment, effectively bypassing the remaining iterations of the loop.

Break in Sequence Diagram Loop
Break in Sequence Diagram Loop

Creating Loop Fragments in Software Ideas Modeler

To create loop fragments in a UML sequence diagram using Software Ideas Modeler, you can use the following methods:

Loop Fragment Tool

  • Select the Loop Fragment Tool: Choose the Loop Fragment tool from the Sequence Diagram toolbox.
  • Specify Loop Fragment Bounds: In the diagram editor, drag from the top left corner to the bottom right corner to define the bounds of the loop fragment. Release the mouse button to add the loop to the diagram.
  • Add Condition: To add a condition for the loop, click on the Add Interaction Operand button in the context bar for the loop fragment. After adding, the operand will be in edit mode, allowing you to enter the condition. Press enter to set it to the guard property, which will be displayed in brackets.

Context Bar Method

  • Select Existing Elements: Select the existing execution occurrences and/or sequence messages that you want to include in the loop fragment.
  • Create Loop Fragment: Click on the Create Loop Fragment button in the context bar. This action will create the loop fragment around the selected elements.

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