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Interacting with Linked Data via semantically annotated widgets

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Interacting with Linked Data via semantically annotated widgets

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The continuous growth of the Linked Data Web brings us closer to the original vision of the Web as an interconnected network of machine-readable resources. There is, however, an essential aspect in principle still missing from this vision, i.e., the ability for the Web user to interact directly with the Linked Data in a read/write manner. In this presentation we introduce a lifecycle and associated mechanism to enable a domain-agnostic read/write interaction with Linked Data in the context of a single data provider. Our solution uses an ontology to build a binding front-end for a given RDF model, in addition to RDFa to maintain the semantics of the resulting form/widget components. On the processing side, a RESTful Web service is provided to seamlessly manage semantic widgets and their associated data, and hence enable the read/write data interaction mechanism. The evaluation shows that the generation process presents no performance issues, while the content overhead required for the actual form-data binding is kept to a minimum.

The continuous growth of the Linked Data Web brings us closer to the original vision of the Web as an interconnected network of machine-readable resources. There is, however, an essential aspect in principle still missing from this vision, i.e., the ability for the Web user to interact directly with the Linked Data in a read/write manner. In this presentation we introduce a lifecycle and associated mechanism to enable a domain-agnostic read/write interaction with Linked Data in the context of a single data provider. Our solution uses an ontology to build a binding front-end for a given RDF model, in addition to RDFa to maintain the semantics of the resulting form/widget components. On the processing side, a RESTful Web service is provided to seamlessly manage semantic widgets and their associated data, and hence enable the read/write data interaction mechanism. The evaluation shows that the generation process presents no performance issues, while the content overhead required for the actual form-data binding is kept to a minimum.

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Interacting with Linked Data via semantically annotated widgets

