Appendix: About SysML version 2

The Ansys System Architecture Modeler supports SysML v2.

SysML v2 is a completely new language compared to SysML v1. There are some important differences between the Ansys SAM and SysML v1.x-based modelers such as Cameo, Rhapsody, or SCADE Architect. Some of the main differences are listed below.

Note: The standardization and definition of the SysML v2 language is still being developed. For more information about SysML v2, including a comparison to SysML v1, refer to Intro to the SysML v2 Language-Graphical Notation document.

Definition vs Usage

SysML v2 standardizes creating definitions that you can then use in different contexts.

SysML v1 uses the terms definition and usage informally. For example, after you define a reusable top-level action in v1, you can then use that action within a specific activity diagram. That specific action in the new activity diagram is a usage that only references the top-level action definition. It does not insert the top level action directly into the diagram. This prevents changes to a specific action sequence from unintentionally affecting other activity diagrams for other systems attempting to reuse that action definition.

In SysML v2, this distinction of def versus usage was made consistent and prominent across the language. Now, where you would previously create a block (SysML v1.x) or class (UML), you instead start by creating a part def. For a ValueType (SysML v1.x) or DataType (UML) you now create either an attribute def or item def. Every feature (without the def keyword) within another element is then implicitly a usage within the context of that parent element, in analogy to part properties from SysML v1. The type of these usages is usually specified by a corresponding def declared elsewhere. However, such feature usages can also be bound as equivalent to another usage declared elsewhere. You can also redefine the feature values on usages without altering anything about the original definition. These distinctions in SysML v2 help to make these important concepts from SysML v1 clearer, more accessible, and more consistent. Explore how best to use these concepts and to collaborate on new methodologies that leverage these language features.

Tip: For more information about these concepts, refer to third-party guides such as A Practical Guide to SysML.

Diagrams

SysML v2 does not use the term diagrams to present and store model elements. Instead, elements are included in views. Views show a partial representation of elements in the model. However, all model elements exist on their own with relationships to other elements.

While the terminology has changed, much of the functionality has not. Using this modeler, you can still view and edit elements. The new terminology clarifies where and how elements are visually presented.

Instances

Unlike UML, SysML v2 does not have an Instance Specification. To represent specific values when designing a system, you can create a top-level part.

Consider creating a top-level part (usage) to represent specific design values for a system under design. Later, the concept of an individual part will likely clarify the difference between a prototypical design iteration and a specific individual instance rolling off an assembly line into an operational environment. Individuals are not currently supported in this modeler, pending finalization of the intended language usage.