btw: my main driver in stating +1 is that I was concerned with how it would be implemented, and given that Mark has the one working parser and is ok with it, then my concern has disappeared!
On 10-Apr-07, at 5:52 PM, Dick Hardt wrote: > Good argument Mark, I concur. +1 > > -- Dick > > On 10-Apr-07, at 4:52 PM, Mark Wahl wrote: > >> >> Section 4.3 of >> http://openid.net/specs/openid-attribute-types-1_0-02.html >> suggests that in URIs defined for attributes for OpenID AX, >> "URI fragment specifiers should not be used." >> >> Now I'm no RDF expert, but I'm in favor of allowing fragments, >> and perhaps even encouraging them. I'd prefer this statement >> be removed from subsequent versions of the OpenID AX, in order >> to not dissuade other schema developers from using fragments. >> Here are some points for discussion on that topic, I'd be >> interested in hearing feedback esp. from other RDF implementors. >> >> 0. Some servers will have but a single, small, fixed schema. I'd >> rather those servers be able to reference and serve a single RDF >> file with their complete schema, instead of needing to break that >> schema into a bunch of little schemas. >> >> For example, suppose a server only supports FOAF. Now FOAF does not >> use fragments for the property definitions for its attribute types, >> but the attribute types defined in FOAF are not currently resolvable >> to an RDF document that describes those attribute types. >> >> If xmlns.com where the FOAF RDF is hosted were to implement having >> these >> attribute type URIs used in FOAF be resolvable, they >> would either need to >> - create a few dozen little RDF files that together mirror the >> content of >> foaf.rdf, or >> - implement a URI rule that http://xmlns.com/foaf/0.1/* >> returns foaf.rdf >> >> If I were redefining FOAF, I'd have its attributes be defined as >> fragments, >> so that there is only one base URI for the FOAF schema. (Also to >> give >> them RDF class definitions, see below). >> >> 1. It appears to be current practice for RDF representations of >> metadata >> for attributes in Higgins to use fragments. >> >> In OWL-based systems, the RDF object at the base URI of the document >> is an OWL Ontology. >> >> In Higgins, which uses OWL, the object at the base URI is an OWL >> Ontology that 'imports' the Higgins Ontology. The RDF file for >> an attribute contains an OWL Class for the attribute named by a >> fragment,e.g., #Firstname, and several related OWL properties and >> RDF instances in that same file that add structure to that class. >> >> 2. In our 'schemat' implementations which attempt to generate RDF for >> existing schemas of 'legacy'/'installed base' protocols, it is >> desirable to >> be able to have additional, named OWL classes, RDF objects, and other >> modelling and descriptive data definitions that are shared across >> multiple attributes of a single schema. For example, a schema may >> define its own value syntax and matching rules, and wish to share >> those syntaxes and matching rules across the attributes of that >> schema. >> It would be desirable if there could be a single RDF file which >> contains >> the attribute type metadata, the syntax definition and matching rule >> definition, rather than needing to have the attribute type metadata >> in a set of files that are separate from the syntax definitions and >> matching rule definitions, or are duplicated in those files. >> >> 3. I find that in our implementation 'schemat' of identity metaschema >> attribute metadata retrieval that is a definite performance gain if >> all the schema elements for a particular schema can be retrieved in >> a single HTTP GET. It is likely that an implementation interested >> in an attribute Firstname of a particular schema would also be >> seeing a few other attributes Lastname, Middlename etc of the same >> schema, and it would be good if a GET that retrieves the data for >> Firstname also gives the implementation the rest of the schema so >> that it does not need to keep going back and GETing for each >> attribute type. >> >> 4. Requiring that each be in a separate document would likely lead to >> duplication of metadata, particularly Dublin Core metadata that >> describes "the schema as a whole". I feel it would be better if the >> RDF object at the base URI has the Dublin Core metadata for the >> schema as a whole, and that the Attribute Type Metadata is a class >> named by a fragment below that base URI. >> >> 5. (appeal to authority) http://www.w3.org/DesignIssues/Fragment.html >> "This means that identifiers for arbitrary RDF concepts should have >> fragment identifiers. " >> >> >> Mark Wahl >> Informed Control Inc. >> >> _______________________________________________ >> specs mailing list >> specs@openid.net >> http://openid.net/mailman/listinfo/specs >> >> > > _______________________________________________ > specs mailing list > specs@openid.net > http://openid.net/mailman/listinfo/specs > > _______________________________________________ specs mailing list specs@openid.net http://openid.net/mailman/listinfo/specs