Re: What is an "up to date" version?

ETag would still need a request to check If-Modified-Since every time,
which is slow.

OK, I could use Cache-Control: max-age and Expires as clues. But what about
servers that do not send them?
On Sun, 29 Oct 2017 at 08.41, Story H.J. <H.J.Story@soton.ac.uk> wrote:

>
>
> > On 29 Oct 2017, at 08:19, Story H.J. <H.J.Story@soton.ac.uk> wrote:
> >
> >> On 29 Oct 2017, at 03:11, Ed - 0x1b, Inc. <w3c@0x1b.com<mailto:
> w3c@0x1b.com>> wrote:
> >>
> >> I would guess an up to date etag is typical for cache freshness.
> >> https://en.wikipedia.org/wiki/HTTP_ETag
> >
> > close. The Etag won't tell the local cache if it needs to update the
> version, it will
> > just be useful when making a request to ask for one where intermediary
> caches
> > can say, nothing has changed since you last looked.
> > Look at
> > https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.6
> > and
> > https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9
> >
>
> Even better there is the Expires header:
> https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.21
>
> And all the text around it in section 14
>
>
>
> > Henry
> >
> >
> > On Sat, Oct 28, 2017 at 2:10 PM, Martynas Jusevičius
> > <martynas@atomgraph.com<mailto:martynas@atomgraph.com>> wrote:
> > Hi,
> >
> > I'm implementing a cache for WebID graphs to improve performance. I was
> > looking at WebID-TLS 4.1 Authentication sequence, which says:
> > "If the WebID Verifier has an up to date version of the graph in its
> graph
> > cache then it can return it."
> >
> https://dvcs.w3.org/hg/WebID/raw-file/tip/spec/tls-respec.html#authentication-sequence
> >
> > The phrase "up to date" is repeated multiple times later on, but not
> defined
> > anywhere.
> >
> > So what is it and who decides that -- the implementor? For how long am I
> > supposed to safely cache the graphs?
> >
> >
> > Martynas
> > atomgraph.com
> >
> >
>
>