Re: [hybi] Last Call: <draft-ietf-hybi-thewebsocketprotocol-10.txt> (The WebSocket protocol) to Proposed Standard

Mark Andrews <marka@isc.org> Mon, 25 July 2011 00:47 UTC

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To: Willy Tarreau <w@1wt.eu>
From: Mark Andrews <marka@isc.org>
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In-reply-to: Your message of "Sun, 24 Jul 2011 20:33:43 +0200." <20110724183343.GY22405@1wt.eu>
Date: Mon, 25 Jul 2011 10:46:58 +1000
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Cc: Server-Initiated HTTP <hybi@ietf.org>, IETF-Discussion <ietf@ietf.org>
Subject: Re: [hybi] Last Call: <draft-ietf-hybi-thewebsocketprotocol-10.txt> (The WebSocket protocol) to Proposed Standard
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In message <20110724183343.GY22405@1wt.eu>eu>, Willy Tarreau writes:
> On Sun, Jul 24, 2011 at 08:25:05PM +0200, I=F1aki Baz Castillo wrote:
> > 2011/7/24 Willy Tarreau <w@1wt.eu>eu>:
> > >> > Making an additional DNS request and a connection come with a cost.
> > >>
> > >> http://tools.ietf.org/html/draft-ibc-websocket-dns-srv-02#section-5.2
> > >
> > > You still need the DNS request : the client does an A/AAAA request for
> > > the HTTP host, then if you ask it to use an SRV record for the WS conne=
> ction,
> > > it must perform that request too, even if it's to conclude that it can =
> reuse
> > > the idle connection.
> > =
> 
> > Ok, but I don't consider a xtra DNS query to be so hard.
> 
> I had to perform sites analysis for a customer a few months ago. Many
> web pages nowadays have between 100 and 200 objects to fetch, spread
> over up to 25-30 host names. If you take even only 100ms for each of
> them, you're at 3 additional seconds to display the page. Granted those
> requests are not WS and only HTTP, but as I said, SRV for WS won't work
> before it works with HTTP, at least due to proxies.

No. It takes 100ms extra.  Only if you serialise all the lookups
does it take 3 extra seconds.  If you are not doing the DNS lookups
in parallel today you are already doing a dis-service to your
customers.

Adding a SRV lookup should add 0ms if it isn't there as you should be
making A, AAAA and SRV lookups in parallel.  Non-existance is as
cachable as existance is.

> But those 3 extra seconds will always be considered a good reason not
> to make SRV mandatory for HTTP. The web is degrading very quickly due
> to poor practices, and we should be careful not to suggest to make it
> even worse.
> 
> Regards,
> Willy
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka@isc.org