Re: [Technical Errata Reported] RFC7232 (5236)

["Roy T. Fielding" <[e-mail]>]

> On Jan 16, 2018, at 7:51 AM, RFC Errata System <[e-mail]> wrote:
> 
> The following errata report has been submitted for RFC7232,
> "Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests".
> 
> --------------------------------------
> You may review the report below and at:
> http://www.rfc-editor.org/errata/eid5236
> 
> --------------------------------------
> Type: Technical
> Reported by: Chris Pacejo <[e-mail]>
> 
> Section: 2.1
> 
> Original Text
> -------------
> Likewise, a validator is weak if it is shared by two or more
> representations of a given resource at the same time, unless those
> representations have identical representation data.  For example, if
> the origin server sends the same validator for a representation with
> a gzip content coding applied as it does for a representation with no
> content coding, then that validator is weak.  However, two
> simultaneous representations might share the same strong validator if
> they differ only in the representation metadata, such as when two
> different media types are available for the same representation data.
> 
> Corrected Text
> --------------
> Likewise, a validator is weak if it is shared by two or more
> representations of a given resource at the same time, even if those
> representations have identical representation data.  For example, if
> the origin server sends the same validator for a representation with
> a gzip content coding applied as it does for a representation with no
> content coding, then that validator is weak.
> 
> Notes
> -----
> This paragraph (and only this paragraph) seems to be in direct conflict with this earlier text from the same section:
> 
> "However, if a resource has distinct representations that differ only in their metadata, such as might occur with content negotiation over media types that happen to share the same data format, then the origin server needs to incorporate additional information in the [strong] validator to distinguish those representations."

This (in Notes) is referring to cases such as text/plain and application/json being two different
media types for what could be the exact same octets. Since a strong validator only
refers to the body data, a server would need to add more info to the validator
to cause clients to distinguish between those two representations.

The Original Text is about weak validators, which don't even require that
the content be the same. The two do not conflict.  The suggested change would be incorrect.

....Roy

> 
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> 
> --------------------------------------
> RFC7232 (draft-ietf-httpbis-p4-conditional-26)
> --------------------------------------
> Title               : Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests
> Publication Date    : June 2014
> Author(s)           : R. Fielding, Ed., J. Reschke, Ed.
> Category            : PROPOSED STANDARD
> Source              : Hypertext Transfer Protocol Bis APP
> Area                : Applications
> Stream              : IETF
> Verifying Party     : IESG