Some impacts of SysML version 2

[avi-mak]

Hi all,

I have come across an OMG presentation about the future SysML v2 by Hans Peter de Koning. On Slide #8, 'Key Elements of SysNL v2', appear three top-level items, where the first is 'New Metamodel that is not constained by UML' , where its sub-item is 'Grounded in formal semantics'.

Questions:

(1) What is meant by 'not constrained by UML' ? And will BDD syntax and semantics still pretty much follow UML class syntax and semantics - or not? 

(2) What is meant by 'Grounded in formal semantics'? Was SysML v1.x not "grounded in formal semantics"? And for that matter, was UML v2.x.y not "grounded in formal semantics"?

(3) Is there a place I can I find the best and shortest and easiest answers to the above questions (1) and (2)? 

(4) Now that I have spent some time on learning (getting used to...) basic SysML concepts (actually means: basic UML concepts...), I was planning to soon start trying to introduce some SysML usage into my company. In the light of (1) and (2) above, is now a good time to start? What would be the challenges of starting now, with a new SysMLversion seemingly looming over the horizon?

Note: I have not yet tried to 'take a look inside' pre-release v2, and even if I did, I do not consider myself so qualified to draw my own conclusions wrt (1), (2), and (4) above. 

Thanks,

Avi

[James Towers]

Hi Avi,

There is a Google Group for the SysML v2 incrementel release https://groups.google.com/g/sysml-v2-release although this may be too specific for general questions.

You can also download the latest specs from GitHub https://github.com/Systems-Modeling/SysML-v2-Release

There are various presentations and articles on the web including some in the PPI newsletter -

https://www.ppi-int.com/syen-newsjournal/ppi-syen-85/ - by me

https://www.ppi-int.com/syen-newsjournal/ppi-syen-95/ - by Sanford Friedenthal and Ed Seidewitz (co-chairs of the Submission Team)

To answer your specific questions -

1) As you know the current version is defined as a profile of UML so while it can add things, and mark others for exclusion, if you want to change any of the underlying meaning you first have to redefine UML - which is a big job and requires agreement from the UML community. As far as I understand it the Block Syntax will be very similar to how it is now, although there will be a stronger focus on Parts and in fact the expectation is that the IBD will become the predominant artefact rather than the BDD (as it is now)

2) SysML v1 (or rather UML v2) is grounded in 'semi-formal semantics’ - that is some aspects are well defined and some aspects not so - as an Example there is a supplementary standard fUML which takes a subset of UML and applies additional formal semantics for execution. SysML 2 is being built ‘from the ground up’ using a formal ‘kernel’ based on the KerML language. See this presentation from Ed Seidewitz https://www.slideshare.net/seidewitz/sysml-v2-and-the-next-generation-of-modeling-languages-135913786

3) These various links should help

4) The SysML v2 spec is not due for submission until later this year (it has already been pushed back), and then it will take time to transit through the acceptance process. Assuming it is released sometime in 2022 (I have no idea if this is realistic or not) then I think it will be a number of years before we see it fully implemented in any of the commercial tools (I would like to be wrong on this). Even with all this, SysML v2 is expected to provide a transition path from V1, plus it will include a UML profile so that it can be implemented in UML based tools. Put all this together and my advise would be to start the introduction now with v1 as there are many challenges you will need to address - not least convincing people that model-based is the way to go - which are independent of the language. 

Thanks

James

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[avi-mak]

Hi James,

Thank you for the detailed response. Sorry that it always takes me a long time to send thanks for the responses that I receive on this forum.

  

>> As far as I understand it the Block Syntax will be very similar to how it is now,

 

Good to hear, as far as I am concerned - because I like many others, I am sure, have invested a lot of time in learning the ‘BDD black art’ (actually, the ‘UML class black art’). And now, once I know it (or enough of it), I could not imagine defining system parts in any other way (with some improvements).

 

>> there will be a stronger focus on Parts and in fact the expectation is that the IBD will become the predominant artefact rather than the BDD (as it is now)

 

re IBDs - I had composed a long question aboוt this, but for now I will just say that on my SysML platform (Sparx EA), I cannot see a way to naturally drill down from an IBD block to the IBD block diagram that “defines” it. Don’t know yet if it is because of my lack of knowledge or because the tool is lacking in a basic ability. I am now writing to the EA forum.

 

Thanks again.

Avi