[Visionaries] RDF/YAML

[Peter Minten]

Hi folks,

I did some experimenting with expressing RDF in YAML and it seems to work. A few 
examples:

##--- RDF, http://www.w3.org/TR/rdf-primer/#example3 ---##

<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
         xmlns:exterms="http://www.example.org/terms/";>

   <rdf:Description rdf:about="http://www.example.org/index.html";>
       <exterms:creation-date>August 16, 1999</exterms:creation-date>
   </rdf:Description>

   <rdf:Description rdf:about="http://www.example.org/index.html";>
       <exterms:language>English</exterms:language>
   </rdf:Description>

</rdf:RDF>

##--- YAML ---##

--- %YAML:1.0

#note that YAML doesn't have namespaces AFAIK, so I invented a notation:
#the slash is like the colon in xml

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  exterms: "http://www.example.org/terms/";

 rdf/Description:
  rdf/about: "http://www.example.org/index.html";
  exterms/creationdate: August 16, 1999

 rdf/Description:
  rdf/about: "http://www.example.org/index.html";
  exterms/language: English

---

RDF/YAML also supports anonymous nodes in two fashions:

##--- RDF, http://www.w3.org/TR/rdf-primer/#example6 ---##

<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
         xmlns:dc="http://purl.org/dc/elements/1.1/";
         xmlns:exterms="http://example.org/stuff/1.0/";>

    <rdf:Description rdf:about="http://www.w3.org/TR/rdf-syntax-grammar";>
      <dc:title>RDF/XML Syntax Specification (Revised)</dc:title>
      <exterms:editor rdf:nodeID="abc"/>
    </rdf:Description>

    <rdf:Description rdf:nodeID="abc">
       <exterms:fullName>Dave Beckett</exterms:fullName>
       <exterms:homePage rdf:resource="http://purl.org/net/dajobe/"/>
   </rdf:Description>

</rdf:RDF>

##--- YAML, 1 ---##

--- %YAML:1.0

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  dc: "http://purl.org/dc/elements/1.1/";
  exterms: "http://example.org/stuff/1.0/";

 rdf/Description:
  rdf/about: "http://www.w3.org/TR/rdf-syntax-grammar";
  dc/title: "RDF/XML Syntax Specification (Revised)"
  exterms/editor: !rdf/nodeID abc

 rdf/Description:
  rdf/nodeID: "abc"
  exterms/fullName: Dave Beckett
  exterms/homePage: !rdf/resource "http://purl.org/net/dajobe/";

---

##--- YAML, 2 ---##

--- %YAML:1.0

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  dc: "http://purl.org/dc/elements/1.1/";
  exterms: "http://example.org/stuff/1.0/";

 rdf/Description:
  rdf/about: "http://www.w3.org/TR/rdf-syntax-grammar";
  dc/title: "RDF/XML Syntax Specification (Revised)"
  exterms/editor:
   exterms/fullName: Dave Beckett
   exterms/homePage: !rdf/resource "http://purl.org/net/dajobe/";

---

Now that the basic stuff is introduced let's move on to collections. Here is an 
example involving a bag:

##--- RDF http://www.w3.org/TR/rdf-primer/#example13 ---##

<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
         xmlns:s="http://example.edu/students/vocab#";>

   <rdf:Description rdf:about="http://example.edu/courses/6.001";>
      <s:students>
         <rdf:Bag>
            <rdf:li rdf:resource="http://example.edu/students/Amy"/>
            <rdf:li rdf:resource="http://example.edu/students/Tim"/>
            <rdf:li rdf:resource="http://example.edu/students/John"/>
            <rdf:li rdf:resource="http://example.edu/students/Mary"/>
            <rdf:li rdf:resource="http://example.edu/students/Sue"/>
         </rdf:Bag>
      </s:students>
   </rdf:Description>
</rdf:RDF>

##--- YAML ---###

--- %YAML:1.0

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  s: "http://example.edu/students/vocab#";

 rdf/Description:
  rdf/about: "http://example.edu/courses/6.001";
  s/students: !rdf/bag
   - !rdf/resource "http://example.edu/students/Amy";
   - !rdf/resource "http://example.edu/students/Tim";
   - !rdf/resource "http://example.edu/students/John";
   - !rdf/resource "http://example.edu/students/Mary";
   - !rdf/resource "http://example.edu/students/Sue";

---

Now the same thing, replacing the bag by an alternative list (which is silly in 
this context I know, but it's the idea that counts):


--- %YAML:1.0

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  s: "http://example.edu/students/vocab#";

 rdf/Description:
  rdf/about: "http://example.edu/courses/6.001";
  s/students: !rdf/alt
   - !rdf/resource "http://example.edu/students/Amy";
   - !rdf/resource "http://example.edu/students/Tim";
   - !rdf/resource "http://example.edu/students/John";
   - !rdf/resource "http://example.edu/students/Mary";
   - !rdf/resource "http://example.edu/students/Sue";

---

And now with a sequence:

--- %YAML:1.0

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  s: "http://example.edu/students/vocab#";

 rdf/Description:
  rdf/about: "http://example.edu/courses/6.001";
  s/students:
   - !rdf/resource "http://example.edu/students/Amy";
   - !rdf/resource "http://example.edu/students/Tim";
   - !rdf/resource "http://example.edu/students/John";
   - !rdf/resource "http://example.edu/students/Mary";
   - !rdf/resource "http://example.edu/students/Sue";

---

Sequences are the default so you don't need to have an extra !rdf/seq type tag.

And now the collection. For reasons not known to me it has a different syntax 
than bag/seq/alt in RDF/XML, but since that doesn't translate very well to YAML 
the syntax is a little different (and more straighforward):

--- %YAML:1.0

rdf/rdf:
 __namespaces__:
  rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#";
  s: "http://example.edu/students/vocab#";

 rdf/Description:
  rdf/about: "http://example.edu/courses/6.001";
  s/students: !rdf/collection
   - !rdf/resource "http://example.edu/students/Amy";
   - !rdf/resource "http://example.edu/students/Tim";
   - !rdf/resource "http://example.edu/students/John";
   - !rdf/resource "http://example.edu/students/Mary";
   - !rdf/resource "http://example.edu/students/Sue";

---

This isn't quite optimal yet, mainly in the namespace section, but it proves 
that it's possible to expres RDF in YAML in an easy and understandable way.

Greetings,

Peter