David  Booth    R D F &  S O A
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  • 1. This Presentation Courtesy of the International SOA Symposium October 7-8, 2008 Amsterdam Arena www.soasymposium.com info@soasymposium.com Founding Sponsors Platinum Sponsors Gold Sponsors Silver Sponsors RDF and SOA David Booth, Ph.D. <dbooth@hp.com> HP Software SOA Symposium, Amsterdam, 8-Oct-2008 [Presented by Andrew Weaver, HP Software] Latest version of these slides: http://dbooth.org/2008/soas/slides.ppt © 2008 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice 1 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 2. Outline • PART 0: The problem • PART 1: RDF: A lingua franca for information exchange • PART 2: Key Techniques for RDF in SOA 3 October 8, 2008 HP Software (c) 2008 - SOA Symposium PART 0 The problem 4 October 8, 2008 HP Software (c) 2008 - SOA Symposium 2 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 3. Problem 1: Babelization • Proliferation of data models (XML schemas, etc.) • Parsing issues influence data models • No consistent semantics • Data chaos Tower of Babel, Abel Grimmer (1570-1619) 5 October 8, 2008 HP Software (c) 2008 - SOA Symposium Problem 2: Integration complexity • Multiple producers/consumers need to share data • Tight coupling hampers independent versioning Compliance Management Incident Discovery Provisioning Management Release Change Management Management Release Managers Operation Centers Compliance Managers Source Control Monitoring Networking Engineers Storage Administrators Unix System Administrators Windows System Networking Ticketing Administrators Administrators 6 October 8, 2008 HP Software (c) 2008 - SOA Symposium 3 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 4. Client/service versioning • Need to version clients and services independently • Data models exchanged must evolve • No such thing as the model: − There are several, slightly different but related models Client v3 Service v3 Client v2 Service v2 Client v1 Service v1 7 October 8, 2008 HP Software (c) 2008 - SOA Symposium What to do? 8 October 8, 2008 HP Software (c) 2008 - SOA Symposium 4 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 5. PART 1 RDF: A lingua franca for information exchange in SOA 9 October 8, 2008 HP Software (c) 2008 - SOA Symposium What is RDF? • Resource Description Framework • Relational data model framework • W3C standard >4 years • Foundation of Semantic Web technology • Language for making statements about things • Used to express both: − Ontologies (classes and relationships), and − Instance data 10 October 8, 2008 HP Software (c) 2008 - SOA Symposium 5 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 6. Key features of RDF • Syntax independent (specifies model) − Some existing serializations: RDF/XML, N3, Turtle − Focus on semantics • Consistent semantics − Based on URIs • Great for data integration problems − Data "mashups" 11 October 8, 2008 HP Software (c) 2008 - SOA Symposium Why RDF for SOA? 1. Emphasis on semantics − RDF is syntax independent 2. RDF is good at data integration 3. RDF helps bridge other formats/models 4. Looser coupling 12 October 8, 2008 HP Software (c) 2008 - SOA Symposium 6 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 7. Why? 1. Emphasis on semantics • RDF is syntax independent • RDF specifies information model -- not serialization • Various serializations can be used − RDF/XML, N3, Turtle, etc. 13 October 8, 2008 HP Software (c) 2008 - SOA Symposium Why? 2. Easier data integration • New data models can be easily added • Old and new data models co-exist in merged model • Relationships between the old and new models are expressed explicitly • Both old and new can be used simultaneously 14 October 8, 2008 HP Software (c) 2008 - SOA Symposium 7 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 8. Why? 2. Easier data integration • Blue App has model 15 October 8, 2008 HP Software (c) 2008 - SOA Symposium Why? 2. Easier data integration • Red App has model • Need to integrate Red & Blue models 16 October 8, 2008 HP Software (c) 2008 - SOA Symposium 8 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 9. Why? 2. Easier data integration • Step 1: Merge RDF • Same nodes (URIs) join automatically 17 October 8, 2008 HP Software (c) 2008 - SOA Symposium Why? 2. Easier data integration • Step 2: Add relationships and rules • (Relationships are also RDF) 18 October 8, 2008 HP Software (c) 2008 - SOA Symposium 9 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 10. Why? 2. Easier data integration • Step 3: Define Green model • (Making use of Red & Blue models) 19 October 8, 2008 HP Software (c) 2008 - SOA Symposium Why? 2. Easier data integration • What the Blue app sees: − No difference! 20 October 8, 2008 HP Software (c) 2008 - SOA Symposium 10 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 11. Why? 2. Easier data integration • What the Red app sees • No difference! 