1. www.sti-innsbruck.at © Copyright 2008 STI INNSBRUCK www.sti-innsbruck.at Semantic Web Services Introduction Lecture I – 5 th March 2009 Dieter Fensel (contribution from Ioan Toma)

2. www.sti-innsbruck.at What is the course about? New, emerging sciences: web science, service science Service based technologies: Web services, Web2.0/Restful services Semantic Web services: vision, approaches, usage

3. www.sti-innsbruck.at Course Organization Course is organized into: –12 lectures (Thursday 14-16) –7 tutorials (Tuesday 15-17) The lecturers are: –Dieter Fensel (dieter.fensel@sti2.at) –Federico M. Facca (federico.facca@sti2.at) The tutor is: –Dumitru Roman (dumitru.roman@sti2.at)

4. www.sti-innsbruck.at Course material Web site: http://www.sti- innsbruck.at/teaching/courses/ss2009/details/ ?title=semantic-web-services –Slides available online before each lecture Mailing list: https://lists.sti2.at/mailman/listinfo/sws2009

5. www.sti-innsbruck.at Where are we? #DateTitle 15 th MarchIntroduction 212 th MarchWeb Science 319 th MarchService Science 426 th MarchWeb Services (WSDL. SOAP, UDDI, XML) 52 nd AprilWeb 2.0 and RESTful services 623 rd AprilWSMO 730 th AprilWSML 87 th MayWSMX 914 th MayOWL-S and others 1028 th MayWSMO-Lite, MicroWSMO 114 th JuneSWS Use Cases 1218 th Juneseekda: the business point of view 1325 th JuneMobile services 142 nd JulyExam Preparation

6. www.sti-innsbruck.at Examination Exam grade: Tutorial and Exam have separate grades since this is not an integrated course score grade 75-1001 65-74.92 55-64.93 45-54.94 0-44.95

7. www.sti-innsbruck.at Outline 1.Motivation 2.Semantic Web 3.Web services 4.Semantic Web services

8. www.sti-innsbruck.at Motivation

9. www.sti-innsbruck.at Motivation http://projects.kmi.open.ac.uk/dip/

10. www.sti-innsbruck.at Semantic Web

11. www.sti-innsbruck.at More than a 2 billion users more than 50 billion pages Static WWW URI, HTML, HTTP The traditional Web

12. www.sti-innsbruck.at WWW URI, HTML, HTTP Serious Problems in information finding, information extracting, information representing, information interpreting and and information maintaining. Semantic Web RDF, RDF(S), OWL Static Semantic Web

13. www.sti-innsbruck.at 13 “An extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.” Sir Tim Berners-Lee et al., Scientific American, 2001: tinyurl.com/i59p “…allowing the Web to reach its full potential…” with far- reaching consequences “The next generation of the Web” Semantic Web

14. www.sti-innsbruck.at Semantic Web The next generation of the WWW Information has machine-processable and machine- understandable semantics Not a separate Web but an augmentation of the current one Ontologies as basic building block

15. www.sti-innsbruck.at Semantic Web Web Data Annotation –connecting (syntactic) Web objects, like text chunks, images, … to their semantic notion (e.g., this image is about Innsbruck, Dieter Fensel is a professor) Data Linking on the Web (Web of Data) –global networking of knowledge through URI, RDF, and SPARQL (e.g., connecting my calendar with my rss feeds, my pictures,...) Data Integration over the Web –Seamless integration of data based on different conceptual models (e.g., integrating data coming from my two favorite book sellers)

16. www.sti-innsbruck.at Semantic Web - Ontologies formal, explicit specification of a shared conzeptualization commonly accepted understanding conceptual model of a domain (ontological theory) unambiguous terminology definitions machine-readability with computational semantics

17. www.sti-innsbruck.at Semantic Web - Ontologies Concept conceptual entity of the domain Property attribute describing a concept Relation relationship between concepts or properties Axiom coherency description between Concepts / Properties / Relations via logical expressions Person Student Professor Lecture isA – hierarchy (taxonomy) nameemail matr.-nr. research field topic lecture nr. attends holds holds(Professor, Lecture) => Lecture.topic = Professor.researchField

18. www.sti-innsbruck.at Semantic Web - Ontologies To make the Semantic Web working we need: Ontology Languages: –expressivity –reasoning support –web compliance Ontology Reasoning: –large scale knowledge handling –fault-tolerant –stable & scalable inference machines Ontology Management Techniques: –editing and browsing –storage and retrieval –versioning and evolution Support Ontology Integration Techniques: –ontology mapping, alignment, merging –semantic interoperability determination and … Applications

19. www.sti-innsbruck.at Ontology Languages Requirements: –”expressivity“ knowledge representation ontology theory support –”reasoning support“ sound (unambiguous, decidable) support reasoners / inference engines Semantic Web languages: –web compatibility –Existing W3C Recommendations: XML, RDF, OWL

20. www.sti-innsbruck.at “Semantic Web Language Layer Cake”

21. www.sti-innsbruck.at Web Services

22. www.sti-innsbruck.at WWW URI, HTML, HTTP Bringing the computer back as a device for computation Semantic Web RDF, RDF(S), OWL Dynamic Web Services UDDI, WSDL, SOAP Static The Vision (contd.)

