Table Of ContentITTALKS: A Case Study in the Semantic
Web and DAML
R.ScottCost,TimFinin,AnupamJoshi,YunPeng,Charles Nicholas,Ian Soboroff,
HarryChen, LalanaKagal,FilipPerich,YouyongZou,SovrinTolia
LaboratoryforAdvancedInformationTechnology
UniversityofMarylandBaltimoreCounty
{cost,finin,ajoshi,ypeng,nicholas,ian,hchen4,lkagal1,fperic1,yzou1,stolia1}@csee.umbc.edu
Abstract.Effectiveuseofthevastquantityofinformationnowavailableontheweb
willrequiretheuseof“SemanticWeb”markuplanguagessuchastheDARPAAgent
MarkupLanguage(DAML).Suchlanguageswillenabletheautomatedgatheringand
processingofmuchinformationthatiscurrentlyavailablebutinsufficientlyutilized.
Effectively,suchlanguageswillfacilitatetheintegrationofmulti-agentsystemswith
the existing informationinfrastructure.As part of our explorationof Semantic Web
technology, and DAML in particular, we have constructed ITTALKS, a web-based
system for automatic and intelligent notificationof informationtechnologytalks. In
thispaper,wedescribetheITTALKSsystem,anddiscussthenumerouswaysinwhich
theuseofSemanticWebconceptsandDAMLextenditsabilitytoprovideanintelligent
onlineservicetoboththehumancommunityandtheagentsassistingthem.
1 Introduction
With the vast quantity of information now available on the Internet, there is a need to man-
age this information by marking it up with a semantic language, such as DARPA Agent
MarkupLanguage(DAML)[14,23],andusingintelligentsearchengines,inconjunctionwith
ontology-based matching, to provide more efficient and accurate information search results.
TheaimoftheSemanticWebistomakethepresentwebmoremachine-readable,inorderto
allowintelligentagentstoretrieveandmanipulatepertinentinformation.Thekeygoalofthe
DAMLprogramistodevelopaSemanticWebmarkuplanguagethatprovidessufficientrules
for ontology development [20] and that is sufficiently rich to support intelligent agents and
otherapplications[22,36].Today’sagentsarenottightlyintegratedintothewebinfrastructure.
If ourgoalistohaveagentsactinguponandconversingaboutwebobjects,theywillhaveto
beseamlesslyintegratedwiththeweb,andtakeadvantageofexistinginfrastructurewhenever
possible (e.g., message sending, security, authentication, directory services, and application
serviceframeworks).We believethatDAMLwillbecentraltotherealizationofthisgoal.
Insupportofthisclaim,wehaveconstructedareal,fieldedapplication,ITTALKS,which
supportsuser andagent interactionin thedomainof talk discovery.It also providesa simple
web-driveninfrastructureforagentinteraction.Inaddition,ITTALKSservesasaplatformfor
designingandprototypingthesoftwarecomponentsrequiredtoenabledeveloperstocreatein-
telligentsoftwareagentscapableofunderstandingandprocessinginformationandknowledge
encoded in DAML and other semanticallyrich markup languages. To date, we have focused
ondevelopingthesupportandinfrastructurerequiredforintelligentagentstointegrateintoan
Report Documentation Page Form Approved
OMB No. 0704-0188
Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and
maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,
including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington
VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it
does not display a currently valid OMB control number.
1. REPORT DATE 3. DATES COVERED
2005 2. REPORT TYPE -
4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER
ITTALKS: A Case Study in the Semantic Web and DAML
5b. GRANT NUMBER
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) 5d. PROJECT NUMBER
5e. TASK NUMBER
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION
Defense Advanced Research projects Agency,3701 North Fairfax REPORT NUMBER
Drive,Arlington,VA,22203-1714
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)
11. SPONSOR/MONITOR’S REPORT
NUMBER(S)
12. DISTRIBUTION/AVAILABILITY STATEMENT
Approved for public release; distribution unlimited
13. SUPPLEMENTARY NOTES
The original document contains color images.
14. ABSTRACT
see report
15. SUBJECT TERMS
16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 18. NUMBER 19a. NAME OF
ABSTRACT OF PAGES RESPONSIBLE PERSON
a. REPORT b. ABSTRACT c. THIS PAGE 18
unclassified unclassified unclassified
Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std Z39-18
Rules
Trust
Data
Proof
Self- Data
ddeoscc.. Ontology VocabLuolagriyc Digitalgnature
Si
RDF + RDF Schema
XML + NS + XML Schema
Unicode URI
Figure1: Tim Berners-Lee’svisionof theSemantic Web is foundedona base that includesURIs, XML and
RDF.
environmentofwebbrowsers,servers,applicationserverplatforms,andassociatedsupporting
languages(e.g.,WEB/SQL,WEBL),protocols(e.g.,SSL,S/MIME,WAP,eSpeak),services
(e.g.,LDAP)andunderlyingtechnologies(e.g.,Java,Jini,PKI).
