Re: [hybi] Fwd: New Version Notification for draft-mcmanus-httpbis-h2-websockets-01.txt

[Amos Jeffries <[e-mail]>]

On 11/11/17 07:10, Takeshi Yoshino wrote:
> On Sat, Nov 11, 2017 at 2:51 AM, Kari Hurtta wrote:
> 
>     SETTINGS   ENABLE_UPGRADE (or ENABLE_CONNECT_PROTOCOL) from server
>     end of connection to client end of connection tells on that case
> 
>     that server end of connection understand
>              :upgrade
>     pseudo header.
> 
>     It tells nothing about that what is behind of that server end of
>     connection.
> 
>     Only after request is sent, http response tells if that authority
>     and path supporting that upgrade. Error is reported as http status code.
> 
>     I see that reverse proxy can send SETTINGS   ENABLE_UPGRADE (or
>     ENABLE_CONNECT_PROTOCOL)
>     even when it does not konw if next hop supports that. Support
>     of next hop or origin server is reported by when that protocol
>     is triedm failure is reported on http status code.


A proxy that sends that ENABLE_UPGRADE is guaranteeing that it *will* 
service the upgrade and handle the resulting traffic syntax. By itself 
if necessary.

In the general case a proxy that negotiates a SETTING it cannot 
guarantee support for is broken. It must instead negotiate a SETTINGS 
without the feature and re-negotiate with another SETTINGS later when it 
has better information.

Amos