[Css-csts] A recommendation re ROCF (and similar spec) updates

Wed May 13 17:32:48 UTC 2015

Hi Erik,

I am passing this along to put into your CSS "standards revision" queue.  I just had a very lengthy exchange with Mike Anderson, all of which was started by him asking the relatively simple question:

Can you point me to a high level description of an OCF.  The ROCF Blue book does not include a definition.  I am trying to figure out what information is included in an OCF.  Is it a fixed set of data or is it completely user defined or some combination?

Mike was trying to understand the ROCF and why it was important.  I was trying to help.  I dug around and provided him with the references to TC, TM, AOS, and the COP.  He complained that the ROCF spec should have told him how the OCF was defined and how it was used (and why ROCF was important).   We argued back and forth for quite a while about how CCSDS (and other) specs are written and why they are constructed in this way.  This is a part of the "Mike and Peter dialogue process" and feel free to ignore it.

However, at the end, and after looking at the ROCF again in detail, I had to admit that another paragraph or two, early in that document, could have avoided all of this discussion.  The ROCF devotes page after page to definitions of the service itself, to the SLE reference model, service management, return frame and OCF production and provisioning, scheduling, underlying services, buffering, security aspects, etc, etc.  These introductory materials are the first 47 pages of the spec.

Nowhere does it say anything as simple as:

"TC defines and uses the CLCW, which is carried in the TM (or AOS) OCF field for use in COP re-transmission operations.  The ROCF service is used to provide this CLCW to the user so that these re-transmission operations may be implemented in the user MOC.".

My suggestion is that the next time that this spec, and the rest of these similar specs, are reviewed for update that another paragraph be added somewhere early in the doc, maybe even in the "Purpose of this recommended standard" section, or in the Overview Section, that provides just exactly this sort of description of the "what" and the "why" and the "how" and the "what for" of the standard.

Does this make sense to you?

Thanks, Peter

From: <Shames>, Peter Shames <peter.m.shames at jpl.nasa.gov<mailto:peter.m.shames at jpl.nasa.gov>>
Date: Wednesday, May 13, 2015 at 9:51 AM
To: Mike Anderson <Anderson_Michael at bah.com<mailto:Anderson_Michael at bah.com>>
Subject: Re: [External] Re: OCF

Hi Mike,

After going back and looking at the SLE R-OCF I find that it does, in fact, include all of the references to TM, AOS, OCF, and CLCW.  What it does not include, however, is some sort of simple statement like "TC defines and uses the CLCW, which is carried in the TM (or AOS) OCF for use in COP re-transmission operations".

So I agree that the spec could carry another paragraph or so that would more clearly state what R-OCF and OCF itself is, why it is important, and how it relates to the other protocols and real world uses that missions might make.  I'll pass that along to the team that is responsible for it.

Ok?

There is always room for improvement.  That said, anyone who is going to work in any of these technical protocol fields is going to have to steep themselves in the literature.  This is the same in most technical and scientific fields and that has been a fact of life for centuries.  A Popular Mechanics view of the world only gets you just so far, after that the hard work begins.

Peter

From: <Anderson>, Mike Anderson <Anderson_Michael at bah.com<mailto:Anderson_Michael at bah.com>>
Date: Wednesday, May 13, 2015 at 8:46 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov<mailto:peter.m.shames at jpl.nasa.gov>>
Subject: RE: [External] Re: OCF

You should be able to read the ROCF Blue Book and have an understanding of what an OCF is and what it is used for.  Yes, you need the references for the details but a high level description is useful and it is not onerous.

I have been doing this stuff for 40 years and the CCSDS documents are among the most difficult to follow.  I must assume they are written and edited by people with intimate knowledge of the subject.  That is not a bad thing but they do not seem to consider that every reader will not have that same knowledge.  There is room for improvement.  A few introductory paragraphs for the novices would go a long way.

[Booz Allen Hamilton]

Michael Anderson
Lead Technologist
443-956-0979
www.boozallen.com<http://www.boozallen.com/>

From: Shames, Peter M (312B) [mailto:peter.m.shames at jpl.nasa.gov]
Sent: Wednesday, May 13, 2015 11:25 AM
To: Anderson, Michael [USA]
Subject: Re: [External] Re: OCF

Yup.  Me and the 1000's of people who actually work in the IETF, ISO, and CCSDS standards organizations, to name just a few.

I'm not trying to be difficult Mike, but just imagine if every spec had to contain all of the relevant info for all of the other specs it referenced.  Not only would it create a huge issue editing all of the related and intertwined specs when any one thing would change, it would also increase the size of each spec by the volume of the included references.

Most of the scientific and technical literature operates in exactly this same way, by reference and not by inclusion.  Just look at the list of references on any scientific or technical paper.

The document I just finished editing, the SCCS-ARD (CCSDS 901x1m0), took the approach of "let's include info on all the stuff that is referenced" (see attached).  Not only was it a huge job to create, but it is pretty big, over 150 pages.  But it's all in there, or at least enough to tell people how all these parts fit together and what they do.   It does cover OCF, ROCF, and CLCW, where they are defined and how they are to be used.

