Session 48 - Principles of Semantic metadata management

Principles and Foundations of Ontologies and Semantic Grids

Session 48. July 15th, 2009

Oscar Corcho (Universidad Politécnica de Madrid)

Work distributed under the license Creative Commons Attribution-Noncommercial-Share Alike 3.0

Overview• Motivation

– Introduction

– What is the Semantic Web

– Semantic Web Technologies

• RDF, RDF Schema and OWL

• Semantic-OGSA (S-OGSA) – S-OGSA Reference Model and Capabilities

– S-OGSA Mechanisms and Interaction Patterns

– Sample Deployments of S-OGSA

• Credits

3

A Satellite Scenario

SpaceSegment

Ground Segment DMOP files

Product files

SATELLITE FILES:

A Sample File in the Satellite Domain

DATA

METADATA

Metadata can be present in file names… Namefile (Product):

RA2_MW__1PNPDK20060201_120535_000000062044_00424_20518_0349.N1"

Corresponds to:

5

Metadata is everywhere• We can attach metadata almost to anything

– Events, notifications, logs

– Services and resources

– Schemas and catalogue entries

– People, meetings, discussions, conference talks

– Scientific publications, recommendations, quality comments

– Models, codes, builds, workflows,

– Data files and data streams

– Sensors and sensor data

• But..., what do we mean by metadata???

Need to Add “Semantics”• External agreement on meaning of annotations

– E.g., Dublin Core for annotation of library/bibliographic information

• Use Ontologies to specify meaning of annotations– Ontologies provide a vocabulary of terms, plus

– a set of explicit assumptions regarding the intended meaning of the vocabulary.

• Almost always including concepts and their classification

• Almost always including properties between concepts

• Similar to an object oriented model

– Meaning (semantics) of terms is formally specified

– Can also specify relationships between terms in multiple ontologies

• Thus, an ontology describes a formal specification of a certain domain:– Shared understanding of a domain of interest

– Formal and machine manipulable model of a domain of interest

14

Types of vocabularies. Formality

Lassila O, McGuiness D. The Role of Frame-Based Representation on the Semantic Web. Technical Report. Knowledge Systems Laboratory. Stanford University. KSL-01-02. 2001.

Some metadata about a workflow

RDF annotations

Social Tags annotations

Free-text annotations

Reference Ontology1

Reference Ontology2

ReferenceControlled vocabulary

A scientific workflow

Metadata content


– Introduction







• Credits

What is the Semantic Web• An extension of the current Web…

– … where information and services are given well-defined and explicitly represented meaning, …

– … so that it can be shared and used by humans and machines, ...

– ... better enabling them to work in cooperation

• How? – Promoting information exchange

by tagging web content with machine processable descriptions of its meaning.

– And technologies and infrastructure to do this

Overview• Motivation (45

minutes)– Introduction




• Semantic-OGSA (S-OGSA) (45 minutes)– S-OGSA Reference Model and Capabilities



• Credits

Ontology Languages• Work on Semantic Web has concentrated on the definition of a

collection or “stack” of languages. – Used to support the representation and use of metadata– Basic machinery that we can use to represent the extra semantic

information needed for the Semantic Web

RDF(S)

Integrating information sources

Associating metadata to resources (bindings)

OWL

Integration

RDFS

RDF

XMLA

nnotation

Integration

Inference

Reasoning over the information we haveCould be light-weight (taxonomy)Could be heavy-weight (logic-style)

RDF• RDF stands for Resource Description Framework• It is a W3C Recommendation

– http://www.w3.org/RDF

• RDF is a graphical formalism ( + XML syntax + semantics)– for representing metadata

– for describing the semantics of information in a machine- accessible way

• Provides a simple data model based on triples.

The RDF Data Model• Statements are <subject, predicate, object> triples:

– <Oscar,presents,Session48>

• Can be represented as a graph:

• Statements describe properties of resources• A resource is any object that can be pointed to by a URI

– The generic set of all names/addresses that are short strings that refer to resources

– a document, a picture, a paragraph on the Web, http://www.dia.fi.upm.es/~ocorcho/index.html, a book in the library, a real person, isbn://0141184280

– Do not mistake them for Grid resources, though they could be the same, as we will see later in this talk!!