23. www.sti-innsbruck.at Web Services: Definition 1) “Loosely coupled, reusable software components that encapsulate discrete functionality and are distributed and programmatically accessible over standard Internet protocols”, The Stencil Group 2) Web service applications are encapsulated, loosely coupled Web “components” that can bind dynamically to each other, F. Curbera 3) “Web Services are a new breed of application. They are self- contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web Services perform functions, which can be anything from simple request to complicated business processes”, The IBM Web Services tutorial Common to all definitions: Components providing functionality Distributed Accessible over the Web

24. www.sti-innsbruck.at Web Services Loosely coupled, reusable components Encapsulate discrete functionality Distributed Programmatically accessible over standard internet protocols Add new level of functionality on top of the current web

25. www.sti-innsbruck.at Web Service vs. Service Service –A provision of value in some domain (not necessarily monetary, independent of how service provider and requestor interact) Web Service –Computational entity accessible over the Internet (using Web Service Standards & Protocols), provides access to (concrete) services for the clients.

26. www.sti-innsbruck.at Definitions Def 1. Software Architecture Def 2. New concept for eWork and eCommerce Def 3. New programming technology

27. www.sti-innsbruck.at Web Services connect computers and devices with each other using the Internet to exchange data and combine data in new ways. The key to Web Services is on-the-fly software creation through the use of loosely coupled, reusable software components. Software can be delivered and paid for as fluid streams of services as opposed to packaged products. Definitions Def 1. Software architecture

28. www.sti-innsbruck.at Def 2. Web Services as a new Concept for eWork and eCommerce Definitions Business services can be completely decentralized and distributed over the Internet and accessed by a wide variety of communications devices. The internet will become a global common platform where organizations and individuals communicate among each other to carry out various commercial activities and to provide value-added services. The dynamic enterprise and dynamic value chains become achievable and may be even mandatory for competitive advantage.

29. www.sti-innsbruck.at Def 3. Web Services as a programming technology Web Services are Remote Procedure Calls (RPC) over HTTP Definitions

30. www.sti-innsbruck.at Web Services

31. www.sti-innsbruck.at UDDI Universal Description, Discovery, and Integration Protocol OASIS driven standardization effort Registry for Web Services: - provider - service information - technical access

32. www.sti-innsbruck.at WSDL Web Service Description Language W3C effort, WSDL 2 final construction phase describes interface for consuming a Web Service: - Interface: operations (in- & output) - Access (protocol binding) - Endpoint (location of service)

33. www.sti-innsbruck.at SOAP Simple Object Access Protocol W3C Recommendation XML data transport: - sender / receiver - protocol binding - communication aspects - content

34. www.sti-innsbruck.at Restful services Another way of realizing services, other then SOAP/WSDL/UDDI approach Follows the Web principles (REST principles) Services expose their data and functionality through resources indentified by URI Services are Web pages that are meant to be consumed by an autonomous program Uniform interfaces for interaction: GET, PUT, DELETE, POST HTTP as the application protocol

35. www.sti-innsbruck.at Google – Unified Cloud Computing An attempt to create an open and standardized cloud interface for the unification of various cloud API’s Key drivers of the unified cloud interface is to create an api about other API's Use of the resource description framework (RDF) to describe a semantic cloud data model (taxonomy & ontology)

36. www.sti-innsbruck.at Amazon - Mechanical Turk “People as a service” Amazon Mechanical Turk –An API to Human Processing Power –The Computer Calls People –An Internet Scale Workforce –Game-Changing Economics

37. www.sti-innsbruck.at Amazon – S3 & EC2 “Infrastructure as a service” Amazon Simple Storage Service (S3) –Write and read objects up to 5GB –15 cents GB / month to store –20 cents GB / month to transfer Amazon Elastic Compute Cloud (EC2) –allows customers to rent computers on which to run their own computer applications –virtual server technology –10 cents / hour

38. www.sti-innsbruck.at Semantic Web Services

39. www.sti-innsbruck.at WWW URI, HTML, HTTP Bringing the web to its full potential Semantic Web RDF, RDF(S), OWL Dynamic Web Services UDDI, WSDL, SOAP Static Semantic Web Services Semantic Web Services

