Introduction to the Semantic Web - 010PHP February 2019

Joind.in: https://joind.in/talk/53955

What if we could evolve our web of individual documents and data to a web of interlinked knowledge, a web where machines can automatically combine data from multiple sources and draw conclusions from it? The Semantic Web technologies from W3C enable us to make sense of the data wilderness on the web and unlock the full potential of the data treasures hidden in it.

In this talk, we will see how RDF enables us to formally describe the meaning of data and how such data can be queried with SPARQL. We will look at how OWL lets us make more expressive statements about the world, so that a computer can logically reason about it and infer new information. We will demonstrate these technologies by showing how they can be used to query seemingly incompatible data sets as if they were one and letting a computer draw logical (and perhaps surprising) conclusions for us.

Contains: 'retro' technology, linked data, fundamental properties of the web, and Donald Trump's opinion on PHP frameworks.

Transcript

1. Introduction to the Semantic Web @arnoutboks Arnout Boks #010php 14-02-2019
2. @arnoutboks #010php What this talk is NOT about…
3. @arnoutboks #010php Finding info on the web An example
4. @arnoutboks #010php “Web 1.0”
5. @arnoutboks #010php “Web 1.0”
6. @arnoutboks #010php “Web 1.0”
7. @arnoutboks #010php Web 1.0 Web of Documents for human consumption
8. @arnoutboks #010php “Web 2.0” Feed of events • iCalendar or vCalendar? • Different types of events?
9. @arnoutboks #010php “Web 2.0” Weather forecast API • XML or JSON? • Which fields and properties? • Which units?
10. @arnoutboks #010php Web 2.0 Web of (individual) API’s for consumption by specialized software
11. @arnoutboks #010php Semantic web • Question to agent (e.g. Siri, Google Assistant) • Agent searches across different sources • Agent combines data • Agent answers question
12. @arnoutboks #010php Semantic Web (“Web 3.0”?) Web of Linked Data for consumption by intelligent agents/PA’s
13. @arnoutboks #010php Revolutionary? Term coined by Tim Berners-Lee in 2001
14. @arnoutboks #010php Revolutionary? Based on W3C-standards • RDF (1998) • RDFS (1998) • SPARQL (2008) • OWL (2004) • …
15. @arnoutboks #010php RDF Cornerstone of the Semantic Web Resource Description Framework Cornerstone of the Semantic Web
16. @arnoutboks #010php Records statements about things
17. @arnoutboks #010php RDF allows reading, merging, relaying and inferring statements without fully understanding them
18. @arnoutboks #010php RDF (triples) Subject Predicate Object
19. @arnoutboks #010php RDF (triples) Subject Predicate Object Arnout worksAt Moxio
20. @arnoutboks #010php RDF (triples) Subject Predicate Object Arnout worksAt Moxio Arnout twitterHandle “@arnoutboks” Arnout livesIn Delft Delft cityIn The Netherlands Moxio basedIn Delft
21. @arnoutboks #010php RDF (graph) Arnout Moxio Delft @arnoutboks worksAt basedIn The Netherlands Subject Predicate Object Arnout worksAt Moxio Arnout twitterHandle “@arnoutboks” Arnout livesIn Delft Delft cityIn The Netherlands Moxio basedIn Delft
22. @arnoutboks #010php Merging RDF (triples) Subject Predicate Object Arnout worksAt Moxio Arnout twitterHandle “@arnoutboks” Arnout livesIn Delft Delft cityIn The Netherlands Moxio basedIn Delft Subject Predicate Object The Netherlands hasCapital Amsterdam The Netherlands population “17.000.000”
23. @arnoutboks #010php Merging RDF (triples) Subject Predicate Object Arnout worksAt Moxio Arnout twitterHandle “@arnoutboks” Arnout livesIn Delft Delft cityIn The Netherlands Moxio basedIn Delft The Netherlands hasCapital Amsterdam The Netherlands population “17.000.000”
24. @arnoutboks #010php Merging RDF (graph) Arnout Moxio Delft @arnoutboks worksAt basedIn The Netherlands Amsterdam hasCapital 17.000.000 population
25. @arnoutboks #010php Serializing RDF: Turtle @prefix : <http://www.example.com/#> . @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax- ns#> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . @base <http://www.example.com/> . :Arnout :livesIn :Delft ; :worksAt :Moxio ; :twitterHandle "@arnoutboks"^^xsd:string . :Delft :cityIn :The_Netherlands . :Moxio :basedIn :Delft .