• Properties themselves are also resources (URIs)

Oscar Session48presents

Linking Statements• The subject of one statement can be the object of another• Such collections of statements form a directed, labeled graph

• The object of a triple can also be a “literal” (a string)


Pinar http://www.iceage-eu.org/issgc09

preparedByhasHomePage

“Oscar Corcho”hasName

preparedBy

RDF Syntax• RDF has an XML syntax that has a specific meaning:• Every Description element describes a resource• Every attribute or nested element inside a Description is a property

of that Resource• We can refer to resources by URIs

<rdf:Description rdf:about="some.uri/person#ocorcho">

<o:presents rdf:resource="some.uri/session#Session48"/>

<o:hasName rdf:datatype="&xsd;string">Oscar Corcho</o:hasName>

</rdf:Description>

<rdf:Description rdf:about="some.uri/session#Session48">

<o:hasHomePage>http://www.iceage-eu.org/issgc09/programme.cfm </o:hasHomePage>

<o:preparedBy rdf:resource=“some.uri/person#ocorcho">

<o:preparedBy rdf:resource=“some.uri/person#pinar_alper">

</rdf:Description>

What does RDF give us?• Single (simple) data model.• Syntactic consistency between names (URIs).

• A mechanism for annotating data and resources.• Low level integration of data.

OWLIntegration

RDFS

RDF

XML

Annotation

Integration

Inference

RDF(S)

What doesn’t RDF give us?• RDF does not give any special meaning to vocabulary

– Such as subClassOf or type (supporting OO-style modelling)

• So, what’s the difference between this graph...

• ... and this one?


“Oscar Corcho”hasName

preparedBy

Oscar Session48talksIn

“Oscar Corcho”isAlsoKnownAs

presentedBy

RDFS: RDF Schema• RDF Schema is another W3C Recommendation

– http://www.w3.org/TR/rdf-schema/

• It extends RDF with a schema vocabulary that allows you to define basic vocabulary terms and the relations between those terms– Class, type, subClassOf,

– Property, subPropertyOf, range, domain

– it gives “extra meaning” to particular RDF predicates and resources

– this “extra meaning”, or semantics, specifies how a term should be interpreted

• The combination of RDF and RDF Schema is normally known as RDF(S)

RDFS simple example<?xml version="1.0" encoding="UTF-8"?><rdf:RDF xml:base="http://www.ontogrid.net/StickyNote#" xmlns="http://www.ontogrid.net/StickyNote#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"> <rdfs:Class rdf:ID="Event"> <rdfs:subClassOf rdf:resource="http://www.w3.org/2002/07/owl#Thing"/> </rdfs:Class> <rdfs:Class rdf:ID="Local_Event"> <rdfs:subClassOf rdf:resource="#Event"/> </rdfs:Class> <rdfs:Class rdf:ID="Regional_Event"> <rdfs:subClassOf rdf:resource="#Event"/> </rdfs:Class> <rdfs:Class rdf:ID="Personal_Event"> <rdfs:subClassOf rdf:resource="#Event"/> </rdfs:Class> <rdfs:Class rdf:ID="Person"> <rdfs:subClassOf rdf:resource="http://www.w3.org/2002/07/owl#Thing"/> </rdfs:Class> <rdfs:Class rdf:ID="Professor"> <rdfs:subClassOf rdf:resource="#Person"/> </rdfs:Class> <rdfs:Class rdf:ID="Researcher"> <rdfs:subClassOf rdf:resource="#Person"/> </rdfs:Class> <rdf:Property rdf:ID="involves">

<rdfs:domain rdf:resource="#Personal_Event"/> <rdfs:range rdf:resource="#Person"/>

</rdf:Property> <rdf:Property rdf:ID="eventDate">

<rdfs:domain rdf:resource="#Event"/> <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#date"/>

