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Ticket #73 (closed design: fixed)

Opened 7 years ago

Last modified 4 years ago

Clarification of the term "deflate"

Reported by: mnot@pobox.com Owned by: julian.reschke@gmx.de
Priority: normal Milestone: 10
Component: p1-messaging Severity: Active WG Document
Keywords: Cc:
Origin: http://www.w3.org/mid/010701c7d8f5$c8f9cdf0$3a3c140a@myopwv.com

Description

Below is the definition of "deflate" from RFC 2616, section 3.5 "Content Codings"

  deflate
The "zlib" format defined in RFC 1950 [31] in combination with
the "deflate" compression mechanism described in RFC 1951 [29].

There is ambiguity in that definition because of the inconsistent use of the term "deflate". This has resulted in a long standing confusion about how to implement "deflate" encoding.

There was a time a few years back when most of the high profile browser and some http server implementations incorrectly implemented http "deflate" encoding using RFC 1951 without the RFC 1950 wrapper. Admittedly most, if not all, of the incorrect implementations have now been fixed, but the fix applied recognises the reality that there are incorrect implementations of "deflate" out in the wild. All browsers now seem to be able to cope with "deflate" in both its RFC1950 or RFC1951 incarnations.

So I suggest there are two issues that need to be addressed

  1. The definition of "deflate" needs to be rewritten to remove the ambiguity.
  1. Document the reality that there are incorrect implementations, and recommend that anyone writing a "deflate" decoder should cope with both forms.

Change History

comment:1 Changed 7 years ago by mnot@pobox.com

  • Component set to non-specific
  • Milestone set to unassigned

comment:2 Changed 6 years ago by julian.reschke@gmx.de

  • Component changed from non-specific to p3-payload

comment:3 Changed 5 years ago by mnot@pobox.com

  • Owner set to henrik@henriknordstrom.net
  • Priority set to normal
  • Severity set to Active WG Document

Proposal:

Note that some incorrect implementations may send deflate encoding without a zlib wrapper when using this encoding.

comment:4 Changed 5 years ago by julian.reschke@gmx.de

  • Owner changed from henrik@henriknordstrom.net to julian.reschke@gmx.de
  • Status changed from new to assigned
  • Component changed from p3-payload to p1-messaging

comment:5 Changed 5 years ago by julian.reschke@gmx.de

From [801]:

Clarify "deflate", add note about broken implementations (addresses #73)

comment:6 Changed 5 years ago by mnot@pobox.com

  • Milestone changed from unassigned to 10

comment:7 Changed 5 years ago by julian.reschke@gmx.de

This is believed to be fixed with [801], pending review.

comment:8 Changed 5 years ago by julian.reschke@gmx.de

From [805]:

"deflate": make the IANA entry more consistent with the actual description (related to #73)

comment:9 Changed 5 years ago by julian.reschke@gmx.de

From [806]:

"deflate": make the IANA entry more consistent with the actual description (related to #73)

comment:10 Changed 4 years ago by julian.reschke@gmx.de

  • Status changed from assigned to closed
  • Resolution set to incorporated

comment:11 Changed 4 years ago by mnot@pobox.com

  • Status changed from closed to reopened
  • Resolution incorporated deleted

comment:12 Changed 4 years ago by mnot@pobox.com

  • Status changed from reopened to closed
  • Resolution set to fixed
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