Welcome to the Advent of SysML v2—a free 24-day learning challenge for systems engineers. This is the first of 24 new SysML v2 lessons and hands-on exercises, taking you from the language fundamentals to applying SysML v2 in common use cases and workflows.

Today’s lesson is all about getting to know SysML v2. We’ll cover the essentials, start modeling right away in Syside Cloud, and even peek under the hood—but don’t worry, unlike the Christmas dinner at the end, everything here will be bite-sized.

SysML v2 – The Next Generation Systems Modeling Language

SysML v2 is the next-generation systems modeling language that’s transforming how complex systems are designed and analyzed. It supports the System as Code paradigm, fitting naturally into today’s engineering workflows, with models you can version, review, integrate into pipelines, and analyze with tools instead of doing everything manually.

As a major step forward, the new version is completely redesigned for clearer semantics, richer expressiveness, and machine-readable models. It is based on KerML, a flexible, application-independent modeling language that serves as a general foundation for domain-oriented languages, replacing UML. Diagrams are still available, but the language also comes with a full textual syntax, making modeling faster, more consistent, and easier to automate.

SysML v2 isn’t just for systems engineers: its clean notation and tool-friendly design make it useful for software teams, architects, and anyone working on complex, multidisciplinary systems. The result is better collaboration, stronger traceability, and models that scale to modern system complexity—from autonomous platforms to aerospace and medical devices. SysML v2 is designed for the future, ready for AI-driven analysis, digital twins, and highly automated engineering workflows.

Under The Hood

Every engineer benefits from understanding the principles underlying their tools—though you don’t need to know combustion engines in detail to drive a car. In this spirit, we’ll take a high-level look at the technical foundations of SysML v2.

As mentioned, SysML v2 is built on KerML, the Kernel Modeling Language, which has formal semantics. This means every SysML model has a precise mathematical meaning. This allows tools to interpret and reason about our designs—but it also means we must ensure models express exactly what we intend.

Take a look at the diagram above. SysML is layered on top of KerML. The two columns represent Abstract Syntax (the language definition) and Semantic Libraries (the semantics).

From the bottom up, KerML first defines the fundamental structure of the language in the Root Syntax—for example, names, namespaces, elements, and relationships. The foundation of the semantics is first-order logic.

The Core Syntax defines elements for modeling types and classifying things and their relationships. The most general types are in the Core Library, with their semantics formalized in first-order logic. You may never need to interact directly with this layer, but it underpins every concept in the language and your models.

The Kernel Syntax and Kernel Library introduce common modeling concepts such as structures and actions. Their meanings are expressed in terms of already-defined concepts, ultimately reducing to the formal Core Layer. The Kernel Syntax also provides built-in keywords to make these concepts easier to use.

On top of this sits SysML. Its syntax refines KerML, introducing keywords for more detailed modeling. The Systems Library defines new concepts similarly to the Kernel concepts, while Domain Libraries offer ready-to-use constructs for your models.

Finally, your models sit on top of this layer. They use SysML, but you can also define new keywords to extend the language. Your models will define the semantics of your domain-specific new concepts by modeling them with SysML elements and leveraging types from the libraries.

Most episodes will focus on modeling your concepts, though some will cover extending the language or creating your own libraries. SysML is complex but flexible—and you’re on your way to mastering it.

Your First SysML v2 Model

In the spirit of the holiday season, let us model our first SysML v2 model: a Christmas tree. You can find it below, and you can also recreate or tweak it in Syside Cloud (get access by registering to Advent of SysML v2).

We put the design of Sensmetry’s Christmas tree in a package that we created for today’s lesson. This is a good practice to isolate your models from the rest of the world. Inside the package, we define what a Christmas tree is. 

We start with the documentation to capture the intent, then model the details in SysML. For now, we use an attribute to record the URL to an image of our tree. Later, we will learn how to do this with metadata, which is a more appropriate way to annotate our models with extra information.

The main structure of the tree starts on line 10. The trunk is the main part of the tree, which has 5 to 10 branches. Each branch has an unspecified number of needles on it.

We also take care of the ornaments. We specify that there are 15 spherical ornaments, 10 bell ornaments, and a single star ornament on the top. Each kind of ornament has a distinct color, which comes from an enumerated datatype defined on line 43.

We add 100 lights and note in the documentation that this should be a string of LED lights.

Finally, we specify that the tree has a base that supports it and holds the tree upright.

That’s it. Now the tree is ready to be manufactured—you still have time to acquire all the components and have Sensmetry’s Christmas tree in your home by Christmas!

Challenge for Tomorrow

Throughout the Advent of SysML v2 series, we will help Santa redesign his famous sleigh with cutting-edge technology. Your challenge after this lesson is to model it in Syside Cloud (get access by registering to Advent of SysML v2). Release your imagination—and don’t forget to model the reindeer!

Summary

In this episode, you learned the essentials about the new Systems Modeling Language, saw your first model, learned about the exciting features of Syside waiting for you to try, and even peeked under the hood. If you haven’t yet done so, it is now time to go to Syside Cloud to do the challenge and design Santa’s new sleigh—and don’t forget to come back tomorrow for another episode of the Advent of SysML v2!