</rdf:Property></rdf:RDF>

Event

Personal_Event Local_Event Regional_Event

Person

Professor Researcher

subClassOf subClassOf

subClassOfsubClassOf

subClassOf

involves

xsd:dateeventDate

RDF(S) Inference

Lecturer

Academic

Person

rdfs:subClassOf

rdf:subClassOf

rdfs:subClassOf

rdf:type

rdfs:Classrdf:type

rdf:type

RDF(S) Inference

Oscar

Lecturer

rdf:type

rdfs:Class

Academic

rdfs:subClassOf

rdf:type

rdf:type

rdf:type

What does RDFS give us?• Ability to use simple schema/vocabularies to describe our resources• Consistent vocabulary use and sharing• Simple inference• Query mechanisms: SPARQL, SeRQL, RDQL, …

– SELECT N FROM {N} rdf:type {sti:Event} USING NAMESPACE sti=<http://www.ontogrid.net/StickyNote#>

• Examples– CS AktiveSpace

• Lightweight schema to integrate data from University sites

– myExperiment• Workflow descriptions for e-Science

What doesn’t RDFS give us?• RDFS is too weak to describe resources in sufficient detail

– No localised range and domain constraints

• Can’t say that the range of hasEducationalMaterial is Slides when applied to TheoreticalSession and Code when applied to HandsonSession

– TheoreticalSession hasEducationalMaterial Slides

– HandsonSession hasEducationalMaterial Code

– No existence/cardinality constraints

• Can’t say:

– Sessions must have some EducationalMaterial

– Sessions have at least one Presenter

– No transitive, inverse or symmetrical properties

• Can’t say that presents is the inverse property of isPresentedBy

Joint EU/US Committee

DAML

OntoKnowledge+Others

The OWL Family Tree

Frames

Description Logics

RDF/RDF(S)

OIL

DAML-ONT

DAML+OIL OWLW3C

OWL• W3C Recommendation (February 2004) • A family of Languages

– OWL Full

– OWL DL

– OWL Lite

• Moving into a new W3C Recommendation (OWL 2)

• Formal semantics– Description Logics (DL/Lite)

– Relationship with RDF

phosphoglucoseisomerase 5.3.1.9

OWL(schema)

Instances (Individuals)

(data)

OWL Ontology ExampleBioPAX Biochemical Reaction

Courtesy Joanne

Luciano

K Wolstencroft, A Brass, I Horrocks, P. Lord, U Sattler, R Stevens, D Turi A little semantics goes a long way in Biology Proc 4th ISWC 2005

OWL Basics (on top of RDF and RDFS)• Set of constructors for concept expressions

– Booleans: and/or/not

• A Session is a TheoreticalSession or a HandsonSession

• Slides are not the same as Code

– Quantification: some/all

• Sessions must have some EducationalMaterial

• Sessions can only have Presenters that have developed Grid applications or Grid middleware

• Axioms for expressing constraints– Necessary and Sufficient conditions on classes

• A Session that hasEducationalMaterial Code is a HandsonSession.

– Disjointness

• TheoreticalSessions are disjoint with HandsonSessions

– Property characteristics: transitivity, inverse

Reasoning Tasks• OWL DL based on a well understood Description Logic (SHOIN(Dn))

– Formal properties well understood (complexity, decidability)– Known reasoning algorithms– Implemented systems (highly optimised)

• Because of this, we can reason about OWL ontologies– Subsumption reasoning

• Allows us to infer when one class is a subclass of another

• Can then build concept hierarchies representing the taxonomy.

• This is classification of classes.

– Satisfiability reasoning

• Tells us when a concept is unsatisfiable

– i.e. when it is impossible to have instances of the class.

• Allows us to check whether our model is consistent.

– Instance Retrieval/Instantiation

• What are the instances of a particular class C?

• What are the classes that x is an instance of?