26. @arnoutboks #010php Serializing RDF: RDF/XML <?xml version="1.0"?> <rdf:RDF xmlns="http://www.example.com/#" <!-- ... -->> <rdf:Description rdf:about="http://www.example.com/#Arnout"> <twitterHandle rdf:datatype="http://www.w3.org/2001/XMLSchema#string">@a rnoutboks</twitterHandle> <worksAt rdf:resource="http://www.example.com/#Moxio"/> <livesIn rdf:resource="http://www.example.com/#Delft"/> </rdf:Description> <!-- ... --> </rdf:RDF>
27. @arnoutboks #010php Serializing RDF: JSON-LD [ { "@id" : "http://www.example.com/#Arnout", "http://www.example.com/#livesIn" : [ { "@id" : "http://www.example.com/#Delft" } ], "http://www.example.com/#twitterHandle" : [ { "@value" : "@arnoutboks" } ], "http://www.example.com/#worksAt" : [ { "@id" : "http://www.example.com/#Moxio" } ] }, ... ]
28. @arnoutboks #010php RDF is an abstract data model with different serialization formats
29. @arnoutboks #010php Identity Because there are multiple things named “Amsterdam”
30. @arnoutboks #010php Identity Subject Predicate Object Amsterdam numberOfGuns “42” Amsterdam status Wrecked National Maritime Museum (“Scheepvaartmuseum”)
31. @arnoutboks #010php Identity Subject Predicate Object Amsterdam numberOfGuns “42” Amsterdam status Wrecked Subject Predicate Object The Netherlands hasCapital Amsterdam The Netherlands population “17.000.000” National Maritime Museum (“Scheepvaartmuseum”) Lonely Planet
32. @arnoutboks #010php Identity The Netherlands Amsterdam hasCapital 17.000.000 population 42 Wrecked
33. @arnoutboks #010php URI’s for namespacing National Maritime Museum (“Scheepvaartmuseum”) https://www.hetscheepvaartmuseum.nl/ships/Amsterdam https://www.hetscheepvaartmuseum.nl/ships/numberOfGuns Lonely Planet https://www.lonelyplanet.com/Amsterdam https://www.lonelyplanet.com/hasCapital
34. @arnoutboks #010php Prefixes & QNames lonelyplanet:Amsterdam === https://www.lonelyplanet.com/Amsterdam QName URI local name local name namespace prefix
35. @arnoutboks #010php Prefixes & QNames National Maritime Museum (“Scheepvaartmuseum”) nmm:Amsterdam nmm:numberOfGuns Lonely Planet lonelyplanet:Amsterdam lonelyplanet:hasCapital
36. @arnoutboks #010php Three fundamental laws of the (Semantic) Web
37. @arnoutboks #010php Different name, different concept? lonelyplanet-en:Brussels lonelyplanet-nl:Brussel lonelyplanet-fr:Bruxelles lonelyplanet-zh:布魯塞爾
38. @arnoutboks #010php Different name, different concept? mi6:007 mi6:JamesBond
39. @arnoutboks #010php Nonunique Naming Assumption Different names do not imply different concepts
40. @arnoutboks #010php Truth & authority Subject Predicate Object whitehouse:Obama nsa:tapped whitehouse:Trump Donald Trump
41. @arnoutboks #010php Truth & authority Subject Predicate Object php-fig:CakePHP fw:isBetterThan php-fig:Symfony Donald Trump
42. @arnoutboks #010php The AAA Slogan “[On the web] Anyone can say Anything about Any topic”
43. @arnoutboks #010php (this slide intentionally left blank)
44. @arnoutboks #010php Absence of information Subject Predicate Object whitehouse:Trump fw:knows php-fig:Symfony whitehouse:Trump fw:knows php-fig:CakePHP whitehouse:Trump fw:knows php-fig:CodeIgniter
