Re: [DNSOP] Should we try to work on DNS over HTTP in dnsop?

[Paul Vixie <[e-mail]>]

On Monday, December 21, 2015 01:13:10 PM Tony Finch wrote:
> Paul Vixie <[e-mail]> wrote:
> > any HTTP initiator who wants out of order response processing will have
> > to negotiate for it (see mogul's 2001 RID draft) and will then have new
> > responsibilities for matching up the out of order HTTP responses with
> > then-outstanding HTTP requests.
> 
> The current way to deal with out-of-order responses and head-of-line
> blocking in HTTP is HTTP/2.

since http/2 is a completely new protocol, i think that's a strange way to say it. as you point 
out below, existing HTTP initiators accomplish out-of-order processing by using multiple 
parallel HTTP/1.1 TCP sessions. how the HTTP asynchrony is achieved is beyond the scope 
of an HTTP application spec such as DNS-over-HTTP. i will suggest some text below.

> 
> If you do DNS over HTTP then there has to be an exact correspondence
> between HTTP requests and responses and DNS requests and responses -
> anything else would be madness. This implies that DNS over HTTP/1 only
> supports in-order pipelined queries and responses in each connection; to
> avoid head-of-line blocking you need either multiple connections or
> HTTP/2.

by all means let us add text to the effect that "HTTP/1.1 or later can be used, with the DNS-
over-HTTP initiator having the responsibility to discover what HTTP protocol version the 
responder supports, and to speak that protocol version correctly -- for example, if an HTTP 
protocol version supports multiple outstanding requests and out of order responses, then 
the DNS-over-HTTP initiator is required to match inbound HTTP responses with outstanding 
DNS requests."

-- 
P Vixie