1. www.sti-innsbruck.at © Copyright 2008 STI INNSBRUCK www.sti-innsbruck.at Intelligent Systems Semantic Web and Exam Preparation Dieter Fensel Mick Kerrigan

2. www.sti-innsbruck.at 2 2 #DateTitle 1Introduction 2Propositional Logic 3Predicate Logic 4Theorem Proving, Logic Programming, and Description Logics 5Search Methods 6CommonKADS 7Problem Solving Methods 8Planning 9Agents 10Rule Learning 11Inductive Logic Programming 12Formal Concept Analysis 13Neural Networks 14Semantic Web and Exam Preparation Where are we?

3. www.sti-innsbruck.at 3 Agenda Semantic Web - Data Motivation Technical Solution: URI, RDF, RDFS, OWL, SPARQL Illustration by Larger Examples: KIM Browser Plugin, Disco Hyperdata Browser Extensions: Linked Open Data Semantic Web – Processes Motivation Technical Solution: Semantic Web Services, WSMO, WSML, SEE, WSMX Illustration by Larger Examples: SWS Challenge, Virtual Travel Agency Extensions: WSMX at work Conclusions 3

4. www.sti-innsbruck.at 4 SEMANTIC WEB - DATA 4

5. www.sti-innsbruck.at 5 MOTIVATION 5

6. www.sti-innsbruck.at 6 Motivation If the Web is about the global networking of data through URL, HTML, and HTTP… … the Semantic Web is about the global networking of knowledge through URI, RDF, and SPARQL This knowledge can be an annotation of Web data (this picture depicts Innsbruck) or just for knowledge‘s sake (Innsbruck is a city in Austria) Structured data: –is a key towards Artificial Intelligence –is background knowledge –enables formal reasoning 6

7. www.sti-innsbruck.at 7 TECHNICAL SOLUTIONS 7

8. www.sti-innsbruck.at 8 Uniform Resource Identifier Taken from http://www.w3.org/TR/webarch/

9. www.sti-innsbruck.at 9 RDF URIs are used to identify resources, not just things that exists on the Web, e.g. Dieter Fensel, University of Innsbruck RDF is used to make statements about resources in the form of triples Results in the creation of a labeled directed graph ex:john ex:bill ex:father-of ex:bill ex:tom ex:father-of 9

10. www.sti-innsbruck.at 10 RDFS RDFS is a language for defining RDF types Define Classes –#Student is a class Relationships between classes –#Student is a sub-class of #Person Properties of classes –#Person has a property hasName –hasName has a domain of Person and a range of a string literal –Can define relationship between properties with rdfs:subPropertyOf ex:john ex:student rdf:type “John Smith” ex:hasName 10

11. www.sti-innsbruck.at 11 RDFS Example 11

12. www.sti-innsbruck.at 12 OWL The limitation of RDFS is that it only allows binary relations OWL provides an ontology language, that is a more expressive Vocabulary Definition Language for use with RDF –Class membership –Equivalance of classes –Consistency –Classification OWL is layered into languages of different expressiveness –OWL Lite: Classification Hierarchies, Simple Constraints –OWL DL: Maximal expressiveness while maintaining tractability –OWL Full: Very high expressiveness, loses tractability, all syntactic freedom of RDF More expressive means harder to reason with 12

13. www.sti-innsbruck.at 13 SPARQL SPARQL is an RDF Query Language Uses a SQL-like syntax Example: Find the names of all the Students PREFIX ex PREFIX rdfs SELECT ?name FROM WHERE{ ?x rdfs:type ex:student. ?x ex:hasName ?name. } ?name John Smith Tom Johnson Bill Thompson 13

14. www.sti-innsbruck.at 14 ILLUSTRATION BY LARGER EXAMPLES 14

15. www.sti-innsbruck.at 15 Annotated Content KIM Browser Plugin Web content is annotated using ontologies Content can be searched and browsed intelligently Select one or more concepts from the ontology… … send the currently loaded web page to the Annotation Server Illustration 1 – KIM Browser Plugin 15

16. www.sti-innsbruck.at 16 Dereferencable URI Disco Hyperdata Browser navigating the Semantic Web as an unbound set of data sources Illustration 2 – Disco Hyperdata Browser 16

17. www.sti-innsbruck.at 17 EXTENSIONS 17

18. www.sti-innsbruck.at 18 Extensions: Linked Open Data Linked Data is a method for exposing and sharing connected data via dereferenceable URI’s on the Web –Use URIs to identify things that you expose to the Web as resources –Use HTTP URIs so that people can locate and look up (dereference) these things –Provide useful information about the resource when its URI is dereferenced –Include links to other, related URIs in the exposed data as a means of improving information discovery on the Web Linked Open Data is an initiative to interlink open data sources –Open: Publicly available data sets that are accessible to everyone –Interlinked: Datasets have references to one another allowing them to be used together 18

