semantic web semantic web-based agent applications based agent applications – from design to...

Semantic WebSemantic Web--based Agent Applications based Agent Applications –– from Design to Collaborative Deploymentfrom Design to Collaborative Deployment

Sabin C. Buraga Faculty of Computer Science

“A.I.Cuza” University of Iasi, Romaniahttp://www.infoiasi.ro/~busaco/

Teodora Rusu“P.Poni” Institute of Macromolecular Chemistry, Iasi

Marius Cioca Faculty of Engineering, “L. Blaga” University of Sibiu

Sabin Buraga, Teodora Rusu, Marius Cioca 2

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AgendaAgenda

• Introduction

• Semantic Web – short description

• Multi-agent systems– Omega – multi-agent system infrastructure

– ADF – framework for agent developing

• Case studies

• Conclusions & Further Work


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• Web became a distributed environment for sharing information, without concerns for its type

• Information can hardly be found and processed–in a uniform and intelligent manner–by heterogeneous applications

IntroIntro


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• A solution is provided by the agent-oriented technologies– A problem can be divided into smaller parts

(objectives), which can be solved independently problem modularization and robust

distributed calculation – We’ll describe 2 original agent-oriented systems,

designed and developed based on semantic Web technologies, to capture, represent and manage the knowledge available on Web

IntroIntro


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• Web ≡

data storage & presentation (Berners-Lee, 1989)

• Semantic Web (Berners-Lee et al., 2001)–Relations between objects that can be

identified ⇒ unified management of distributed information

–Information needs no longer to be intended for human readers only, but also for machine processing

Semantic WebSemantic Web


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• Semantic Web is…–A vision of Sir Tim Berners-Lee

(the creator of World Wide Web)–A transition from “classical” Web

to a more structured and flexible one–A way of describing data, in terms of

metadata (data about data) and explain certain relations between resources



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• From “opaque” documents to machine understandable data (resources + links between them)

• A plenty of tools, applications, services, expertise available



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RDF (Resource Description Framework)– Defining & describing data and

relations among data

– Suitable to attach metadata to certain resources

– Data modeling must make the implicit explicit: “Teodora is a person.” “I*PROMS is an event attended by Teodora.” “Teodora knows Sabin.”

Some people can understand these assertions. How about the machines?

Semantic Web: technologiesSemantic Web: technologies


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RDF (Resource Description Framework)– A triple {subject, property, object} model

hasWebsite ("#iproms", "http://www.iproms.org/") isA ("#teodora", "#person") knowns ("#teodora", "#sabin")

– Triples of URIs (Uniform Resource Identifiers)

– Many syntactic representations, including XML (Extensible Markup Language)



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RDF (Resource Description Framework)<rdf:RDF>

<rdf:Description rdf:about="http://www.iproms.org/"><s:Title>A great online conference.</s:Title><s:Participants s:year="2007" s:total="300" />

</rdf:Description></rdf:RDF>


Our defined metadata vocabulary


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OWL (Web Ontology Language)– Structuring and characterizing

resources/relations (e.g., “Teodora” is an instance of “Person” class)

– Defining logical relationships among resources and the relationships (1-to-1, 1-to-many,…)

– Based on RDF

– Used to denote taxonomies, thesauri, ontologies



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• Agent paradigm is one of the promising technologies for information retrieval in general and for certain types of resource discovery in particular

• Mobile agents provide a way to think about solving software problems in a distributed environment (like the WWW)

AgentsAgents


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• Important attributes (Bradshow, 1997):– reactive – ability to respond to changes

within agent environment – autonomous – able to exercise control

over its own actions– goal-oriented – having a planned aim– communicative – ability to communicate

with other agents, by exchanging information and/or knowledge

– mobile – agents can transfer themselves from one host to another

AgentsAgents


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• Agents can be integrated into a coherent and consistent software system – e.g., a multi-agent system – in which they work together to better meet the needs of the entire application–utilizing autonomy, responsiveness,

pro-activeness and social ability

AgentsAgents


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• A multi-agent system infrastructure• Implemented in C++• Started as a project in 2002• Offers an addressing space (viewed as a tree)

for the Web objects and different techniques to remotely access the Web distributed resources

• Details in (Alboaie & Buraga, 2004) and (Buraga & Alboaie, 2005)

OmegaOmega


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• Each object can be viewed as a collection of objects included in that one– Links (edges) between the vertices of the tree are

given by the aggregation relationship exposed by the object-oriented methodologies

• A basic scripting support is also available via OmegaKernel component

OmegaOmega


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• For each object, different metadata constructs (expressed in RDF) are attached to specify semantic properties

• We are using different XML vocabularies• Relations between agents are expressed

by RDF statements• Omega was used within ITW system

(Buraga & Rusu, I*PROMS 2006)

OmegaOmega


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• For each Web resource, a RDF document is generated in order to: – attach metadata: location, type (e.g., XHTML

page, JPEG image, etc.), owner, access method, timestamp of last modification – XFiles (Buraga, 2002) language based on XML

– express temporal information regarding the relationship between two resources – TRSL – Temporal Relation Specification Language (Buraga & Ciobanu, 2002; Buraga & Gabureanu, 2003) – based on ITL (Interval Temporal Logic)