45. @arnoutboks #010php Open World Assumption We never have all information
46. @arnoutboks #010php SPARQL Query language for Semantic Web data
47. @arnoutboks #010php Triple Store Database for RDF triples
48. @arnoutboks #010php SPARQL SELECT ?employee ?company WHERE { ?employee :worksAt ?company . ?company :basedIn :Delft . }
49. @arnoutboks #010php SPARQL SELECT ?employee ?company WHERE { ?employee :worksAt ?company . ?company :basedIn :Delft . } ?employee ?company :Arnout :Moxio
50. @arnoutboks #010php SPARQL SELECT ?employee ?company ?city WHERE { ?employee :worksAt ?company . ?company :basedIn ?city . ?employee :livesIn ?city . } ?employee ?company ?city :Arnout :Moxio :Delft
51. @arnoutboks #010php Online SPARQL endpoints http://dbpedia.org/sparql
52. @arnoutboks #010php Online SPARQL endpoints
53. @arnoutboks #010php Online SPARQL endpoints PREFIX dbo: <http://dbpedia.org/ontology/> PREFIX dbr: <http://dbpedia.org/resource/> SELECT ?song ?runtime WHERE { ?song dbo:artist dbr:The_Beatles . ?song dbo:runtime ?runtime . ?song rdf:type dbo:Song . } ORDER BY DESC (?runtime)
54. @arnoutboks #010php Online SPARQL endpoints
55. @arnoutboks #010php Online SPARQL endpoints PREFIX dbo: <http://dbpedia.org/ontology/> PREFIX dbr: <http://dbpedia.org/resource/> SELECT ?ancestor WHERE { dbr:Willem-Alexander_of_the_Netherlands dbo:parent+ ?ancestor . }
56. @arnoutboks #010php RDF Schema Schema language for Semantic Web data
57. @arnoutboks #010php RDF Schema (RDFS) Describes the structure of RDF-data… in RDF • Classes • Properties • Domain and range of properties • Inheritance of classes • ‘Inheritance’ of properties
58. @arnoutboks #010php RDF Schema (RDFS) Subject Predicate Object :DonaldTrump :isFatherOf :IvankaTrump
59. @arnoutboks #010php RDF Schema (RDFS) Subject Predicate Object :DonaldTrump :isFatherOf :IvankaTrump :isFatherOf rdfs:range :Person :isFatherOf rdfs:domain :Father :Father rdfs:subclassOf :Parent :Parent rdfs:subclassOf :Person :isFatherOf rdfs:subpropertyOf :isParentOf
60. @arnoutboks #010php RDF Schema & Inference Subject Predicate Object :DonaldTrump :isFatherOf :IvankaTrump :isFatherOf rdfs:range :Person :isFatherOf rdfs:domain :Father :Father rdfs:subclassOf :Parent :Parent rdfs:subclassOf :Person :isFatherOf rdfs:subpropertyOf :isParentOf :IvankaTrump rdf:type :Person :DonaldTrump rdf:type :Father :DonaldTrump rdf:type :Parent :DonaldTrump rdf:type :Person :DonaldTrump :isParentOf :IvankaTrump
61. @arnoutboks #010php Inference Reasoner (asserted) triples inferred/virtual triples
62. @arnoutboks #010php Inference Reasoner (asserted) triples inferred/virtual triples
63. @arnoutboks #010php SPARQL & Inference SELECT ?person WHERE { ?person rdf:type :Person . } ?person :IvankaTrump :DonaldTrump
64. @arnoutboks #010php Combining data using inference Subject Predicate Object a:DonaldTrump rdf:type a:Person Datasource A Subject Predicate Object b:MelaniaTrump rdf:type b:Human Datasource B