19. www.sti-innsbruck.at 19 Extensions: Linked Open Data 19

20. www.sti-innsbruck.at 20 Extensions: Linked Open Data - FOAF Friend Of A Friend (FOAF) provides a way to create machine-readable pages about: –People –The links between them –The things they do and create Anyone can publish a FOAF file on the web about themselves and this data becomes part of the Web of Data FOAF is connected to many other data sets, including –Data sets describing music and musicians (Audio Scrobbler, MusicBrainz) –Data sets describing photographs and who took them (Flickr) –Data sets describing places and their relationship (GeoNames) Dieter Fensel Dieter Fensel 20

21. www.sti-innsbruck.at 21 Extensions: Linked Open Data - GeoNames The GeoNames Ontology makes it possible to add geospatial semantic information to the Web of Data We can utilize GeoNames location within the FOAF profile GeoNames is also linked to more datasets –US Census Data –Movie Database (Linked MDB) –Extracted data from Wikipedia (DBpedia) Dieter Fensel Dieter Fensel 21

22. www.sti-innsbruck.at 22 Extensions: Linked Open Data - DBpedia DBpedia is a community effort to extract structured information from Wikipedia and to make this information available on the Web As our FOAF profile has been linked to GeoNames, and GeoNames is linked to DBpedia, we can ask some interesting queries over the Web of Data –What is the population of the city in which Dieter Fensel lives? => 117916 people –At which elevation does Dieter Fensel live? => 574m –Who is the mayor of the city in which Dieter Fensel lives => Hilde Zach 22

23. www.sti-innsbruck.at 23 SEMANTIC WEB - PROCESSES 23

24. www.sti-innsbruck.at 24 MOTIVATION 24

25. www.sti-innsbruck.at 25 Motivation The Web is moving from static data to dynamic functionality –Web services: a piece of software available over the Internet, using standardized XML messaging systems over the SOAP protocol –Mashups: The compounding of two or more pieces of web functionality to create powerful web applications –Significant growth of Web APIs 1.100 Web APIs on ProgrammableWeb.com (including SOAP and REST APIs) 3.700 Mashups on ProgrammableWeb.com (combining Web APIs from one or more sources) Examples: –Amazon Web Services –iGoogle –Yahoo Pipes –RSS Feeds 25

26. www.sti-innsbruck.at 26 Motivation 26

27. www.sti-innsbruck.at 27 Web services and mashups are limited by their syntactic nature As the amount of services on the Web increases it will be harder to find Web services in order to use them in mashups The current amount of human effort required to build applications is not sustainable at a Web scale Motivation 27

28. www.sti-innsbruck.at 28 TECHNICAL SOLUTIONS 28

29. www.sti-innsbruck.at 29 Semantic Web Services Brings the benefits of Semantics to the executable part of the Web –Ontologies as data model –Unambiguous definition of service functionality and external interface Reduce human effort in integrating services in SOA –Many tasks in the process of using Web services can be automated Improve dynamism –New services available for use as they appear –Service Producers and Consumers don’t need to know of each others existence Improve stability –Service interfaces are not tightly integrated so even less impact from changes –Services can be easily replaced if they are no longer available –Failover possibilities are limited only by the number of available services 29

30. www.sti-innsbruck.at 30 Semantic Web Services Semantic Web Services are a layer on top of existing Web service technologies and do not aim to replace them Provide a formal description of services, while still being compliant with existing and emerging technologies Distinguish between a Web service (computational entity) and a service (value provided by invocation) Make Web services easier to: –Find –Compare –Compose –Invoke 30

31. www.sti-innsbruck.at 31 Conceptual Model for SWS Formal Language for WSMO Ontology & Rule Language for the Semantic Web Technical Overview 31 Execution Environment For SWS

32. www.sti-innsbruck.at 32 Strict Decoupling of Modeling Elements Centrality of Mediation Ontological Role Separation Description versus Implementation WSMO Ontology-Based Web Service versus Service WSMO – Design Principles 32

33. www.sti-innsbruck.at 33 WSMO – Conceptual Model Objectives that a client wants to achieve by using Web Services Formally specified terminology used by all other components Semantic description of Web Services Capability (functional)‏ Interfaces (usage) Connectors between components with mediation facilities for handling heterogeneities 33

34. www.sti-innsbruck.at 34 WSML – Language Family WSML - Core WSML - DL WSML - Full WSML - Flight WSML - Rule f with without 34 Expressivity

35. www.sti-innsbruck.at 35 Semantic Execution Environment 35 Semantic Execution Environment Discovery Ranking Selection Composition Data Mediation Process Mediation Process Execution Lifting & Lowering base broker vertical Monitoring Reasoning Storage

36. www.sti-innsbruck.at 36 Semantic Execution Environment - WSMX 36

37. www.sti-innsbruck.at 37 ILLUSTRATION BY LARGER EXAMPLES 37

38. www.sti-innsbruck.at 38 Blue company has discovered Moon company on the Web Blue company wishes to communicate with Moon company Broker required to resolve data and process interoperability issues Purchase Order Confirmation id cid openOrder addItem* closeOrder Blue Company can only send POs and receive PO Confirmations Allows the opening of a PO, the specification of the items to be purchased and the closing of the PO Receives a customer id and returns a full customer description Illustration 1: SWS Challenge 38

