Interacting with Linked Data via semantically annotated widgets

ϕArmin Haller | δTudor Groza | ξFlorian RosenbergInteracting with Linked Data viaSemantically Annotated WidgetsJoint International Semantic Technology ConferenceϕCSIRO ICT Centre, Australia|W3C AustraliaδQueensland University, AustraliaξIBM T.J. Watson, NY, USA

A little motivation for the work…… why interacting with the Linked data Web?

Linked data WebBuilding a Web of Data …… four principlesPublishing, interlinking data in RDFvia de-referenceable URIs

Publishing RDFTwo (standardised) serializationformats to publish RDF (graphs)1. RDF/XML2. RDFa

RDF/XMLWidely used to publish linked dataAll benefits of XML, but …… syntax difficult for humans to read and write… additional to HTML… needs full control over publishing infrastructure (Rewrites etc.)

RDFaRelatively new format, but used byalready 5% of web sitesInterwoven within the HTML DOM …… existing content within the pagecan be marked up with RDFa… no additional control overpublishing infrastructure needed

RDFa exampleSimple 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>

RDFa exampleSimple 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>

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" .

RDFa – provider vs. user contentRDFa only usable for provider createdcontentIdeally, all user input data should bepart of the RDF graph, …… currently no mechanism in RDFato type user created content (withinthe DOM)

Example user created content in Web forms e.g. Buy a TV online (e.g. Amazon, Ebay)First Name: JaneLast Name: DoeEmail: jane.doe@example.comPassword: ********Gender: Male FemaleBirthday: 03 04 1976

Example user created content in Web forms e.g. Buy a TV online (e.g. Amazon, Ebay)First Name: JaneLast Name: DoeEmail: jane.doe@example.comPassword: ********Gender: Male Category: Female Female LCD TelevisionBirthday: 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

Example user created content in Web forms e.g. Buy a TV online (e.g. Amazon, Ebay)First Name: JaneLast Name: DoeEmail: jane.doe@example.comPassword: ********Gender: Male Category: Female Female LCD TelevisionBirthday: 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

No annotation for user created contentForm input elements can be annotatedwith RDFa …… but, RDFa annotations for input dataare not possible no bindingmechanism in RDFa

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

No annotation for user created content (cont’d)e.g. “Jane” can not be defined asfoaf: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!

Publishing and Reusing usercreated content on the Linked Data Web!

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

ActiveRaUL system architecture Controller: Web service that maps HTTP terms to CRUD operations on RaUL widgetsModel: View:RaUL RDF model Rendering service to serialise RaUL-based widgets in XHTML+RDFa

Usage Scenario1. Form Modeling: Model widgets (forms) in RDF based on the RaUL ontology2. Form Deployment: Submit form with HTTP POST to ActiveRaUL3. Form Usage: Access/Use a form model with GET/POST to ActiveRaUL

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)

RaUL Form ModelWidget (form) meta model

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

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

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:…/>

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 uploadCreated (201)Location: http://w3c.org.au/raul/public/forms/add-product

Form Usage1. Web user retrieves Web forms (and content) using ActiveRaUL (via browser)2. ActiveRaUL returns web form in: • RDF/XML, RDF/JSON • HTML+RDFa view rendering3. User fills out forms and submits data to ActiveRaul

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>

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 controlsProduct:Category:Product Name:Description:Price: USDAmount

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 controlsProduct: http://bestbuy.com/…Category:Product Name:Description:Price: USDAmount

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 controlsProduct URI: http://bestbuy.com/…Category: LCD TelevisionProduct Name: Sony Bravia LX9000 Your complete 3DDescription: experience from SonyPrice: USDAmount

EvaluationQuantitative evaluation to analyse possibleperformance issues of our approachPerformance of the ActiveRaUL framework isinfluenced by two factors:(i) overhead introduced by the RDFa annotations(ii) performance of the widget/model generation

Evaluation - Overhead • Comparison of request sizes for HTTP GET requests and HTTP PUT/POST requests and responsesForm XHTML XHTML + # of Triples Overhead in %Element (in Byte) RDFa (Byte) min max min max min max min maxWidget 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%

Evaluation - Overhead • Comparison of request sizes for HTTP GET and HTTP PUT/POST requests and responseForm XHTML XHTML + # of Triples Overhead in %Element (in Byte) RDFa (Byte) min max min max min max min maxWidget 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%

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

Evaluation – Performance of view generationMeasured time required togenerate an increasing number(1, 10 and 100) of widgetelementsResults• 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 between10 and 30 widget elements

ConclusionActiveRaUL combines Web engineering withprinciples of Linked Open Data/Semantic Web • RDFa annotated Web forms • well-defined publishing and usage lifecycleAdvantages:(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)

Interacting with Linked Data via semantically annotated widgets

by Armin Haller

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