RDF is a way of presenting knowledge, relationship or a thing in the format of triples. For everything in the web will be represented as a triples format. As we know about grammer we read it in our child hood, like every basic sentence is represented as format of triples. That means subject, predicate & objects.
FOAF:
FOAF is the vocabulary to represent RDF the objects & relationship between them. FOAF is a way of describing a person / company. FOAF is Friend of A friend using RDF to represent its data. It will describe a person in the following way.
nandakumar -> is -> http://www.desiji.com/ndotnanda
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:foaf="http://xmlns.com/foaf/0.1/">
<foaf:Person>
<foaf:name>Nandakumar</foaf:name>
<foaf:mbox rdf:resource="http://www.desiji.com/ndotnanda"/>
</foaf:Person>
</rdf:RDF>
N3 Notation & triples:
A syntax to represent RDF.
@prefix pref <http://www.example.org/vacobulary #>.
<#nandakumar><pref:working><#ndot>
RDFa:
RDFa is way to integrate RDF into XHTML pages. It reduces the lot of work & difficulties for
normal people those who want to represent their blog / personal data into semantic web. RDFa helps
them to represent their information to semantic web with XTHML. we can take an small example about
how we can represent a data with RDFa,
Here we are going to explain a FOAF integration into XHTML page.
Triples:
Nandakumar knows Preethi
RDFa:
<body xmlns:foaf="http://xmlns.com/foaf/0.1">
<span about="#Nandakumar" property="foaf:name">
Nandakumar Somasundaram
</span>
</body>
Triple : Nandakumar -> Name -> Nandakumar Somasundaram
RDFa : example 2<body xmlns:foaf="http://xmlns.com/foaf/0.1">
<span about="#Nandakumar" property="foaf:name">
Nandakumar Somasundaram
</span>
<span about="#Preethi" property="foaf:name">
Preethi
</span>
<span about="#Nandakumar" rel="foaf:knows" resource="#Preethi">
Nandakumar is classmate of preethi
</span
</body>
Resource Description Framework – is the w3c standard, language to describe information in (semantic) web.Is it a new language / structure that we have to read? Absolutely not. It’s an XML /N3 format of representing the data.
RDF is about describing relationship between web resources ex. URLs. It will be represented as triples format.
Basic Structure:
http://www.desiji.com/ndotnanda has a profile whose value is Nandakumar Somasundaram
It is in triples format.
the subject is the URL http://www.desiji.com/ndotnanda
the predicate is the word “profile”
the object is the phrase “Nandakumar Somasundaram”
Normally RDF data is represented as triples Triples are a sequence of (subject, predicate, object) terms. N-Triples is a line-based, plain text format for encoding an RDF graph.
There are few ways to define RDF data.
RDF/XML ( for machine reading ) rdf/xml
RDF/Notation3(N3) ( for human reading ) MIME type : text/rdf+n3
Turtleis a subset of N3 to represent the RDF data
RDF/XML representation: RDF defines a specific XML markup language, referred to as RDF/XML, for use in representing RDF information, and for exchanging it between machines.
Posted by ndotnanda 
Posted by ndotnanda 