-p

From: <Anderson>, Mike Anderson <Anderson_Michael at bah.com<mailto:Anderson_Michael at bah.com>>
Date: Wednesday, May 13, 2015 at 6:08 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov<mailto:peter.m.shames at jpl.nasa.gov>>
Subject: RE: [External] Re: OCF

“Everything should be made as simple as possible, but not simpler.”  CCSDS documentation is much more complicated than it needs to be.  You shouldn’t have to go to three different documents to understand what ROCF is meant to do.  The ROCF Blue Book should describe the OCF and its intended use.  The RAF and other service interface documents should do the same.

[Booz Allen Hamilton]

Michael Anderson
Lead Technologist
443-956-0979
www.boozallen.com<http://www.boozallen.com/>

From: Shames, Peter M (312B) [mailto:peter.m.shames at jpl.nasa.gov]
Sent: Tuesday, May 12, 2015 11:23 PM
To: Anderson, Michael [USA]
Subject: Re: [External] Re: OCF

ROCF is just a service interface to deliver the data, it really doesn't care, nor does it need to, about what is inside.  Ditto RAF & most service interfaces.  Just like HTTP doesn't care what web sites you look at.

All the Internet standards are exactly the same in format & content.  They do not repeat anything defined elsewhere.

Cheers, Peter

Sent from Peter's iPhone 6

Everything should be made as simple as possible,
but not simpler.

~Albert Einstein

On May 12, 2015, at 5:29 PM, Anderson, Michael [USA] <Anderson_Michael at bah.com<mailto:Anderson_Michael at bah.com>> wrote:

Thanks, I found it eventually.  It still boggles the mind that the OCF description wouldn’t be in the ROCF blue book.  Too many back and forth between CCSDS documentation.

<image001.png>

Michael Anderson
Lead Technologist
443-956-0979
www.boozallen.com<http://www.boozallen.com/>

From: Shames, Peter M (312B) [mailto:peter.m.shames at jpl.nasa.gov]
Sent: Tuesday, May 12, 2015 4:41 PM
To: Anderson, Michael [USA]
Subject: Re: [External] Re: OCF

Hi Mike,

To quote the email I sent you …

The actual CLCW data structure is defined in the TC protocol (CCSDS 232x0b2), since it is the TC protocol that operates the COP which uses the CLCW.  Look at Sec 4.2 of 232x0b2 (attached) for the definition of the CLCW.

…

So the short version of this is that the TC defines and uses the CLCW, which is carried in the TM (or AOS) OCF for use in COP re-transmission operations.

And yeah, it can be a bit dense, that's why I dug out the actual definition for you.

Peter

From: <Anderson>, Mike Anderson <Anderson_Michael at bah.com<mailto:Anderson_Michael at bah.com>>
Date: Tuesday, May 12, 2015 at 11:36 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov<mailto:peter.m.shames at jpl.nasa.gov>>
Subject: RE: [External] Re: OCF

Thanks.  I bounced from reference to reference.  I found high level descriptions but was realy hoping to find something that actually showed the content.  Bit 1 means this, bit means that, etc.  I actually did find the definition for bit 1 but the rest was pretty ambiguous.  CCSDS speak is very difficult to master, to many references to other documents rather than spelling things out.

[Booz Allen Hamilton]

Michael Anderson
Lead Technologist
443-956-0979
www.boozallen.com<http://www.boozallen.com/>

From: Shames, Peter M (312B) [mailto:peter.m.shames at jpl.nasa.gov]
Sent: Tuesday, May 12, 2015 2:26 PM
To: Anderson, Michael [USA]
Subject: [External] Re: OCF

Hi Mike,

The OCF carries the Command Link Control Word.  The OCF is a field in the TM and AOS telemetry protocols that carries the CLCW.  The OCF_SDU is defined in CCSDS 132x0b1 (attached) in Sec 4.1.5 where it refers to Type-1-Report.  The Type-1-Report cross references CCSDS 232x0b2 for the CLCW definition.  The actual CLCW data structure is defined in the TC protocol (CCSDS 232x0b2), since it is the TC protocol that operates the COP which uses the CLCW.  Look at Sec 4.2 of 232x0b2 (attached) for the definition of the CLCW.

So the short version of this is that the TC defines and uses the CLCW, which is carried in the TM (or AOS) OCF for use in COP re-transmission operations.

You can also look at the COP (CCSDS 232x1b2) for more info on how the CLCW is used in the COP.

Peter

From: <Anderson>, Mike Anderson <Anderson_Michael at bah.com<mailto:Anderson_Michael at bah.com>>
Date: Tuesday, May 12, 2015 at 10:45 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov<mailto:peter.m.shames at jpl.nasa.gov>>
Subject: OCF

Peter,

Can you point me to a high level description of an OCF.  The ROCF Blue book does not include a definition.  I am trying to figure out what information is included in an OCF.  Is it a fixed set of data or is it completely user defined or some combination?

Mike

<image003.png>

Michael Anderson
Lead Technologist
443-956-0979
www.boozallen.com<http://www.boozallen.com/>

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