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Suggestion for NEW Issue: Pipelining problems

From: Yngve N. Pettersen (Developer Opera Software ASA) <yngve@opera.com>
Date: Tue, 17 Jul 2007 13:04:14 +0200
To: ietf-http-wg@w3.org
Message-ID: <op.tvlvpcvhqrq7tp@nimisha.oslo.opera.com>

Hello all,

I thought I should mention this particular issue I am seeing.

There are a number of servers that does not handle pipelining at all well.

Problems that have been observed:

   - Handle the first m of n requests in order, then skip to request n  
(IIRC I saw this on IIS/5)
   - Handle the first request in a packet, ignore the rest, then process  
the first in the next, and so on. I have seen this problem in WebSeal 5  
(IBM) where it was fixed, and then recently broke in WebSeal 6, and is  
apparently fixed again recently. The problem is particularly visible for  
HTTPS in Opera 9, but is not limited to HTTPS.
   - Handle one or more requests, then stall
   - Handle a request, then stall when the next arrives.
   - Not quite pipelining: Server sending Content-Length of original  
content, then apply Content-Encoding without removing or updating the  
Content-Length header. I have seen this happen with PHP using global  
compression when the script sets the Content-Length header.

Opera has had to implement quite a lot of heuristics, as well as having  
blacklisted a number of servers, in order to handle or recover (partially)  
 from such problems.

Yngve N. Pettersen
Senior Developer                     Email: yngve@opera.com
Opera Software ASA                   http://www.opera.com/
Phone:  +47 24 16 42 60              Fax:    +47 24 16 40 01
Received on Tuesday, 17 July 2007 11:04:50 UTC

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