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Re: [higgins-dev] Improving Higgins XDI syntax
Paul,

Yes, both your proposed improvements are correct. As a matter of fact, this is exactly what I called "Special case 1" and "Special case 2" back when I wrote this section:
http://wiki.eclipse.org/IdAS_XDI_Mapping#Mapping

Implementing these improvements should bring the Higgins flavor of XDI very close to "native XDI".

The Higgins Attribute Service already implements them.

But the IdAS Client doesn't, it always uses the "verbose" patterns, mainly because of strong time constraints, which were also the reason for putting everything into CDATA structures, just to make something work quickly and "be on the safe side".

Regarding serialization formats, I currently like to think that X3 is best for components that understand XDI well (e.g. IdAS Client), and X3J is simply nice for anyone who likes JSON. But there's nothing wrong with XDI/XML either, I think..

Markus

On Thu, Aug 5, 2010 at 12:47 PM, Paul Trevithick <ptrevithick@xxxxxxxxx> wrote:
Whereas over the long haul there are lots of semantic changes [1] we'd like to make to the XDI that Higgins is exposing, in the very short term there is an urgent need to make it far less verbose and more developer/human friendly the XDI on a syntactic level. I'm concerned about the aesthetics and verbosity. 

Here is a sample of what Higgins is creating today: [2] (http://wiki.eclipse.org/Higgins_PDS_Access#XDI_Representation).

I've collected here [3] some suggestions for how it could be improved. I repeat [3] here:

The XDI below contains a repeated idiom for representing complex attributes (object-valued predicates) that is far more verbose than required. Every section represented like this:

<xdi:xdi>
  <xdi:s xri="$value$hash$sha$256!f68f4bb3513a89c6ea41b6eeffe6af0ea2a7d2f3f172b72bf26ecb29d9713020">
    <xdi:p xri="$value">
      <xdi:data><![CDATA[urn:efa25e71-5b6f-4844-b139-4ed26dd1c3e5]]></xdi:data>
    </xdi:p>
  </xdi:s>
</xdi:xdi>

...should be written like this:

<xdi:ref xri="=(urn:efa25e71-5b6f-4844-b139-4ed26dd1c3e5)"/>

Similarly, since in every case above there is only a single value for a literal, every section that looks like this:

      <xdi:xdi>
        <xdi:s xri="$value$hash$sha$256!0a38e8a3c328b1616ac3c34720d0ceb578bd3f5e8bfff9841bb0804dd4d2b5eb">
          <xdi:p xri="$value">
            <xdi:data><![CDATA[55555-1234]]></xdi:data>
          </xdi:p>
        </xdi:s>
      </xdi:xdi>
    </xdi:p>

...should look like this:

  <xdi:data><![CDATA[55555-1234]]></xdi:data> <-- Drummond/Markus please verify
</xdi:p>

Other Ideas

*Should we be using the JSON serialization of XDI instead of the XML serialization?

*It would be nice if XDI had a convention for URI shortening based on a default namespace. That if relative entityIDs were used (e.g. "#245") we wouldn't have to have these long entityIDs like this one used below: "urn:efa25e71-5b6f-4844-b139-4ed26dd1c3e5". 

* In addition to a default (per document) namespace, if arbitrary namespace definitions were allowed then instead of "http://www.w3.org/2006/vcard/ns#n" we could say "vcard:n" (where vcard="http://www.w3.org/2006/vcard/ns#")

*The above example could be significantly shortened if it only described a single address (the second address doesn't have any illustrative value).

For reference here is an RDF representation of a single persona (Contactable_1) and their address, name and telephone number. Some "cheating" is going on here: entityIDs have been hand-crafted to be pretty (e.g. :Address_1 vs. :efa25e71-5b6f-4844-b139-4ed26dd1c3e5):

 :Contactable_1
     rdf:type p:Contactable ;
     p:role  p:Buyer ;
     vcard:adr :Address_1 ;
     vcard:n :Name_1 ;
     vcard:tel Voice_1 .
 
 :Address_1
     rdf:type vcard:Address ;
     vcard:extended-address "Suite 1000"^^xsd:string ;
     vcard:locality "Peoria"^^xsd:string ;
     vcard:postal-code "61604"^^xsd:string ;
     vcard:region "IL"^^xsd:string ;
     vcard:street-address
             "123 S Main Street"^^xsd:string .
 
 :Name_1
     rdf:type vcard:Name ;
     rdfs:label "Name_1"^^xsd:string ;
     vcard:family-name "Jones"^^xsd:string ;
     vcard:given-name "Alice"^^xsd:string .
 
 :Voice_1
     rdf:type vcard:Voice ;
     rdf:value "tel:+358-555-1234567" 




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