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Re: comments on draft-mbelshe-httpbis-spdy-00

From: Eliot Lear <lear@cisco.com>
Date: Wed, 15 Aug 2012 20:41:36 +0200
Message-ID: <502BED60.9020807@cisco.com>
To: "William Chan (陈智昌)" <willchan@chromium.org>
CC: Patrick McManus <pmcmanus@mozilla.com>, Phillip Hallam-Baker <hallam@gmail.com>, "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>
Patrick's idea is the happy eyeballs approach (see related work on IPv6
by Dan Wing et al).  You're right, tho, that you probably can't do it in
a single packet, but multiple rapid fired.  That solves the issue you
raise below.


On 8/15/12 8:23 PM, William Chan (陈智昌) wrote:
> I'm confused by this comment. My understanding is that multiple
> questions per query does not work in practice. Also, how does the
> response work? If the A record is cached, but the SRV record is
> uncached, does the server not respond to the client until the SRV
> record comes back? Or does it stream the records back somehow and have
> the client block on responses?
> Patrick's explanation makes more sense to me.
> On Wed, Aug 15, 2012 at 10:40 AM, Eliot Lear <lear@cisco.com
> <mailto:lear@cisco.com>> wrote:
>     On 8/15/12 7:19 PM, William Chan (陈智昌) wrote:
>>     Can you elaborate how SRV would work here from a client
>>     perspective? Do you propose making the client block on the SRV
>>     lookup? Or are you proposing doing this out of band and switching
>>     to HTTP/2.0 if we discover support?
>     Block is the wrong word.  You're already doing A-Record queries. 
>     Adding another record in the question only adds latency if you
>     must serially query.  Also, I myself am not convinced that SRV
>     records are sufficient to the task.  For instance, what happens if
>     there is a port # in the URL?  How do you identify the version #? 
>     Paul Hoffman did some work on a draft that sort-of looked at this
>     problem.  I'm going to guess that he stopped short because of
>     potential downgrade attacks.
>     Eliot
Received on Wednesday, 15 August 2012 18:42:05 UTC

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