James M Snell wrote:
Also, the description and examples of the Date element here:
http://www.dublincore.org/documents/usageguide/elements.shtml
/Element Description:/ A date associated with an event in the life cycle
of the resource. Typically, Date will be associated with the creation or
availability of the resource. Recommended best practice for encoding the
date value is defined in a profile of ISO 8601 [Date and Time Formats, W3C
Note, http://www.w3.org/TR/NOTE-datetime] and follows the YYYY-MM-DD
format.
Guidelines for content creation:
If the full date is unknown, month and year (YYYY-MM) or just year (YYYY)
may be used. Many other schemes are possible, but if used, they may not be
easily interpreted by users or software.
Examples:
Date="1998-02-16"
Date="1998-02"
Date="1998"
According to the authoritative descriptions, there is no mention of a time
component.
That's a fair interpretation, but I don't think it's the only one. Best
practice recommends use of the W3C-DTF profile of ISO 8601 which
specifically supports hours, minutes and seconds - even fractions of a
second. They may go on to recommend the YYYY-MM-DD subset as being more
easily interpreted, but they also say "Many other schemes are possible". If
you look at the current usage of dc:date in the wild you'll find many
examples with a full date and time (like say all of RSS 1.0 and many RSS 2.0
documents).
And regardless of your interpretation of their W3C-DTF usage, the usage
guide for Dublin Core Qualifiers
(http://dublincore.org/documents/usageguide/qualifiers.shtml) specifically
lists DCMI Period as a valid encoding scheme for dcterms:valid and
dcterms:available. And if you look at the documentation for DCMI Period
(http://dublincore.org/documents/dcmi-period/) you will see a nice example
of a date range with full W3C-DTF date and time.
That documentation comes straight from the Dublin Core website. Is that not
authoritative enough?
With max-age, if your entry is supposed to expire after 6-months from the
time it was updated, there is no need to recalculate the value. If I used
expires for this, my software would have to recalculate the expiration
with every update operation. It may be a minor savings of cycles, but it
is still a savings.
Fair enough, but if that's the only justification for this extension is it
really worth the effort?
That said, if you still want to go ahead with the spec I don't really have a
problem with it. Aggregator authors wishing to support this kind of
functionality will have twice the work to do, but they're probably used to
that by now. ;-)
Regards
James
