In message <20110724183343(_dot_)GY22405(_at_)1wt(_dot_)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(_at_)1wt(_dot_)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
_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www.ietf.org/mailman/listinfo/ietf
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka(_at_)isc(_dot_)org
_______________________________________________
Ietf mailing list
Ietf(_at_)ietf(_dot_)org
https://www.ietf.org/mailman/listinfo/ietf