Overview of Semantic Tools

Semantic Technology Boot Camp

Day 3

2

Overview

▼ Categories of Semantic Tools▼ Category Overview

Purpose & Role in Architecture Example Tools Tradeoffs and Evaluation Criteria

3

Categories of Semantic Tools

▼ RDF Parsers▼ Triplestores▼ Ontology Editors & Workbenches▼ SPARQL Query Engines▼ Reasoners▼ Middleware & Servers▼ Ontology Documentation Tools▼ Web Development Kits▼ Specialty Libraries

4

RDF Parsers

Like an XML parser, an RDF parser is a software library that will interpret an RDF dataset (or ontology) and construct a memory model of the graph described.

▼ Open Source: Jena, OWLAPI, Raptor.

5

Triplestores

A triplestore (also “triple store”) is a type of database optimized for the storage and retrieval of RDF data.

▼ Commercial stores: Allegrograph, Stardog▼ Open Source stores: Virtuoso, Sesame, Mulgara

6

Ontology Editors & Workbenches

An ontology editor offers a visual interface for the composition of OWL ontologies. Many editors go further and offer facilities for ontology publishing, batch operations and script processing over a set of ontologies.

▼ Commercial: TopBraid Composer▼ Open Source: Protégé, NeOn Toolkit

7

SPARQL Query Engines

A SPARQL query engine will evaluate a SPARQL expression over a specified graph and return an appropriate response for the expression type (ASK, CONSTRUCT, DELETE, SELECT, etc.).

▼OpenSource: ARQ

8

Reasoners

A semantic reasoner (aka “rules engine”) will apply inherent and specified rules to infer new facts (as triples) from a given set of asserted triples.

▼OpenSource: OWLIM, Pellet

▼Commercial: RacerPro, OntoBroker

9

Ontology Documentation Tools

Ontology documentation tools will parse an ontology file and produce formatted documentation generally in HTML or PDF form.

▼Open Source: Neologism

▼Commercial: UISPIN

10

Web Development Kits

Web development kits for RDF datasets and ontology provide dynamic interfaces to a triplestore to facilitate search and exploration of RDF content.

▼Open Source: Open Semantic Framework

Leveraging existing (non-RDF) data

Day 3 - Basics

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Overview

▼ Mapping relational data to RDF using D2RQ ▼ Mapping Excel Documents to RDF▼ Mapping XML to RDF/OWL ▼ Other Mappings (JSON, UML, Java/EMF Objects)

13

Mapping relational data to RDF using D2RQ

▼ Problem Description

▼ Custom Importers

▼ The D2RQ Approach

▼ Related Mappers

▼ Mapping SPARQL to SQL

14

Mapping Excel Documents to RDF

▼ Similar to the RDBMS conversion problem.▼ Spreadsheets lend themselves to complex tabular

structures.▼ Schema and data can appear anywhere.▼ One sheet may have any number of independent

tables.▼ Meaning given to style. I.E. bold, italic, font color or

cell color may encode meaning.▼ Multiple cells and formulas.

15

Mapping XML to RDF/OWL

▼ The XML Data Model

▼ Mapping Between Data Models Finding Meaning between XML Nodes

▼ Custom Conversion

▼ Tools and Toolkits

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Mapping XML to RDF/OWL

Differences in XML• The XML model is a tree structure.• XML provides structure to a document.• The XML utility is data packaging for transmission as

messages.• Uses schema for conformance validation.• Provides a standard that allows parsers to interpret

any XML document.

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Other Mappings

▼ Converting JSON

▼ Importing UML

▼ Importing EMF Objects

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Sample Applications

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Design time applications

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▼ Completed Work on Weather Integrated Surveillance

▼ Started Work on Unmanned Aircraft System Flight and Flow

▼ Key Deliverables COI Ontology Business Context (DoDAF Artifacts) Other Artifacts

▼ Consistent with DoD Net-Centric Data Strategy

Process for Inter-Agency Shared Understanding

Service Description (WSDL)

Message Schema (XSD)

Transformation Rules (XSLT)

Business Process Analysis (OV-2)

Systems Communications Description

(SV-2)

Operational Activity Model

(OV-5b)

Requirements Document(SV-4)

Architectural Impact Report

Business Rules Service Constraints

Information Exchange Description

(OV-3)

COI Ontology (RDF/OWL)

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▼ Purpose: To be a collaborative web application through which users can publish, access,

search, browse, map, and update ontologies and their terms. Reference Implementation only

▼ Supports: COI participants (e.g., ontologists, SMEs, and enterprise architects), developers

and managers.

