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Why Semantic Web Services ?

Why Semantic Web Services ?. New Opportunity for the Semantic Technology. Vagan Terziyan. Semantic Web Services Basis. The question we should answer today: “Why these are necessary ?”. Semantic Web Services. Web Services. Distributed Artificial Intelligence. Semantic Web.

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Why Semantic Web Services ?

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  1. Why Semantic Web Services ? New Opportunity for the Semantic Technology Vagan Terziyan

  2. Semantic Web Services Basis The question we should answer today: “Why these are necessary ?” Semantic Web Services Web Services Distributed Artificial Intelligence Semantic Web Service Oriented Design Semantic Technology Software Technologies

  3. Students´ Background and Expectations Software Engineering Background Telecommunication / Mobile Computing Background Artificial Intelligence Background Why Semantic Web Services? Motivation to study techniques to design Intelligent (adaptive, learnable) Web applications based on Web-services Motivation to study techniques for designing semantically marked-up Web-services and applications, which integrate heterogeneous Web-services Motivation to study techniques for designing personalized mobile context-aware interoperable Web-services

  4. Useful Research References • [Rajasekaran et al., 2004] P. Rajasekaran, J. Miller, K. Verma, A. Sheth, Enhancing Web Services Description and Discovery to Facilitate Composition, Proceedings of SWSWPC, 2004 • [METEOR-S, 2002] METEOR-S: Semantic Web Services and Processes, http://swp.semanticweb.org , 2002. • [Ankolenkar et al., 2003] The DAML Services Coalition, DAML-S: Web Service Description for the Semantic Web, The First International Semantic Web Conference -ISWC, Italy • [Roman et al., 2004] D.Roman, U. Keller, H. Lausen, WSMO – Web Service Modeling Ontology (WSMO), DERI Working Draft, 14 February 2004, http://www.wsmo.org/2004/d2/v0.1/20040214/

  5. Where to find out more: Web-Sites • OWL, OWL-S • http://www.w3.org/2004/01/sws-pressrelease • http://www.w3.org/2004/01/sws-testimonial • Semantic Web • http://www.w3.org/2001/sw/ • http://www.semwebcentral.org/ • Semantic Web Services • http://www.daml.org/services/ • http://www.swsi.org/ • http://www.wsmo.org

  6. Contents* • Background Information: • Reminder:Semantic Web; • Reminder: Semantic Technology; • Reminder: Service-Oriented Design; • Why Semantic Web Services (6 reasons); • Conclusions; • Additional Material Available: • World-Wide Trends, Activities and Expectation Related to Semantic Web Services • Practical Training Opportunities for Students; • Relevant Topics for Master Theses. *Full version with detailed content for grayed topics is available in printed version of the slides and in the Web: http://www.cs.jyu.fi/ai/vagan/Why_SWS.ppt

  7. Background Information(from previous lectures):Reminder 1:Semantic WebReminder 2:Semantic TechnologyReminder 3:Service-Oriented Design

  8. Reminder 1:Semantic Web

  9. Semantic Web “ The Semantic Web is an extension of the current Web in which information is given a well-defined meaning, better enabling computers and people to work in cooperation. It is the idea of having data on the Web defined and linked in a way that it can be used formore effective discovery, automation, integration and reuse across various applications.” From the W3C Semantic Web Activity statement “ … machine-readable descriptions of the content and capabilities of web accessible resources… must be in addition to the human-readable versions of that information.“ From the OWL Guide

  10. The Semantic Stack OWL CD CD Reasoning RDFS A CD Classes Is-a RDF A B Relationships hasTrack XML Structures

  11. Reminder 2:Semantic Technology

  12. Semantic Technology Semantic technology as a software technology allows the meaning of information to be known and processed at execution time. For a semantic technology there must be a knowledge model of some part of the world that is used by one or more applications at execution time.

  13. Semantic Technology Semantics is the study of meanings. Semantic Technologies are software technologies that make this meaning more explicit. Semantic Technologies represent meanings separately from data, content, or program code, using the open standards for the semantic web. The Semantic Web initiative have recently (February 2004) anointed RDF and OWL as W3C standards, which is expected to bring a flood of products based on Semantic Technologies. “If software is ever going to be able to effectively interoperate (in ways that were not explicitly preconceived and engineered), it will be because applications share enough of the semantics of their data elements”,Doug Lenat, President, Cycorp

  14. Semantic Models Taxonomy – a simple Semantic Model Ontology – a richer Semantic Model Relationships are explicitly named and differentiated Homogeneous “parent-child” relationships

  15. Object Model Object Model in an object-oriented program is a networked data set that describes the system itself. In an object model, classes high in the hierarchy express properties that are shared by many system elements; classes low in the hierarchy describe properties that are specific to small sets of elements. Therefore, it is a model that reflects and describes properties and functions of a specific system.

