The properties of an entity are the properties of an entity -- and
this includes entity headers. Transferring the feed via rsync to
another host means that the serving scenario is likely different, and
therefore different metadata is appropriate. Meanwhile, duplicating
the data in the feed introduces opportunities for misalignment and
encourages people not to set the proper headers -- which means that
caching intermediaries and clients (which have a much larger
deployment footprint than any feed infrastructure) can't do the right
thing.
Personally, I'm getting sick of the "can't set HTTP headers" scenario
driving abuse of HTTP.
/me returns to cave
On 08/07/2009, at 8:30 AM, Erik Wilde wrote:
Stephane Bortzmeyer wrote:
On Mon, Jul 06, 2009 at 12:41:32PM +0100,
James Abley <[email protected]> wrote
HTTP already provides Cache-Control: / Expires: to indicate how long
a client may like to wait before checking if the representation has
been updated. Would that meet your requirement?
IMHO (I'm not the OP), no. Feed producers (who know the duration of
the feed) may not have a way to set HTTP headers. Also, HTTP headers
are not end-to-end, they are lost if, for instance, the feed is
transferred by non-HTTP means (such as rsync or scp). I would
prefer a
solution inside the feed.
+1. the update properties of a feed are a property of the feed, not
of the protocol. these things are related, but keeping the
properties as part of the feed format would make a feed document
more self-contained, would allow feed publication in scenarios where
HTTP headers cannot be easily set, and might also allow more
sophisticated/specialized properties than HTTP's cache control.
thanks for the pointer to RSS 1.0's properties. i am not quite sure
whether i like what has been done there, but now that i know that it
exists in RSS 1.0, it would be really interesting to know how many
feed providers and consumers actually use it, and why it is one of
those properties that did exist in some RSS version, but did not
make it into Atom...
cheers,
erik wilde tel:+1-510-6432253 - fax:+1-510-6425814
[email protected] - http://dret.net/netdret
UC Berkeley - School of Information (ISchool)
--
Mark Nottingham http://www.mnot.net/
