tu/e technische universiteit eindhoven hera: development of semantic web information systems...

TU/e technische universiteit eindhoven

Hera: Development of Semantic Web Information Systems

Geert-Jan Houben

Peter Barna

Flavius Frasincar

Richard Vdovjak

[email protected]


Overview

• WIS design

• Hera methodology, RDF(S)

• Conceptual model and integration

• Application model and adaptation

• User interaction


Motivation

• From Web pages to Web information system (WIS)

• Technologies from Semantic Web: RDF(S)

• Hera uses RDF(S) for effective support of WIS design


WIS Design

• Generation of hypermedia presentations: navigation structure– Presentation objects, e.g. pages

– Navigation connections, e.g. hyperlinks

• Integration from different sources: transparent repository– Management of semi-structured data

• Personalization: user adaptation


Adaptation

• Presentations must be adaptable to different users/user platforms

• Devices (PC, PDA, WAP Phone, WebTV etc.)• Device capabilities (display size, memory size,

network speed, etc.)• User preferences (desired layout, navigation

patterns, etc.)• User browsing history


HERA Architecture

Relational Database

Object-Oriented Database

XML Database

ODB-XML Wrapper

RDB-XML Wrapper

Mediator/ Integrator

Logical Presentation

Logical-WML Presentation

HTML Presentation

SMIL Presentation

WML Presentation

Logical-SMIL Presentation

Logical-HTML Presentation

Information Retrieval

Hypermedia Presentation

…

…Query

Use

r/P

latf

orm

A

dapt

atio

n


Hera: WIS Design Methodology

• RMM, OOHDM, WebML, etc.• Sequence of steps in designing a web application• Model-driven approach:

– data/navigation/presentation

• Data transformations:– towards HTML, WML, SMIL, etc.

• Use of RDF(S) to specify different models and XSLT to transform (meta)data– subclass/subproperty – extensibility, e.g. CC/PP vocabulary


Conceptual Model (CM)

• Provides a uniform semantic view over different data sources that are integrated within a given Web application

• Consists of hierarchies of concepts relevant within the given domain, their properties, and relations

• Encoded in RDF(S)


Conceptual Model Example


Source Clusters Equipment Catalogue Photo Rental

Photo Stock Agency

Sources are• Autonomous • (Virtually) grouped to clusters

based on the content they provide• RDF(S), RQL capable


Integration ModelIM decouples the CM and Sources • Articulations

– actual links between the CM and the source ontologies– (a part of it) serves as a query on the source side

• Decorations– offer a way to rank sources within the same cluster– capture explicitly designer’s knowledge about sources– open possibilities for queries with constraints

e.g. “I’m interested in the answer within 1s, otherwise forget it”


Integration Model Ontology

Integration ModelSpecialization

IntegrationModel Ontology

Reliability

ResponseTime

Decoration

Articulation To

FromLiteral

Comparator

PathExpressionNode

rdfs:Resource

Edge

rdf:Property

begins

ends

starts ToNode

starts FromNode

PrimaryNode

ProcInstruction

Transformer

Literal2String

Sn2UriTrans

xy property "xy"subPropertyOfsubClassOf

backtrack

follow

target

applies

obtainedFrom

srcAddress

Literal

App

lica

tion

inde

pend

ent

• Path expression

• Articulation

• Decoration

• Processing instruction


Application Model (AM)

• Captures navigational view over CM, describing hypermedia aspects

• Slices are meaningful presentation units:– Associated to concepts from CM– Containing properties/attributes and possibly other slices

• Slices are linked together with slice relationships:– Aggregation relationships: index, tour, indexed guided tour

etc.– Reference relationships: link with an anchor specified

• Encoded in RDF(S)


Application Model Example


Adaptation

• WIS are accessed through multitude of devices and by different users– Device capabilities

– User preferences

– Browsing history

• Adaptation based on conditioning the appearance of slices in AM


Adaptation/User Model

• Captures two kinds of adaptation• Adaptability takes into account the context in which the user will

use the presentation (e.g. the browsing platform) • Adaptivity means that the presentation changes itself according to

the “state of the user’s mind” while being browsed

• Consists of • Device/User Profile captures “static” visual and platform

preferences encoded in CC/PP• User Model represents the dynamic user’s state, e.g. did the user

visit (learn) this slice (concept)• Application and Update Rules describe the behavior of the

presentation (e.g. conditional slices in AM) and keep the user model up-to-date (AHAM rules)


Profile Example

Device/User Profile (CC/PP encoding)• Screen size: 100x80

• Preferred language: English

<ccpp:component>

<up:UserPreferences>

<up:Language>English</up:Language>

…

</up:UserPreferences>

</ccpp:component>

</rdf:Description>

<rdf:Description rdf:about=“Profile”>

<ccpp:component>

<prf:HardwarePlatform>

<prf:ImageCapable>No</prf:ImageCapable>

<prf:ScreenSize>100x80</prf:ScreenSize>

…

</prf:HardwarePlatform>

</ccpp:component>


Adaptation Model Syntax

Adaptability Condition

Adaptivity Condition<rdfs:Class rdf:ID=“Slice.painter.main”

slice:condition=“um:Biography = false”>

<rdf:subClassOf rdf:resource=“#Slice”/>

</rdfs:Class>

<rdfs:Class rdf:ID=“Slice.painting.picture”

slice:condition=“prf:ImageCapable=Yes”>


</rdfs:Class>

<rdfs:Class rdf:ID=“Slice.painting.main”

slice:condition=“um:Painter > 10”>


</rdfs:Class>


User Interaction

• E-commerce applications often require WIS with broader functionality than just navigation through static web sites (known patterns: shopping carts, on-line payments, searches, etc.)

• The functionality includes also richer means of interaction with users via interaction elements: buttons, text entry forms, checkboxes, etc.

• Navigation objects (slices) with data content may depend on the interaction and/or system business logic, so it cannot be static


User Interaction Specification

• Extension of AM specification:– Structural: interaction elements as “active” attributes

capturing user actions (buttons, text fields, etc.)– Behavioural: operations assigned to interaction

elements (dynamic navigation, data manipulation, adaptation, call of external Web Services, etc.)

• Consequence on WIS architecture: need for an engine providing the operations (as AHA! for adaptivity)


Shopping Cart: example of CM data manipulations


Conclusion & Future Work

• Explicit semantics in models, expressing concepts, their hierarchies and relationships

• Adaptation in all design steps including the CM and IM, and full support of adaptivity

• Experiment with higher ontology languages (e.g. OWL) as the basis for the different models

• Further development of authoring tools helping the designer to build models in all design steps– Query and transformation language, e.g. RAL

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