40. www.sti-innsbruck.at Deficiencies of WS Technology

41. www.sti-innsbruck.at Deficiencies of WS Technology current technologies allow usage of Web Services but: –only syntactical information descriptions –syntactic support for discovery, composition and execution => Web Service usability, usage, and integration needs to be inspected manually –no semantically marked up content / services –no support for the Semantic Web => current Web Service Technology Stack failed to realize the promise of Web Services

42. www.sti-innsbruck.at So what is needed? Mechanized support is needed for –Annotating/designing services and the data they use –Finding and comparing service providers –Negotiating and contracting services –Composing, enacting, and monitoring services –Dealing with numerous and heterogeneous data formats, protocols and processes, i.e. mediation => Conceptual Models, Formal Languages, Execution Environments

43. www.sti-innsbruck.at Semantic Web Technology + Web Service Technology Semantic Web Services => Semantic Web Services as integrated solution for realizing the vision of the next generation of the Web allow machine supported data interpretation ontologies as data model automated discovery, selection, composition, and web-based execution of services

44. www.sti-innsbruck.at Semantic Web Services define exhaustive description frameworks for describing Web Services and related aspects (Web Service Description Ontologies) support ontologies as underlying data model to allow machine supported data interpretation (Semantic Web aspect) define semantically driven technologies for automation of the Web Service usage process (Web Service aspect)

45. www.sti-innsbruck.at Tasks to be automated Service Publishing Service Description Service Enactment & Monitoring Describe the service explicitly, in a formal way Make available the description of the service Locate different services suitable for a given goal Combine services to achieve a goal Choose the most appropriate services among the available ones Invoke & Monitor services following programmatic conventions Service Composition Service Negotiation & Contracting Service Discovery Service Mediation

46. www.sti-innsbruck.at Semantic Web Services Usage Process: Publication: Make available the description of the capability of a service Discovery: Locate different services suitable for a given task Selection: Choose the most appropriate services among the available ones Composition: Combine services to achieve a goal Mediation: Solve mismatches (data, protocol, process) among the combined Execution: Invoke services following programmatic conventions

47. www.sti-innsbruck.at Semantic Web Services Execution support: Monitoring: Control the execution process Compensation: Provide transactional support and undo or mitigate unwanted effects Replacement: Facilitate the substitution of services by equivalent ones Auditing: Verify that service execution occurred in the expected way

48. www.sti-innsbruck.at SEE - WSMX WSMX: The Web Service EXecution Environment A service oriented architecture. Reference implementation of SESA and WSMO More on Lecture 8 48

49. www.sti-innsbruck.at W : Triple Space Computing Human net Message Email Email: –Human to Human communication (Human net) –Dissemination of information was based on message exchange (Message)

50. www.sti-innsbruck.at W : Triple Space Computing Human net MessagePublishing Web Email Web: –Human to Human communication (Human net) –Dissemination of information based on publishing (Publishing)

51. www.sti-innsbruck.at W : Triple Space Computing So-called Web Service Human net Machine net MessagePublishing Web Email Web Services: –Machine to Machine communication (Machine net) –Dissemination of information based on messages (Message)

52. www.sti-innsbruck.at W : Triple Space Computing So-called Web Service Human net Machine net MessagePublishing Web Triple Space Email Triple Space: –Machine to Machine communication (Machine net) –Dissemination of information based on Web principles (Publishing)

53. www.sti-innsbruck.at W : Triple Space Computing Communication platform for Semantic Web services based on Web principles: “Persistently publish and read semantic data that is denoted by unique identifiers” Fundamentals: –Space-based computing – sharing information, knowledge –RDF triples of the form: –URI – Uniform Resource Identifier 53

54. www.sti-innsbruck.at W : Triple Space Computing Triple Spaces allow for: –Time autonomy –Location autonomy –Reference autonomy –Vocabulary autonomy Triple Spaces provide a communication paradigm for anonymous, asynchronous information exchange that ensure the persistency and unique identification of the communicated semantic data. 54

55. www.sti-innsbruck.at Conclusions: Why Semantic Web Services ? To overcome limitations of traditional Web-Services Technology by integrating it with Semantic Technology; To enable automatic and personalized service discovery; To enable automatic service invocation and execution monitoring; To enable automatic service integration; To enable semantic mediation of Web-Services.

56. www.sti-innsbruck.at Next lecture #DateTitle 15 th MarchIntroduction 212 th MarchWeb Science 319 th MarchService Science 426 th MarchWeb Services (WSDL. SOAP, UDDI, XML) 52 nd AprilWeb 2.0 services/ restful services 623 rd AprilWSMO 730 th AprilWSML 87 th MayWSMX 914 th MayOWL-S and others 1028 th MaySA-WSDL, WSMO-Lite, MicroWSMO 114 th JuneSWS are good for what 1218 th Juneseekda: the business point of view 1325 th JuneMobile services 142 nd JulyExam

57. www.sti-innsbruck.at Questions?