Semantic Web Bootcamp

Dominic DiFranzoPhD Student/Research AssistantRensselaer Polytechnic InstituteTetherless World Constellation

http://tw.rpi.edu/portal/Mashathon

Interwebs?

Internet – graph of computers connected to one another

Web – graph of documents hyper-linked to one another

Semantic web – graph of concepts/ideas/data linked together by named relations.

128.21.52.3

122.121.53.13

138.41.32.13

122.11.32.43

125.71.26.73

128.21.52.3

122.121.53.13

138.41.32.13

122.11.32.43

125.71.26.73

128.21.52.3

122.121.53.13

138.41.32.13

122.11.32.43

125.71.26.73

Example.com

Cat.com/new.html dog.com/dog.html

Hat.com/hog.html

Dig.net/log.html

http://difranzo.com/index http://rpi.edu/~hendler

http://difranzo.com/index http://rpi.edu/~hendler

http://example.com/isAdvisedBy

Example.com

Cat.com/new.html dog.com/dog.html

Hat.com/hog.html

Dig.net/log.html

RDF•Triple: Subject Predicate Object

•Use URI for universal naming

•New York has the postal abbreviation NY

•<urn:x-states:New%20York> <http://purl.org/dc/terms/alternative> "NY" .

urn:x-states:New%20York

“NY”http://purl.org/dc/terms/alternative

serialize in many ways

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dcterms="http://purl.org/dc/terms/">

<rdf:Description rdf:about="urn:x-states:New%20York"> <dcterms:alternative>NY</dcterms:alternative>

</rdf:Description></rdf:RDF>

Linking

•I found a new dataset and it has the following triple

•<http://dbpedia.org/page/New_York> <http://dbpedia.org/ontology/Place/otherName> “The Empire State” .

http://dbpedia.org/page/New_York

“The Empire State”

http://dbpedia.org/ontology/Place/otherName

owl:sameAS

•<urn:x-states:New%20York> <http://www.w3.org/2002/07/owl#sameAs> <http://dbpedia.org/page/New_York> .

urn:x-states:New%20York http://dbpedia.org/page/New_York

http://www.w3.org/2002/07/owl#sameAs

“NY” “The Empire State”

Linked Datadecentralized - sources may be spread out

and referenced across the Web modular - linked without advance planning

or coordination scalable - once store in place, it’s easy to

extend advantages hold even when definitions and

structure of the data changes over time.

Other Sem Web Tech Resource Description Framework Schema

(RDFS)

Defining the vocabularies intended to be used in RDF

class, property, type, subClassOf, range, and domain

Allows for reasoning over data

• Web Ontology Language (OWL)

• more expressive ontologies and more complex reasoning of them

Sparql

•SPARQL is a query language for the Semantic Web.

Sparql

SELECT ?node ?title WHERE{  ?node <http://purl.org/dc/elements/1.1/title> ?title . } LIMIT 1

?node

http://purl.org/dc/elements/1.1/title

?title

Long! SELECT ?node ?name WHERE{  ?node <http://xmlns.com/foaf/0.1/givenname> ?name .  ?node <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> . } LIMIT 10

?node

http://purl.org/dc/elements/1.1/title

?title

foaf:Person

http://www.w3.org/1999/02/22-rdf-syntax-ns#type

Prefix

PREFIX foaf: <http://xmlns.com/foaf/0.1/>PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT ?node ?name WHERE{  ?node foaf:givenname ?name .  ?node rdf:type foaf:Person . } LIMIT 10

Shortcuts

PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT ?node ?name WHERE{  ?node foaf:givenname ?name ; rdf:type foaf:Person . } LIMIT 10

Graphs

Named Graph

PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT ?graph ?node ?title WHERE{ GRAPH ?graph{  ?node dc:title ?title . } } LIMIT 3

Named GraphPREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT  ?node8 ?desc8 ?node401 ?desc401 WHERE{ GRAPH <http://data-gov.tw.rpi.edu/vocab/Dataset_401>{  ?node401 dc:description ?desc401 . } GRAPH <http://data-gov.tw.rpi.edu/vocab/Dataset_8>{  ?node8 dc:description ?desc8 . } } LIMIT 3

Union PREFIX dc: <http://purl.org/dc/elements/1.1/> SELECT  ?node8 ?desc8 ?node401 ?desc401 WHERE{ { GRAPH <http://data-gov.tw.rpi.edu/vocab/Dataset_401>{  ?node401 dc:description ?desc401 . } }UNION{ GRAPH <http://data-gov.tw.rpi.edu/vocab/Dataset_8>{  ?node8 dc:description ?desc8 . } } } LIMIT 3

Optional

PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT  ?node ?name ?givenname WHERE{  ?node foaf:name ?name . OPTIONAL{  ?node foaf:givenname ?givenname . } }

Filter

PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT  ?node ?name ?givenname WHERE{  ?node foaf:name ?name .  ?node foaf:givenname ?givenname . FILTER regex(?name, "Biden") . }

SPARQLProxy

This is a web service that allows you to query any SPARQL endpoint, and get back the results in any format you want.

A RESTful way to query any endpoint in any environment.

SPARQLProxyhttp://logd.tw.rpi.edu/sparql?Paramiters:query: [required] encoded String of SPARQL queryquery-uri :[required] URI of SPARQL query (use as an

alternative to "query" parameter. These two parameters are mutul-exclusive)

SPARQLProxyservice-uri: [required] URI of SPARQL Endpoint – default

is the LOGD endpoint

output: output format. ''xml'' - SPARQL/XML (default) : ''exhibit'' - JSON for MIT Exhibit : ''gvds'' - JSON for Google Visualization : ''csv'' - CSV : ''html'' - HTML table : “sparql” - SPARQL JSON

Examplehttp://logd.tw.rpi.edu/sparql.php?query-

option=text&query=PREFIX+conversion%3A+%3Chttp%3A%2F%2Fpurl.org%2Ftwc%2Fvocab%2Fconversion%2F%3E%0D%0ASELECT+%3Fg+sum%28+%3Ftriples+%29+as+%3Festimated_triples%0D%0AWHERE+{%0D%0A++GRAPH+%3Fg++{%0D%0A+++%3Fg+void%3Asubset+%3Fsubdataset+.%0D%0A+++%3Fsubdataset+conversion%3Anum_triples+%3Ftriples+.%0D%0A++}%0D%0A}+%0D%0AGROUP+BY+%3Fg%0D%0A&service-uri=&output=html&callback=&tqx=&tp=

Example// compose query $sparqlproxy_uri = "http://logd.tw.rpi.edu/ws/sparqlproxy.php" $params = array(); $params["query-uri"] = "http://logd.tw.rpi.edu/demo/retrieving-sparql-results/datagov-list-loaded-dataset.sparql"; $params["service-uri"] = "http://services.data.gov/sparql"; $params["output"] = "gvds"; $query= $sparqlproxy_uri."?". http_build_query($params,,'&') ; //specific for Drupal //show query result echo file_get_contents($query);

Try some on your own

Questions?