65. @arnoutboks #010php Combining data using inference Subject Predicate Object a:DonaldTrump rdf:type a:Person Datasource A Subject Predicate Object b:MelaniaTrump rdf:type b:Human Datasource B Subject Predicate Object a:Person rdfs:subclassOf b:Human b:Human rdfs:subclassOf a:Person Mapping rules
66. @arnoutboks #010php Combining data using inference Subject Predicate Object a:DonaldTrump rdf:type a:Person b:MelaniaTrump rdf:type b:Human a:Person rdfs:subclassOf b:Human b:Human rdfs:subclassOf a:Person a:DonaldTrump rdf:type b:Human b:MelaniaTrump rdf:type a:Person
67. @arnoutboks #010php Query different sources as if they were one
68. @arnoutboks #010php RDF Schema vs. JSON/XML Schema Subject Predicate Object mi6:JamesBond rdf:type mi6:SecretAgent mi6:JamesBond nmm:numberOfGuns “1” MI6 files
69. @arnoutboks #010php RDF Schema vs. JSON/XML Schema Subject Predicate Object mi6:JamesBond rdf:type mi6:SecretAgent mi6:JamesBond nmm:numberOfGuns “1” MI6 files
70. @arnoutboks #010php RDF Schema vs. JSON/XML Schema Subject Predicate Object mi6:JamesBond rdf:type mi6:SecretAgent mi6:JamesBond nmm:numberOfGuns “1” MI6 files Subject Predicate Object nmm:numberOfGuns rdf:domain nmm:Ship National Maritime Museum (“Scheepvaartmuseum”)
71. @arnoutboks #010php RDF Schema vs. JSON/XML Schema Subject Predicate Object mi6:JamesBond rdf:type mi6:SecretAgent mi6:JamesBond nmm:numberOfGuns “1” nmm:numberOfGuns rdf:domain nmm:Ship mi6:JamesBond rdf:type nmm:Ship
72. @arnoutboks #010php RDF Schema vs. JSON/XML Schema
73. @arnoutboks #010php RDF Schema will never consider data to be invalid
74. @arnoutboks #010php Web Ontology Language (OWL) Even smarter inferencing Web Ontology Language (OWL) Even smarter inferencing
75. @arnoutboks #010php OWL OWL ≈ RDFS++
76. @arnoutboks #010php OWL Power comes at a price…
77. @arnoutboks #010php OWL: Inverse properties Subject Predicate Object :DonaldTrump :isParentOf :IvankaTrump :isParentOf owl:inverseOf :isChildOf :IvankaTrump :isChildOf :DonaldTrump
78. @arnoutboks #010php OWL: Symmetric properties Subject Predicate Object :DonaldTrump :isMarriedTo :MelaniaTrump :isMarriedTo rdf:type owl:SymmetricProperty :MelaniaTrump :isMarriedTo :DonaldTrump
79. @arnoutboks #010php OWL: Equality Subject Predicate Object :DonaldTrump :isMarriedTo :MelaniaTrump :DonaldTrump owl:sameAs :TheDon :TheDon :isMarriedTo :MelaniaTrump
80. @arnoutboks #010php OWL: Functional properties Subject Predicate Object :IvankaTrump :hasFather :DonaldTrump :IvankaTrump :hasFather :TheDon :hasFather rdf:type owl:FunctionalProperty :TheDon owl:sameAs :DonaldTrump
81. @arnoutboks #010php Inconsistency Subject Predicate Object :IvankaTrump :hasFather :DonaldTrump :IvankaTrump :hasFather :TheDon :hasFather rdf:type owl:FunctionalProperty :TheDon owl:differentFrom :DonaldTrump
82. @arnoutboks #010php Inconsistency
83. @arnoutboks #010php Inconsistency
84. @arnoutboks #010php It’s okay to be inconsistent… (remember the AAA slogan)
85. @arnoutboks #010php It’s okay to be inconsistent… (remember the AAA slogan) …but the reasoner won’t help you anymore
86. @arnoutboks #010php Self-test Subject Predicate Object :George :hasChild :Michelle :George :hasChild :James How many children does George have?
