The Next Generation Systems Modeling Language (SysML v2)

The Systems Modeling Language (SysML) has long been a cornerstone in systems engineering, providing a standardized notation for describing complex systems.

A final specification of the next generation SysML v2 is expected to be published in 2024.

In this article, we'll take a closer look at three key differences between SysML Version 2 and its predecessors.

1. Metamodel

One of the most noticeable changes in SysML Version 2 is its adoption of a new metamodel.

The SysML v2 metamodel extends the Kernel Modeling Language (KerML) metamodel. The older SysML v1 used a different foundation called the UML metamodel, which was mainly created for software modeling.

Picture 1: How it used to be: Connection between UML v2 and SysML v1

This new metamodel in SysML Version 2 gives a clear set of rules and better ways to show very detailed plans of how parts of a system work together. It also has a special way to add more domain specific extensions.

“The Kernel Modeling Language (KerML) is an application-independent modeling language with a well-grounded formal semantics for modeling existing or planned systems.” (https://www.omg.org/spec/KerML/). KerML is a new way of defining new modeling languages.

2. New Graphical and Textual Notation

While SysML v1 allows only standardized graphical notation, SysML v2 introduces textual notation in addition to graphical notation. This approach gives you a whole new way to create or edit models, including the ability to do so in an automated manner.

Picture 2a: New Textual notation, OMG Systems Modeling Language (SysML) v2.0, Beta 1, Table 14. Actions – Representative Notation, p.92

Picture 2b: New Textual notation, OMG Systems Modeling Language (SysML) v2.0, Beta 1, Table 16. States – Representative Notation, p. 112

In addition to the introduction of the new textual notation, much will also change in the existing graphical notation. Below are new graphical ways to describe some relationships:

Picture 3: New intriguing graphic notations for relationships, OMG Systems Modeling Language (SysML) v2.0 Beta 1, 8.2.3.6 Definition and Usage Graphical Notation, p. 194

Even well-known UML use cases will no longer be represented graphically as ellipses, but rectangles.

Picture 4: SysML Use Cases represented as rectangles, OMG Systems Modeling Language (SysML) v2.0, Beta 1, Table 22. Use Cases – Representative Notation, p. 143

3. Standard Application Programming Interface (API)

The standard SysML 2.0 API will serve as a programming interface for developers to interact with SysML 2.0 models programmatically using Create, Read, Update, Delete (CRUD) operations.

This should solve many of the problems with importing and exporting models, interacting with models, accessing models, and problems with portability and data integrity. It will also be much easier to resume SysML models.

Here are some functionalities that a SysML 2.0 API could provide:

Model Creation and Modification: The API will allow developers to create and modify SysML 2.0 models programmatically. This will include adding or removing elements, creating relationships, and setting properties.
Validation and Analysis: An API will allow the validation of SysML models against the SysML 2.0 specification. It might also provide tools for analyzing models for consistency, completeness, and correctness.
Integration with Development Tools: The API will enable integration with various development tools and environments, allowing seamless interaction between SysML v2 models and other software engineering models.
Automated Documentation: Developers might use the API to generate documentation automatically from SysML v2 models, ensuring that project documentation stays up-to-date with the evolving system design.
Collaboration and Version Control: The API could support collaborative modeling efforts by providing mechanisms for version control, conflict resolution, and synchronization of SysML v2 models across different team members and tools.

Conclusion

There are MANY changes and new features in the new version of the SysML language.

Many elements of the language have been improved, integrated and cleaned up. We can see more consistency and coherence in the way the language is described. The Next Generation Systems Modeling Language (SysML v2) will be a game changer for the software industry.

However, it will take some time to fully adapt to the new reality. The SysML v2 specification suggests migration mechanisms that will streamline the process of migrating models from SysML v1 to SysML v2.

In any case, there is a lot of work and learning ahead of us before the new version of SysML becomes widely used and applicable.

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