Re: How to reset ALTSVC

[Martin Thomson <[e-mail]>]

On 31 March 2015 at 13:51, Bence Béky <[e-mail]> wrote:
> I would like to be able to construct HTTP/1.1 Alt-Svc headers and HTTP/2
> ALTSVC frames that indicate that the client should forget all previously
> discovered alternative services for that given origin.  (With the caveat
> from the earlier "Alt-Svc alternative cache invalidation (ext#16)" thread
> that they would only invalidate alternative services that came from the same
> discovery mechanism.)  The most obvious way would be to send an Alt-Svc
> header field with an empty value, or an HTTP/2 ALTSVC frame with an empty
> Alt-Svc-Field-Value.  However, the current draft calls for at least one
> alternative in Section 3, and a mandatory Alt-Svc-Field-Value field in
> Section 4.  I propose to allow zero alternatives like this:
>
> Alt-Svc = *( alternative *( OWS ";" OWS parameter ) )
>
> and to make Alt-Svc-Field-Value optional.

You could send a redirect-to-self value without changing the grammar
too.  Or you could set the max-age to 0.  Or both.