1. Semantic Web Mobile Internet Technical Architecture Omair Javed Institute of Software Systems Tampere University of Technology

2. 05/11/2003Mobile Internet Technical Architecture / TUT2 Web Services—Semantic Web Web Services is the name for a marketing initiative –The technology has been scrambling to catch up and provide some grounding for the phrase ever since it was invented The Semantic Web is the name for a vision of the future –Originally Tim Berners-Lee's attempt to answer the question: What is the full potential of the (World Wide) Web? They have a common dependency

3. 05/11/2003Mobile Internet Technical Architecture / TUT3 Web Services My quick summary: –Loosely-coupled distributed applications Three key aspects: –Messages—XMLP (ex-SOAP), XML Schema –Definition—WSDL: XML->XML function signatures –Discovery—UDDI

4. 05/11/2003Mobile Internet Technical Architecture / TUT4 Towards the Semantic Web WWW now –Humans do everything –Computers as tools –Problems abound WWW in the future –Computers do a lot more –Computers work on our behalf –Fewer problems… How do we get there…?

5. 05/11/2003Mobile Internet Technical Architecture / TUT5 Semantic Web The semantic web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation. T. Berners-Lee, J. Hendler, O. Lassila, “The Semantic Web”, Scientific American, May 2001.

6. 05/11/2003Mobile Internet Technical Architecture / TUT6 Motivation for the Semantic Web Problem: Web was built for humans –Human interpretation needed to “understand” content (it does not scale) –Consequently, automation is difficult –It is particularly difficult to automate “unforeseen” situations Rough solution: make the Web friendlier for machines –We need “machine-understandable” content (not “machine-readable”, we already have that) –(note: by “machine-understandable” we mean content with accessible formal semantics) The Web is more than just a “library” –Think of it as infrastructure for services & functionality Drivers –Automation (e.g., in search), interoperability (e.g., in e-commerce) –but: compelling business models are still missing

7. 05/11/2003Mobile Internet Technical Architecture / TUT7 How to make this work? What would we need to do? –A standard syntax, so metadata can be recognised –One or more standard vocabularies, so search engines, producers and consumers all speak the same language –Lots of resources with metadata attached –Attribution and trust XML as such is just ASCII for the 21 st century Web-appropriate linearization For tree-structured documents with internal links Tree-structured documents are a pretty good transfer syntax In short XML allows designers to add structure to their documents but says nothing about what these structure means

8. 05/11/2003Mobile Internet Technical Architecture / TUT8 Ontology 1. Controlled vocabulary 2. Concept taxonomy 3. Other relations between concepts “A specification of conceptualization” Gruber.

9. 05/11/2003Mobile Internet Technical Architecture / TUT9 Resource Description Framework (RDF) Initially (RDF) just a simple relation-triple model of assertions about resources –Uses XML for Serialisation Adds abstract data models that allows systems to share the meaning of the structures –Describe resources URI –Uniform resource identifier when naming is not based on mere words, name conflicts can be avoided –Builds a layer on top of XML Making interoperable exchange of semantic information possible

10. 05/11/2003Mobile Internet Technical Architecture / TUT10 RDF Simple data model –Directed labeled graphs –More powerful than the trees of XML Graphs have object/attribute/value - triples –“subject/predicate/object” = a statement –In RDF parlance, nodes are called “resources” and arcs “properties” Alice Bob Mike Works With Trusts Meaning of “Works With” Meaning of “Trusts”

11. 05/11/2003Mobile Internet Technical Architecture / TUT11 DARPA Agent Markup Language DAML+OIL Based on RDF –Reworking on the syntax and cleaning up the model Extending the definition mechanism –DAML+OIL –> Ontology Web Language (OWL)

12. 05/11/2003Mobile Internet Technical Architecture / TUT12 Semantic Web as a Web of Services Automatic Discovery –Location of Web Service Automatic Invocation –Execution of discovered Web Service Software Agents Interpret the markup, Knows inputs and handle outputs and execute the service Automatic Composition and Interoperation –Using many services to perform a task Automatic Execution Monitoring –User may want to know the status of the Service Solution to Problems –DAML-S (Web service Ontology) targets these functionalities

13. 05/11/2003Mobile Internet Technical Architecture / TUT13 Interoperability Autonomous agents –Delegation of decision-making power –Computers/systems working on users’ behalf “Serendipitous” interoperability –Exchange ontology->Partial match -> Compose exact required functionality –Ease pressures on a prior standardization But: we need certain things –“processing models” for the Semantic Web –How do agents conduct dialogues e.g., when acquiring additional functionality –AI (reasoning)

14. 05/11/2003Mobile Internet Technical Architecture / TUT14 Future of WWW “We can imagine a web-enabled microwave oven consulting the popcorn manufacturer’s website for optimal popping parameters”

15. 05/11/2003Mobile Internet Technical Architecture / TUT15 Summary System Interoperability Use of human interpretation does not scale –We need to Move from tools to autonomous systems that work on our behalf Introduce formal semantics (machine-understandable content) Ontologies ->Reasoning->Agents We need artificial intelligence to ultimately fulfill the Semantic Web vision (May be) Departure from Strict standardization towards more flexible mechanisms

16. 05/11/2003Mobile Internet Technical Architecture / TUT16 References MITA Vol. I (127-135) References from the MITA Book Pages

17. 05/11/2003Mobile Internet Technical Architecture / TUT17 Thank You ! Questions ?