  1. 1. ϕArmin Haller | δTudor Groza | ξFlorian Rosenberg Interacting with Linked Data via Semantically Annotated Widgets Joint International Semantic Technology Conference ϕCSIRO ICT Centre, Australia|W3C Australia δQueensland University, Australia ξIBM T.J. Watson, NY, USA
  2. 2. A little motivation for the work… … why interacting with the Linked data Web?
  3. 3. Linked data Web Building a Web of Data … … four principles Publishing, interlinking data in RDF via de-referenceable URIs
  4. 4. Publishing RDF Two (standardised) serialization formats to publish RDF (graphs) 1. RDF/XML 2. RDFa
  5. 5. RDF/XML Widely used to publish linked data All benefits of XML, but … … syntax difficult for humans to read and write … additional to HTML … needs full control over publishing infrastructure (Rewrites etc.)
  6. 6. RDFa Relatively new format, but used by already 5% of web sites Interwoven within the HTML DOM … … existing content within the page can be marked up with RDFa … no additional control over publishing infrastructure needed
  7. 7. RDFa example Simple page about a book <html> <head> <title>The Art of Computer Programming, Volume 1: Fundamental Algorithms</title> </head> <body> <div><img src="theartofprogramming.jpg" /></div> <div>Donald E. Knuth</div> <div>Edition 3</div> <div>Addison-Wesley Professional</div> <div>672 pages</div> <div>ISBN-10: 0201896834</div> </body> </html>
  8. 8. RDFa example Simple page about a book <html> <head prefix="dc: http://purl.org/dc/terms/“ base="http://example.org/book/TAoCP> <title about="" property="dc:title">The Art of Computer Programming, Volume 1: Fundamental Algorithms</title> </head> <body> <div about=""> <div><img src="theartofprogramming.jpg" /></div> <div property="dc:creator">Donald E. Knuth</div> <div>Edition 3</div> <div property="dc:publisher">Addison-Wesley Professional</div> <div property="dc:SizeOrDuration">672 pages</div> <div property="dc:identifier">ISBN-10: 0201896834</div> </div> </body> </html>
  9. 9. Embedded triples @prefix dc: <http://purl.org/dc/terms/> . @prefix : <http://example.org/book/> . :TAoCP dc:title "Art of Computer Programming, Volume 1: Fundamental Algorithms" . :TAoCP dc:creator "Donald E. Knuth" . :TAoCP dc:publisher "Addison-Wesley Professional" . :TAoCP dc:SizeOrDuration ”672 pages" . :TAoCP dc:identifier "ISBN-10: 0201896834" .
  10. 10. RDFa – provider vs. user content RDFa only usable for provider created content Ideally, all user input data should be part of the RDF graph, … … currently no mechanism in RDFa to type user created content (within the DOM)
  11. 11. Example user created content in Web forms e.g. Buy a TV online (e.g. Amazon, Ebay) First Name: Jane Last Name: Doe Email: jane.doe@example.com Password: ******** Gender: Male Female Birthday: 03 04 1976
  12. 12. Example user created content in Web forms e.g. Buy a TV online (e.g. Amazon, Ebay) First Name: Jane Last Name: Doe Email: jane.doe@example.com Password: ******** Gender: Male Category: Female Female LCD Television Birthday: 03 04 Product1976 1976 Name: Sony Bravia LX9000 Description: Your complete 3D experience from Sony Price: 1500 USD Amount 1 Delivery 10 Downing Street Address: London SW1A 2AA United Kingdom
  13. 13. Example user created content in Web forms e.g. Buy a TV online (e.g. Amazon, Ebay) First Name: Jane Last Name: Doe Email: jane.doe@example.com Password: ******** Gender: Male Category: Female Female LCD Television Birthday: 03 04 Product1976 1976 Name: Sony Bravia LX9000 Description: Your complete 3D experience from Sony Price: Price: 1500 USD 25 GBP Type: Mastercard Amount 1 Delivery Cardholder: 1 04 1976 Jane Doe 10 Downing Street Address: CC Number: 5999 9999 9999 9999 London SW1A 2AAExpiry Date: 04 13 CVV: United Kingdom 999
  14. 14. No annotation for user created content Form input elements can be annotated with RDFa … … but, RDFa annotations for input data are not possible no binding mechanism in RDFa
  15. 15. No annotation for user created content (cont’d) Provider content vs. User created content Category: Female LCD Television Provider data | RDFa Product1976 Sony Bravia LX9000 Name: Provider data | RDFa Description: Your complete 3D Provider data | RDFa experience from Sony Price: 1500 USD Provider data | RDFa Amount 1 User data | Key/Value pair Delivery 10 Downing Street User data | Key/Value pair Address: London User data | Key/Value pair SW1A 2AA User data | Key/Value pair United Kingdom User data | Key/Value pair
  16. 16. No annotation for user created content (cont’d) e.g. “Jane” can not be defined as foaf:firstName First Name: Jane Last Name: Doe Email: jane.doe@example.com Password: ******** Gender: Male Female Birthday: 03 04 1976 <div about="" property="foaf:firstName" content=""> <input type="text" name=“First Name" value="" /> </div>span> No binding!
  17. 17. Publishing and Reusing user created content on the Linked Data Web!
  18. 18. Model and System for semantic Web applications – RDF-based model for forms (RaUL) http://purl.org/NET/raul# – RESTful Web service (ActiveRaUL) http://w3c.org.au/raul – Client-side JavaScript RDFa API
  19. 19. ActiveRaUL system architecture Controller: Web service that maps HTTP terms to CRUD operations on RaUL widgets Model: View: RaUL RDF model Rendering service to serialise RaUL-based widgets in XHTML+RDFa
  20. 20. Usage Scenario 1. Form Modeling: Model widgets (forms) in RDF based on the RaUL ontology 2. Form Deployment: Submit form with HTTP POST to ActiveRaUL 3. Form Usage: Access/Use a form model with GET/POST to ActiveRaUL
  21. 21. Form Modeling • RDFa User Interface Language (RaUL) Ontology for widget (form) control elements • Data binding mechanism to reference external schemas for data (e.g. foaf:firstname, gr:category)
  22. 22. RaUL Form Model Widget (form) meta model
