Re: Server push - use cases

> On Mon, 14 Aug 2023 at 19:02, Mark Thomas <> wrote:
> > Hi all,
> >
> > I'm currently working on a update to the Jakarta Servlet specification
> > and we are discussing whether or not to deprecate, and in a future
> > version remove, support for server push.
> >
> > My impression from scanning this list's archives is that server push has
> > not been widely adopted. I am aware that browsers have dropped / are
> > dropping support for server push.
> >
> > Can anyone point me to a current (or even proposed) use of server push
> > that might be a reason not to deprecate server push in the Select spec?

On the server side, I considered but never got around to implementing a
limited Server Push in order to provide cache hints for local resources,
e.g. where the server would follow a GET request for .html with a
Server Push of the response to a HEAD request -- including ETag and/or
Last-Modified -- for locally-hosted static resources such as .css, .js
already present in Link response headers for the primary .html resource.

Instead of Server Push, I wonder if the Link response header could be
usefully extended to include ETag, size, digest, or potentionally
other information which might otherwise later be returned by a
conditional GET with cache revalidation (e.g. If-None-Match or
If-Modified-Since), and if clients would check for those parameters
and update the client cache with that information (after validating
server as authoritative origin for those resources).

With the deprecation of h2 Server Push, I shelved the above idea,
but chose to share it here per Mark's request.  I think Server Push
might _theoretically_ be useful in pushing cache revalidation hints,
though there might be better ways to do this than Server Push.

(Alternatively, if anyone is interested in working with me to extend
Link (RFC 8288) to define additional target attributes for caching,
then please DM.)

Cheers, Glenn

Received on Tuesday, 15 August 2023 00:42:01 UTC