[DFDL-WG] bit order documents updated

[Steve Hanson]

I am very concerned that we do not understand these formats properly. We 
need to engage an SME to verify that these proposals are enough to model 
MIL-STD-2045 and Link-16 (and other related formats). Until that happens 
IBM will not be able to close action 233.

Regards
 
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848



From:   Mike Beckerle <mbeckerle.dfdl at gmail.com>
To:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>, 
Date:   24/07/2014 23:08
Subject:        Re: [DFDL-WG] bit order documents updated
Sent by:        dfdl-wg-bounces at ogf.org



Of course as soon as I post this I get the information needed to resolve 
several things. 

The new byte-order enum is not needed, so I removed that material. The bit 
order document is now a fairly clean thing trying to be an errata.

Please review: draft-gwdi-bit-order-features-v3.0.docx

I created a separate working document on "Mixed Endian Byte Order" should 
we ever take this up again.

I also removed the TDML stuff into the TDML document. (now v2). 


Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | 
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are 
subject to the OGF Intellectual Property Policy



On Thu, Jul 24, 2014 at 5:16 PM, Mike Beckerle <mbeckerle.dfdl at gmail.com> 
wrote:

There are now several working documents having to do with bit-order. The 
prior document has been taken down and replaced by 3 others.

These are all up on redmine: 
http://redmine.ogf.org/dmsf/dfdl-wg?folder_id=5485

1) draft-gwdi-bit-order-features-v2.05.docx - Just describes the new 
features + TDML extension. The biggest section is organized like an errata 
specifying where things change in the spec. This should get incorporated 
into errata, or perhaps just referenced from an errata. 

Section 3 of this doc is the proposed errata and spec language for review.

There is one major open issue here, which is it is unclear whether the 
mixed-endian byte order that was previously proposed is actually needed or 
not. The swapping of 16-bit words appears to be not a per-element thing, 
but something done as a pre-processing of an entire message body before 
parsing. This isn't something we can handle in DFDL, much like 
base64-encoded data and so forth. This may be the only place that needed 
the 16-bit word swapping. 

2) Understanding Bit Orderings - 
draft-gwdi-mil-std-2045-understanding-bit-order-v2.05.docx - Material 
about bit order - the Wire model vs. Number model material. This is 
effectively just archiving this material for posterity.

If you already read this, you don't need to read it again.

3) draft-gwdi-mil-std-2045-additional-features-v2.05.docx - Material about 
additional DFDL features that would be helpful in modeling MIL-STD-2045.

This can also be reviewed. Not as urgent as (1) above.

4) draft-gwdi-dfdl-standard-encodings-v03.docx - This is material that 
will be integrated back into the spec as an appendix, but this 
incorporates feedback on prior versions, and adds a 6-bit ascii encoding 
that is used by the same binary format standards as the 7-bit one. Works 
same way, just 6 bits not 7, so there's some codepoint changes.

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | 
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are 
subject to the OGF Intellectual Property Policy

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