Ontology Portals

National Center for Biomedical Ontology BioPortal

Marine Metadata Interoperability Ontology Registry and Repository

Air Force Vocabulary OneSource

Open Biomedical Ontologies Foundry

Example Portals

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Semantic Metadata Catalog and PortalWeather

Community

Integrated Surveillance Community

JPDO User Interface Layer

Semantic Metadata

Portal

External Systems

GIIEP

SWIM

Semantic Processing Layer

Artifact Catalog

Existing SOA

Registry

ebXML

UDDI

Web

Ser

vices

Lay

er

Service Registration and Discovery

Access

Semantic Metadata Catalog and Portal Architecture

Semantic Metadata Catalog

Semantic ExternalColor Key:

Future

Service Registration and Discovery

Integration of Federated Registry

NextGen Ontology

Community Ontology Portal In

tegr

atio

n La

yer

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Sample Ontology Portals

▼ NCBO BioPortal http://bioportal.bioontology.org/

▼ One Source http://onesource.afc2ic.org/

▼ Marine Metadata Interoperabiligy (MMI) Ontology Registry and Repository (ORR)

▼ http://mmisw.org/

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Run time application

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SMB Approach: Semantics to Solutions SOAFoundation for Service Interoperability

SemanticsCommon Understanding of Business Concepts

Problems• How I can improve Interoperability between different services

and reduce system integration costs?• I have already invested a lot in my SOA infrastructure, how

do I leverage it for for Semantic Interoperability?• How can Semantics help reduce service development cost

and help my enterprise operations?

Semantics Mediation Bus™

Runtime infrastructure enables semantic interoperability through common ontologies, even if the services are implemented using different data models and message standards.

26

SOA: Benefits and Limitations

• Service Oriented Architecture (SOA) • Key Benefits:

− Provides standards based mechanism to access Services at the transport and protocol level

− Promotes re-use of existing services

− Enables fast adaptation to business needs

− Aligns information resources to business goals

• Limitations:

− Current Web Service standards provide the syntactic description of the service interface, but do not describe the meaning or the semantics of the data or behavior. Hence the consumer of the service; whether another service or a human, needs to have intimate knowledge and awareness about the data and its elements

− Current Enterprise Service Buses (ESBs) don’t have an out of the box ability to perform Semantic Mediation, that is the transformation and co-relation of data elements and services based on a pre-defined vocabulary

− Manual intervention and deep domain knowledge is required to develop custom mappings to correctly use data exposed by these related but different Web Services

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Service Consumer FAA

Demo: Traditional SOA

Original Track Data

Provider

Google Earth Client

28

SOA Silos

SLIDE 28

Excess time is spent interpreting data from different sources despite the usage of advanced IT techniques like Web Services

FAA Flight Track Web

Service

AF Flight TrackWeb

Service

HR ArmyHR

Marine

Other Data

Provider

User

Field Name:Commercial FlightData: 122

Airline Code Lookup TableData: UA

Field Name: Flight of InterestData: United 122

Field Name:FlightIDData: UA122

Flight Track

DisplayReference

DeveloperSME

AF SME

1

1

Human Communication

Custom Mapping

Custom Mapping

2

2

Custom Development

3

3 System Integration

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Problem with Custom Development

▼ Discovery of Relevant Information▼ Human in the Loop for Interoperability Assessment▼ Custom Mapping and Custom Development

Often requires significant resources and takes a long time

▼ Change Management Transformation often embed in code Code and ontology could become disconnected

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Service Consumer FAA

Demo: SOA Silo

Original Track Data

Provider

Google Earth Client

Air Force

AlternateTrack Data

Provider

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SOA Infrastructure

Service Consumer FAA

Demo: Semantic Service Provisioning

Original Track Data

Provider

Google Earth Client

Air Force

AlternateTrack Data

Provider

Semantic Metadata Catalog

Annotation

Discover

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Benefits of Semantic Service Provisioning

▼ Discovery of Relevant Information Beyond traditional keyword search

▼ No Need for Human in the Loop for Interoperability Assessment Machine readable ontologies describe relationships among concept

▼ Avoid Custom Mapping and Custom Development Faster Development Lifecycle

Reduced Development Cost

▼ Built for Change Allow transformations and business rules to be managed independent of the

code

Consistent with Model Driven Architecture principals

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Data

Open Standard Compliance

▼ Web Ontology Language (OWL)▼ Semantic Annotations for WSDL and XML Schema (SAWSDL)▼ Minimal Service Model (MSM) and WSMO-Lite ▼ Extensible Stylesheet Language Transformations (XSLT)▼ Web Service Definition Language (WSDL)

XML URIXSLT

Services

WSDL REST

Semantics

OWL WSMO-LiteSAWSDL

SOAP

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Minimal Service Model

Source: http://cms-wg.sti2.org/minimal-service-model/

Service Ontology

Semantic Annotations for WSDL and XML Schema (SAWSDL)

• Relate the Service and Message description to the meaning captured in an Ontology.– Annotations can be applied to all WSDL elements and XML Schema types.

• Define transformation between wired message format and the ontology representation.

