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Re: The use of binary data in any part of HTTP 2.0 is not good

From: Adrien W. de Croy <adrien@qbik.com>
Date: Mon, 21 Jan 2013 00:05:28 +0000
To: William Chan (陈智昌) <willchan@chromium.org>, "Mark Nottingham" <mnot@mnot.net>
Cc: Pablo <paa.listas@gmail.com>, "HTTP Working Group" <ietf-http-wg@w3.org>
Message-Id: <em21210af6-9780-4ccc-985d-babf647b9a51@bombed>


------ Original Message ------
From: "William Chan (陈智昌)" <willchan@chromium.org>
>Maybe it falls upon me to be the voice of concern here :) Depending on
>what a "debug" option entails, I'm worried about it being used to
>disable a performance feature. As an example of how options can be
>dangerous, we've seen intermediaries that strip out Accept-Encoding
>headers in order to force responses to be uncompressed (probably so
>they can inspect the payloads more easily/cheaply), which is an issue
>from a web performance perspective.
guilty as charged.  we don't do that any more.

>Back to the use case, if you're in a position to use the debug option,
>is it likely that you would not also be in a position to capture
>enough to decode? I'd like to understand the use case so I can
>properly weigh the benefit of such an option, in contrast to the cost
>that I highlighted above.

often one is dealing with a customer who you can reasonably expect to be 
capable enough to click a checkbox and send you a file, but maybe not to 
install a packet capturing utility, set up filters etc etc.  Maybe even 
not permitted to install e.g. wireshark.

I agree in most cases, ability to select debug and try a problem case 
would come along with an ability to capture enough packets.

So I guess it's a small use-case in that instance.

I can imagine other areas where reducing all messages to a single frame 
could be useful, like debugging issues with load balancers or http 
routers which may be switching frames incorrectly.

In short, we can't know all the issues we may come up against.


>On Sun, Jan 20, 2013 at 3:48 PM, Mark Nottingham <mnot@mnot.net> wrote:
>>  On 21/01/2013, at 10:38 AM, "Adrien W. de Croy" <adrien@qbik.com> 
>>>  the thing that will make debugging harder won't be binary vs text, 
>>>but the inter-dependence of messages. Especially when it comes to 
>>>looking through debug logs for issues.
>>>  On-the-wire, you already need to piece together a TCP stream to see 
>>>what's going on, so having http messages effectively split over 
>>>multiple frames (e.g. delta encoding, or compression) only becomes a 
>>>problem when you don't capture enough to decode.
>>>  I think it might be worth-while specifying a requirement for a 
>>>"debug" option for senders of binary messages which turns off all 
>>>other optimisations, such as caching unchanged headers etc (so they 
>>>are sent every time). Just an idea.
>>  That's been brought up a few times, and the reaction has been pretty 
>>  Cheers,
>>  --
>>  Mark Nottingham http://www.mnot.net/
Received on Monday, 21 January 2013 00:06:21 UTC

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