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Subject: Feedback requested on terms used in Metadata spec
I'm happy to report that Marty and I, after a series of in-depth work
sessions (abetted by Dave McAlpin when he's been in town), believe we have
wrestled the metadata dragon most of the way to the ground. The "dragon" is a tighter, more consistent ABNF for all forms
of XRI metadata as well as a much cleaner set of rules about what it describes. Without going into all the gory detail, what XRI Metadata 2.0 Working
Draft 08 will recommend is a very simple ABNF for "tagging" an
identifier with XRI metadata, which can then be used as a cross-reference inside
another XRI. The important clarification we will be making is that this metadata
only describes the "subject" identifier (the identifier being
described, to borrow term from RDF). For example, in the XRI… xri://xri.example.com/some/filename*($v*2.3) …the metadata "$v" only describes the identifier
"2.3". It tells you it’s a version number. That's it. From the
identifier above, it would be a pretty obvious conclusion that the identifier
authority intended the cross-reference "($v*2.3)" to identify a
version namespace for the resource identifier by "filename". However in
the following XRI… xri://xri.example.com/some/filename*($v*2.3)*anotherfile …it may not be quite as clear – does the identifier
"($v*2.3)" create a version namespace for "filename" or for
"anotherfile"? The answer is: that's up to the identifier authority and out of scope
for the XRI Metadata spec. The scope of the Metadata spec is limited to
defining well-known semantics and syntax for a limited set of broadly useful
identifier metadata (versions, dates, languages, types, and annotations). With that explained, here's what we'd like feedback on: the semantics
of the actual production names used in the ABNF – which (per our
experience with XRI syntax) we'd like to match up with the terms used in the text
of the Metadata spec itself. Following are four "versions" of the ABNF that are all
identical structurally but different in the production names for the first two of
the three productions in the proposed syntax. (Marty and I both like the term
"subject" for the third component -- the identifier being described
-- since this is consistent with RDF and SAML and other similar uses.) We'd just like to know which of these (if any) are preferred by other
members of the TC, since semantics is not something that can be determined by
fiat. Please send a reply email to the list with a comment about your
preference if you have one (or a different suggestion if you feel something
else altogether would work better). Thanks, =Drummond and Marty Example 1 ("tag" wording) xri-metadata =
"$" metadata-tag [ “*” metadata-tag-value ] “*”
subject metadata-tag =
( alpha / xref ) metadata-tag-value = ( xri-subseg / xref ) subject =
( xri-subseg / xref ) Example 2 ("attribute" wording) xri-metadata =
"$" attribute [ “*” attribute-value ] “*”
subject attribute =
( alpha / xref ) attribute-value = (
xri-subseg / xref ) subject =
( xri-subseg / xref ) Example 3 ("property" wording) xri-metadata =
"$" property [ “*” property-value ] “*”
subject property =
( alpha / xref ) property-value = (
xri-subseg / xref ) subject =
( xri-subseg / xref ) Example 4 ("RDF" wording) xri-metadata =
"$" predicate [ “*” object ] “*” subject predicate =
( alpha / xref ) object =
( xri-subseg / xref ) subject =
( xri-subseg / xref ) Examples of the five types of XRI metadata: ($l*fr*pays) ($t*ces* john%20henry%20doe) ($v*2.3) ($d*2002-10-10T17:00:00Z) ($-*some.comment.here) How these examples parse to the ABNF above:
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