ESWC, June 1st, 2010

LESS - Template-based Syndication and

Presentation of Linked Data for End-users

Sören Auer, Raphael Doehring, Sebastian Tramp (formerly Dietzold)

Research Group AKSW

How can I show the Linked Data Web to my grandma?

July 2007 April 2008 September 2008

July 2009

Steradent Triple Action Denture Cleaning Powder pricesActive Adult

CommunitiesKaffeefahrten (promotional trips)

How can we make LODvisible & usable to end-users?

LESS in a nutshell: Create visualization templates for

common entity types

Enable people to publish, share,

discuss, refine, reuse templates

RESTful API facilitates embedding of processed templates into arbitrary Web sites (blogs, Wikis, CMSes, …)

= “LOD syndication”

Websites update, once LOD resources

do

LESS System Architecture

LeTL – Less Template Language

• Extension of the well-known SMARTY template language:

Template Example

Template Repository: publish, rate, browse, reuse templates

• Categorization based on supported RDF classes and user-defined tags• rate, comment and reuse existing templates• Implemented on top of a relational database, available as RDF by

using Triplify at http://less.aksw.org/triplify• Each template has unique template id, every revision its revision id• registered LESS users can only change their own templates

– prevents conflicts– a user can create own copy of any template

• public availability of templates has a number of advantages:– templates serve as examples for new users,– they can be used by other third-party applications,– the reuse of templates facilitates a natural modularization,– popularity tracking.

Template Processor• Input: LESS template + linked data resource or SPARQL query • iterates through all resource descriptions or SPARQL query result

items– Enables processing of RDF documents containing >1 resource descriptions

• template application can be restricted to resources of a certain type i.e. RDF class (e.g. foaf:Person in a FOAF profile)

• sortBy parameter: order the resources based on the values of a certain property

• user-defined parameters: can be accessed from within the template definition

• cached version of LOD resource or SPARQL query can be used (based on per system, template or request configuration)– Mitigates endpoint outages and slow responses

LESS Integration Interface

REST API via the URL http://less.aksw.org/build

URL parameters • id of the template, • LOD URI or SPARQL query• revision of the template (optional)• ttl (optional)

Returns the rendered output as text (in most cases HTML snippets)• optional URL parameter output: Javascript or JSON can be alternatively

selected as output format

http://less.aksw.org/build?id=2&uri=http%3A%2F%2Fdbpedia.org%2Fresource%2FBerlin

Usage scenario: Linked Data View Creation and Visualization

GoodRelations example© Martin Hepp

Usage scenario: Integration of Information from Various Sources

Create LOD Visualization Mashups

• Mashup template combining the Google Charts API with Eurostats data:

Template Integration into Existing Applications: Typo3

Can LOD make grandmas happy?

Extensive investigations by the presenter revealed:

No information yet on LOD about:

Steradent Triple Action Denture Cleaning Powder pricesActive Adult

CommunitiesKaffeefahrten (promotional trips)

But if it would be, at least with LESS we could present it in a way grandmas would understand ;-)

ESWC, June 1st, 2010

Thanks!Sören Auerauer@informatik.uni-leipzig.deResearch group Agile Knowledge Engineering & Semantic Web

(AKSW): http://aksw.orghttp://less.aksw.org