39. www.sti-innsbruck.at 39 Rail Services Flight Services Hotel Services Car Hire Services Illustration 2: Virtual Travel Agency 39

40. www.sti-innsbruck.at 40 EXTENSIONS 40

41. www.sti-innsbruck.at 41 Extensions: WSMX At Work 41

42. www.sti-innsbruck.at 42 Extensions: WSMX At Work Request to discover Web services. 42

43. www.sti-innsbruck.at 43 Goal expressed in WSML is sent to WSMX System Interface Extensions: WSMX At Work 43

44. www.sti-innsbruck.at 44 Com. M. implements the interface to receive WSML goals Extensions: WSMX At Work 44

45. www.sti-innsbruck.at 45 Com. M. informs Core that Goal has been received Extensions: WSMX At Work 45

46. www.sti-innsbruck.at 46 Chor. wrapper picks up event for Chor. component Extensions: WSMX At Work 46

47. www.sti-innsbruck.at 47 New choreography Instance is created Extensions: WSMX At Work 47

48. www.sti-innsbruck.at 48 Core is notified that choreography instance has been created. Extensions: WSMX At Work 48

49. www.sti-innsbruck.at 49 WSML goal is parsed to internal format. Extensions: WSMX At Work 49

50. www.sti-innsbruck.at 50 Discovery is invoked for parsed goal. Extensions: WSMX At Work 50

51. www.sti-innsbruck.at 51 Discovery may requires ontology mediation. Extensions: WSMX At Work 51

52. www.sti-innsbruck.at 52 After data mediation, Discovery iterates, if needed through last steps until result set is finished. Extensions: WSMX At Work 52

53. www.sti-innsbruck.at 53 Selection is invoked to relax result set to finally one service. Extensions: WSMX At Work 53

54. www.sti-innsbruck.at 54 Choreography instance for goal requester is checked for next steps. Extensions: WSMX At Work 54

55. www.sti-innsbruck.at 55 Result is returned to Com. Man. to be forwarded to the service requester. Extensions: WSMX At Work 55

56. www.sti-innsbruck.at 56 Set of Web Service descriptions expressed in WSML sent to adapter. Extensions: WSMX At Work 56

57. www.sti-innsbruck.at 57 Set of Web Service descriptions expressed in requester’s own format returned to goal requester. Extensions: WSMX At Work 57

58. www.sti-innsbruck.at 58 SUMMARY 58

59. www.sti-innsbruck.at 59 Summary The Semantic Web provides a mechanism for –Representing knowledge on the Web –Annotating data on the Web –Annotating services on the Web Everything is identified by a URI RDF to assert relations between resources RDFS and OWL to make statements about types SPARQL to query RDF data WSMO as a conceptual model WSML for describing services at different levels of expressivity WSMX as a Semantic Execution Environment for bringing requesters and providers together 59

60. www.sti-innsbruck.at 60 REFERENCES 60

61. www.sti-innsbruck.at 61 References Semantic Web Primer: http://www.ics.forth.gr/isl/swprimer/http://www.ics.forth.gr/isl/swprimer/ Linked Open Data: http://linkeddata.org/http://linkeddata.org/ Linked Open Data Tutorial: http://www4.wiwiss.fu- berlin.de/bizer/pub/LinkedDataTutorial/http://www4.wiwiss.fu- berlin.de/bizer/pub/LinkedDataTutorial/ WSMO: http://www.wsmo.org/TR/d2/http://www.wsmo.org/TR/d2/ WSML: http://www.wsmo.org/TR/d16/d16.1/http://www.wsmo.org/TR/d16/d16.1/ WSMO/WSML Tutorials: http://wiki.sti2.at/index.php?title=WSMT_Tutorialshttp://wiki.sti2.at/index.php?title=WSMT_Tutorials Wikipedia: –URI: http://en.wikipedia.org/wiki/URIhttp://en.wikipedia.org/wiki/URI –RDF; http://en.wikipedia.org/wiki/Resource_Description_Frameworkhttp://en.wikipedia.org/wiki/Resource_Description_Framework –RDFS: http://en.wikipedia.org/wiki/RDFShttp://en.wikipedia.org/wiki/RDFS –SPARQL: http://en.wikipedia.org/wiki/SPARQLhttp://en.wikipedia.org/wiki/SPARQL –WSMO: http://en.wikipedia.org/wiki/WSMOhttp://en.wikipedia.org/wiki/WSMO –WSML: http://en.wikipedia.org/wiki/Web_Services_Modeling_Languagehttp://en.wikipedia.org/wiki/Web_Services_Modeling_Language 61

62. www.sti-innsbruck.at 62 Exam Preparation Tbd.

63. www.sti-innsbruck.at 63 Questions?