Model the structure before you model the behavior.

Learn how parts, ports, and connections define the architecture of a system in SysML v2 — and why that structure becomes the backbone for everything that follows.

High-resolution close-up of detailed architectural blueprints showcasing precision design layouts.

System Structure

A system model becomes easier to reason about when relationships are explicit.

What you’ll learn

Learning objectives

Distinguish between a part definition and a part usage in SysML v2.

Use ports to expose interaction points without revealing internal implementation.

Recognize when a connection represents flow, interaction, or structural relationship.

Core concepts

Three ideas to keep in view

SysML v2 Syntax

Part

Represents a structural element of the system and the role it plays within the whole.

Port

Defines a point of interaction where a part exchanges signals, items, or energy.

Connection

Shows how structural elements relate, interface, and work together across the model.

In SysML v2, structural modeling is the foundation for all other modeling activities. By defining parts with clear responsibilities and interaction points (ports), you create a system architecture that is easy to understand, maintain, and extend. Parts represent the building blocks of your system, while ports expose exactly how those parts interact with one another without revealing internal complexity. This separation of concerns—encapsulation—allows different teams to work on different parts independently, knowing that all interactions happen through well-defined, explicit ports. As your system evolves, this explicit structure becomes invaluable.

Practice check

Try an exam-style question

Review the syntax, then choose the best answer.

Question 1 of 3

Example code

part def Vehicle {
  port powerInput : ElectricalPower;
  port dataLink : DataSignal;
}

In this example, ports define the interaction points exposed by the Vehicle part.

In SysML v2, what is the primary purpose of a port on a part?