Post on 24-Dec-2015
transcript
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
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?