Interacting with Linked Data via semantically annotated widgets

ϕArmin Haller | δTudor Groza | ξFlorian Rosenberg

Interacting with Linked Data via Semantically Annotated WidgetsJoint International Semantic Technology Conference

ϕCSIRO 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 Web

Building a Web of Data …

… four principles

Publishing, interlinking data in RDF via de-referenceable URIs

Publishing RDF

Two (standardised) serialization formats to publish RDF (graphs)

1. RDF/XML

2. RDFa

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.)

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

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>

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>

@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" .

Embedded triples

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)

Example user created content in Web forms

e.g. Buy a TV online (e.g. Amazon, Ebay)First Name:

Last Name:

Jane

Doe

Email: [email protected]

Password: ********

Gender:

Birthday: 03 04 1976

Male Female


e.g. Buy a TV online (e.g. Amazon, Ebay)

1976

First Name:

Last Name:

Jane

Doe


Password: ********

Gender:

Birthday: 03 04

Male Female

1976

Female

Delivery Address:

10 Downing Street

London

SW1A 2AA

United Kingdom

Category:

Product Name:Description:

Price:

Amount

LCD Television

Sony Bravia LX9000

Your complete 3D experience from Sony

1500

1

USD


e.g. Buy a TV online (e.g. Amazon, Ebay)

1976

First Name:

Last Name:

Jane

Doe


Password: ********

Gender:

Birthday: 03 04

Male Female

1976

Female

Delivery Address:

10 Downing Street

London

SW1A 2AA

United Kingdom

Category:


Price:

Amount

LCD Television

Sony Bravia LX9000


1500

1

USD

1 197604Cardholder:

CC Number:

Expiry Date:

CVV: 999

Price:

Type: Mastercard

Jane Doe

5999 9999 9999 9999

04 13

25 GBP

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

No annotation for user created content (cont’d)

Provider content vs. User created content

1976

Female

Delivery Address:

10 Downing Street

London

SW1A 2AA

United Kingdom

® Provider data | RDFa® Provider data | RDFa® Provider data | RDFa

® Provider data | RDFa® User data | Key/Value

pair® User data | Key/Value




pair

Category:


Price:

Amount

LCD Television

Sony Bravia LX9000


1500

1

USD

No annotation for user created content (cont’d)

e.g. “Jane” can not be defined as foaf:firstName

First Name:

Last Name:

Jane

Doe


Password: ********

Gender:

Birthday: 03 04 1976

Male Female

<div about="" property="foaf:firstName" content=""> <input type="text" name=“First Name" value="" />

</div>span>

No binding!

Publishing and Reusing user created 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

http://purl.org/NET/raul

http://raul.deri.ie/raul

ActiveRaUL system architecture

Model:RaUL RDF model

Controller:Web service that maps HTTP terms to CRUD operations on RaUL widgets

View:Rendering service to serialise RaUL-based widgets in XHTML+RDFa

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

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 Model

Widget (form) meta model

RaUL Form Model – Triples defining the form structure

Category:

Product Name:

LCD Television

Sony Bravia LX9000

Description:

Price:

® raul:textbox

® raul:textbox

® raul:textbox

® raul:textbox/raul:listbox

® raul:textbox


1500

Amount 1

USD

RaUL Form Model – Triples defining the form input data

Category:

Product Name:

LCD Television

Sony Bravia LX9000

Description:

Price:

® gr:category

® rdfs:label

® rdfs:comment

® gr:currency/gr:hasUnitOfMeasurement

® gr:amountOfThisGood


1500

Amount 1

USD

Form Deployment• RESTful service for managing

Web widgets (forms)

• Maps HTTP verbs to SPARQLqueries on RaUL model

• Algorithm for generating widget models from arbitrary RDF graphs

• Example: Form uploadPOST /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 SPARQLqueries 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

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

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>

http://www.w3.org/1999/xhtml

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

Category:


Price:

Amount

USD

Product:

Form Usage


the Linked Data Web– Client JS API retrieves data directly from URI

or via Sindice and prefills form controls

Category:


Price:

Amount

USD

Product: http://bestbuy.com/…

Form Usage


the Linked Data Web– Client JS API retrieves data directly from URI

or via Sindice and prefills form controls

Category:

Product Name:

LCD Television

Sony Bravia LX9000

Description:

Price:


Amount

USD

Product URI: http://bestbuy.com/…

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

Evaluation - Overhead

• Comparison of request sizes for HTTP GET requests and HTTP PUT/POST requests and responses

Form Element

XHTML (in Byte)

XHTML + RDFa (Byte)

# of Triples Overhead in %

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%

Evaluation - Overhead

• Comparison of request sizes for HTTP GET and HTTP PUT/POST requests and response

Form Element

XHTML (in Byte)

XHTML + RDFa (Byte)

# of Triples Overhead in %

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%

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 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

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)

Interacting with Linked Data via semantically annotated widgets

Technology

Transcript of Interacting with Linked Data via semantically annotated widgets