Resource Desciptor Framework

RDF

In my own words the Resource Descriptor Framework (RDF) is a way to get/indicate specific information (metadata) about resources in the Web.
By example, you cannot get the name of the author of the page www.example.org/index.html.
But with the RDF specification, you are able to provide this information.

For the statement

http://www.example.org/index.html has a creator whose value is John Smith

 
There are 3 terms in the RDF specification:

• The subject (http://www.example.org/index.html)
• The predicate (creator)
• The object (John Smith)

There is a graphic way to describe the statement:

The triples notation allows us to write down the statement in a 3 peers way:

ex:index.html   dc:creator   exstaff:85740 .

We can also have blank nodes, that allows us to get information from the resource.

exstaff:85740   exterms:address         _:johnaddress .
_:johnaddress   exterms:street          "1501 Grant Avenue" .
_:johnaddress   exterms:city            "Bedford" .
_:johnaddress   exterms:state           "Massachusetts" .
_:johnaddress   exterms:postalCode      "01730" .

We can request the type of the object:

ex2terms:book78354   rdf:type          ex2terms:Book .
ex2terms:book78354   ex2terms:author   _:author78354 .
_:author78354        rdf:type          ex2terms:Person .
_:author78354        ex2terms:name     "Jane Smith" .

What about the specification of the data (by default all is a string)

ex:index.html  exterms:creation-date  "1999-08-16"^^xsd:date .

How does it looks in code?

1.  
2.  <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
3.              xmlns:dc="http://purl.org/dc/elements/1.1/"
4.              xmlns:exterms="http://www.example.org/terms/">

5.    <rdf:Description rdf:about="http://www.example.org/index.html">
6.         <exterms:creation-date rdf:datatype=
         "http://www.w3.org/2001/XMLSchema#date">1999-08-16

7. <dc:language>en 8. <dc:creator rdf:resource="http://www.example.org/staffid/85740"/> 9. 10.
How about a set of products?

1.   
2.   ]>
3.   xml:base="http://www.example.com/2002/04/products">

6. rdf:ID="item10245"> 7. rdf:resource="http://www.example.com/terms/Tent"/> 8. Overnighter 9. 2 10. 2.4 11. 784 12. ...other product descriptions... 13.
This is the subject:

http://www.example.com/2002/04/products#item10245

References 

http://www.w3.org/TR/rdf-primer/