87. @arnoutboks #010php Reification Adding more nuance
88. @arnoutboks #010php Reifying a statement Subject Predicate Object php-fig:CakePHP fw:isBetterThan php-fig:Symfony
89. @arnoutboks #010php Reifying a statement Subject Predicate Object php-fig:CakePHP fw:isBetterThan php-fig:Symfony Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony Reification
90. @arnoutboks #010php Talking about a statement rather than making it
91. @arnoutboks #010php Use cases for reification Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony
92. @arnoutboks #010php Use cases for reification Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony whitehouse:Trump :says :Statement1
93. @arnoutboks #010php Use cases for reification Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony whitehouse:Trump :says :Statement1 :Statement1 :reliability "0.1"
94. @arnoutboks #010php Use cases for reification Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony whitehouse:Trump :says :Statement1 :Statement1 :reliability "0.1" :Statement1 :validUntil "2010-01-01"
95. @arnoutboks #010php Use cases for reification Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony whitehouse:Trump :says :Statement1 :Statement1 :reliability "0.1" :Statement1 :validUntil "2010-01-01"
96. @arnoutboks #010php Let’s get meta
97. @arnoutboks #010php Let’s get meta Subject Predicate Object :Statement1 rdf:subject php-fig:CakePHP :Statement1 rdf:predicate fw:isBetterThan :Statement1 rdf:object php-fig:Symfony :Statement2 rdf:subject whitehouse:Trump :Statement2 rdf:predicate :says :Statement2 rdf:object :Statement1 whitehouse:PressSec :says :Statement2
98. @arnoutboks #010php Further steps Get going with the Semantic Web
99. @arnoutboks #010php Leveraging the Semantic Web Network effect
100. @arnoutboks #010php Leveraging the Semantic Web Only useful when multiple parties speak the same ‘language’
101. @arnoutboks #010php Align with existing vocabularies
102. @arnoutboks #010php Leveraging the Semantic Web Mapping between vocabularies: • rdfs:subclassOf • rdfs:subpropertyOf • owl:inverseOf • owl:sameAs
103. @arnoutboks #010php Existing vocabularies • Dublin Core • Metadata about publications and authors • Friend of a Friend • People, connections, social networks • GoodRelations • Products, prices, eCommerce • CB-NL • Construction, infrastructure, spatial planning • QUDT • Quantities, units, dimensions, conversions
104. @arnoutboks #010php Resources • Apache Jena (includes Fuseki triple store) • Semantic web framework/tools (written in Java) • easyrdf/easyrdf • RDF parser/writer for PHP • semsol/arc2 • PHP RDF library and MySQL-based triple store • FaCT++, HermiT & Pellet • Open source OWL reasoners • Protégé • RDF/OWL IDE with various reasoner plugins
105. @arnoutboks #010php Resources
106. @arnoutboks #010php Resources • https://www.w3.org/2013/data/ • https://www.w3.org/2001/sw/wiki/ • https://www.w3.org/TR/rdf11-primer/ • https://www.w3.org/TR/owl2-primer/ • https://www.w3.org/TR/sparql11-query/ • http://wiki.dbpedia.org/OnlineAccess • https://www.data.gov/ • http://lod-cloud.net/
107. @arnoutboks #010php Feedback & Questions @arnoutboks @arnoutboks @aboks Arnout Boks Please leave your feedback on joind.in: https://joind.in/talk/53955
108. @arnoutboks #010php Image Credits • https://www.flickr.com/photos/lex-photographic/32521124574 • https://www.flickr.com/photos/flamesworddragon/19686463141 • https://www.flickr.com/photos/littlehuw/15236543728 • https://www.flickr.com/photos/crdominguez/422517106 • https://www.flickr.com/photos/pamwood707/5646757752 • https://www.flickr.com/photos/blair25/3240686470 • https://www.flickr.com/photos/tylerbeaulawrence/15167523690 • https://www.flickr.com/photos/23975018@N04/3675503072 • https://pixabay.com/nl/nuance-stalen-kleur-pantone-1074766/ • https://www.flickr.com/photos/borkurdotnet/9682277597