OmegaOmega


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• Agent Development Framework• Second, more recent (since 2004),

open-source Java-based approach• Built as a Service-Oriented Architecture

(SOA) to assure loose coupling between the interacting software agents

• http://adf.sourceforge.net/

ADFADF


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• Main goals (Nichifor & Buraga, 2004; Hritcu & Buraga, 2005):–Interoperability–Flexibility and Extensibility–Scalability–Platform independence–Easy to use–Pragmatism

ADFADF


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• Agents invoke and use the services provided by other agents– to be able to offer their own specialized services

• Every agent can specialize only in several tasks, while delegating the remaining tasks to other expert agents separation of concerns

• A provider can register its services and a potential consumer to discover the providers that offer the services it needs, in a dynamic manner

ADFADF


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• Overview of the ADF platform:

ADFADF


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• Interaction between agents is done by exchanging descriptive messages through the standard interfaces

• Agent communication is message-oriented and asynchronous – Compatible with FIPA (Foundation for Intelligent

Physical Agents) model– Exchanging messages via a message transport

service: HTTP (HyperText Transport Protocol) or JMS (Java Messaging Service)

ADFADF


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1. Describing Omega agents via RDF– the use of RDF to capture the state of

the Omega internal objects2. Meeting Scheduling in ADF

– involves ADF agents collaborating in order to schedule a meeting on behalf of the users

Case StudiesCase Studies


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• For each object stored within the Omega multi-agent system, we can attach different metadata – Assuring control versioning and security

(via permissions)• The system keeps these descriptions as RDF

assertions that can be transported to other objects during the information updating activities (i.e., object replication)

Case Study #1Case Study #1


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• To catch the dynamics of the involved agents built within Omega and the links between them, a high-level RDF-based description of temporal relations is adopted – We use our TRSL (Temporal Relation

Specification Language), based on ITL –Interval Temporal Logic (Allen, 1991)



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• Scenario: an object-maintainer Web agent can discover different temporal relations between the Omega objects that are distributed in the intranet of an organization and can automatically generate a TRSL document


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<rdf:Bag rdf:id="RecentlyChanged"><rdf:li resource="object1" /><rdf:li resource="object2" /></rdf:Bag><rdf:Description rdf:about="#RecentlyChanged">

<f:Location f:dns="www.site.org">193.231.30.1 </f:Location>

<f:Owner> <rdf:Description rdf:about="http://www.omega.site/">

<f:Login f:uid="714">busaco</f:Login></rdf:Description></f:Owner>

...<t:link t:type="temporal" t:action="Serialize" t:end="20070102T102033">

<t:Finishes t:dur="T000002" /></t:link>

</rdf:Description>


Collection of objects to be serialized

The serialization action is planned to be performed on this date


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• ADF agents are collaborating in order to schedule a meeting on behalf of their owners (for example, team workers)

• Each agent has access to relevant information about its owner’s identity, schedule and the relationships between the owner and other people – Schedule is represented in RDF – Relationships between persons is expressed

by using an extension of the FOAF (Friend of a Friend) vocabulary



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• The exchange of agent messages follows the Contract Net interaction protocol (Smith, 1980)



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• We presented two multi-agent systems – Omega and ADF – that are designed, implemented and deployed by using actual (semantic) Web technologies

• Our general goal was to present the advantages of metadata and ontologies used to rigorously capture, represent and manage the knowledge available on Web, in a pragmatic manner

ConclusionsConclusions


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• Our studies denote that various properties and relations established between the components (agents, objects, processes) of a multi-agent system can be expressed in a standardized and machine-understandable manner

• This approach could be an interesting solution for exchanging knowledge within an e-enterprise via the actual service oriented architecture technologies

ConclusionsConclusions


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• We intend to study the integration of agent software into the social Web systems, such as blogs/wikis

• Other interest is to build a more complex multi-agent platform and to integrate it into a wide-area distributed system, such a Grid

Further workFurther work


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• Sabin Buraga thanks to L. Alboaie, S. Alboaie, C. Hritcu, and O. Nichifor for their collaboration regarding several aspects of the paper

• “P. Poni” Institute of Macromolecular Chemistry, Iasi, Romania is associated partner of the EU-funded FP6 Innovative Production Machines and Systems (I*PROMS) Network of Excellence

AcknowledgmentAcknowledgment


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Online ResourcesOnline Resources

• AgentLink: http://www.agentlink.org/• Agent Development Framework (ADF):

http://adf.sourceforge.net/• Foundation for Intelligent Physical Agents (FIPA):

http://www.fipa.org/• Semantic Web: http://www.semanticweb.org/• Web Services: http://www.webservices.org/• World-Wide Web Consortium:

http://www.w3.org/

• Our publications: http://www.infoiasi.ro/~busaco/pub.html


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SummarySummary

• Introduction

• Semantic Web – short description

• Multi-agent systems– Omega – multi-agent system infrastructure

– ADF – framework for agent developing

• Case studies

• Conclusions & Further Work


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Thank you for your attention!

semantic web semantic web-based agent applications based agent applications – from design to...

Technology

work sabin buraga

cuza university of iasi

rusu p

teodora rusu

marius cioca2

collaborative deployment

blaga university of

case studies conclusions