[Sea-sa] Feedback on the current ASL GB Draft
r.krosley at andropogon.org
Mon Jun 4 23:29:41 UTC 2018
I see what you are looking for, but I don’t find it or it’s not in the form that you might expect it in the current conversation in the SOIS working groups. This is an opportunity for me to try some drafty explanations that might develop into material for the ASL green book:
* For the general emphasis on EDS: People seem to find this concept to be a panacea for adapting to a diversity of technologies where there is clearly an interface, but it is an interface that cannot be standardized. Emphasis on adaptation to a particular technology in the ASL green book can be an informative example, but not an introduction to a normative standard.
* For subnetworks: The role of the content of the SOIS Subnet magenta books has been questioned in the last two face-to-face meetings of CCSDS, and an answer has emerged that is due to Richard Melvin’s work on generating device services from SEDS. First, some background: During the SUMO conference a few years ago, I asked a Lockheed-Martin engineer what he thought of the magenta books, and he said that they were “incomplete”. Based on that conversation, I think he meant that they were so general that they could not be implemented in an interoperable way by two different implementers. Back to the present: Richard found that the general patterns of the subnetwork magenta book interfaces could be used to map requests from device services to behavior paradigms of devices; for example, he found that the SOIS Memory Access Service (MAS) could model a device on a 1553 subnetwork, and the SOIS Packet Service (PS) could model a non-RMAP device on a SpaceWire subnetwork. So now there is a SEDS Package File that describes the interfaces in the SOIS Subnet magenta books, and the SEDS for a device on a given subnetwork makes reference to that Package File for its subnetwork interactions. Each agency has its own implementation of subnetwork interfaces, which are not interoperable with other agencies, and there is little perception of incentive to make them interoperable. The tool chain generates the software to implement the mapping for a given agency’s subnetwork interface, using the patterns in the SOIS Subnet magenta books. This is one of the points to come out of the recent work on the SOIS EDS & DoT green book.
* For support services, alas: The conversation on support services in the SOIS working groups has been tepid. For example, the Time Access Service (TAS), it has been suggested, would be better replaced with a device service for a clock or a GPS receiver. It could be argued that the TAS is at a different level than is the substituted device service, but this discussion has no takers at the present time. This is one of the points that is the victim of the current focus of discussion in SOIS, which manifested as silverization of the SOIS application support magenta books. In the future, we may resurrect the application support magenta books in the style of the subnetwork interfaces, but the interest is simply not present at this time (maybe He Xiongwen has this interest)
* For wireless: Given the current conversation, it seems to me that a likely path for integration of the wireless working group with the other two SOIS working groups is to test the hypothesis that devices on a wireless subnetwork can be described in a pattern like that of MAS, PS, or something new. I promised Kevin Gifford to pass this on to him as soon as I could express it sufficiently well. I think that I’ll have something for Kevin in about a week now, to start that conversation.
So, in summary, I can add material for the missing topics that you listed, in the manner described above, labelled by the qualities of standards that you listed, “got it”, “got a plan for it”, “nothing yet”. If you see additional avenues that I have missed, let me know.
From: Shames, Peter M (312B) <peter.m.shames at jpl.nasa.gov>
Sent: Monday, June 4, 2018 3:19 PM
To: ramon krosley <r.krosley at andropogon.org>; 'Roger Thompson' <roger.rocketbrain at btinternet.com>
Cc: 'SEA-SA' <sea-sa at mailman.ccsds.org>
Subject: Re: Feedback on the current ASL GB Draft
What are you running in, "Skeletoes"?
Actually, what you just stated " The work on the SOIS EDS & DoT green book during the last couple of months has produced some highly detailed descriptions of the process for generating device services from SEDS, which I intend to summarize at a higher level of abstraction in the ASL green book. I think that will address at least some of your concern." Does not alleviate my concern at all. On the contrary is it exactly what I had in mind when I said
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.
IMHO the whole SOIS effort has pivoted around to where the EDS is the ONLY thing that is emphasized. And yet there are still subnet, support services, and wireless that are on the books, and IN the books. There is no question in my mind that the EDS and DOT is one of the most powerful, and "real", things that SOIS has defined, but it is not the only thing.
I really do expect to see these other topics given an adequate description in this document.
From: Ramon Krosley <r.krosley at andropogon.org <mailto:r.krosley at andropogon.org> >
Date: Monday, June 4, 2018 at 1:54 PM
To: Peter Shames <peter.m.shames at jpl.nasa.gov <mailto:peter.m.shames at jpl.nasa.gov> >, Roger Thompson <roger.rocketbrain at btinternet.com <mailto:roger.rocketbrain at btinternet.com> >
Cc: SEA-SA <sea-sa at mailman.ccsds.org <mailto:sea-sa at mailman.ccsds.org> >
Subject: RE: Feedback on the current ASL GB Draft
Thanks for this guidance; it’s always helpful to know where the work is needed.
I agree with your observations on the SOIS material; you should see my running shoes (minimal, but not barefoot). The work on the SOIS EDS & DoT green book during the last couple of months has produced some highly detailed descriptions of the process for generating device services from SEDS, which I intend to summarize at a higher level of abstraction in the ASL green book. I think that will address at least some of your concern.
From: Shames, Peter M (312B) <peter.m.shames at jpl.nasa.gov <mailto:peter.m.shames at jpl.nasa.gov> >
Sent: Monday, June 4, 2018 2:32 PM
To: Roger Thompson <roger.rocketbrain at btinternet.com <mailto:roger.rocketbrain at btinternet.com> >; Ramon Krosley <r.krosley at andropogon.org <mailto:r.krosley at andropogon.org> >
Cc: SEA-SA <sea-sa at mailman.ccsds.org <mailto:sea-sa at mailman.ccsds.org> >
Subject: Feedback on the current ASL GB Draft
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.
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.
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.
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.
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".
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.
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