[Css-rasg] RE: Exomars Reference model

Tue Apr 12 04:20:31 EDT 2011

Dear Erik,

Thank you for your detailed comments.

Regarding figure 5; I agree that the diagram attempts to show two
things, the functional viewpoint (the objects and their connections) and
the assembly for ExoMars (the packages). It may be a good idea to have a
separate model showing only the functional viewpoint, as RMODP / RASDS
forsees.

Personally I would argue that a functional viewpoint can never be
completely abstract as RMODP / RASDS forsees, but will always be a
specific example assembly; if a function is defined to depend on another
function, then that is in fact the introduction of an implementation
concerns, as the model assume that the function will always be
implemented using the other function. Which violates the idea behind the
functional viewpoint, as its intended to be an abstract model, and leave
the implementation concerns to the communication viewpoint. By showing
functions depending on other functions, the model therefore in my view
automatically becomes non-abstract. 

The module naming and the grouping of functions follows the ExoMars
architecture directly. The model is an example assembly for ExoMars,
mapping the ExoMars architecture (the packages) to the operational
functions of the reference model. 

Regarding the profile used; In the first version of the document,
reviewed by Peter Shames, a description of the profile was included. It
was commented that this should not be in reference model but either in
the RASDS or in the document being prepared by Takahiro. I agree that's
it is important to agree on a (descriptive?) UML profile for the RASDS
and describe its usage in detail to help people understand the models.
The question is where this should be.

For the reference model we have used the parts of the publically
available RMODP profile that are aligned with RASDS. If / when the RASDS
specific viewpoints gets used, a profile should be created for them.

Kind regards,
Gert Villemos.

From: Barkley, Erik J (317H) [mailto:erik.j.barkley at jpl.nasa.gov] 
Sent: Freitag, 1. April 2011 01:57
To: CCSDS RASG; Colin.Haddow at esa.int
Cc: Shames, Peter M (313B); Nestor.Peccia at esa.int; Mario.Merri at esa.int;
Villemos, Gert; James, Steven
Subject: FW: Exomars Reference model

RASG Colleagues,

FYI.

Colin,

My apologies for not at least acknowledging receipt sooner. Thanks for
sending out the update.

I have only had time for a very brief scan, but based on that I have a
couple questions.

Figure 5 is indicated as a functional viewpoint.  But it comes across to
me as a bit of a mix of different concerns. For example, the labels on
the packages all essentially are different enterprises/administrative
domains that are yoked together to provide the complete system. But one
of the packages is labeled "entry, descent and landing" - this is really
not in the same general classification of functions indicated but rather
an activity that is carried out with the lander.  (Best architectural
practices would also suggest that this is in fact to be a functional
view based on the specification of the viewpoint -- i.e. labeled as
functional view.  Ultimately it would be of benefit to have the formal
definition of the viewpoint such that the reader understands what the
criteria for stating a function are in this diagram - but at this point
I'm not really too concerned about these kind of formalisms. )

Another question which may just be simply my ignorance, is that there is
a lot of application of the <<CV_Object>> stereotype and I must admit I
do not know nor is there any definition offered as to what the
<<CV_Object>> connotes.  By the same token,
<<CV_OperationInterfaceSignature>> does not really tell me that much
without some identification/definition of what the stereotype implies. 

I would certainly be willing to support a telecon to discuss this the
week of 11 April or later if that makes sense to you. 

Best regards,

-Erik 

From: Colin.Haddow at esa.int [mailto:Colin.Haddow at esa.int] 
Sent: Wednesday, March 02, 2011 9:02 AM
To: Shames, Peter M (313B); Barkley, Erik J (317H);
Nestor.Peccia at esa.int; Mario.Merri at esa.int
Cc: Gert.Villemos at Logica.com; Steven.James at Logica.com
Subject: Exomars Reference model

Dear all, 
                  please find attached the latest draft of the ExoMars
reference model. I'm afraid this iteration took somewhat longer than
expected. Anyway I look forward to your comments and with a bit of luck
we should be able to get the next revision completed faster. 

Cheers for now, 

Colin 

------------------------------------------------------------------------
---------------------------------
Dr. Colin R. Haddow,
OPS-GI, European Space Agency,
European Space Operations Centre,
Robert-Bosch-Str 5,
64293 Darmstadt,
Germany.

Phone; +49 6151 90 2896
Fax;      +49 6151 90 3010
E-Mail;  colin.haddow at esa.int
------------------------------------------------------------------------
---------------------------------

Think green - keep it on the screen.

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