Reasoning Tasks. Classification

What does OWL give us?• Ability to use complex schema/vocabularies to describe our

resources.• Consistent vocabulary use and sharing.• Robust data integration techniques• Complex inference and several reasoning functions• Query mechanisms: OWL QL


– Introduction




• Semantic-OGSA (S-OGSA)– S-OGSA Reference Model and Capabilities



• Credits

The motivation behind S-OGSA• Metadata deserves a better treatment

– In most cases it appears together with files or other resources

– It is difficult to deal with

– What about trying to query about all the files that deal with instrument X and where the information was taken from time T1 to T2?

Our goal:Let’s make metadata a FIRST-CLASS CITIZEN in our systemsAnd let’s make it FLEXIBLE to changes

Introduction. Semantic-OGSA• Semantic-OGSA (S-OGSA) is...

– A Semantic Grid architecture– A low-impact extension of OGSA

• Mixed ecosystem of Grid and Semantic Grid services

– Services ignorant of semantics

– Services aware of semantics but unable to process them

– Services aware of semantics and able to process (part of) them

• Everything is OGSA compliant

– Defined by

• Information model

– New entities

• Capabilites

– New functionalities

• Mechanisms

– How it is delivered

Model

Capabilities Mechanisms

provide/consume

expose

use

S-OGSA Model

METADATAas SemanticAnnotations

S-OGSA Model Example

S-OGSA Model. Grid Entities• We can attach Semantic Bindings to anything

– Events, notifications, logs

– Services and resources

– Schemas and catalogue entries

– People, meetings, discussions, conference talks

– Scientific publications, recommendations, quality comments

– Models, codes, builds, workflows,

– Data files and data streams

– Sensors and sensor data …

• To make it more useful, we should agree on– Controlled vocabularies / Ontologies

• Resource description models

• Grid Resource Ontologies

• Application domain vocabularies

S-OGSA Model. Knowledge Entities

45

OGSA Ontology

S-OGSA Ontology

Foundational Grid Ontology

Unicore Ontology

Globus Ontology

Satellite Ontology OWL-DL ontology

http://www.unigrids.org/ontology.html

S-OGSA Model. A sample Grid Ontology

S-OGSA Model. A sample Data Mining Ontology• http://www.admire-project.eu/

Optimization

Execution Management

Resourcemanagement

Data

Security

Information Management

Infrastructure Services

Application 1 Application N

OG

SA

Sem

antic

-OG

SA

Semantic Provisioning

Services

S-OGSA Capabilities

Ontology

ReasoningKno

wle

dge

Metadata

Annotation

Sem

antic

bin

ding

Semantic Provisioning Services

OntoKit: An implementation of S-OGSA

OntoKit: An implementation of S-OGSA

Semantic

Ontology

Reasoning

Metadata

Annotation

S-OGSA Mechanisms. Patterns

Lifetime

MetadataService

Service

ResourceMetadataSeekingClient

Properties

Others….

Access/Query MetadataRefers to

Resource properties

OntologyService

A semantic ignorant service


Lifetime

MetadataService

OntologyService

Service


Properties

Others…

Access/Query Semantic Bindings

Refers to

Get Semantic Binding Pointers

2

1Resource

properties

A semantic aware service, but incapable of processing semantics


Lifetime

MetadataService

Service


Properties

Others…

Access/Query Semantic Bindings1Semantics

1.1

Farm out request

OntologyService

A semantic aware service, capable of processing semantics

S-OGSA Metadata Access/Management

SB Factory

Client

Semantic Binding

Metadata Query

SBSB

SB

create

Query w/o Inference, UpdateContent

Query( over unified view)

WS-RP: Get/Set/Query Properties

WS-Addressing: epr

RDFRDF

create

query

Inspect-props . . .

query

Semantic Binding Service Suite

WS-RL: Destroy , SetTerminationTime

WS-RL ++: archive

WS-Notif: Subscribe / Notify

Semantic Binding Service. Lifetime Specification• What happens if...

