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Functional chains [message #1829750] Fri, 10 July 2020 07:58 Go to next message
Ouafa BENAHSENE is currently offline Ouafa BENAHSENEFriend
Messages: 8
Registered: February 2020
Junior Member
Hello,

One of the conditions for functional chains is: "The path of selected elements shall only have two ends, which means that it can be composed by only one branch."
I was wondering: how can I represent a function that needs two informations from two other functions to be executed. My functional chain needs two beginnings...

Thank you
Re: Functional chains [message #1829773 is a reply to message #1829750] Fri, 10 July 2020 11:48 Go to previous messageGo to next message
Fábio Guarita is currently offline Fábio GuaritaFriend
Messages: 64
Registered: December 2019
Member
Have you tried creating the functional chain you need in your model? I was able to as seen on the attachments. Please check if it is what you need.

The Architecture diagram:

index.php/fa/38544/0/

The Functional Chain Description diagram:

index.php/fa/38543/0/

Also, I didn't get any validation errors.
Re: Functional chains [message #1829774 is a reply to message #1829773] Fri, 10 July 2020 12:10 Go to previous messageGo to next message
Ouafa BENAHSENE is currently offline Ouafa BENAHSENEFriend
Messages: 8
Registered: February 2020
Junior Member
Thank you for your answer.
Indeed, I was able to do this but is it correct from a modeling point of view?
I mean this rule must exist for some reason?

[Updated on: Fri, 10 July 2020 12:11]

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Re: Functional chains [message #1829779 is a reply to message #1829774] Fri, 10 July 2020 12:49 Go to previous messageGo to next message
Fábio Guarita is currently offline Fábio GuaritaFriend
Messages: 64
Registered: December 2019
Member
Can you provide the origin of the phrase "The path of selected elements shall only have two ends, which means that it can be composed by only one branch."?

Is it from the Capella help or one of the reference books? Like Jean Luc Voirin's or Pascal Roques'?
Re: Functional chains [message #1829780 is a reply to message #1829779] Fri, 10 July 2020 12:53 Go to previous messageGo to next message
Ouafa BENAHSENE is currently offline Ouafa BENAHSENEFriend
Messages: 8
Registered: February 2020
Junior Member
It's from Capella help
  • Attachment: aaaaa.PNG
    (Size: 36.01KB, Downloaded 23 times)
Re: Functional chains [message #1829782 is a reply to message #1829780] Fri, 10 July 2020 13:20 Go to previous messageGo to next message
Fábio Guarita is currently offline Fábio GuaritaFriend
Messages: 64
Registered: December 2019
Member
Maybe that's an error on the Capella Help pages.

Mr Voirin's book on Capella, which I believe is the main methodological reference, has a couple of examples that are not "single branch" like. You can see on the Level Crossing Traffic Control model some examples. The only real constraint I see to well-formed functional chains is that all elements must be connected by functional exchanges. Which is enforced by the tool - FCs that become invalid are marked with a (invalid) or (broken) tag, I don't recall exactly which.
Re: Functional chains [message #1829783 is a reply to message #1829782] Fri, 10 July 2020 14:24 Go to previous messageGo to next message
Ouafa BENAHSENE is currently offline Ouafa BENAHSENEFriend
Messages: 8
Registered: February 2020
Junior Member
Well thank you! All of these things convinced me.
Re: Functional chains [message #1829809 is a reply to message #1829783] Fri, 10 July 2020 20:03 Go to previous messageGo to next message
Stephane LACRAMPE is currently offline Stephane LACRAMPEFriend
Messages: 196
Registered: July 2009
Senior Member
Ouafa, maybe you can raise a bug about this: https://bugs.eclipse.org/bugs/enter_bug.cgi?product=Capella selecting the documentation component.
Thanks
Stephane


Stephane LACRAMPE
Obeo Canada
Re: Functional chains [message #1829876 is a reply to message #1829750] Mon, 13 July 2020 10:32 Go to previous message
Jean-Luc Voirin is currently offline Jean-Luc VoirinFriend
Messages: 5
Registered: February 2020
Junior Member
Functional chains may be used for different purposes, possibly requiring some specific building rules, including one start/one end.
In Arcadia book (1) :
"A functional chain is an ordered set of references to functions and the functional exchanges that link them, describing one possible path among all the paths forming the dataflow (...) in a particular usage context (...). If a functional chain should carry data from end to end (latency, etc.), then some interpretation conventions should be defined (only one a single function allowed as the start or end of the chain, for example)."

If you have a latency constraint to be applied to a given path in the dataflow, then you need one starting function and one ending function so as to avoid any ambiguity. But this is not to apply to any kind of functional chain.

(1) Model-based System and Architecture Engineering with the Arcadia Method, ISTE Press, London & Elsevier, Oxford, 2017, (c) ISTE
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