Re: p2: Expect: 100-continue and "final" status codes
Amos Jeffries <squid3@treenet.co.nz> Wed, 24 April 2013 06:12 UTC
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Date: Wed, 24 Apr 2013 18:10:23 +1200
From: Amos Jeffries <squid3@treenet.co.nz>
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Subject: Re: p2: Expect: 100-continue and "final" status codes
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On 24/04/2013 4:39 p.m., Adrien W. de Croy wrote: > > > ------ Original Message ------ > From: "Mark Nottingham" <mnot@mnot.net> >> >> On 24/04/2013, at 12:41 PM, Amos Jeffries <squid3@treenet.co.nz> wrote: >>>>> >>>>> I think we can give better advice than that. If a server responds >>>>> with a final status code instead of 100 (Continue) >>>>> >>>>> 1. The response must be the last response on the connection. The >>>>> response should contain "Connection: close" header. After the >>>>> response is written, the server must initiate a lingering close of >>>>> the connection (p1#6.6). >>>> That seems too restrictive; as long as the server reads the rest >>>> of the request properly (discarding it), it should be able to >>>> recover and reuse the connection. >>> >>> The problem comes with intermediaries. How are they to know the >>> bytes following were the original advertised payload or not? the >>> status from server has no guarantee of arriving after the client >>> payload starts arriving. >>> The only way to guarantee safety on the connection is to close it >>> or always send payload. > > > I'm really struggling to see what benefit can be derived by a client > in knowing whether a server supports 100 continue or not. So to me > Expects: 100-continue is a complete waste of space. I've never seen > one so I guess implementors by and large agree. I guess you have never tried uploading a video to the YouTube through an old intermediary which requires authentication. At best (Basic) it doubles the upload time and can cause the whole transaction to abort with a timeout. At worst (NTLM) it can do the same while consuming up to 3x the total size of the uncompressed video in bandwidth. This exact use-case is why we pushed HTTP/1.1 experiments into Squid-2.7. > > Regardless of 100 continue being transmitted, the client has to send > the payload if it wants to reuse the connection. The only early-out > options involve closing the connection. Regarding pipelining sure. The benefits come from avoiding the above mentioned resource waste and timeouts. Adding a whole TCP setup overhead and RTT (few hundred ms) is far faster and cheaper that transferring >10 MB of data multiple times (from whole seconds to whole minutes). > > There was quite a lot of discussion about this in the past, and my > understanding was that 100 continue couldn't be used to negotiate > whether or not the payload would be sent. The outcome of this > discussion was not satisfactory IMO, since the "answer" was for the > client to send request bodies always chunked, and send a 0 chunk if it > needed to abort early. Agred. I too am unhappy with that. It does work however. Amos
- p2: Expect: 100-continue and "final" status codes Mark Nottingham
- Re: p2: Expect: 100-continue and "final" status c… Zhong Yu
- Re: p2: Expect: 100-continue and "final" status c… Ken Murchison
- Re: p2: Expect: 100-continue and "final" status c… James M Snell
- Re: p2: Expect: 100-continue and "final" status c… Mark Nottingham
- Re: p2: Expect: 100-continue and "final" status c… Amos Jeffries
- Re: p2: Expect: 100-continue and "final" status c… Mark Nottingham
- Re: p2: Expect: 100-continue and "final" status c… Adrien W. de Croy
- Re: p2: Expect: 100-continue and "final" status c… Amos Jeffries
- Re: p2: Expect: 100-continue and "final" status c… Willy Tarreau
- Re: p2: Expect: 100-continue and "final" status c… Willy Tarreau
- Re: p2: Expect: 100-continue and "final" status c… Adrien W. de Croy
- Re: p2: Expect: 100-continue and "final" status c… Adrien W. de Croy
- Re: p2: Expect: 100-continue and "final" status c… Amos Jeffries
- Re: p2: Expect: 100-continue and "final" status c… Zhong Yu
- Re: p2: Expect: 100-continue and "final" status c… Ken Murchison
- Re: p2: Expect: 100-continue and "final" status c… Willy Tarreau
- Re: p2: Expect: 100-continue and "final" status c… Ken Murchison
- Re: p2: Expect: 100-continue and "final" status c… Willy Tarreau
- Re: p2: Expect: 100-continue and "final" status c… Daniel Stenberg
- Re: p2: Expect: 100-continue and "final" status c… Ken Murchison
- #467: Expect: 100-continue and "final" status cod… Mark Nottingham
- Re: #467: Expect: 100-continue and "final" status… Mark Nottingham
- Re: #467: Expect: 100-continue and "final" status… Willy Tarreau
- Re: #467: Expect: 100-continue and "final" status… Ken Murchison
- Re: #467: Expect: 100-continue and "final" status… Zhong Yu
- Re: #467: Expect: 100-continue and "final" status… Alex Rousskov
- Re: #467: Expect: 100-continue and "final" status… Mark Nottingham
- Re: #467: Expect: 100-continue and "final" status… Mark Nottingham
- Re: #467: Expect: 100-continue and "final" status… Willy Tarreau
- Re: #467: Expect: 100-continue and "final" status… Zhong Yu
- Re: #467: Expect: 100-continue and "final" status… Michael Sweet
- Re: Expect: 100-continue and "final" status codes Peter Occil
- Re: #467: Expect: 100-continue and "final" status… Willy Tarreau
- Re: #467: Expect: 100-continue and "final" status… Mark Nottingham