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

Dave Cridland <> Thu, 21 July 2011 20:19 UTC

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Date: Thu, 21 Jul 2011 21:19:06 +0100
From: Dave Cridland <>
To: David Endicott <>, Server-Initiated HTTP <>, IETF-Discussion <>, Willy Tarreau <>, =?UTF-8?Q?I=C3=B1aki_Baz_Castillo?= <>
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Subject: Re: [hybi] Last Call: <draft-ietf-hybi-thewebsocketprotocol-10.txt> (The WebSocket protocol) to Proposed Standard
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On Thu Jul 21 19:43:07 2011, David Endicott wrote:
> I do not know SIP or XMPP well enough to comment on why they  
> mandated the
> name resolution mechanisms they did.    However, XMPP is used in a  
> highly
> dynamic host environment, so having flexible & extensible name  
> resolution is
> likely an excellent choice.
I have no idea what you might mean by "highly dynamic host  
environment" in this context, but XMPP servers are normally found at  
the same location consistently. However, it is *not* always (or  
typically) the same location as a simple A record lookup:

;; ANSWER SECTION: 259200 IN	SRV	5 0 5269



This property alone is very useful - in a websockets case this would  
mean being able to provide websockets services from a different host  
(or network) to the traditional web services in a simple manner,  
fully compatible with SOP.

The fact that this also allows cheap lightweight load balancing and  
fallback control is also useful in other cases; none of this relates  
to dynamic hosts, but simply richer service location.

> I do not oppose DNS's MX records for SMTP as email addresses are  
> name@domain,
> so obviously the Domain Name System is appropriate.    Also, I fail  
> to see
> why a mail admin should care how the SMTP clients arrive at the  
> server.  DNS
> MX is a reasonable solution, but there may be other methods, any  
> and all of
> which are irrelevant to the SMTP server.    Especially when the  
> SMTP server
> supports multiple email domains....
A mail admin does need to care *that* the service is located, and  
therefore will care *how* it is located.

You can be as theoretical as you like, by all means, but in practical  
terms, your email address (and my XMPP address) work because they use  
a defined, interoperable, service location mechanism, which operates  
via DNS record lookup.

(Also, I have no idea what multiple domains has to do with this.)

> Since WS is intended as a browser supported protocol, WS should  
> follow the
> same URI resolution mechanisms as HTTP (or how URI resolution is  
> done in
> general)  Having URLs that could resolve differently for a HTTP  
> request and
> a WS setup is a problem.
But they do resolve differently anyway. You don't get a page from a  
'ws' scheme URI, you get a transport protocol connection. This is  
good, indeed, it's kind of the point.

Your suggestion of "how URI resolution is done in general" is  
somewhat self-defeating, too, since aside from 'http' and 'https',  
there are 'mailto', which uses MX, 'sip' and 'xmpp', which both use  

I think opponents of SRV records need to mount a stronger argument  
than the kind of luddite argument that if it's hard for one protocol  
in use by the browser, it should be hard for them all.

Dave Cridland - -
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Infotrope Polymer - ACAP, IMAP, ESMTP, and Lemonade