Slide 1Slide 2Slide 3Slide 4Slide 5Pop QuizSlide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Qualified Property ValueSlide 31Pop QuizSlide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55RDF and RDF Schema – Part 2Grigoris AntoniouFrank van HarmelenEdited by Jeff PartykaEditied by Keven AtesBlank NodesAll named resources in RDF resolve to a global URI (people, courses, books, etc.)However, sometimes in an RDF graph, there is a need to model a resource that exists, but does not resolve to a global URI The resource represents the existence of something, but it does not necessarily have a name and/or URIBlank Nodes (cont)Example: Jeff may have a mobile phone, an office phone and a home phone. Each of these might have URIs. But we also want to model a generic phone resource that serves as the parent of those 3 phone numbersBlank Nodes (cont)utd:Jeff_:bn111-222-3333utd:hasPhoneutd:hasHomePhoneutd:hasOfficePhone222-333-4444333-444-5555utd:hasMobilePhoneBlank Nodes Example #2utd:Johnutd:hasResidencemap:hasCityDallasmap:hasStateTexas08859map:hasZipmap:hasAddress29 Park Lane_:bnPop QuizExample:<rdf:Description rdf:about="#KnightOwlRestaurant"> <website> <rdf:Description rdf:about="&kor;"> <webmaster>Jorge Garcia</webmaster> </rdf:Description> <website></rdf:description>Does an rdf:Description have to be followed by an rdf:about or rdf:id? Explain.Ans: No. Then it makes a blank node.RDF/XML Serialization of Blank Nodes<?xml version="1.0"?><rdf:RDF xmlns:owl="http://www.w3.org/2002/07/owl#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:utd="http://www.utdallas.edu/utd#”> <rdf:Description rdf:about=“utd:Jeff"> <utd:hasPhone> <rdf:Description> <utd:hasHomePhone>111-222-3333</utd:hasHomePhone> <utd:hasMobilePhone>222-333-4444</utd:hasMobilePhone> <utd:hasOfficePhone>333-444-5555</utd:hasOfficePhone> </rdf:Description> </utd:hasPhone> </rdf:Description></rdf:RDF>Turtle Serialization of Blank Nodes#Turtle representation of document with a blank node@prefix owl: <http://www.w3.org/2002/07/owl#> .@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.@prefix utd: <http://www.utdallas.edu/utd#>.utd:Jeff utd:hasPhone _:GeneralPhone ._:GeneralPhone utd:hasHomePhone “111-222-3333” ._:GeneralPhone utd:hasMobilePhone “222-333-4444” ._:GeneralPhone utd:hasOfficePhone “333-444-5555” .Turtle Serialization of Blank Node: Shorthand Syntax#Turtle representation of document with a blank node@prefix owl: <http://www.w3.org/2002/07/owl#> .@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.@prefix utd: <http://www.utdallas.edu/utd#>.utd:Jeff utd:hasPhone [ utd:hasHomePhone “111-222-3333” ; utd:hasMobilePhone “222-333-4444” ; utd:hasOfficePhone “333-444-5555” ] .Blank Nodes (cont)Because blank nodes do not have global names, they are given names local to the document in which they exist (local names of blank nodes always start with ‘_:’)2 different documents may refer to the same resource using different namesWhen merging these documents, there will not be a naming conflict (because local names do not apply outside of the document)Blank Nodes (cont)Blank nodes can be used as subject and objectsHowever, blank nodes cannot be a predicate in a tripleOWL uses blank nodes for restrictions, unions of classes, and intersections of classesTwo Grouping TypesRDF ContainersOpenAdhocEasy to manageRDF CollectionsClosedStructuredHarder to manageRDF ContainersContain a number of resources or attributes about which we want to make statements as a wholee.g., we may wish to talk about the courses given by a particular lecturer The content of containers are elements named rdf:_1, rdf:_2, etc. –Alternatively rdf:liThree Types of Containersrdf:Bag an unordered container, allowing multiple occurrences –e.g., members of the faculty board, documents in a folderrdf:Seq an ordered container, which may contain multiple occurrences–e.g., modules of a course, items on an agenda, an alphabetized list of staff members (order is imposed)rdf:Alt a set of alternatives (only one applies)–e.g., the document home and mirrors, translations of a document in various languages Structures are the same, semantics changeExample for a Bag <uni:lecturer rdf:ID="#949352"><uni:coursesTaught><rdf:Bag><rdf:_1 rdf:resource="#CIT1112"/><rdf:_2 rdf:resource="#CIT3116"/></rdf:Bag></uni:coursesTaught></uni:lecturer>Graph for Bag Example #949352_:123uni:coursesTaughtrdf:typerdf:_2 #CIT1112 #CIT3116rdf:_1rdf:typeuni:lecturer rdf:Bag<?xml version="1.0"?><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:s="http://example.org/students/vocab#"> <rdf:Description rdf:about="http://example.org/courses/6.001"> <s:students> <rdf:Bag> <rdf:li rdf:resource="http://example.org/students/Amy"/> <rdf:li rdf:resource="http://example.org/students/Mohamed"/> <rdf:li rdf:resource="http://example.org/students/Johann"/> <rdf:li rdf:resource="http://example.org/students/Maria"/> <rdf:li rdf:resource="http://example.org/students/Phuong"/> </rdf:Bag> </s:students> </rdf:Description></rdf:RDF>ExampleXML and Graph_:bnExample for Alternative<uni:course rdf:ID="CIT1111"><uni:lecturer><rdf:Alt><rdf:li rdf:resource="#949352"/><rdf:li rdf:resource="#949318"/></rdf:Alt></uni:lecturer></uni:course>RDF CollectionsConsider the turtle snippet below:@prefix ex: <http://example.com/> .@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .@prefix people: <http://www.semwebprogramming.net/people/> .@prefix foaf: <http://xmlns.com/foaf/0.1/> .ex:Authors a rdf:Bag ; rdf:_1 people:Ryan ; rdf:_2 people:Matt ; rdf:_3 people:Andrew ; rdf:_4 people:John .ex:Book ex:writtenBy ex:Authors .RDF Collections (cont)If the graph represented by that syntax was merged with the graph representing this syntax:Then, the resulting graph would show that this author was actually one of the authors when he should not be@prefix ex: <http://example.com/> .ex:Authors rdf:_5 ex:SomeOtherPersonThatIsntAnAuthor .RDF