On the surface, ITTALKS is a web portal offering access to information about talks,
seminars and colloquia related to information technology (IT). It is organized around do-
mains, which typically represent event hosting organizations such as universities, research
laboratories or professional groups, and which are represented by independent web sites.
ITTALKS utilizes DAML for its knowledge base representation, reasoning, and agent com-
munication. DAML is used to markup all the information in the knowledge base to provide
additional reasoning capabilities otherwise unavailable. With information denoted in a se-
manticallymachine-understandableformat,thecomputercandeduceadditionalinformation,
a task whichis difficult in a traditionaldatabase system.For example,if bothITTALKS and
the user agree on a common semantics, the ITTALKS web portal can provide not only the
talks that correspond to the user’s profile in terms of interest, time, and location constraints,
but can further filter the IT events based on information about the user’s personal schedule,
inferred location at the time of the talk, distance and current traffic patterns, etc. ITTALKS
can also dynamically update the user’s profile with incremental learning of the user’s usage
patterns.
ITTALKSdemonstratesthepowerofmarkuplanguagessuchasDAMLfortheSemantic
Web,drawingonitsabilitytorepresentontologies,agentcontentlanguagesanditsabilityto
improvethefunctionalityofagentsontheweb.WehavedevelopedDAML-encodedontologies
fordescribingevent,temporal,spatial,personal,andconversationalinformation,whichenable
ustorepresentallrequiredknowledgeinaDAML-encodedformat.Moreover,theseontologies
enable us to execute a computer understandable conversation. In addition, we have created
severalDAML-encodedclassificationontologies,whichprovideuswithadditionalreasoning
capabilities in order to find the best matching IT talks for a particular user. Furthermore, in
the ITTALKS application, any web page presented on the ITTALKS web sites contains the
necessary information for an agent to retrieve the DAML-encoded description of this page
as well as the contact information of a responsible agent in order to provide more effective
conversation.ITTALKSthusprovideseachagentwiththecapabilitytoretrieveandmanipulate
anyITTALKS-relatedinformationviaa websiteinterface orthroughadirect agent-to-agent
conversation. Hence, by combining the features of currently existing web applications with
the DAML-based knowledgeand reasoning capabilities,ITTALKS presents a true Semantic
Webapplication.
<daml:class rdf:ID="Animal"> <daml:class rdf:ID="Female">
<rdfs:label>Animal</rdfs:label> <rdfs:subClassOf rdf:resource="#Animal" />
<rdfs:comment>An Example</rdfs:comment> <daml:disjointWith rdf:resource="#Male" />
</daml:Class> </daml:Class>
<daml:Class rdf:ID="Male"> <daml:Class rdf:ID="Man">
<rdfs:subClassOf rdf:resource="#Animal"/> <rdfs:subClassOf rdf:resource="#Person" />
</daml:Class> <rdfs:subClassOf rdf:resource="#Male" />
</daml:Class>
Figure2:AnexampleofDAML-encodedknowledge.
2 Background
TheSemanticWeb[4,3]isavisioninwhichwebpagesareaugmentedwithinformationand
data that is expressed in a way that facilitates its understanding my machines. The current
human-centered web is still largely encoded in HTML, which focuses largely on how text
and images would be rendered for human viewing. Over the past few years we have seen a
rapidincreaseinheuseofXMLasanalternativeencoding,onethatisintendedprimarilyfor
machineprocessing.ThemachinewhichprocessXMLdocumentscanbetheendconsumers
oftheinformationortheycanbeusedtotransformtheinformationintoaformappropriatefor
humanunderstanding(e.g.,asHTML,graphics,synthesizedspeech,etc.)Asarepresentation
language,XMLprovidesessentiallyamechanismtodeclareandusesimpledatastructuresand
thusleavemuchtobedesiredasalanguageinwhichtoexpresscomplexknowledge.Recent
enhancements to basic XML, such as XML Scheme, address some of the shortcomings, but
still do not result in an adequate language for representing and reasoning about the kind of
knowledgeessentialtorealizingtheSemanticWebvision.