  23. 23. RaUL Form Model – Triples defining the form structure Category: LCD Television raul:textbox Product Name: Sony Bravia LX9000 raul:textbox Description: Your complete 3D raul:textbox experience from Sony Price: 1500 USD raul:textbox/raul:listbox Amount 1 raul:textbox
  24. 24. RaUL Form Model – Triples defining the form input data Category: LCD Television gr:category Product Name: Sony Bravia LX9000 rdfs:label Description: Your complete 3D rdfs:comment experience from Sony Price: 1500 USD gr:currency/gr:hasUnitOfMeasurement Amount 1 gr:amountOfThisGood
  25. 25. Form Deployment • RESTful service for managing Web widgets (forms) • Maps HTTP verbs to SPARQL queries on RaUL model • Algorithm for generating widget models from arbitrary RDF graphs • Example: Form upload POST /public/forms HTTP/1.1 Host: w3c.org.au/raul Content-Type: application/xml <rdf:…/>
  26. 26. Form Deployment • RESTful service for managing Web widgets (forms) • Maps HTTP verbs to SPARQL queries on RaUL model • Algorithm for generating widget models from arbitrary RDF graphs • Example: Form upload Created (201) Location: http://w3c.org.au/raul/public/forms/add-product
  27. 27. Form Usage 1. Web user retrieves Web forms (and content) using ActiveRaUL (via browser) 2. ActiveRaUL returns web form in: • RDF/XML, RDF/JSON • HTML+RDFa view rendering 3. User fills out forms and submits data to ActiveRaul
  28. 28. HTML+RDFa view rendering <html> <head> <base href="#addProduct"/> <meta property="raul:title" content="Add Product"/> <title>Add Product</title> </head> <body> … <div xmlns=http://www.w3.org/1999/xhtml about="http://w3c.org.au/forms/productAdd1#product" typeof="raul:Textbox"> <span property="raul:label">Product URI:</span> <span style="display:none;"> <span property="raul:id">product</span> <span property="raul:name">product</span> <span property="raul:value">http://w3c.org.au/forms/productAdd1#value_product</span> </span> </div> … <div xmlns="http://www.w3.org/1999/xhtml" about="http://w3c.org.au/forms/productAdd1#product_name" typeof="raul:Textbox"> <span property="raul:label">Product Name:</span> <span style="display:none;"> <span property="raul:id">product_name</span> <span property="raul:name">product_name</span> <span property="raul:value">http://w3c.org.au/forms/productAdd1#value_product_name</span> </span> </div> <div style="display:none;" about="http://w3c.org.au/forms/productAdd1#value_product_name"> <span xmlns="http://www.w3.org/1999/xhtml" property="rdf:subject">http://w3c.org.au/forms/productAdd1#defaultSubject</span> <span xmlns="http://www.w3.org/1999/xhtml" property="rdf:predicate">gr:name</span> <span xmlns="http://www.w3.org/1999/xhtml" property="rdf:object"></span> </div>
  29. 29. Form Usage Data Reuse • Link to existing, local data or data in the Linked Data Web – Client-side JS RDFa API can retrieve data directly from URI or via Sindice and prefills form controls Product: Category: Product Name: Description: Price: USD Amount
  30. 30. Form Usage Data Reuse • Link to existing, local data or data in the Linked Data Web – Client JS API retrieves data directly from URI or via Sindice and prefills form controls Product: http://bestbuy.com/… Category: Product Name: Description: Price: USD Amount
  31. 31. Form Usage Data Reuse • Link to existing, local data or data in the Linked Data Web – Client JS API retrieves data directly from URI or via Sindice and prefills form controls Product URI: http://bestbuy.com/… Category: LCD Television Product Name: Sony Bravia LX9000 Your complete 3D Description: experience from Sony Price: USD Amount
  32. 32. Evaluation Quantitative evaluation to analyse possible performance issues of our approach Performance of the ActiveRaUL framework is influenced by two factors: (i) overhead introduced by the RDFa annotations (ii) performance of the widget/model generation
  33. 33. Evaluation - Overhead • Comparison of request sizes for HTTP GET requests and HTTP PUT/POST requests and responses Form XHTML XHTML + # of Triples Overhead in % Element (in Byte) RDFa (Byte) min max min max min max min max Widget 72 115 251 376 3 6 248% 226% Textbox 41 100 88 377 2 7 114% 277% Listbox 49 125 228 459 5 9 365% 367% Button 48 81 98 415 2 8 104% 412%
  34. 34. Evaluation - Overhead • Comparison of request sizes for HTTP GET and HTTP PUT/POST requests and response Form XHTML XHTML + # of Triples Overhead in % Element (in Byte) RDFa (Byte) min max min max min max min max Widget 278 321 525 617 3 6 89% 92% Textbox 239 298 454 613 2 7 90% 105% Listbox 274 323 656 758 5 9 139% 135% Button 245 278 459 720 2 8 87% 159%
  35. 35. Evaluation – Overhead – Discussion • Content overhead a result of using RDFa for the annotation of the semantic forms/widgets • We talk about adding one/two digit numbers of Kilobytes! – Acceptable in most cases – Common and accepted practice to add RDFa to HTML
  36. 36. Evaluation – Performance of view generation Measured time required to generate an increasing number (1, 10 and 100) of widget elements Results • linear scalability for all widget elements • Listbox and Listitems, also linear, but with a much higher factor (100x10) In reality (for usability reasons) interesting ranges are between 10 and 30 widget elements
  37. 37. Conclusion ActiveRaUL combines Web engineering with principles of Linked Open Data/Semantic Web • RDFa annotated Web forms • well-defined publishing and usage lifecycle Advantages: (a) full machine understandable structured form data (b) structured form data is encoded directly in the Web page and usable to any SW application (c) typing of the form data via reference to standard ontologies (d) automatic retrieval of form data from the Linked Data Web, and (e) fully browser agnostic approach (rendering in XHTML + RDFa)

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