RDF & SPARQL Introduction Dongfang Xu Ph.D student, School of Information, University of Arizona Sept 10, 2015

Catalog Semantic Web RDF RDF Schema SPARQL

Semantic Web The Limits of today’s Web (2.0): 1.High recall and low precision; 2. Low recall and even on recall; 3. Results are highly sensitive to vocabulary. 4. Single Web pages. Reference: Antoniou, G., & Van Harmelen, F. (2008). A semantic web primer (2 nd ed.). Cambridge, Mass: MIT press.

Semantic Web What can be done?

Semantic Web The Semantic Web Technologies (standard technologies ): 1.Format the web content. 2.Relate the data Machine-processable web information

Semantic Web Physiotherapy Agilitas Physiotherapy Centre Lisa Davenport Steve Matthews Kelly Townsend

XML & RDF David Billing David Billing”> Discrete Mathematics David Billing Discrete Mathematics XML does not provide any means of talking about the semantics (meaning) of data

Catalog Semantic Web RDF RDF Schema SPARQL

What is RDF? A data model for objects (“resources”) and relations between them; Provides a simple semantics for the data model; The model can be represented in an xml syntax. Basic building block is an object-attribute-value triple, called statement. RDF

<River id="Yangtze" xmlns=" kilometers western China's Qinghai-Tibet Plateau East China Sea XML Modify the following XML document so that it is also a valid RDF document: <rdf:RDF xmlns:rdf=" xmlns=" <rdf:Description rdf:ID="Yangtze" 6300 kilometers western China's Qinghai-Tibet Plateau East China Sea RDF Yangtze.xml Yangtze.rdf "convert to"

RDF Data Model As you read the RDF literature you may see the following terminology: Subject: this term refers to the item that is playing the role of the resource. predicate: this term refers to the item that is playing the role of the property. Object: this term refers to the item that is playing the role of the value. Subject Object predicate Resource Value property Equivalent! <rdf:Description rdf:ID="Yangtze" 6300 kilometers

RDF resource A Resource is any object identifiable by a URI. 1.Resources can use any URI, e.g.: URI-s can also use different forms: CIT11111 =( CIT11111) The resource is defined like below, with Usually means referencing an existing resource; means creating a new resource;

RDF resource Discrete Mathematics David Bill Associate Professor Resource reference

RDF property & value Property value must be a Literal or a Resource Discrete Mathematics property Value

RDF element 1.Root element <rdf:RDF xmlns:rdf=" xmlns:cd=" 2. Description element define resource 3. Property eelement define attribute 4. Bag/Seq/Alt element define a few attributes within the property. See more:

Catalog Semantic Web RDF RDF Schema SPARQL

RDF Schema  RDF schema is a vocabulary description language for describing properties and classes of RDF resources, with a semantics for generalization hierarchies of such properties and classes.  RDF Schema is a primitive ontology language.  RDFS will use RDF itself to define the semantics of particular domain.

RDF Schema

Catalog Semantic Web RDF RDF Schema SPARQL

 SPARQL is the query language to search resource & value;  It is based on matching graph patterns ( like RDF triple pattern, but the resource and value can be variable) ?res uni:phone ?pho  use “?” to define variable, for both string and numeric type  Like in SQL, it has a Select-From-Where structure.

SPARQL PREFIX rdf: PREFIX uni: (namespace make quries shorter and easier to read) Select ?X Where { ?x uni: phone : }

SPARQL Select ?X ?Y Where { ?x uni: phone ?y }

SPARQL Select ?name ?Y Where { ?X rdf:type uni:Lecturer; uni: name ?name. ?X uni: phone ?Y. }

SPARQL Select ?name ?Y Where { ?X rdf:type uni:Lecturer; uni: name ?name. ?X uni: phone ?Y. OPTIONAL{?X uni:phone ?Y} }

SPARQL Select ?Y Where { ?X rdf:type uni:Lecturer; uni: name :David Bill. ?C uni: phone ?Y. Filter(?X=?C) }

SPARQL

1.SPARQL has several query forms. 2.The CONSTRUCT query form returns an RDF graph.

SPARQL More resources:

Thank you! Q&A