RDF (Resource Description Framework) [40] and RDFS (RDF Schema) [41] attempt to
address these deficiencies by building on top of XML. They provide representation frame-
worksthatareroughlytheequivalenttosemanticnetworksinthecaseofRDFandverysimple
framelanguagesinthecaseofRDFS.However,RDFSisstillquitelimitedasaknowledgerep-
resentationlanguage,lackingsupportfor variables,general quantification,rules,etc. DAML
is one attempt to build on XML, RDF and RDFS and produce a language that is well suited
forbuildingtheSemanticWeb.
ThegoaloftheDAMLprogram(http://www.daml.org/),whichofficiallybeganinAugust
2000, is to develop a universal Semantic Web markup language that is sufficiently rich to
supportintelligentagentsandotherapplications.DAMLcandramaticallyimprovetraditional
adhocinformationretrievalbecauseitssemanticswillimprovethequalityofretrievalresults.
Also,itwillallowtheintelligentagentsoftomorrowtoretrieveandmanipulatetheinformation
onthesemanticweb.
3 ITTALKS
AspartofUMBC’sroleintheDAMLProgram,wehavedevelopedITTALKS;awebportalthat
offersaccesstoinformationabouttalks,seminars,colloquia,andotherinformationtechnology
(IT)relatedevents.ITTALKSprovidesuserswithnumerousdetailsdescribingtheITevents,
includinglocation,speaker,hostingorganization,andtalktopic.Moreimportantly,ITTALKS
also provides agents with the ability to retrieve and manipulate information stored in the
ITTALKSknowledgebase.Below,wediscussvariousaspectsofthesysteminmoredetail.
Unlike other web services, ITTALKS employs DAML for knowledge base representa-
tion,reasoning, and agent communication.The use of DAML to represent informationin its
knowledgebase,inconjunctionwithitsuseforinterchangeabletypeontologiesasdescribed
in Section 5.5, enables more sophisticated reasoning than would otherwise be available. For
example,asimplerrepresentationschememightbeabletoprovidetheuserwithtalksbasedon
interest,timeandlocation.WhenbothITTALKSandtheuseragreeonacommonsemantics,
theITTALKSwebportalwillbeabletoperformfurtherfiltering,basedonmoresophisticated
inference. In addition to enhancing knowledge representation and reasoning, DAML is used
for all communication, including simple messages and queries, using the ITTALKS defined
ontology.Moreover,ITTALKSoffersthecapabilityforeachusertousehis/herpersonalagent
tocommunicatewithITTALKSonhis/herbehalfandprovideahigherlevelofservice.
3.1 Users
ITTALKS can be used anonymously, or, more effectively, with personalized user accounts.
UsershavetheoptiontoregisterwithITTALKSeitherbyenteringinformationmanuallyvia
webforms,orbyprovidingthelocation(URL)ofauniversallyaccessibleDAMLizedpersonal
profile, which includes information such as the users location, his/her interests and contact
details,aswellasaschedule.Thisschedulemightbeasrudimentaryasalistofavailabletime
periodsforgivendays,orcouldevenincludeadetailedscheduleforeachday.Subsequently,
thisinformationis usedto provideeach user with a personalized viewof the site, displaying
onlytalksthatmatchtheuser’sinterestsand/orschedule.
SinceDAMLisnotyetinwidespreaduse,ITTALKSprovidesatoolforcreatingaDAML
personal profile. Currently, the tool constructs a profile containing only items used by the
ITTALKSsystem.However,webelievethattheprofile,inoneformoranother,willultimately
provide a unique and universal point for obtaining personal information about the user, not
justforITTALKS,butforallinformationneeds,andwillincludeanysortofinformationthe
userwouldliketoshare.Inthefuture,allservicesthatrequirepersonalinformationaboutthe
usershouldaccessthesameuserprofile,eliminatingtheneedfortheusertorepeatedlyenter
the same informationfor a multitudeof services. We believethat the new standardfor XML
Signature and Encryption under developmentmay providea mechanism by which users can
havesomecontroloveraccesstopartsoftheirprofile.
3.2 Domains
To support our vision of a universal resource for the international IT research community,
ITTALKSisorganizedarounddomains,whichtypicallyrepresenteventhostingorganization
suchasuniversities,researchlaboratoriesorprofessionalgroups.Eachdomainisrepresented
byaseparatewebsiteandisindependentlymaintainedbyamoderatorwhocan,amongother
things, define the scope of the domain and delegate to other registered users the ability to
edit talk entries. For example, the stanford.ittalks.org domain might be config-
ured to include onlytalks hosted at Stanford University.On the other hand, another domain,
sri.ittalks.org, might be configured to include not only talks about Semantic Web
topicsthatareheldatSRI,butalsothoseatStanford,aswellasanytalkswithin15milerange
oftheSRI facilityinPaloAlto.
