Semantic web – programmer’s approach

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>

Leave a Comment » | Application Samples, Basics of semantic web | Tagged: Semantic Web, rdf, rdfa, foaf, triples | Permalink
Posted by ndotnanda

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.

RDF/XML ( for machine reading ) rdf/xml
RDF/Notation3(N3) ( for human reading ) MIME type : text/rdf+n3
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 subsets More 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.

1 Comment | Basics of semantic web | Tagged: Semantic Web, Resource Description Framework, VML, Resource, XML, Wikipedia, Canberra, Windows Media Video, Machine-readable, rdf, N3, turtle, N-triples | Permalink
Posted by ndotnanda

Open Calais API & examples – PHP

June 27, 2008

Open Calais is a rapidly growing toolkit of capabilities that allow you to readily incorporate state-of-the-art semantic functionality within your blog & provide more or less same functionality as what zemanta guys do.

Open calais use NLP to manipulate user’s queries. They are giving API access to multiple languages. Here i can explain the samples with php.

Live URL : http://livebillion.com/calais/

index.php

URL : <input type=”text” name=”url” value=”" /> <input type=”submit” name=”submit” value=”Get Tags!” />

</form>

octest.php

$apikey = “XXXXXXXXXX”;

$oc = new OpenCalais($apikey);

if(isset($_REQUEST["url"])){
$content = file_get_contents($_REQUEST["url"]);
}

//echo $content;

$entities = $oc->getEntities($content);

foreach ($entities as $type => $values) {

echo “<b>” . $type . “</b>”;
echo “<ul>”;

foreach ($values as $entity) {
echo “<li>” . $entity . “</li>”;
}

echo “</ul>”;

}

opencalais.php

http://www.dangrossman.info/open-calais-tagsopen-calais-tags
All the best

Leave a Comment » | Application Samples | Tagged: Fixer, Free, Hosted Components and Services, Hosting, Redirects, Uniform Resource Locator, Web Design and Development, Zen master | Permalink
Posted by ndotnanda

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>’;
}

Leave a Comment » | Application Samples | Tagged: Keyword, know3, Languages, Natural language processing, Programming, Semantic Web, WordPress, Zemanta ltd. | Permalink
Posted by ndotnanda

Buzzwords of semantic web

June 26, 2008

Since 2000, people are talking much about semantic web, web 2, web 3 .. what are the buzzwords behind the semantic web ?

semantic web – a meaning of web by the web itself. Making the web understandable by machines.

RDF - Resource Description Framework – W3C Standards to descripe anything in semantic web – it is an XML - RDF is a directed, labeled graph data format for representing information in the Web

FOAF - Friend Of A Friend – W3C standards to describe people & networks, the links between them and the things they create and do

SIOC - Semantically interconnected Online Communities - a Semantic Web ontology for representing rich data from the Social Web in RDF

OWL - Web Ontology Language (Ontology – representation of a set of concepts within a domain and the relationships between them) – it is a family of ontologies to describe semantic web – OWL ontologies are most commonly serialized using RDF/XML syntax

SPARQL - SPARQL Protocol and RDF Query Language , is an RDF query language

Linked Open Data – is a community lead effort to create openly accessible, and interlinked, RDF Data on the Web

APML - allows users to share their own personal Attention Profile

Attention Profile – A profile that have build with a combination of your Semantic data

Open ID - open decentralized ID system that provides single access to the web

OAuth - OAuth is a simple way to publish and interact with protected data. It’s also a safer and more secure way for people to give you access.

Single Sign ON (SS0) - a secured authentication for over the web.

Data Portability – a mixing of open standars inclucing RDF,OPML,Micro formats,APML,OpenID ..

Microformats - Designed for humans first and machines second, microformats are a set of simple, open data formats built upon existing and widely adopted standards

NLP – Natural Language Processing - handling human languages

Some Buzz Applications :

know3 – http://www.know3.com

Twine – http://www.twine.com

powerset – http://www.powerset.com

Yahoo Search Monkey

DBpedia

freebase

radarnetworks

trueknowledge.com

talis platform

opencalais

Data Portability.org

zemanta.com

Add more applications & buzzwords & comments to make this a library for beginners .. thanks for reading this..

Leave a Comment » | Basics of semantic web, Uncategorized | Tagged: dbpedia, know3, SPARQL | Permalink
Posted by ndotnanda