Semantic Web Applications

Semantic Web Applications dev8D 2009

About Me
Julian Higman
Talis Information Ltd
Building semantic web applications for libraries and educational institutions
[email_address]
http://julianhigman.com/blog

About this talk
The Semantic Web and why it’s needed
Linked Open Data
Ontologies, RDF and Sparql
What we’ve built and how we built it
Hints and Tips
More info

The Semantic Web
Web of Data
Machine readable
Structured, distributed, linked
Co-exists with web of documents

Why it’s needed
Linking silos of data
Social networks demonstrate problem
Querying over combined sets of data
Data mashups

Linked Open Data
“ Best practice for exposing, sharing and connecting pieces of data, information and knowledge on the Semantic Web using URIs and RDF” (Wikipedia)
Identify resources with unique URIs
Make URIs dereferenceable
Link to other data sets

Linked Open Data

Ontologies
RDF
FOAF
SIOC
Bibliontology
Dublin Core
SKOS
AIISO

RDF
Subject – Predicate – Object
<http://talis.com/jhigman> <http://xmlns.com/foaf/0.1/name> “julian”
Several representations
RDX/XML
Turtle
N3

RDFXML
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:foaf="http://xmlns.com/foaf/0.1/">
<rdf:Description rdf:about="http://life.ac.uk/people/benstongeorgej">
<rdf:type rdf:resource="http://xmlns.com/foaf/0.1/Person"/>
<foaf:name>Benston, George J.</foaf:name>
</rdf:Description>
</rdf:RDF>

SPARQL
DESCRIBE <http://life.ac.uk/people/benstongeorgej>
PREFIX aiiso: <http://purl.org/vocab/aiiso/schema#>
DESCRIBE <$institution> ?s
WHERE { <$institution> aiiso:organisationalUnit ?s }

RDF Libraries
ARC2 (PHP)
Jena (Java)
Python, Ruby, etc

What we’ve built
Talis Aspire
Resource list management
Collect, organise, share course reading materials
http:// blogs.talis.com /aspire/

http://life.ac.uk/lists/abf203.html

http://life.ac.uk/items/abf203-1.html

http://life.ac.uk/items/abf203-1.rdf

http://life.ac.uk/items/abf203-1.json
{
"http://life.ac.uk/resources/id3781" : {
"http://www.w3.org/1999/02/22-rdf-syntax-ns#type" : [
{ "value" : "http://purl.org/ontology/bibo/WebPage", "type" : "uri" }
],
"http://purl.org/vocab/resourcelist/schema#list" : [
{ "value" : "http://life.ac.uk/lists/abf203", "type" : "uri" }
],
"http://purl.org/ontology/bibo/uri" : [
{ "value" : "http://www.google.co.uk/products?q=Elliott+and+Elliott+Financial+reporting+and+accounting+12th+edition&hl=en&cr=countryUK%7CcountryGB&um=1&sa=X&oi=froogle&ct=title", "type" : "uri" }
],
"http://purl.org/dc/terms/title" : [
{ "value" : "Elliott and Elliott Financial reporting and accounting 12th edition - Google Product Search", "type" : "literal" }
]
},

A closer look at the RDF
xmlns:ns1="http://rdfs.org/sioc/spec/"
xmlns:ns2="http://purl.org/vocab/resourcelist/schema#"
xmlns:ns3="http://purl.org/vocab/lifecycle/schema#"
xmlns:ns4="http://purl.org/dc/terms/"
xmlns:ns5="http://purl.org/ontology/bibo/"
<rdf:Description rdf:about="http://life.ac.uk/items/abf203-46">
<ns2:resource rdf:resource="http://life.ac.uk/resources/id3787"/>
<ns1:note>This the most recent edition</ns1:note>
<ns3:state rdf:resource="http://purl.org/vocab/resourcelist/schema#status-published"/>
<ns1:has_container rdf:resource="http://life.ac.uk/sections/abf203-9"/>
<ns2:list rdf:resource="http://life.ac.uk/lists/abf203"/>
<rdf:type rdf:resource="http://purl.org/vocab/resourcelist/schema#Item"/>
</rdf:Description>
<rdf:Description rdf:about="http://life.ac.uk/resources/id3787">
<ns2:list rdf:resource="http://life.ac.uk/lists/abf203"/>
<ns4:title>Elliott and Elliott Financial reporting and accounting 12th edition</ns4:title>
<ns5:uri rdf:resource="http://www.google.co.uk/products?q=Elliott+and+Elliott"/>
<rdf:type rdf:resource="http://purl.org/ontology/bibo/WebPage"/>
</rdf:Description>

