[Sea-sa] Feedback on the current ASL GB Draft

Tue Jul 10 17:46:44 UTC 2018

Dear SAWG,

In the interest of timely feedback, I am sending the rough notes from today's telecon, documenting the agreements., embedded in the following email discussion  I have also uploaded the ASL draft, Rev E-ps, that includes my updates.  Many of these, particularly the security sections, are just "rough-in" and need much editing.

Thanks for the support, Peter
.

From: Roger Thompson <roger.rocketbrain at btinternet.com>
Date: Wednesday, June 27, 2018 at 8:45 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov>, Ramon Krosley <r.krosley at andropogon.org>
Cc: SEA-SA <sea-sa at mailman.ccsds.org>
Subject: RE: Feedback on the current ASL GB Draft

Hi Peter (and Ray),

I got back from Ireland a week ago, but spent last week on MPS WG activities, so only just now catching up on your comments.
Some initial responses embedded below.

I am updating my Implementation View diagrams in the light of our discussions at the last telecon.  Pity I didn’t write down my understanding at the time – I’m not so clear on what we agreed now!
What is the latest version of the GB in case I get around to making updates to it before next week?

Cheers,

Roger

From: Shames, Peter M (312B) [mailto:peter.m.shames at jpl.nasa.gov]
Sent: 04 June 2018 21:32
To: Roger Thompson; Ramon Krosley
Cc: SEA-SA
Subject: Feedback on the current ASL GB Draft
Importance: High

Hi Guys,

Over the last few days I have been reading through the current (or latest) ASL GB draft.   I think that you guys have made great progress and this document is coming together rather nicely.  At this point I am up to page 61, the end of Section 4, or something like 1/3 of the way done.

In the attached version you will see my mark-up notes.  There are a lot of inputs that are simply editorial, and others that are somewhat more substantive.  In the "substantive" column I would put the following:

1.      Most of what is now in Sec 1.1 really, IMHO, belongs in Sec 1.3, Rationale.  This is the expected usage in CCSDS Green Books, but they have been known to vary.
[RST] I agree that it covers the Rationale – but then what should go in Purpose?  Also, what we now have in Scope needs this “rationale” to explain it (and therefore to precede it).  I would prefer to leave as is and delete the Rationale section, or to change the title to Purpose and Rationale.

<<PS>> Agree to leave the intro as it is and see if the "Document Police" feel that it needs to be converted to the "normal form".

2.      The MOIMS sections that I have reviewed so far. are very good and quite complete.  In fact, they almost seem too complete, but that is another discussion. If everything is done to this level, as it should be to have an "even" appearance, the doc will be huge.
[RST] We aim to please.  I have tried to keep it terse where possible.  I’m not so sure that the SOIS sections will be as extensive as the MOIMS – as MOIMS covers many individual interactions, whilst SOIS is really one big concept.

<<PS>> Recognize that MOIMS is different in nature than SOIS.  MOIMS is many application domain topics that are inter-related, SOIS is three or more separate topics that do not strongly interact.  We will all need to keep this clear.>>

3.      The handling of the interfaces between MOIMS and CSS does not strike me as satisfactory.  The MOIMS MO services must plan for space links, send data over space links, and get data of various kinds from space links.  It just does not seem acceptable to say " telemetry acquisition and telecommand uplink are communications layer functions that do not directly interact at the application layer with MOIMS functions ".  If not MOIMS, then where?  Is there an air gap?  Does some other CCSDS area have responsibility?  In SCCS-ADD parlance it is "applications" that interact with the SLE and CSTS services.  Those application, IMHO, ought to be MOIMS.
[RST] I believe what is shown for these interfaces is both correct and complete – I don’t see why it is not satisfactory.  You are correct that at the application level, there is planning – but it is not “MO Services” that do this planning (they are effectively just an interface).  It is Mission Planning and Mission Control applications themselves that do the planning and related mission control functions – these functions are shown as interacting with the relevant CSS services for Service Management, M&C, etc.  (where these are themselves Application Level Services, but following the “London Agreement” the planning of CSS Service provision is outside the scope of MOIMS.  That Planning function is assumed to be within the scope of the external TT&C function.  We have other external ground segment functions that are outside the scope of MOIMS: not least the Mission Data Processing, so this is not unique.  I personally may have some sympathy with the view that application level functions associated with Mission Control should be considered within the MOIMS domain – but this is not the current CCSDS position.  End-to-end MO Services that use the SLE Transfer Services do so as a protocol layer, which is shown in the Communications Viewpoint.  Any MO Service deployed in a Space Link Context may use the SLE Transfer Services.  What we could do is find somewhere to add a section to explain the relationship between MOIMS and CSS – although this could highlight some irrationality.

<<PS>> Agree to add clarifying text early in the document, and to the functional viewpoint pointing to the communications viewpoint.   Work to clean up the specific language relating to how MOS depends upon underlying SLE and space link services and uses their service interfaces.  Avoid pejorative language like "space links merely carry the data".

4.      The SOIS materials, by contrast, are good, but seem really incomplete.  Notwithstanding that the scope of SOIS is considerably less than that of MOIMS, the treatment of the SOIS functions and services is itself truncated in the extreme.  As much as MOIMS seems a little overblown, SOIS seems totally underinflated.  I think we need to seek parallel construction in each of the sections wherever possible.  See in particular my comments in Sec 2.4.2 and 4.3.
5.      Some of the SOIS limitations are due to the "silverizing" activity that occurred, some of it seems due to a shift in focus by the leadership to implementation approaches and EDS.  Regardless, those SOIS functions and features (support, subnet, wireless) that remain in MB and GB materials really should be adequately covered in this document.
6.      I like the materials in Sec 3.3, but worry a little that we may be putting too much "RASDS 2.0" materials into this document.  There may not really be much choice, because we have agreed to use these extensions and really must explain what we are doing and why, but it is a little concern.
[RST] I think we have to explain the representation used somewhere, and there won’t be a RASDS 2.0 book before this GB is published (I hope).

<<PS>> Agreed.  We just need to provide the minimum essential set.

7.      The distinctions in type and representation that are used in Sec 3.3 among unspecified, published, under development, proposed, and "no standard identified" seem, in general, to be not sufficiently distinct to be useful.  I think the important distinction is really only between "do we have a standard" and "do we have any sort of plan for a standard".   Everything else is just so much idle speculation.  Three levels are probably enough: "it exists", "we have a plan for it", and "something could be (might be) here, but isn’t".
[RST] I could possibly live with that – but do not have the budget to change all the diagrams yet again (as I said when I undertook the last change).  It is relatively minor whether we split the “we have a plan for it” into “ we are working on it” and “it’s on the roadmap” – which is effectively what we have.  I do not think it would be a good use of resources to make any change here.

<<PS>> Agree, in the interest of focusing our resources, to leave the current a=elaborations in place.  We may have to revisit this if there is reviewer feedback.

I'll keep on plugging away at this.  Do take a look and see if what I have identified seems reasonable or really off base.

Thanks, Peter

<<PS>> Discussed use the existing names and abbreviations for standards, such as TD-CSTS (tracking data), CSSM (service management), and the generic SLE-TS (transfer services as a group).

<<PS>> Discussed the best approach for the Implementation Viewpoint.  We saw materials from Roger.  Ray's approach is in his section of the Rev E document.  For next time review these and focus on this viewpoint to get it nailed down.

Thanks, Peter

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