Last Call Review of draft-kucherawy-dispatch-zstd-01
review-kucherawy-dispatch-zstd-01-opsdir-lc-hares-2018-04-26-00

Request Review of draft-kucherawy-dispatch-zstd
Requested rev. no specific revision (document currently at 03)
Type Last Call Review
Team Ops Directorate (opsdir)
Deadline 2018-04-23
Requested 2018-03-26
Other Reviews Secdir Last Call review of -01 by Scott Kelly (diff)
Genart Last Call review of -01 by Vijay Gurbani (diff)
Review State Completed
Reviewer Susan Hares
Review review-kucherawy-dispatch-zstd-01-opsdir-lc-hares-2018-04-26
Posted at https://mailarchive.ietf.org/arch/msg/ops-dir/rzr2HHrckBX_kVvGAHTRTtnCYM8
Reviewed rev. 01 (document currently at 03)
Review result Has Issues
Draft last updated 2018-04-26
Review completed: 2018-04-26

Review
review-kucherawy-dispatch-zstd-01-opsdir-lc-hares-2018-04-26

Status: ready with issues 
Overal-comment: This specification has carefully defined all the Careful specification the bits and bytes of the compression /decompression.  However, it unclear how common error codes are shared between implementations.

Error code issues:  Compression/Decompression is normally a specific library function.  As a library function, it is often tested with reference test suites against a referece implementation.  What I do not undersatnd form this specification is how errors get passed to the calling program. 

A face book implementation of this zstd return errors codes:
(https://facebook.github.io/zstd/zstd_manual.html) 
#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1)
#define ZSTD_CONTENTSIZE_ERROR   (0ULL - 2)

Should this type of operational information be included in the compression specification?  It seems like common error codes would help the interoperability of different implementations  so that compression by one implementation would correctly be decompressed by a second. 

Authors: What you need to do to clear my issue question: 
Please talk to your AD and experts to determine the need for the error codes or the specific codes.  I'm only qualified to suggest this area of inquiry might be fruitful.   After you consider this concept with your AD, you can send a message to the OPS-DIR list to indicate the resolution of my question.  

reviewer caveat: I am not a expert on compression in media types.  If the OPS-NM area ADs, feel this should be reviewed again with compression/decompression expert for media data to determine what error codes are needed, they should probably select someone who has worked with these libraries.