<font size=2 face="sans-serif">Ho Peter,</font>
<br><font size=2 face="sans-serif">Nice to hear from you, you really read
these emails - very good! I think you have a point, and very practically
I am also scratching my head how update ESA's B-1 implementation of the
CSTS Specification Framework to B-2 in a way that both, B-1 and B-2 are
supported. Which leads my thinking in a direction that at the end, users
only cares about what an implementation of a standard supports, not so
much if a standard itself is backward compatible.</font>
<br>
<br><font size=2 face="sans-serif">Of course you are fully right that we
should change standards backward compatible if we can. And believe me,
that is one of my concerns. However, for the CSTS Services this is really
a particular case where I think that with the chosen (ASN.1) technology
and all the relations between a CSTS Service Specification and the CSTS
Specification Framework, adding another dimension, namely the applicability
of newer CSTS Specification to a CSTS Service, would render this unusable.
It would be simply too complex, both to specify and to understand.</font>
<br>
<br><font size=2 face="sans-serif">Coming back to the word example, I think
that is what I talk above. For instance the docx format is really differently
specified than the old doc format. Still, an implementation can open both.
Specification of the new format (docx) is not backward compatible, the
implementation is. BTW, I am not a big Microsoft fan, but I think what
they provide in terms of backward compatibility is outstanding. I am already
complaining that I need to support 5 different versions of SLE in one implementation...</font>
<br>
<br><font size=2 face="sans-serif">Best regards,</font>
<br><font size=2 face="sans-serif">Holger</font>
<br>
<br><font size=2 face="sans-serif">Holger Dreihahn<br>
European Spacecraft Operations Centre | European Space Agency | S-431<br>
+49 6151 90 2233 | </font><a href=http://www.esa.int/esoc><font size=2 face="sans-serif">http://www.esa.int/esoc</font></a>
<br>
<br>
<br>
<br><font size=1 color=#5f5f5f face="sans-serif">From:
</font><font size=1 face="sans-serif">"Shames, Peter
M (US 312B)" <peter.m.shames@jpl.nasa.gov></font>
<br><font size=1 color=#5f5f5f face="sans-serif">To:
</font><font size=1 face="sans-serif">"Holger.Dreihahn@esa.int"
<Holger.Dreihahn@esa.int>, "EXTERNAL-Pietras, John V (US 332C-Affiliate)"
<john.pietras@gst.com></font>
<br><font size=1 color=#5f5f5f face="sans-serif">Cc:
</font><font size=1 face="sans-serif">"CSS-CSTS"
<css-csts-bounces@mailman.ccsds.org>, "CCSDS_CSTSWG (css-csts@mailman.ccsds.org)"
<css-csts@mailman.ccsds.org></font>
<br><font size=1 color=#5f5f5f face="sans-serif">Date:
</font><font size=1 face="sans-serif">04/03/2020 17:16</font>
<br><font size=1 color=#5f5f5f face="sans-serif">Subject:
</font><font size=1 face="sans-serif">Re: [EXTERNAL]
Re: [Css-csts] Forward Frame CSTS WG Review Package on CWE</font>
<br>
<hr noshade>
<br>
<br>
<br><font size=3 face="Calibri">Ho Holger,</font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">I like your analogy, but it immediately
brings to mind, for me, the question "Why wouldn't it exactly be the
case that </font><font size=3 face="Arial">this version of Word will work
with any future version of Windows once available</font><font size=3 face="Calibri">?"
Striving hard to ensure backward compatibility ought to be a major
objective, even while we move into the future.</font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">When I look at Microsoft, and some of the
choices that they have taken to drop backward compatibility in their products,
I get really annoyed. I have been working long enough that I have
written a lot of docs and presentations that I still have on my computer.
Some are "seminal" and are still relevant, some are merely
historical and of value to me. But frequently, when I try to open
these older (like even 10 years) Word and PPT files with the current crop
of MS tools I get messages that say "we do not have a clue what to
do with this file". That is just sad and really annoying. </font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">And note that it is not that the file is
broken, but that the tool no longer supports this older format at all.