– ...any or all of the Grid entities it refers to disappears?• Instrument and planning files for satellites do not disappear• Insurance contracts, cars, repair companies, etc., may disappear

– ...the Knowledge entities disappear or evolve?• Ontologies may change

– ... a SB is no longer available (its content is not useful any more)? • Damage claims: add witness reports, improve info about location, create

new hypothesis...

• When do/should SBs become invalid? How often should this be checked?

• What is the status of the content of a SB (e.g., content checked, stable, unchecked, etc.)?

• Is a SB always active or can it be archived after a period of time?– Satellite data that is not used after some time

Semantic Binding Service. WS-SBResourceLifetime• SB Housekeeping service

Stable

Stale

GEchanged

KEchanged

Archived Deleted

Semantic Binding Service

WS-Notif.[state]

WS-Notif[lastModificationTime]

Client

Grid Entity

Knowledge Entity

Client Client

Query-RP [state]

subscribe subscribe

subscribe

57Final Review, Manchester, July 17th 2007

WS

-DA

IOn

t-R

DF

(S)

Sp

ecif

icat

ion

RDF(S) Grid Access Bridge

RepositorySelectorService

RepositoryService

ResourceService

ListService

ContainerService

StatementService

PropertyService

ClassService

AltService

Grid Compliant

RDF(S) Ontology Access Mechanism

Ontology management: WS-DAIOnt-RDF(S)

Resources

Ontology management: WS-DAIOnt-RDF(S)• Two-tier architecture:

– Web Service tier, different layers according to access granularity

• Upper layer: management of multiple repositories

• Intermediate layer: management of a single repository

• Lower layer: management of knowledge elements of a given repository

– RDF(S) access tier:• Abstracts the interaction with

specific RDF(S) storages

RepositorySelectorService

RepositoryService

ResourceService

ListService

ContainerService

StatementService

PropertyService

ClassService

AltService

RDFSConnector

We

b S

erv

ice

Tie

rR

DF

(S) S

tora

ge

La

ye

r

WS-DAIOnt-RDF(S) Implementation Architecture

. . .

Sesame RDF Storage

SesameConnector

Jena RDF Storage

JenaConnector

OracleRDF Storage

OracleConnector

Upper service layerUpper service layer

Internediate service layerInternediate service layer

Lower service layerLower service layer


– Introduction







• Credits

Generating files in RDFFILE ; DMOP (generated by FOS Mission Planning System) RECORD fhr FILENAME="DMOP_SOF__VFOS20060124_103709_00000000_00001215_20060131_014048_20060202_035846.N1" DESTINATION="PDCC" PHASE_START=2 CYCLE_START=44 REL_START_ORBIT=404 ABS_START_ORBIT=20498

ENDRECORD fhr................................ RECORD dmop_er RECORD dmop_er_gen_part RECORD gen_event_params

EVENT_TYPE=RA2_MEA EVENT_ID="RA2_MEA_00000000002063" NB_EVENT_PR1=1 NB_EVENT_PR3=0 ORBIT_NUMBER=20521 ELAPSED_TIME=623635 DURATION=41627862 ENDRECORD gen_event_params ENDRECORD dmop_erENDLIST all_dmop_erENDFILE

RECORD ID

RECORD parameters

RECORD parameters corresponding to other

RECORD structure.

<?xml version='1.0' encoding='ISO-8859-1'?><rdf:RDF xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#' xmlns:rdfs='http://www.w3.org/2000/01/rdf-schema#' xmlns:NS0='http://protege.stanford.edu/kb#' > <rdf:Description rdf:about='http://protege.stanford.edu/kb#10822'> <rdf:type rdf:resource='http://protege.stanford.edu/kb#Instrument_mode'/> <NS0:instrument_mode_id>MS</NS0:instrument_mode_id> </rdf:Description> <rdf:Description rdf:about='http://protege.stanford.edu/kb#11224'> <rdf:type rdf:resource='http://protege.stanford.edu/kb#DMOP_ER'/> <NS0:event_id>"GOM_OCC_00000000541299"</NS0:event_id> <NS0:duration rdf:datatype='http://www.w3.org/2001/XMLSchema#int'>53000</NS0:duration> <NS0:orbit_number rdf:datatype='http://www.w3.org/2001/XMLSchema#int'>20552</NS0:orbit_number> <NS0:elapsed_time rdf:datatype='http://www.w3.org/2001/XMLSchema#int'>2452293</NS0:elapsed_time> <NS0:event_type rdf:resource='http://protege.stanford.edu/kb#10713'/> </rdf:Description>

