On 17/08/2017 10:56, John Levine wrote:
> In article <CACZ1GiooBdEZ_YcBZPQNFkbT0DsGf-Cu25fPYzWcLamLUAH+TA@xxxxxxxxxxxxxx> you write:
>> This seems to work for me. Any problems which could come up with having a
>> central authority for this feature?
>
> Many. What if I tell the central authority that I implement
> self-destructive e-mail but I'm lying? How could the central
> authority tell? I'm pretty sure I can pass whatever audits they make
> since they have no way to tell what data I'm hiding in places they
> can't see.
>
>> 4.) A really boiled down version of ephemeral mails could just mark the
>> mail "outdated" if the information provided in the mail is not expected to
>> hold good after some time, instead of actually expunging the mail.
>
> As others have said, that feature has come and gone many times in the past. In
> netnews, which is similar in some ways to mail, there's an Expires: header which
> works reasonably well, typically used to mark messages that stop being interesting
> after some point like weather forecasts or event reminders. There's no guarantee
> that anyone will follow the advice, and you certainly can't use it to force stuff
> to disappear, but it's been occasionally useful.
I thought of changing the title to "Scope for self-destructing web pages?"
After I heard an early internal presentation of the design of the World-Wide Web
from my CERN colleague Tim Berners-Lee, probably in 1993, I asked him why he didn't
make an expiry date a mandatory feature of every HTML document. Being a man of some
foresight, he explained exactly why it wouldn't work in practice, despite being
a wonderful idea in theory.
And yes, according to RFC 1866 (and for all I know, more recent definitions
of HTML) you can include things like
<META HTTP-EQUIV="Expires" CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">
and the server may then include "Expires: Tue, 04 Dec 1993 21:29:02 GMT"
in the reply to an HTTP GET.
Only, have you noticed any web pages expiring recently? Maybe there are
browsers that annoy their users by not displaying expired pages?
Bits don't expire.
Brian