Re: Last Call: <draft-ietf-httpbis-early-hints-03.txt> (An HTTP Status Code for Indicating Hints) to Experimental RFC

[Willy Tarreau <[e-mail]>]

On Sun, Jun 25, 2017 at 01:36:59PM +0200, Julian Reschke wrote:
> > > Understood. But is this a requirement or just a suggestion? Does
> > > a client
> > > need to forget the information from the 103 when it's not repeated in the
> > > final response?
> > 
> > Hmmm the text says :
> >    "This memo defines a status code for sending an informational response
> >     ([RFC7231], Section 6.2) that contains header fields that are likely
> >     to be included in the final response"
> > 
> > Thus I think that the final header fields are the real ones, and that
> > those sent early are more about hints to help the client get mostly
> > prepared. Can there be a conflict between two overlapping header field
> > values for the same link ? If so, some text needs to be appended to
> > mandate that the final response the the only authoritative one and that
> > the interim ones are only here to help fill silence periods on the link.
> 
> I'm interested in the case where the Link appears in the 103 but not in the
> final response...

I think it will be very common, because I see a cool opportunity here for
edge gateways to send a few links regardless of what the origin server thinks
about this. I'm even considering implementing this capability into haproxy
because I think it can bring some value. So if this is going to have side
effects, it would be nice that they are properly estimated.

Willy