The planningfiles

<RDF triple><RDF triple><RDF triple><RDF triple><RDF triple><RDF triple><RDF triple>

<RDF triple><RDF triple><RDF triple><RDF triple><RDF triple><RDF triple><RDF triple>

The productfiles

1 reference ontology for annotating all filesRDF files are distributed

DistributedMetadata for Planning files

DistributedMetadata for Product files

1 Ontology

62

Satellite Use Case: Technical issues

63

Satellite Use Case (System Infrastructure): S-OGSA Scenario

WS-DAIOnt

SatelliteDomain Ontology

Grid-KP

XML SummaryFile

Annotationfront-end

Atlas

MetadataQueryService

QUARC-SG client JSP

3

4

6

1

1

3

Annotate file

Obtain ontology

Create

Query

Input criteria

Select files to be annotated

Metadata generation processMetadata querying process

RDF

RDF

RDF

RDF

Planning fileserverGermany

Product fileserver

ItalyGT4GT4

File directorySpain

1a Get file names

Get file summaries2

ONTO-DSI ONTO-DSI

WebDAV

5RDF File Upload

SemanticBinding Service

7Store

2’ Upload XML Summary file

OverlapCheckingService

8Store (start-time, stop-time, gen-time, EPR)

8

Notify (start-time, stop-

time)

9

Destroy (if needed)

64

PREFIX suc: <http://www.ontogrid.net/OWL/Satellite_Use_Case#>SELECT ?PRODUCT ?P_T1 ?P_T2 WHERE { ?PRODUCT suc:sensing_start ?P_T1 ; suc:sensing_stop ?P_T2 ; suc:represents_event ?PRODUCT_EVENT_TYPE . ?PRODUCT_EVENT_TYPE suc:plan_event_id ?

PRODUCT_EVENT_ID . FILTER(REGEX(?PRODUCT_EVENT_ID, ".*RA.*") &&

?P_T2 >= 192067200 && ?P_T1 <= 197247599 ) }

Metadata queries in SPARQL

http://www.youtube.com/watch?v=TSbb_8vmKvk

A simple Authorisation Scenario • A role-based Access Control Scenario in the insurance domain.

• What?– Role based Access Control Policy is:

• “Good Reputation Drivers are allowed to ask for an insurance policy. Bad Reputation ones are not.”

• How?– VO ontology based on

• KaOS ontologies (Actors, Groups and Actions)– Role definitions

• Extend ontology with domain-specific classes and properties• Define roles wrt these extensions

– E.g., a blacklistedDriver is a driver that has had at least 3 accident claims in the past

– E.g., a goodReputationDriver is a driver that has been insured at least by one trusted company and that has had at most 2 accident claims

– The Access Control Function uses an OWL classifier to obtain roles of a Subject.

WS-DAIOnt

XACML_AuthZService(PDP)

CarFraudService (PEP)

