Re: SETTINGS_ENABLE_CONNECT_PROTOCOL and new protocols

On Tue, Nov 2, 2021 at 8:38 PM Martin Thomson <mt@lowentropy.net> wrote:

> On Wed, Nov 3, 2021, at 12:03, David Schinazi wrote:
> > I'm not sure it's really possible to solve the "as a client I want to
> > know all the feature set of this server" because the first intermediary
> > might know what all its backends support.
>
> That's a nice philosophy.  That seems like the cleanest outcome.  However,
> it doesn't give me an answer to the dilemma from before:
>
> > That means that there are cases where the connection supports the
> ability to negotiate :protocols in general, the resource supports this
> specific :protocol, and the combination of the two doesn't.
>
> I'm aware of cases where this happens already and we jump through all
> sorts of hoops as a result.  Are you suggesting that we just live with this
> situation because it is unavoidable?
>

One potential solution to this dilemma is to find a way to communicate to
the client what is supported (e.g. settings as you mentioned). Another
solution would be to have the client try and have a way to communicate the
reason for failure. There's discussion of a new status code in this thread,
and I like that. In general I much prefer the "try what you want to do and
failover if you fail" approach over the "ask for permission first" approach
because the latter introduces time-to-check-to-time-of-use issues.

David