Query the store
<?php
require_once ( '../src/data/sparql-functions.php' );
$institution = $conceptUri;
$query = "PREFIX aiiso: <http://purl.org/vocab/aiiso/schema#>
DESCRIBE <$institution> ?s WHERE { <$institution> aiiso:organisationalUnit ?s }";
$rdfxml = query_store_xml($tenant->listStore, $query);
$triples = parse_to_triples_array($rdfxml);
?>

Render HTML page
<?php
if (resourceHasProperty($triples, $conceptUri, ONT_aiiso. 'description' ))
{
echo '<p id="Description">' . getFirstValue($triples, $conceptUri, ONT_aiiso. 'description' ) . '</p>' ;
}
if (resourceHasProperty($triples, $conceptUri, ONT_resource. 'usesList' ))
{
echo '<h2 id="Lists-header">Lists</h2>' ;
echo '<ul id="lists">' ;
foreach ($triples["$conceptUri"][ONT_resource. 'usesList' ] as $list)
{
$name = $triples[$list[ 'value' ]][ONT_sioc. 'name' ][0][ 'value' ];
echo “<li class="List"><a href="{$list['value']}“ title="".trim($name)."">{$name}</a></li>";
}
echo '</ul>' ;
}
?>

Render RDF page
<?php
header( 'Content-Type: application/rdf+xml; charset=UTF-8' );
echo $rdfxml;
?>

Hint and Tips
Reuse existing ontologies
essential
Create and publish an ontology
but only if you need to
Include links to other ontologies
owl:sameAs

Hints and Tips
The data is not yours
expect incomplete data
expect extra data
expect multiple values
Avoid strong typing
#ResourceList can also be #Seq

Hints and Tips
URIs are Nouns not Verbs
permalinks for resources
HTTP methods
GET, POST, PUT, DEL
Use HTTP codes
404 if resource not found
303 (See Also) to redirect
405 Method Not Allowed
etc

Hints and Tips
Writing data is more difficult than reading it
If data is gathered from many sources, who owns the triples?
How do you indicate which triples are to be replaced and which are to be added?
SPARQL Update, Changesets

Hints and Tips
Editing with RDFa
rdfQuery library (by Jeni Tennison)
Markup html with RDFa
Edit elements in the browser
Extract new RDF model
Post new model to server

Hints and Tips
<ol class="list" id="theList"
xmlns:tenant="http://purl.org/ontology/tenant/1.0/"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:sioc="http://rdfs.org/sioc/spec/"
xmlns:resource="http://purl.org/vocab/resourcelist/schema#"
xml:lang="en"
about="[tenant:lists/abf203]"
typeof="resource:List rdf:Seq">
<li class="section" id="section-abf203-1" typeof="resource:Section rdf:Seq" about="[tenant:sections/abf203-1]">
<div class="sectionDetails">
<span class="sequenceNumber" rev="rdf:_1" resource="[tenant:lists/abf203]"></span>
<span rev="resource:contains" resource="[tenant:lists/abf203]"></span>
<span class="hasParent" rel="sioc:has_parent" resource="[tenant:lists/abf203]"></span>
<span class="name" property="sioc:name">Recommended Text</span>
<ol id="section-abf203-1-items" class="sectionItems">
<li class="item" id="item-abf203-1">
<div typeof="resource:Item" about="[tenant:items/abf203-1]">
<span rev="resource:contains" resource="[tenant:lists/abf203]"></span>

Getting Started
Talis Platform triple store
http://n2.talis.com/
Moriarty PHP platform access library
http://code.google.com/p/moriarty/

More
dbpedia
Open Calais
Search Monkey
Twine
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Semantic Web Applications

by jhigman on Feb 22, 2009

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Semantic Web Applications — Presentation Transcript