I'm not sure there's a role for RDF here - maybe it's best that the RDF
describes the document(s) according to how they appear at creation/indexing
time - i.e. "to the best of my knowledge". I can't really see any benefit in
marking something (or part of something) as volatile - it may be the same a
year later, whereas something marked permanent may have (perhaps
inadvertently) changed. If an engine discovers a reference to doc X, it can
work with what it knows from the metadata or in many cases it would be
possible if necessary to reexamine that doc (even just to compare
In the cases of intentionally volatile stuff, e.g. newsfeeds, there are two
roles for metadata - describing the feed mechanism (including the
characteristics common to everything fed), and describing the content of the
individual, short-lived, 'reports'. I reckon this is probably all we can do,
and significantly all we need to do.

Danny Ayers

<- -----Original Message-----
<- From:
<- []On Behalf Of Charles F. Munat
<- Sent: 11 April 2001 03:23
<- To:
<- Subject: RE: URIs / URLs
<- Some types of resources on the Web are volatile by nature. John
<- Doe puts up
<- a personal web page. Three weeks later, he decides he doesn't
<- really want a
<- personal Web page - too much trouble to update it - and deletes it.
<- It seems to me that there are some resources that *should* be persistent,
<- others that have no need to be. Has anyone given any thought to how to
<- distinguish the two? Should RDF mark persistent documents as such? Should
<- anything not so marked be presumed to be volatile? Are there different
<- degrees of persistence (e.g., a page that is persistent while some of the
<- data on the page changes, or a page that represents the latest
<- version of a
<- document - but always that document).
<- What about the way in which these documents are referenced. Would it be
<- better to have both permanent and temporary links? Could links be set to
<- expire? Could documents include an expire date and links to that document
<- automatically expire when the document did?
<- My brain hurts.
<- Charles F. Munat
<- Seattle, Washington

Received on Wednesday, 11 April 2001 04:58:27 UTC