Happily, in many cases, there are other tools like Open Office that
do continue to support the older formats. So I can open these files
in Open Office, save them in a more recent format, and then go back into
the new MS Office tools and open these "re-saved" files. It
works, but it is awkward, painful, and must be done one by one.</font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">All of that could be avoided. IMHO,
we should, in our own work, attempt to do avoid these kinds of situations
wherever we can. I realize that there are situations where we have
to make changes to data structures and available operations sets and features
in order to move ahead. That is proper and that is what versioning
is for. But please, let's try and not break older stuff when moving
forward, and let's try and keep our existing standards up to date with
the most current frameworks.</font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">Thanks, Peter</font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri"><b>From: </b>CSS-CSTS <css-csts-bounces@mailman.ccsds.org>
on behalf of "Holger.Dreihahn@esa.int" <Holger.Dreihahn@esa.int><b><br>
Date: </b>Tuesday, March 3, 2020 at 11:33 PM<b><br>
To: </b>John Pietras <john.pietras@gst.com><b><br>
Cc: </b>CSS-CSTS <css-csts-bounces@mailman.ccsds.org>, CSTS-WG <css-csts@mailman.ccsds.org><b><br>
Subject: </b>[EXTERNAL] Re: [Css-csts] Forward Frame CSTS WG Review Package
on CWE</font>
<br><font size=3 face="Calibri"> </font>
<br><font size=3 face="Arial">Dear John,</font><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
Thanks a lot, I'll put JPL PS-3 on the agenda. However, I am afraid but
it is a consequence of the taken approach that a CSTS Service Specification
has this close relation to the CSTS Service Specification Framework. No
problem to be clear on that, but we cannot allow the adoption of newer
versions once they are available. This would be like stating 'oh yes, this
version of Word will work with any future version of Windows once available...'.</font><font size=3 face="Calibri">
<br>
</font><font size=3 face="Arial"><br>
Best regards,</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
Holger</font><font size=3 face="Calibri"> <br>
</font><font size=3 face="Arial"><br>
Holger Dreihahn<br>
European Spacecraft Operations Centre | European Space Agency | S-431<br>
+49 6151 90 2233 | </font><a href=http://www.esa.int/esoc><font size=3 color=blue face="Arial"><u>http://www.esa.int/esoc</u></font></a><font size=3 face="Calibri">
<br>
<br>
<br>
</font><font size=3 color=#5f5f5f face="Arial"><br>
From: </font><font size=3 face="Arial">"John
Pietras" <john.pietras@gst.com></font><font size=3 face="Calibri">
</font><font size=3 color=#5f5f5f face="Arial"><br>
To: </font><font size=3 face="Arial">"CCSDS_CSTSWG
(css-csts@mailman.ccsds.org)" <css-csts@mailman.ccsds.org>,
"Wolfgang Hell" <wo_._he@t-online.de></font><font size=3 face="Calibri">
</font><font size=3 color=#5f5f5f face="Arial"><br>
Date: </font><font size=3 face="Arial">03/03/2020
22:42</font><font size=3 face="Calibri"> </font><font size=3 color=#5f5f5f face="Arial"><br>
Subject: </font><font size=3 face="Arial">[Css-csts]
Forward Frame CSTS WG Review Package on CWE</font><font size=3 face="Calibri">
</font><font size=3 color=#5f5f5f face="Arial"><br>
Sent by: </font><font size=3 face="Arial">"CSS-CSTS"
<css-csts-bounces@mailman.ccsds.org></font><font size=3 face="Calibri">
</font>
<div align=center>
<hr noshade></div>
<br><font size=3 face="Calibri"><br>
<br>
</font><font size=3 face="Arial"><br>
CSTSWG colleagues ---</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
I have been informed that the FF-CSTS prototype testing has successfully
concluded with no changes required of the FF-CSTS specification. I have
therefore put together a working group review package and posted it to
the CWE at URL:</font><font size=3 face="Calibri"> </font><font size=3 color=blue face="Calibri"><u><br>
</u></font><a href="https://cwe.ccsds.org/css/docs/CSS-CSTS/CWE%20Private/Future%20Services%20using%20Toolkit/Forward%20Frame%20CSTS/FF-CSTS-922x3r2.2-1200303-CSTSWG_Review.zip"><font size=3 color=#0082bf face="Arial"><u>https://cwe.ccsds.org/css/docs/CSS-CSTS/CWE%20Private/Future%20Services%20using%20Toolkit/Forward%20Frame%20CSTS/FF-CSTS-922x3r2.2-1200303-CSTSWG_Review.zip</u></font></a><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
The zip file contains 3 files:</font><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">1. </font><font size=3 face="Arial">An
annotated version of the FF-CSTS book, in which the annotation consists
of Word markup balloons that identify the reasons for the changes from
the internationally-reviewed Red Book version. Most of these references
are to the RIDs that caused them, but a few others refer to changes resulting
in test compilations if the ASN.1 modules and typo that were discovered
along the way. When the book is ready to go to the Secretariat for publication,
these annotations will of course be removed.</font><font size=3 face="Calibri">
</font>
<br><font size=3 face="Calibri">2. </font><font size=3 face="Arial">An
updated copy of the RID resolutions. Note at all RIDs and pseudo RIDs have
been resolved, accepted by the WG, and incorporated into the document except
the following three, which all stem from Peter Shames’ request to have
the book more explicitly address the role of the FF service in Delay-Tolerant
Networking (DTN) and Pater’s subsequent review of the document as a whole:</font><font size=3 face="Calibri">
</font>
<br><font size=3 face="Calibri">3. </font><font size=3 face="Arial">Pseudo
RID JPL PS-1: This pseudo RID documents Peter Shames’ request for an explicit
discussion of the role of the FF service in Delay-Tolerant Networking (DTN)
configurations. Proposed changes have already been drafted in the book.