  16. Data Model Data Model describes the world outside of the system. Many applications can share the same database, but in reality the schema of the data is typically fine-tuned to the needs of specific application. In a data model, each table in the schema dictates what this collection of records has in common; another schema denotes this for other records. Differences are represented both by individual records, as well as record types. The relationships are held in special index tables and are not explicitly defined.

  17. Semantic Model Semantic models are intended as a way for different agents (applications and/or people) to interoperate and to share meaning. Unlike object models they describe the world that is outside of any of the application that uses the model. Furthermore, the variations and commonalities semantic models represent are not of a single entity or stakeholder. By definition semantic models support multiple viewpoints. This makes them especially suitable for solving interoperability problems.

  18. Semantic Application Architecture Typical Application Architecture Semantic Application Architecture

  19. Architecture for Semantic Interoperability Interoperability is achieved by using a common set of models describing business concepts and their relationships Semantic Interface Enterprise Resource Planning Customer Relationships Management Product Data Management Semantic technology could be used to encapsulate business domain knowledge used by many applications. This means that the applications would become thinner as they no longer need to have their own representation of business logic. Instead they would need to have a way to consult a knowledge model. Such access is made possible through the use of semantic engines.

  20. Reminder 3:Service-Oriented Design

  21. Service-Oriented Design • SOD aims to provide enterprise business solutions composed of reusable services, with well-defined, published and standards-compliant interfaces. SOD provides a mechanism for integrating existing legacy applications regardless of their platform or language. SOD is an evolution of COD. It provides a distributed computing approach for integrating extremely heterogeneous applications over the Internet. Web-services are well suited to implementing a service-oriented design. Web services are self-describing and modular applications that can be published, discovered, and invoked over the Internet. Based on XML standards, Web services can be developed as loosely coupled application components using any programming language, any protocol, or any platform. COD is an emerging paradigm concerned with the development of software intensive systems from reusable parts (components).

  22. The Web Services Stack Wire Protocol Description Discovery SOAP WSDL Registry (UDDI) provides a standard, flexible way to discover where a Web service is located and where to find more information about what the Web service does provides a standard, flexible way to describe what and how a Web service does what it does provides a standard, flexible communications channel interoperability at the lowest level interoperability at the content level dynamic discovery

  23. Semantic Grid • “Semantic Grid as a service-oriented architecture in which entities provide services to one another under various forms of contract”. David De Roure, Nicholas R. Jennings and Nigel R. Shadbolt, The Semantic Grid: A Future e-Science Infrastructure

  24. Recommended book • Zoran Stojanovic , Ajantha Dahanayake, Service-Oriented Software System Engineering, Idea Group Publ., 2005

  25. Why Semantic Web Services ?

  26. Why Semantic Web Services? Reason 1:Limitations of Traditional Web Services

  27. Web Services - Liberating the Machine • Web Services traditionally have a human interface • Required information is presented using forms • Humans interpret labels and enter required information • Humans interpret resulting information Limitations of Web-Services Technology • Manual Discovery • Manual Invocation • Manual (ad hoc) Mediation • Manual (ad hoc) Composition

  28. Why Semantic Web Services? Intelligent Web Services According to Dieter Fensel (Univ. of Innsbruck) Bringing the Web to its full potential Web Services UDDI, WSDL, SOAP Dynamic Minimization of any human intervention.Web-services described in a formal, semantic way, so programs can find, compose and invoke them automatically in a task-driven way. Lack of proper support for semantics. Human intervention is needed to actually discover, combine, and execute Web Services WWW Semantic Web URI, HTML, HTTP RDF, RDF(S), OWL Static Shallow Deep

  29. Why Semantic Web Services? Process description + Automatic service discovery + Automatic service composition + Automatic service execution = DYNAMIC + SCALABLE + REUSABLE INTEGRATION

  30. Semantic Web Services Definition “ Self-contained, self-described, semantically marked-up software resources that can be published, discovered, composed and executed across the Web in a task-driven way ”. S. Arroyo, R. Lara, J. Gomez, D. Berka, Y. Ding and D. Fensel, Semantic Aspects of Web Services: Practical Handbook of Internet Computing, Chapman & Hall and CRC Press, 2004

  31. Reason 2:Automatic and Personalized Service Discovery Why Semantic Web Services?

  32. Service discovery problem Service Provider Service Consumer I want to buy “Das Kapital” This is what I provide And pay by Credit Card This is what I provide This is what I provide And I want to receive it at home How to express “what”? Match? … How to express the request?

