RDF- Crack (RDFa, triples,FOAF) ( part 2 )

July 1, 2008

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>

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RDF – Crack ( part I )

June 29, 2008

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.

  1. RDF/XML ( for machine reading ) rdf/xml
  2. RDF/Notation3(N3) ( for human reading ) MIME type : text/rdf+n3
  3. Turtle is 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.

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns:dc="http://purl.org/dc/elements/1.1/">
  <rdf:Description rdf:about="http://www.w3.org/2001/08/rdf-test/">
    <dc:creator>Jan Grant</dc:creator>
    <dc:creator>Dave Beckett</dc:creator>
    <dc:publisher>
      <rdf:Description>
        <dc:title>World Wide Web Consortium</dc:title>
        <dc:source rdf:resource="http://www.w3.org/"/>
      </rdf:Description>
    </dc:publisher>
  </rdf:Description>
</rdf:RDF>

RDF example

N3 (Notation 3)

Notation 3 is a way of presenting semantic data in human understandable format. N3 representation of above RDF graph.

<http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/creator> <http://www.example.org/staffid/85740> .

<http://www.example.org/index.html> <http://www.example.org/terms/creation-date> "August 16, 1999" .

<http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/language> "en" .

N3 Subsets

N3 subsetsMore Information:

RDF Schema – http://www.w3.org/TR/rdf-schema/

RDF Syntax – http://www.w3.org/TR/REC-rdf-syntax/#basicconcepts

RDF – http://vanirsystems.com/danielsblog/2008/04/23/rdf-simpler-if-you-look-at-it-in-a-different-way/

http://infolab.stanford.edu/~melnik/rdf/syntax.html

http://www.w3.org/TR/rdf-syntax-grammar/#section-Syntax

Upcoming “RDF- Crack” versions will have lot of examples, details.

Zemanta Pixie

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Zemanta API & examples – over view with PHP

June 27, 2008

Zemanta provides live suggesions when you start writing blogs.  Zemanta also a browser based plugin gives you suggestions based on your text that you typing, image, url’s & more.

What is the purpose of using Zemanta ?

You can get relevant tags what you have typed.

NLP – Natural Language processing, it analyze your input text with lexical analyzer & find out the tags(/objects/names)

Based on that tags, it lists the number of URL’s/ images found related to those tags.

Input  : “text”

Output : Related URLs, Tags & images

Sample Code how it works,

Contact Zemanta & get API from them.

Live Testing URL :  http://livebillion.com/calais/test_zemanta.php

test_zemanta.php

——–

<form action=”dozemanta.php”>
<table width=”100%”>
<tr><th colspan=”2″>Testing Zemanta API</th></tr>
<tr><td>Text:</td><td>
<textarea name=”text” style=”width:500px;”></textarea>
</td></tr>
<tr><td> ——— Or ————–</td></tr>
<tr><td>URL:</td><td>
<input name=”url” type=”text” value=”" style=”width:500px;”/>
</td></tr>
<tr><td> <input type=”submit” name=”btn” value=”Extract” /></td></tr>
</table>
</form>

dozemanta.php

$url = ‘http://api.zemanta.com/services/rest/0.0/’; //Should be in a conffile
$format = ‘xml’; // May depend of your application context
$text = $_REQUEST["text"];
if($_REQUEST["url"]!=”"){
$text = strip_tags(file_get_contents($_REQUEST["url"]));
}

$key = “YOUR_API_KEY”; //Should be in a conf file
$method = “zemanta.suggest”; // May depend of your application context

$args = array(
‘method’=> $method,
‘api_key’=> $key,
‘text’=> $text,
‘format’=> $format
);

$data = “Here we build the data we want to POST to Zementa”;
foreach($args as $key=>$value)
{
$data .= ($data != “”)?”&”:”";
$data .= urlencode($key).”=”.urlencode($value);
}

/* Initialisation of curl */
$ch = curl_init();
/* Setup of the url*/
curl_setopt($ch, CURLOPT_URL, $url);
/* We want a post request */
curl_setopt($ch, CURLOPT_POST, 1);
/* Here we give to curl the data we want to send to Zementa*/
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
/* We setup the response method of curl */
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
/* Execute curl and fetch the result */
$response = curl_exec ($ch);
/* Close curl connection */
curl_close ($ch);
//echo $response;

$xmlArray = xml2array($response); // XML2ARRAY is a function to covert xml to array

// Get the top array

$content = $xmlArray["rsp"];

// Related Articles

foreach($content["articles"] as $articles){
$i = 0;
echo ‘<table width=”100%”><tr><th colspan=2>Related Articles:</th></tr>’;
foreach($articles as $article){
//echo $i;
//echo $article["url"]["value"];
echo ‘<tr><td><a href=”‘.$article["url"]["value"].’” target=”_new” >’.$article["title"]["value"].’</a></td></tr>’;
$i++;
}
//print_r($articles[0]["url"]["value"]);
echo ‘</table>’;
}

// Related Keywords

foreach($content["keywords"] as $keywords){
//print_r($markup);
$i = 0;
echo ‘<table width=”100%”><tr><th colspan=2>Keywords:</th></tr><tr><td>’;
foreach($keywords as $keyword){
//echo $i;
//echo $article["url"]["value"];
echo ‘<a href=”http://www.popdup.com/tag/’.$keyword["name"]["value"].’” target=”_new” >’.$keyword["name"]["value"].’</a>   ’;
$i++;
}
//print_r($articles[0]["url"]["value"]);
echo ‘</td></tr></table>’;
}

// Related Images

foreach($content["images"] as $images){
//print_r($markup);
$i = 0;
echo ‘<table width=”100%”><tr><th colspan=2>Images:</th></tr>’;
foreach($images as $image){
//echo $i;
//echo $article["url"]["value"];
echo ‘<tr><td><a href=”‘.$image["url_l"]["value"].’” target=”_new” ><img src=”‘.$image["url_s"]["value"].’” style=” border:0px;” /></a></td><td>’.$image["description"]["value"].’</td></tr>’;
$i++;
}
//print_r($articles[0]["url"]["value"]);
echo ‘</table>’;
}

Zemanta Pixie

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