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Re: Rev03 changes to 19.2, multipart/byteranges

From: Dave Kristol <dmk@bell-labs.com>
Date: Mon, 27 Jul 1998 10:06:39 -0400
Message-Id: <35BC896F.794E@bell-labs.com>
To: HTTP Working Group <http-wg@cuckoo.hpl.hp.com>
Cc: jg@w3.org
Last week I wrote:
> 
> I propose here corrective wording for open issue RANGEDELIM (described
> in <http://www.ics.uci.edu/pub/ietf/http/hypermail/1998q2/0141.html>).
> [...]
> Now, HTTP introduces an interesting ambiguity, because the first line
> of an entity body could well be considered the beginning of a line, and
> it follows a CRLF.  However, since we must ignore the CRLF that
> separates the headers from the body, the body does not really begin
> with a CRLF.  So by my reading of RFC 2046, an HTTP multipart entity
> would have to include an extra CRLF preceding the boundary.  I have
> amended Section 19.2 of the HTTP spec. accordingly, along with the
> example.

After discussions over the weekend, especially exchanges with Ned Freed,
co-author of RFC 2046, I am amending my proposed changes.  In
particular, most of them go away.  It turns out that a careful reading
of RFC 2046 shows that an extra leading CRLF is unnecessary, and that
the HTTP example was correct.  (Details:  the multipart-body grammar
begins "[preamble CRLF]", which makes the cruft that often precedes
multipart bodies, plus the CRLF that ends it, optional.)

Thus the only changes that remain are to reference RFC 2046, to caution
about quoted boundary strings, and to add 2046 to the reference section.

Dave Kristol
===================

   19.2 Internet Media Type multipart/byteranges
 
   When an HTTP 206 (Partial Content) response message includes the
   content of multiple ranges (a response to a request for multiple
   non-overlapping ranges), these are transmitted as a multipart
   message-body (RFC 2046). The media type for this purpose is called
   "multipart/byteranges".
 
[Following the example:]
Caution:  Although RFC 2046 permits the boundary string to be quoted,
some existing implementations handle a quoted boundary string
incorrectly.
 
   19.2.1 Multipart/x-byteranges
   ...
 
 Note to Jim Gettys:  need to add reference to RFC 2046:
     Freed, N., and N. Borenstein. "Multipurpose Internet Mail
     Extensions (MIME) Part Two: Format of Internet Message Bodies." RFC
     2046, Innosoft, First Virtual, November 1996.
Received on Monday, 27 July 1998 07:10:24 EDT

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