Those changes have been accepted by the pseudo RID author. If and when
the CSTSWG agrees with the changes, pseudo RID JPL-PS-1 will be closed.</font><font size=3 face="Calibri">
</font>
<br><font size=3 face="Calibri">4. </font><font size=3 face="Arial">Pseudo
RID JPL PS-2: This pseudo RID documents multiple comments made by Peter
Shames on the Red Book. Proposed resolutions for all items in the pseudo
RID have been generated, either as changes that have already been drafted
in the book or as explanations of questions asked. All of the proposed
resolutions have been accepted by the pseudo RID author. If and when the
CSTSWG agrees with the changes, pseudo RID JPL-PS-2 will be closed.</font><font size=3 face="Calibri">
</font>
<br><font size=3 face="Calibri">5. </font><font size=3 face="Arial">Pseudo
RID JPL PS-3: This pseudo RID deals with the change in the CCSDS Blue Book
“boiler plate” introduction to the References sections of CSTS specifications.
For reasons having to do with the close synchronization of CSTS specification
versions and CSTS SFW versions, the introductory paragraph now prohibits
subsequent versions of the SFW from being used with any given issue of
a CSTS specification. This change in approach has elicited concern by Peter
about the desirability and feasibility of essentially maintaining multiple
active versions of the SFW book. I have copied the relevant portions of
our email exchange at the bottom of this email (below my signature). The
most recent response (today) from Peter is “I am willing to close out
the comment, but only if the CSS CSTS WG makes a commitment to a) making
sure that this situation] is made blazingly clear, and b) make a commitment
to fixing this at the soonest possible opportunity.“</font>
<br><font size=3 face="Arial"> </font><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
Pseudo RIDs JLP-PS-1 and JPL-PS-2 only require the WG’s concurrence for
their closer. However, JP-PS-3 requires some thought on how to clarify
the situation and how the WG will prioritize updating the MD and TD books.
<br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
I would like to request that we put pseudo-RID JPL-PS-3 on the agenda for
next Thursday’s telecon. I have included the relevant contents of the
emails between Peter and myself in the text of pseudo-RID JPL-PS-3. I would
encourage WG members to read through that pseudo RID before next week’s
telecon so as many as possible of us will have some understanding of the
situation.</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
Thanks.</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
Best regards,</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
John</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
EMAIL EXCHANGE BWTWEEN PETER SHAMES AND JOHN PIETRAS</font><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><b><br>
Original Comment from Peter: Section 1.9 (References): Regarding the sentence
“All other publications in the list are subject to revision, and users
of this document are encouraged to investigate the possibility of applying
the most recent editions of the publications (other than the Specification
Framework) indicated below.” RID author commented “Is it really
true that ALL of these other references are suspect? Even the most
recent of them?” </b><br>
Response (26 November 2019) This is a variation of the standard boilerplate
for all Blue Books, which is ”All publications are subject to revision,
and users of this document are encouraged to investigate the possibility
of applying the most recent editions of the publications indicated below”
(CCSDS A20.0-Y-4 Cor. 1, February 2015, 3.4.1.8 (a) (2)). Our CSTS modification
(which will apply to all CSTS specifications) calls out the fact that a
given issue of a CSTS spec is tied to a single issue of the Framework and
so no version of the Framework beyond the one explicitly cited can possibly
be applicable to a particular issue of the CSTS spec. <b><br>
Reply from Peter (4 December 2019) For sec 1.9 it was what I read
as a peculiar shift of language that bothered me. It is always that case
the specs are only aligned with those others that are current at the time
of publication. This is not any different for the Framework than for any
other doc. And it is entirely possible that a future change may be made
to the Framework without necessarily changing all of the other docs that
use it. I think what is different here is that this doc is explicitly tied
to the version of the Framework that contains the updates that are require
to support FF-CSTS. I think you can just state that somewhere in the doc.</b></font><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
Pietras esponse to reply (24 February 2020) In response to the statement
“I think what is different here is that this doc is explicitly tied to
the version of the Framework that contains the updates that are required
to support FF-CSTS.” That statement is not exactly true, because although
future versions of the Framework could theoretically also be used by “this”
version of the FF spec insofar as the functionality defined therein doesn’t
change for the procedures that are used by FF, there are version-specific
numbers that are embedded in the SFW ASN.1 modules that increment with
every version of the SFW and the FF procedures are tied to the specific
SFW version numbers. A CSTS will work with *<b>only</b>* the version of
the SFW that is specified in the Reference Documents section. And that’s
