Lesson 2 - SysML v2 questions, and a visualization question

Syside Advent of SysML v2
1

I didn’t understand some of the syntax introduced used in L02_SantaSleigh.sysml. For example:

SysML questions

  1. I think I understand why “ref” is used for santa, the abstract reindeer, and the specific reindeer parts, since the sleigh would not “own” santa or the reindeer, but why is there no corresponding definition for these parts? Or is it not required to have a “part” or “item”?
  2. Why “ref item” and not “ref part” for driver?
  3. Why is there not a [0..1] reference for a GiftBag in the cargoBay?
  4. Why no runner parts for the sleigh, or reins?

Also, why isn’t there a generalization/specialization relationship shown between “reindeer” and the individual reindeer when I use the visualization? Is it because of the use of “ref”?

2

Hello Kennie,

These are great questions that show you are already involved in the language! However, you must be patient—these aspects are covered in later lessons.

The idea was that we use more or less the same running example throughout the series, gradually clearing up the fog around all the model element. This can give a sense of progress, and also teaches to tolerate unknown constructs—because there will be many even after the last lesson. SysML v2 is a huge language, and it will be critical that we don’t presume we know the meaning of everything, otherwise the rigor will be replaced by guesswork.

What you did is the right approach: ask and learn about the unknown or unexpected elements.

Regarding your questions:

  1. Modifiers are covered in Lesson 5, while definitions and usages are right around the corner in Lesson 3.
  2. Items are covered in Lesson 13, but your question is not completely answered there: item is slightly more general than part, and we don’t assume here that Santa will be a full-fledged component modeled by a part definition.
  3. Multiplicity is covered in Lesson 5, and we will revisit this aspect of the model there.
  4. This is just a simplification—we omitted many components that could make sense, some of which will be up to you to add in the challenges.

+1: I am not sure about the visualization, but you will also learn more about specializations in Lesson 4.

I hope you’ll enjoy the rest of the series, and we’ll be here to answer more questions! We will also add cross-links between the Lessons later.

Happy Holidays!

Vince