Semantic Web Cake(Architecture)Semantic Web Cake(Architecture)

URI/IRI LAYERURI/IRI LAYER

URI- Universal Resource Identifier

IRI- International Resource Identifier

Bottom Layer

Sits upon Unicode(basis of Semantic Web Languages)

Why URL → URI?Why URL → URI?

The Internationalization Problem ( a scalability problem)

The Privatization Problem ( a scalability problem)

The terminology problem ( a semantic problem)

The identity problem ( a semantic problem)

XML LayerXML Layer

Namespaces•Integral part of the overall language•Provide a simple method for qualifying element and attribute names in a XML document

XML Schema

•Describes the structure of XML document•Entails data typing and constrains document structure to maintain predictable computable processing•Defines the content and semantics

XML Layer (Contd…)XML Layer (Contd…)

XML Query•Standardized Query language for combining documents, databases, Web pages and almost everything.•Provides flexible query facilities to extract data from real and virtual documents on the WWW

XML Topic Maps•Addresses the issue of Internationalization and Identity•Provides an Interchange syntax for finding aids( index, glossaries etc.)•Creates associations among topics- electronic proxies of subjects•Basenames that can be scoped by human languages are built into the data model•Explicitly distinguishes between addressable and non-addressable subjects

XML Layer (Contd…)XML Layer (Contd…)

Semantic BaseSemantic BaseData Interchange Layer: RDF

RDF Schema Layer: RDFS

Ontology Layer: OWL

Query and Rule Layers: RIF and SPARQL ( and Ontologies)

Unifying Logic Layer

Data Interchange Layer: RDFData Interchange Layer: RDF

Provides a basic assertion model

Uses semantics provided by RDF

Allows Entity-relationship-like model to be made for data representation

and exchange

Simple Data Integration, Aggregation and Interoperability are enabled

using RDF standards

RDF Schema Layer: RDFSRDF Schema Layer: RDFS

Describes specific kinds or classes of resources by using properties

Extends basic RDF specification to support the expression of

structured Vocabularies

Provides information of statements in RDF Data Model

Ontology Layer (OWL)Ontology Layer (OWL)

Most effective and innovative layer

Web Ontology Language (OWL)

Adds more vocabulary for describing properties and classes:

•Disjointness

•Cardinality

•Equalify

•Rich typing

•Enumeration

Ontology Layer (OWL) (Contd…)Ontology Layer (OWL) (Contd…)

Design GoalsShared Ontologies:

•Should be available publicly•Should be extensible

Ontology Evolution:•Change during lifetime•Ontology Version

Ontology Interoperability:

•Provide primitives for relating different representation

Ontology Layer (OWL) (Contd…)Ontology Layer (OWL) (Contd…)

Design Goals (Contd…)Inconsistency Detection

Balance of expressivity and scalability

Ease of Use

Compatibility with other standards

Internationalization

Ontology Layer (OWL) (Contd…)Ontology Layer (OWL) (Contd…)

Existing Ontologies:

•DDC (Dewey Decimal Classification)

•MeSH ( Medical Subject Heading)

Existing Meta-Ontologies:

•Cyc

•Conceptual Graphs

•OIL (Ontology Inferencing Layer)

Query and Rule Layers: RIF & Query and Rule Layers: RIF & SPARQL SPARQL

SPARQL Features:

Express queries across diverse data source

Query Audit and Optional graph

Supports extensible value testing

Provide resolved queries as result sets

Unifying Logic LayerUnifying Logic Layer

Status

Universal language for monotonic logic

Any rule system can export, generally cannot import

No one standard engine – inference capabilities differ

Many engines exist (SQL to KIF, Cycl, etc.)

Any system can validate proofs

Web assumptions different from closed world

Unifying Logic Layer (Contd…)Unifying Logic Layer (Contd…)

Turns a Limited Declarative Language into Turing-complete

logical language with inference and functions

Allows any 2 RDFs to be connected together

Universal Language to unify all data just like HTML

ProofProof

Validation

Two disciplines:

• Formal methods for proving programs correct

• Automated theorem proving

TrustTrust

Extension of “Proof Validation”

Rate data in terms of Trustworthiness

CryptoCrypto

Encryption

Provides security to the data in the lower layers

User Interfaces and Application User Interfaces and Application LayerLayer

Provides the user accessible area

User Interaction

SamplesSamplesSPARQL

OWL

ReferencesReferences

1. ‘XML and Web Services Unleashed’ by Schmelzer, Travis, Jason, Madhu,

Sam, Qualls, Houlding, Darby, Diane Kennedy, Sams Publishing

2. ‘Implementing Semantic Web Services’ by Fensel, Kerrigan, Zaremba,

Springer Press

3. ‘Semantic Web for Dummies’ by Jeffrey T. Pollock, Wiley Publishing Inc.

4. ‘Programming the Semantic Web’ by Tobie, Evans and Taylor, O’Reilly

Media

5. ‘XML Databases and the Semantic Web’ by Bhavani Thuraisingham, CRC

Press

6. ‘Semantic Web Programming’ by Hebeler, Fisher, Blace and Lopez,

Wiley Publishing Inc.

Thank you!Thank you!