Building Semantic Web Portals with WebML

Building Semantic Web Portals with WebML Marco Brambilla and Federico M. Facca ICWE 2007 Como, 20th July 2007 http://home.dei.polimi.it/mbrambil http://twitter.com/MarcoBrambi http://www.slideshare.net/mbrambil

Agenda
Introduction
Requirements for metamodels of Semantic Web applications
Extending WebML towards Semantic Web
Evolving existing primitives
New Advanced units for ontology querying
Primitives for Ontology management
Example of Usage of Advanced Units
Case Study Example
Implementation expirience
Conclusions & Future Works

Introduction
Model-driven techniques aims to reduce the cost of design and implementation of software
The Semantic Web can benefit from Web Engineering field and viceversa
there’s a lack of well engineered solution in SW
SW technologies provide more “flexibility” and allow complex reasoning task
Some effort have been already done: HERA, SHDM, …
A Web Portal is a Web site providing personalization to to its visitors and designed to use distributed data sources
One of the assumptions of Semantic Web is the use of distributed data sources and reuse of existing ones

Introduction Requirements for metamodels of Semantic Web applications
Support of semantic languages (OWL, RDF, WSML, …)
Models should be “semantic”
i.e., grant self-annotation and explicit semantic annotation extraction
Allow for flexible integration of heterogeneous sources and applications
Transformations towards a semantic query language
allowing for inference, verification, query on schema and instances
Allow for (semi-)automatic annotation of generated Web pages
Support the import and reference of remote ontologies
reuse and sharing of the knowledge

WebML methodology extended to support the new requirements
+ Reuse of existing ontological data source + Specialized units for advanced queries over semantic data and annotation extraction

WebML methodology extended to support the new requirements

Extending WebML towards Semantic Web Evolving existing primitives
Existing units can be adapted for direct access to ontology
Changes in their “semantic” (query both on schemas and instances )
instance uri class uri e.g. mf:Artist no input class uri e.g. vin:RedWine […] […] […] […]

Extending WebML towards Semantic Web New Advanced units for ontology querying Is x subproperty of y? Or: find subproperties/ find superproperties The list of URIs where property p has value v Or: find values/ find properties Is x property of y? Or: find the properties/ find the class Is x an instance of y? Or: find instances/ find classes Is x subclass of y? Or: find subclasses/ find superclasses

Extending WebML towards Semantic Web New Advanced units for ontology querying class uri instance uris instace uri classes uris instace & class uri boolean

Extending WebML towards Semantic Web Primitives for Ontology management
Ontology composition: union, intersection, difference
Ontology importing: for direct query of existing ontologies
Semantic description extraction: for extracting semantic annotation of contents / pages

Extending WebML towards Semantic Web Example of Usage of Advanced Units The value submitted in the form is passed to the HasPropertyValue unit that extracts a set of URIs of instances (albums or artists) with mm:soundsLike property equal to Val. The InstanceOf unit that checks if they are instances of the class Artist. The URIs are then shown in a list of Artists.

Case Study Example

Current extension is for RDF/OWL and uses SPARQL queries
New set of runtime components created to support semantic data sources based on Jena API and Pellet
Modeling environment extended for the use of the new units

The automatic code generation phase is based on the generation of configuration files for the generic components
The transformation from design time descriptor to runtime descriptor is based on XSLT
Design Time Descriptor Runtime Descriptor <SWINDEXUNIT class="mf:Track" id="swinu1" name="Tracks" ontology="onto1"> <DisplayedProperties property="mf:title"/> <DisplayedProperties property="mf:descripion"/> <SortProperties order="ascending" property="mf:title"/> <Filter boolean="or"> <FilterCondition id="fselector1" property="mf:playedBy" predicate="eq" name="Artist"/> </Filter> </SWINDEXUNIT> <descriptor service="org.webml.onto. SWIndexUnitService"> <onto>onto1</onto> ... <input-params> <input-param type="mm:Artist" name="swdau2.rdf:ID" /> </input-params> ... <query type="SELECT"> SELECT DISTINCT ?instance ?p1 ?p2 WHERE {?instance rdf:type mm:Track . ?instance mm:title ?p1 . ?instance mm:descriptor ?p2 . ?instance mm:playedBy ?fs1 . FILTER (?fs1 = $swdau2.rdf:ID$)} ORDER BY DESC(?p1) </query> </descriptor>

Conclusions & Future Works
Good abstractions are still valid even when new technologies become available
Schema querying become relevant in the context of Semantic Web and Models should provide support for it
Semantic Web introduces new query “types” and metamodels for Web applications should deal with this
Our solution is missing a real integration layer for better allowing seamless integration of the different datasources
Current implementations suffers performance issue when executed the first time

Thanks for the attention!
For comments or questions:
Marco Brambilla
Politecnico di Milano
Dipartimento di Elettronica e Informazione
[email_address]
Resources:
http://home.dei.polimi.it/mbrambil
http://marcobrambi.blogspot.com
http://twitter.com/MarcoBrambi
http://home.dei.polimi.it/mbrambil http://twitter.com/MarcoBrambi http://www.slideshare.net/mbrambil

Building Semantic Web Portals with WebML

by Marco Brambilla on Jul 16, 2010

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