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Re: HTTP/1.1 : Chunking

From: Adrien de Croy <adrien@qbik.com>
Date: Fri, 30 Jan 1998 10:09:19 +1200
Message-Id: <>
To: Ben Laurie <ben@algroup.co.uk>
Cc: http-wg@cuckoo.hpl.hp.com
X-Mailing-List: <http-wg@cuckoo.hpl.hp.com> archive/latest/5313

At 18:21 29/01/98 +0000, Ben Laurie wrote:
>Adrien de Croy wrote:
>> A proposal for the end tag could be say a 4 byte magic number. So there
>> would be a 1 in 4 billion chance of there being a natural conflict caused by
>> a premature close on the connection with the last 4 bytes of the last packet
>> being the magic number.  If this were thought too risky, simply increasing
>> the length would serve to render this event less likely.
>That's a pretty dodgy bit of maths. What you mean is that for any
>particular 4-byte sequence there's a 1 in 4 billion chance, so in 1 MB
>of data, the probability is (roughly) 1 in 4000. Or, over a 64 kb/s link
>at full capacity, about one mistake a week.

I would have thought that in a random data stream, the chances of any
particular 4 byte sequence would have been 1 in 4 Billion, but we are only
looking at the last 4 bytes before a close.  So, given there is only one
close per session, there is only one inspected 4 byte sequence, hence the
chance of any one file causing confusion over an OEF marker is 1 in 4 billion.

However, as pointed out by John Franks, this method would not, and cannot
allow for multiple transactions per connection, since it relies on the close
event being a signal as well.

However, reflecting more on that issue, the chances of a client requiring
multiple created entitities (i.e those where the server cannot know a priori
the size) in a single connection is rather low, at least at the moment.
Multiple normal requests per connection would still be possible, and
unaffected by this proposal.  

>Ben Laurie            |Phone: +44 (181) 735 0686|Apache Group member
>Freelance Consultant  |Fax:   +44 (181) 735 0689|http://www.apache.org
>and Technical Director|Email: ben@algroup.co.uk |Apache-SSL author
>A.L. Digital Ltd,     |http://www.algroup.co.uk/Apache-SSL
>London, England.      |"Apache: TDG" http://www.ora.com/catalog/apache
Adrien de Croy - adrien@qbik.com.  Qbik New Zealand Limited, Auckland, New
                 See our pages and learn about WinGate at http://www.qbik.com/
Received on Thursday, 29 January 1998 13:18:27 UTC

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