On 17 May 2013, at 14:49, Wendy Roome wrote:
> I assume you're referring to {13.2} of RFC 2616. That section strikes me as
> "a royal kludge." (Privately I'd apply a much stronger adjective, but I'm too
> much of a lady to use such language in public.)
>
> The problem is that HTTP defines multiple ways to declare expiration times --
> Expires header, cache directives, etc. Those mechanisms have evolved over
> time, and not all servers use them consistently. So I think {13.2} is mostly
> about how to cope with legacy HTTP servers and missing or inconsistent
> information.
>
> Since we're starting fresh, why not just say that if an ALTO server wants to
> indicate a polling interval, it SHOULD set the Expires and the Date headers,
> and the client SHOULD use the difference as the approximate polling interval?
That's basically what I was suggesting except rather than being specific about
what the server must use, leave it to the client to determine based on how the
client calculates freshness (as the client is likely in the best position to
know what rate it might want to poll at as it know how up-to-date with any
changes it might want to be).
If we're going to pick one mechnaism I;d prefer we pick Cache-Control: max-age
myself rather than Date/Expires (as max-age takes priority over Expires
according to RFC2616).
Ben
>
> - Wendy Roome
>
> From: Ben Niven-Jenkins <[email protected]>
> Date: Thu, May 16, 2013 17:27
> Subject: Re: [alto] Should server use "Expires" HTTP header
>
> Best current practice is to only to poll as often as you would revalidate the
> content (i.e. no more frequently than the instant the content becomes stale
> according to RFC2616).
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