[SystemSafety] Another question

[SPRIGGS, John J]

... and M. Saint Exupéry was writing about modern aeroplanes; I am not sure that we have made them simpler, but they are more dependable and resilient than the ones he flew.

-----Original Message-----
From: systemsafety [mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of Coq, Thierry
Sent: 26 September 2018 09:47
To: systemsafety at lists.techfak.uni-bielefeld.de
Subject: Re: [SystemSafety] Another question

Hello,
UML is only a language, not a method or a modelling technique. It can be used in numerous ways, most of them unsuited for critical real-time systems.
It's also very sad that, like other languages such as C, C++, Java, it has bloated instead of become more lean. Antoine de Saint Exupery once said (loosely translated from French): "perfection is achieved, not when there's nothing more to add, but when there's nothing more to remove".
I had expected after UML 1 that UML 2 would be more concise and have less diagrams, and that there would be an easy-to-understand mix of textual and graphical notations to express requirements to architecture to design to implementation to validation and safety cases. It has not happened.

On the other hand, I would like to testify that although it has not been easy, it has been possible to integrate ESTEREL and UML in a real-time method in order to produce time-provable pieces of software. It was done some time ago. My guess is that there are several teams out there that have done the same thing using a subset of UML (like other subsets mentioned in this thread) and using that subset to define requirements, architecture, design and/or implementation, combined it with their preferred semi-formal or formal modelling techniques and built part of their validation documentation with it. The added value was the easier understanding of the simple and precise (subset of) UML for the non-engineers, non-system-engineers and non-functional-safety-engineers in the team and in the client's team.

Best regards,
Thierry Coq


-----Original Message-----
From: systemsafety [mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of Les Chambers
Sent: Tuesday, September 25, 2018 1:34 PM
To: Olwen Morgan <olwen.morgan at btinternet.com>; systemsafety at lists.techfak.uni-bielefeld.de
Subject: Re: [SystemSafety] Another question

Olwen
Re comment:
If you explore the formal methods literature, you'll easily find modelling techniques that UML does not properly embrace.

Can you name one or two. Always ready to be educated.

Les


> On 24/09/18 23:41, Les Chambers wrote
>
> <snip>
>
>  >>> ... I am with you on the UML. It's just a container for all the 
> modelling techniques we've developed over the past 50 years. No 
> developer has to consume all the Kool-Aid. You just take a sip and use 
> what's useful in your own special >>> context. Why anyone would take a 
> dislike to it is a mystery to me.
>
> Beg to differ. If you explore the formal methods literature, you'll 
> easily find modelling techniques that UML does not properly embrace. I 
> dislike any formalism for systems engineering that is:
>
> (a) not formally defined or has had formal definitions (clumsily) 
> retro-fitted, or
>
> (b) forces upon me a verbosity that more mathematically-based 
> techniques do not.
>
> ... and as regards "lunatic fringe" environments, it remains true to 
> say that if you don't know what you want:
>
> (i)Â Â Â  you won't know when you've got it, or
>
> (ii)Â Â  if you've belatedly decided what you do want, reworking what 
> you've got that isn't what you want does not exactly have an 
> impressive track record in systems engineering.
>
> I may be wrong but I doubt that you'd find Sukhoi systems engineers 
> working the way the F35 systems engineers have. Russian engineering 
> seems to be predicated on a much more incremental philosophy ... which 
> is quite possibly why US astronauts have to go to Baikonur to thumb a 
> lift to the ISS.
>
> O
>
> _______________________________________________
> The System Safety Mailing List
> systemsafety at TechFak.Uni-Bielefeld.DE



--
Les Chambers
les at chambers.com.au
+61 (0)412 648 992

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