Am 05.12.2006 um 01:39 schrieb Reed Hedges: > > Hi Karsten, the HTTP "hypervos" extension in s4 has a mode where it > can > emit a description of the Vobjects in RDF (instead of a simple HTML > listing) for objects that aren't actually meant to be served as an XML > document by hypervos. > > I don't know if it's correct or not (probably not, I bascially guessed > at stuff, and I think I see some XML sytax errors even), I added it > as a > starting point for someone who knows much more about RDF than I > do. We > should probebly improve it and perhaps make it compatible with your > software (since your use of RDF is, I assume, much richer and > generally > better than mine!). > Now that you mention it, I remember seeing this in the source code. I'll have another look at it, maybe I get the time to tinker with it a bit.
> The code is at libs/vos/extensions/http/httpserver.cc in the > describeVobject_RDF() function. It only describes one Vobject, not a > whole tree of them. Like this: > > <rdf:RDF xmlns:rdf="..." xmlns:rdfs="..." xmlns:vos="..fake schema..." > xmlns:xsd="...." xml:base="http://interreality.org/otd/";> > <rdf:Description rdf:about="vip://host/obj"> > <rdf:type>http://interreality.org/otd/objectType</rdf:type> > <!-- I guess the idea was that all object types would > define > their required children in the > http://interreality.org/otd/objectType or the > http://interreality.org/otd/ namespace --> > <childContextualName1 rdf:resource="vip://host/childObj" /> > <childContextualName2 rdfs:datatype="string">property object > value</childContextualName2> > </rdf:Description> > </rdf:RDF> > This basically looks good, though you should not use xml:base this way in RDF. Typically, you have qnames for all RDF properties, and only use the base to resolve rdf:ID names and relative URIs in rdf:about. Also, I don't use a single xmlns:vos, but several namespaces corresponding to the "package names" you have in VOS. For example, I'd use xmlns:a3dl="http://interreality.org/otd/a3dl/"; as a sort of "include", and then write the a3dl:position contextual name as <a3dl:position rdf:resource="..."/> element. I like the concise way you handle VOS properties, but since property:Property is just another metatype, it could well be mixed with other metatypes that require children; you cannot do that with RDF labels, unfortunately. So instead of <childContextualName2 rdfs:datatype="string">property object value</ childContextualName2> I model property Vobjects as RDF resources of their own, which also preserves their VOS URI. Serializing this in a nested way, you get for example: <rdf:Description rdf:about="vip://host/obj"> <rdf:type rdf:resource="http://interreality.org/otd/a3dl/Cone"/> <a3dl:position> <rdf:Description rdf:about="vip://host/childProperty"> <rdf:value>1 2 3</rdf:value> <vos:datatype>list: float</vos:datatype> <vos:length>5</vos:length> </rdf:Description> <a3dl:position> </rdf:Description> Of course, you can abbreviate this even more in RDF/XML if you want: <rdf:Description rdf:about="vip://host/obj"> <rdf:type rdf:resource="http://interreality.org/otd/a3dl/Cone"/> <a3dl:position> <rdf:Description rdf:about="vip://host/childProperty" rdf:value="1 2 3" vos:datatype="list: float" vos:length="5"/> </a3dl:position> </rdf:Description> Means the same :-) Actually, to preserve ordering, I use two RDF properties with the same rdf:about target: <rdf:Description rdf:about="vip://host/obj"> <rdf:type rdf:resource="http://interreality.org/otd/a3dl/Cone"/> <a3dl:position rdf:resource="vip://host/childProperty"/> <rdf:_1 rdf:resource="vip://host/childProperty"/> </rdf:Description> and describe vip://host/childProperty separately, instead of embedding it as above. Regards, Karsten _______________________________________________ vos-d mailing list vos-d@interreality.org http://www.interreality.org/cgi-bin/mailman/listinfo/vos-d