XACML AuthZ Request

getInsurancePolicy

VO Ontology Class Hierarchy -RDFS

RDF

RDF

John Doe has had 2 distinct accidents

Role OpMapping

Pellet Reasoner

Obtain Semantic Bindings of John Doe

Obtain all classes that are subclass of ROLE

Classify John Doe wrt VO ont

Lookup whether the ROLE that is inferred permits or not

XACML AuthZ Response

1

2

3

4

5

6

7

Atlas

PIPProxy

PDPProxy

VO OntologyOWL

S-OGSA Scenario. Authorisation

8 Result or Exception

/C=GB/O=PERMIS/CN=User0

WS-DAIOnt



XACML AuthZ Request

getInsurancePolicy


RDF

RDF


Role OpMapping

Pellet Reasoner






1

2

3

4

5

6

7

Atlas

PIPProxy

PDPProxy

VO OntologyOWL



WS-DAIOnt



XACML AuthZ Request

getInsurancePolicy


RDF

RDF


Role OpMapping

Pellet Reasoner






1

2

3

4

5

6

7

Atlas

PIPProxy

PDPProxy

VO OntologyOWL



WS-DAIOnt



XACML AuthZ Request

getInsurancePolicy


RDF

RDF


Role OpMapping

Pellet Reasoner






1

2

3

4

5

6

7

Atlas

PIPProxy

PDPProxy

VO OntologyOWL



WS-DAIOnt



XACML AuthZ Request

getInsurancePolicy


RDF

RDF


Role OpMapping

Pellet Reasoner






1

2

3

4

5

6

7

Atlas

PIPProxy

PDPProxy

VO OntologyOWL



WS-DAIOnt



XACML AuthZ Request

getInsurancePolicy


RDF

RDF


Role OpMapping

Pellet Reasoner






1

2

3

4

5

6

7

Atlas

PIPProxy

PDPProxy

VO OntologyOWL



Ignorant of semantics

Semantic aware and capable of processing semantics

Semantic provisioning services

Semantic aware but incapable of processing semantics

http://www.youtube.com/watch?v=Z_Jac2H0H3w

Overview• Motivation (45

minutes)– Introduction




• Semantic-OGSA (S-OGSA) (45 minutes)– S-OGSA Reference Model and Capabilities



• Credits

Summary• Metadata appears in most of the resources that we manage in Grid

applications– It is often hidden

– … or mixed with data

– … or simply IMPLICIT

• We can get many advantages by making metadata EXPLICIT– Decoupling data and metadata

– Managing it with appropriate services

– Relying on existing languages and technologies that make our life easier (RDF, RDF Schema, OWL)

• S-OGSA supports this vision and provides basic tools– Use it as much as you want…

Optimization

Execution Management

Resourcemanagement

Data

Security

Information Management

Infrastructure Services

Application 1 Application N

OG

SA

Sem

antic

-OG

SA

Semantic Provisioning

Services

S-OGSA Future Work

Ontology

ReasoningKno

wle

dge

Metadata

Annotation

Sem

antic

bin

ding

Semantic Provisioning Services

Distribution of reasoningStateful reasoning support

Automation, automation, automation…

(plus other features)

WS-DAIOnt-OWLAuthz over ontology models

AuthZ and Trust over metadata models

Credits• This tutorial is based on contributions from many authors. I hope to

acknowledge all of them...• Sean Bechhofer, Carole Goble and David de Roure

– Section “Ontologies and the Semantic Web”, based on Semantic Grid 101 presented at GGF16 in February 2006

• The OntoGrid team @ Manchester: Pinar Alper, Ioannis Kotsiopoulos, Paolo Missier, Sean Bechhofer, Carole Goble

– S-OGSA work

• Many others whose names appear on the slides

• This tutorial has been funded in part by the European Commission, under the projects OntoGrid and RSSGRID

More information• Publications

– An overview of S-OGSA: a Reference Semantic Grid Architecture. Corcho O, Alper P, Kotsiopoulos I, Missier P, Bechhofer S, Goble C. Journal of Web Semantics 4(2):102-115. June 2006

– Accessing RDF(S) data resources in service-based Grid infrastructures. Miguel Esteban Gutiérrez, Isao Kojima, Said Mirza Pahlevi, Óscar Corcho, Asunción Gómez-Pérez. Concurrency and Computation: Practice and Experience 21(8): 1029-1051 (2009)

– Requirements and Services for Metadata Management. Missier P, Alper P, Corcho O, Dunlop I, Goble C. IEEE Internet Computing 11(5): 16-24

• Source code– http://www.ontogrid.eu/, For Downloading Distributions

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