  33. Automatic Web Service Discovery • Involves the automatic location of Web services that provide a particular service. • Currently, this task must be performed by a human who uses a search engine to find a service, read the Web page, and execute the service manually. • With an ontology of services, the information necessary for Web service discovery could be specified so that ontology-enhanced (semantic) search engine will locate the services automatically. • Alternatively, a server could proactively advertise itself in the ontology with a service registry so that requesters can find it when they query the registry.

  34. Upper Ontology of Services • A Service is a kind-of Resourcein the Web, i.e. some Web resources provide services. • What does the service require of the user, or other agents, and provides for them? The answer to this question is in ServiceProfile • How does it work? • The answer to this question is in ServiceModel • How is it used? • The answer to this question is in ServiceGrounding.

  35. Service Provides some Function G X Service Model Service Grounding F Service Profile Y

  36. Service Provides some Function x1: movie_name; x2: time; x3: number_of_tickets; x4: seats preference; x5: money G X 1: takes x1, x2, x3, x4; 2: checks availability of x3 tickets for the x1movie, at x2 time, which suits x4 constraint ; 3: finds one_ticket_prise from the price list; 4: calculates price for x3 tickets: price = one_seet_price * x3; 5: takes x5; 6: calculates y2 ( y2 = x5 – price ); 7: gives y1, y2. F 1: cinema address; 2: cinema movie schedule; 3: cinema cash-desk location; 4: nock to the cash-desk window and, when it opens, make your order (X) Y y1: movie tickets; y2: change

  37. Service Profile (OWL-S ontology)

  38. Automated Service Discovery Web Service Service Ontology Service profile Service consumer Semantic query for service Semantic matchmaking engine

  39. Semantic Web: What to Annotate? External world resources Web resources: Web-pages/ Web-Services / Web-DBs / etc. Web users (profiles, preferences) Shared ontology Web agents / applications Service consumer’s profile can be considered as an additional filter (context) for automated service discovery Smart machines and devices Web access devices

  40. Shared ontology Shared ontology Semantic Personalization Service consumer Semantic matchmaking engine Consumer’s profile Service profile Web Service

  41. Why Semantic Web Services? Reason 3:Automatic Service Invocation and Execution Monitoring

  42. Automatic Web Service Invocation • Involves the automatic execution of a Web service by a computer program or agent. • Currently, a user must go to the service Web site, fill out a form, and click to execute the service (or send a direct HTTP request with the appropriate parameters in HTML). • With service ontology, execution of a Web service is a collection of function calls. Ontology provides a declarative, computer-interpretable API for executing these calls. A software agent should be able to interpret the markup to understand what input is necessary to the service call, what information will be returned, and how to execute the service automatically. • Thus, ontology must provide declarative APIs for Web services that are necessary for automated Web service execution.

  43. Automated Service Invocation and Execution Monitoring Execution of a Web service is a collection of function calls. Ontology provides a declarative, computer-interpretable API for executing these calls. Execution of a Web service is a collection of function calls. Ontology provides a declarative, computer-interpretable API for executing these calls. Service Ontology A user may want to know during service execution period what the status of the request is, or plans may have changed, etc. Thus ontology should also provide declarative descriptors for the state of execution of services. Web Service Application Function calls Should be able to interpret the markup

  44. Why Semantic Web Services? Reason 4:Automatic Service Integration(composition / orchestration / interoperation)

  45. Automatic Web Service Composition (and Interoperation) • Involves the automatic selection, composition, and interoperation of Web services to perform some task, given a high-level description of an objective. • Currently, the user must select the Web services, specify the composition manually, and make sure that any software needed for the interoperation is custom-created. • With ontology of Web services, the information necessary to select and compose services will be encoded at the service Web sites. Software can be written to manipulate these representations, together with a specification of the objectives of the task, to achieve the task automatically. • Thus, ontology must provide declarative specifications of the prerequisites and consequences of individual service use that are necessary for automatic service composition and interoperation.

  46. Web-Services Choreography • Web Services Choreography concerns the observable interactions of services with their users. Any user of a Web Service, automated or otherwise, is a client of that service. These users may, in turn, be other Web Services, applications or human beings. • A choreography description is a multi-party contract that describes the external observable behavior across multiple clients (services) in which external observable behavior is defined as the presence or absence of messages that are exchanged between a Web Service and it's clients.

  47. Web-Services Choreography

  48. Web-Services Composition Composed service Objective for a new service Service profile Shared ontology Web Service

  49. Why Semantic Web Services? Reason 5:Web-Services Proactivity and Learnability

  50. Common ontology Proactive Web-Services:adding an agent to service platform – allows agent-based S2S communication Goal-driven behavior Web-Service Service Platform Service Agent

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