21 October 8, 2008 HP Software (c) 2008 - SOA Symposium Why? 3. RDF helps bridge other formats/models • Producers and consumers may use different formats/models • Rules can specify transformations • Inference engine finds path to desired result model A1 X A2 A3 RDF B1 Y Model Transform B2 C1 C2 Z Ontologies Ontologies & Ontologies &Rules &Rules Rules 22 October 8, 2008 HP Software (c) 2008 - SOA Symposium 11 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 12. Why? 4. Looser coupling • Without breaking consumers: − Ontologies can be mixed and extended − Information can be added • Producer & consumer can be versioned more independently 23 October 8, 2008 HP Software (c) 2008 - SOA Symposium Example of looser coupling • RedCust and GreenCust ontologies added • Blue app is not affected (Blue app) Consumer Producer 24 October 8, 2008 HP Software (c) 2008 - SOA Symposium 12 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 13. PART 2 Key Techniques for RDF in SOA 25 October 8, 2008 HP Software (c) 2008 - SOA Symposium 1. RDF message semantics • Interface contract can specify RDF, regardless of serialization • RDF pins the semantics RDF Consumer Producer 26 October 8, 2008 HP Software (c) 2008 - SOA Symposium 13 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 14. But Web services already use XML! • XML is well known and used • Legacy apps may require specific XML or other formats that cannot be changed • How can we gain the benefits of RDF message semantics while still accommodating XML? 27 October 8, 2008 HP Software (c) 2008 - SOA Symposium Custom XML serializations of RDF Recall: RDF is syntax independent • Specifies info model -- not syntax! • Can be serialized in any agreed-upon way Therefore: • Can view existing XML formats as custom serialization of RDF! How? GRDDL . . . 28 October 8, 2008 HP Software (c) 2008 - SOA Symposium 14 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 15. What is GRDDL? • Gleaning Resource Descriptions from Dialects of Languages • W3C standard • Permits RDF to be "gleaned" from XML • XML document or schema specifies GRDDL transformation for that document (or type) − Each XML document/type can use a different GRDDL transformation • GRDDL transformation produces RDF from XML document − Typically written in XSLT 29 October 8, 2008 HP Software (c) 2008 - SOA Symposium 2. GRDDL transformations from XML to RDF Therefore: • Same XML document can be consumed by: − Legacy XML app − RDF app • App interface contract can specify RDF − Serializations can vary − Semantics are pinned by RDF • Helps bridge XML and RDF worlds 30 October 8, 2008 HP Software (c) 2008 - SOA Symposium 15 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 16. Bridging XML and RDF Service XML/other Normalize to RDF Core App Client Processing Serialize as XML/other/RDF • Input: Accept whatever formats are required − Use GRDDL to transform XML to RDF • Output: Serialize to whatever formats are required − Generate XML/other directly (or even RDF!), or − SPARQL query can generate specific view first 31 October 8, 2008 HP Software (c) 2008 - SOA Symposium 3. REST-based SPARQL endpoints HTTP SPARQL RDF Consumer Producer 32 October 8, 2008 HP Software (c) 2008 - SOA Symposium 16 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 17. REST-based SPARQL endpoints • Why REST: − HTTP is ubiquitous − Simpler than SOAP-based Web services (WS*) − Looser process coupling 33 October 8, 2008 HP Software (c) 2008 - SOA Symposium REST-based SPARQL endpoints • What is SPARQL: − Simple Protocol And RDF Query Language − W3C standard − Query language for RDF − Modeled after SQL: SELECT ... WHERE ... 34 October 8, 2008 HP Software (c) 2008 - SOA Symposium 17 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 18. REST-based SPARQL endpoints • Why SPARQL: − RDF gives looser data coupling − Insulates consumers from internal model changes • Inferencing can transforms data to consumer's desired model − One endpoint supports multiple consumer needs • Each consumer gets what it wants − Simpler interface for consumers • Uniform SPARQL interface instead of a different set of parameters for each REST endpoint • Takes the REST notion of "uniform interface" one step farther 35 October 8, 2008 HP Software (c) 2008 - SOA Symposium 4. Aggregators • Gets data from multiple sources • Provides data to consumers • Does model transformation, caching, etc. • Conceptual component -- not necessarily a separate service A1 X A2 A3 SPARQL B1 Y Aggregator B2 C1 C2 Z Ontologies Ontologies & Ontologies &Rules &Rules Rules 36 October 8, 2008 HP Software (c) 2008 - SOA Symposium 18 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 19. Conclusions • Value of RDF in data integration is well proven • RDF can bring looser coupling to SOA • Key techniques: 1. RDF message semantics 2. REST-based SPARQL endpoints 3. GRDDL to bridge from XML to RDF 4. Aggregators 37 October 8, 2008 HP Software (c) 2008 - SOA Symposium More information • RDF and SOA: http://dbooth.org/2007/rdf-and-soa/rdf-and-soa-paper.htm • RDF: http://www.w3.org/TR/REC-rdf-syntax/ • SPARQL: http://jena.sourceforge.net/ARQ/Tutorial/ • GRDDL: http://www.w3.org/TR/grddl-primer/ 38 October 8, 2008 HP Software (c) 2008 - SOA Symposium 19 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.
  • 20. Outline • PART 0: The problem • PART 1: RDF: A lingua franca for information exchange • PART 2: Key Techniques for RDF in SOA 39 October 8, 2008 HP Software (c) 2008 - SOA Symposium Questions? © 2008 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice 20 October 2003 Copyright © 2006 HP corporate presentation. All rights reserved.