SLIDE 35

WSDL

XML Schema

Import

<xsd:ComplexType name=“FlightTrack” sawsdl:modelReference=“… …”sawsdl:liftingSchemaMapping=“…”sawsdl:loweringSchemaMapping=“…”>

<operation name=“getFlightTrack” sawsdl:modelReference=“… …”>

<input message=”…”>

Enterprise Vocabulary

ont:AirTrack a rdfs:Class … …

svc:airTrackProvider svc:payload ont:AirTrack … …

SPARQL+XSLT

XSLT

36

Alion Semantic Mediation Bus™• An ontology-based web services mediation component (Semantic Mediator) that enables

services with different message formats to interoperate• Embedding the Semantic Mediator in an Enterprise Service Bus (ESB) enables runtime

semantic mediation within traditional SOA infrastructure, creating a Semantic Mediation BusTM

Enterprise Service Bus

Registry/ Repository

Traditional SOA infrastructure Semantic Mediation Infrastructure

Semantic Mediator

Protocol Adaption Message Transformation

Message Routing Security Service Discovery

Semantic Lookup and Interoperability Assessment

Message Schema Mapping Semantic Annotation

Metadata Management

Web Service Proxy

Common Ontology

Semantic Mediation BusTM

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Semantic Mediation:

HR Army

FAAWeb

Service

Air ForceWeb

Service

HR ArmyHR

Marine

3rd PartyWeb

Service

User

Semantic Mediation

Bus™

Semantic Lookup

Field Name:Commercial FlightData: 211

Airline Code Lookup TableData: UA

Field Name: Flight of Interest Data: UA211

Field Name:FlightIDData: United 211

Common Air Track Ontology

Message Transformation

Web Service Endpoint

Flight Track

DisplayReference

Dynamically Map Information to User Needs

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Demo: Semantic Service Mediation

SOA InfrastructureService Consumer FAA

Original Track Data

Provider

Google Earth Client

Air Force

AlternateTrack Data

Provider

Semantic Metadata Catalog

Annotation

Semantic DiscoveryInteroperability Assessment

Alion Semantic Mediation Bus™

Message Transformation

Dynamic Service

Endpoint

39

Key Characteristics

▼ Cooperation through federation, instead of standardization The ontology driven approach avoids imposing a standard that has to be agreed by

everybody, thus allowing the agencies to select the formats best suited for their business needs, while still being able to use services offered by other agencies.

▼ Increased ability to adapt to the ever changing business needs in a timely and cost effective manner The semantic mediation approach encourages transformation logic to be declaratively

defined in the ontology, instead of buried in the code, often in multiple places.

▼ No need for rigid conformance Through loose coupling, the SMB allows transformation between message formats

which might not be a complete match.

▼ Building on SOA infrastructure, instead of replacing it By extending ESB infrastructure, organization can leverage their SOA investment and

the existing expertise of their personnel.

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Extensibility Considerations

▼ Pluggable to SOA Platforms Integrate with existing Enterprise Service Buses (ESB) Interact with Service Registry (ebXML, UDDI, proprietary)

▼ Adaptable to Service Design Choices Mediate SOAP-based Web Services Support REST and Plain XML Data Service Metadata

▼ Provide Intelligent Mediation Assess service compatibilities based on semantics

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Technical Architecture

Enterprise Service Bus

Semantic Mediation Bus

Service EndpointService

Endpoint

Registry/Repository

OWL Ontology

XML Schema

SAWSDL Annotation

Web Service Aggregation Proxy

Semantic Lookup

XML Schema

WSDL WSDL

SAWSDL Annotation Lifting and

Lowering RulesLifting and

Lowering Rules

Service ConsumerService Provider

Service Consumer cannot process the WSDL as implemented by the provider

Mediation Engine is implemented as component of the ESB.

However, the WSDL messages can be traced to an ontology understood by the consumer.

Initial implementation uses SAWSDL lifting and lowering rules, which define how XML messages are transformed to and created from an ontology

The engine dynamically exposes a web service endpoint as a proxy to the service. The endpoint expose a WSDL that can be accepted by the consumer

Extension Framework XML/WSDL-OWL

Mapping

Interoperability Assessment Algorithm

ESB Adapter

ESB API

Exte

nsio

n AP

I

Message Transformation

Service Endpoint

The service proxy may aggregate service from multiple providers based on the need of consumer.

Traditional SOA infrastructure

Semantic Mediation Infrastructure

42

Building Block for Enterprise Solutions

▼ Enterprise Challenge: Data integration is as much an issue as in the inter-organizational context Data mash up solution from disparate systems Incorporation of unanticipated sources in business intelligence Enhancement of situational awareness through on-demand integration of data

▼ Opportunity: Ontology is not only a tool for understanding, but also a basis for executable solutions

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The SMB Message

▼ Put Ontologies to Work Enhance service understandability at design time Facilitate service interoperability at runtime

▼ Leverage Existing SOA Investment Increase service discoverability and interoperability through semantic annotation Build on existing services Use in-house expertise Ready to deployed now

▼ Streamline Service Integration Shorten development lifecycle by eliminating the need for custom message

mapping Reduce maintenance cost by leveraging existing infrastructure