just not FF-CSTS: it’ll be true for every CSTS. Plans for the next revision
of the CSTS Guidelines are to include that re-wording of the boilerplate
for all CSTS specifications. <br>
So it’s not that this is a one-off situation for FF-CSTS, it’s something
that has to be addressed for all CSTS specifications. The WG chose to address
it right up front, and to explicitly clarify that the boilerplate statement
“</font><font size=3 face="Calibri">users of this document are encouraged
to investigate the possibility of applying the most recent editions of
the publications indicated below” </font><font size=3 face="Arial">does
not, and cannot, apply to the SFW. The feeling of the WG was that if this
was left “unchallenged” in the Reference Documents boilerplate the constraint
might still be overlooked even if it were stated somewhere else (later)
in the document.</font><font size=3 face="Calibri"> </font><font size=3 face="Courier New"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><b><br>
Reply from Peter (2 March 2020): What I am getting from this is that the
WG has adopted an SFW and associated standard versioning approach, if I
understand it correctly, such that each CSTS spec is tied to a specific
version of the SFW. What this says to me is that there is no stated
policy for backwards compatibility such that any future changes to the
SFW would continue to be compatible with earlier CSTS specs. If that
is truly the case, and I can understand situations where future changes
might break that "rule", the consequence would appear to be that
the CSS (and the users of these specs) will have to maintain ALL versions
of the SFW forever. This seems really cumbersome at best. Am I misunderstanding
this?</b></font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><br>
Pietras Response to Reply (3 March 2020): I think that you’ve got it right.
However, there are a couple of additional points that I should have made:
</font><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">1. Any new CSTS specification
will always be written citing the then-current version of the SFW. There
will be no option for, say, using the 2-issues-back version of the SFW
as the basis of a CSTS. </font>
<br><font size=3 face="Calibri">2. The WG’s intention
is to update all CSTS specifications to use the latest SFW ASAP (where
the “soon” part is a function of available resources and other commitments
by the WG). So older version of the SFW would be “active” only until
all CSTS specs are aligned with the “current” SFW, at which point all
the older books are truly “silverized”. Note that, like today, people
may still choose to implement a silver version of a specification anyway
(e.g., for backward compatibility with the user community) and this approach
doesn’t address this issue any better or worse than it’s addressed for
other CCSDS Silver books.</font>
<br><font size=3 face="Arial"> </font><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
Case in point – the forthcoming FF-CSTS book uses “features” of the
forthcoming SFW-B-2 (and indeed it was the need for these features that
triggered many/most of the changes in SFW-B-2). But SFW-B-2 also changes
(and simplifies) some of the data structures used not only by FF but also
the already-blue MD and the on-the-verge-of-blue TD services. MD and TD
can be changed from the B-1 to B-2 SFW data structures, and the WG intends
to create projects to do so, but that will take time/resources to modify
the respective “older” CSTS specs. The already-published MD book uses
the SFW-B-1 data structures so it must reference SFW-B-1 or the implementation
would be broken. In the case of the not-yet-published TD book (which also
uses the SFW-B-1 data structures, the WG decided to go ahead and publish
it with reference to SFW-B-1 in order to get it out the door, even though
we know that it will have to be changed in the (near) future (I think the
idea is to update the MD and TD books concurrently). <br>
</font><font size=3 face="Calibri"> </font>
<br><font size=3 face="Calibri">1. This may now seem
like an administrative headache, but hopefully the changes to core elements
of the SFW will settle down in the near future, and new versions of the
SFW will only add new features, procedures, and/or operations that don’t
affect existing CSTSes. In that (rosy) scenario, “updating” a CSTS spec
to a new SFW will only involve a short Technical Corrigendum that points
to the latest SFW issue and relevant paragraphs within that SFW issue.
</font>
<br><font size=3 face="Arial"> </font><font size=3 face="Calibri">
</font><font size=3 face="Arial"><br>
Maybe one way to think about this is that, unlike the other references
that CCSDS “encourages [users] to investigate the possibility of applying
the most recent editions”, the CSTSWG *<b>knows</b>* what SFW version
will work with the service as specified in the specification and essentially
tells users up front not to waste their time thinking about it with respect
to the SFW.</font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><b><br>
</b></font><font size=3 face="Calibri"> </font><font size=3 face="Arial"><b><br>
Peter’s Response (3 March): I am willing to close out the comment, but
only if the CSS CSTS WG makes a commitment to a) making sure that this
situation is made blazingly clear, and b) make a commitment to fixing this
at the soonest possible opportunity.</b></font><font size=3 face="Courier New">_______________________________________________<br>
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