Figure3:AscreenshotdepictingthemainpageoftheITTALKSsystem.
3.3 Access
TheITTALKSsystemisaccessibleeithertousersdirectlyviatheweb,ortoagentsactingon
theirbehalf.Thewebportalprovidesnumerousfeatures,includingregistration,search,entry
and domain administration. An agent-based interface allows interaction with user agents or
otherservices.
3.3.1 HumanInterface
Thewebportalallowsausertobrowsedesiredinformationinavarietyofformats,toprovide
the highest degree of interoperability. It permits a user to retrieve information in DAML,
standard HTML format, which includes a short DAML annotation for DAML-enabled web
crawlers, or WML [42] format, which supports WAP enabled phones. The ITTALKS web
portalalsohastheabilitytogenerateRDFSiteSummary(RSS)[37]filesforcertainqueries.
TheseRSSfilescanthenbeusedforvariousexternalpurposes,suchasdisplayingupcoming
talksonadepartmentalwebsiteforsomeparticularuniversityordomain.
3.3.2 AgentInterface
To provide access for agent based services, ITTALKS makes use of Jackal [12], a commu-
nication infrastructure for Java-based agents developed by our research group at UMBC.
Jackal is a Java package, which provides a comprehensive communications infrastructure
whilemaintainingmaximumflexibilityandeaseofintegration.TheheartofJackalisasimple
conversationsystem,servingtomaintaincontextforconcurrentthreadsofconversationwhile
providingaguideforjudgingbehavioralcorrectnessandmodelingtheactionsofotheragents.
Jackalprovidesfacilitiesforcreatingandmanipulatinguser-definedconversationstructuresof
arbitraryextent.Jackalhasaverymodular,looselycoupledarchitecture,designedtosupport
maximalconcurrencyamongcomponents,accomplishedwiththeuseofmultiplethreadsand
bufferedinterfacesbetweensubsystems.ItsconciseAPIallowsforcomprehensivespecifica-
People
Web HTTP
Email, HTML, SMS, WAP +se Jravvear HWTebTSPc, r a pi ng W eb services
servlet HTTP, K Q ML,
DBId T a tt aalbkass e RMDSB S Q L s <d <d <da HPrToDTloPAg,M K L Q M L, DAML, D A ML s pr eDe aakAsinoMgn aLing egn ts
DAML files
Figure4:ThearchitectureforITTALKSisbuiltaroundawebserverbackedbyarelationaldatabase.Interfaces
areprovidedtohumanusers,softwareagentsandwebservices.
tion of message requests, and for blocking or non-blocking message retrieval. Currently, it
facilitatestheuseofKQMLagentcommunicationlanguage[18]andemploysasophisticated
protocolforagentnaming,addressingandidentity(KNS).Additionally,itisintheprocessof
adapting to the FIPA standards [19, 2]. In addition, our research group, in cooperation with
otheruniversities,isdevelopingaDAMLontologyfor thenecessaryconversationprotocols.
3.4 Agents
In order to extend the capabilities of the system, we have defined a number of agents that
supporttheoperationofITTALKS.Somecanbeseenassupportingservices(suchasexternal
information services), while others we assume will exist in the general environment in the
future.
3.4.1 ITTALKS Agent
The ITTALKS agent is a front-end for the ITTALKS system. It interacts with ITTALKS
through the same web-based interface as human users, but communicates via an ACL with
other agents on the web, extending the system’s accessibility.At present, the agent does not
supportanyadvancedfunctionality,butactsprimarilyasagatewayforagentaccess.
3.4.2 UserAgents
Onelongtimegoalofagentresearchisthatuserswillberepresentedonlinebyagentsthatcan
service queries and filter information for them. While ITTALKS does not require that such
agents exist, we recognize the added power that could be gained by the use of such agents.
Therefore, ITTALKS supports interaction with User Agents as well as their human counter-
parts. The User Agent that we have developed understands DAML, supports sophisticated
reasoning, and communicates via a standard agent communication language. Reasoning is
accomplished with the use of the XSB, a logic programming and deductivedatabase system
forUnixandWindowsdevelopedatSUNYStonyBrook.
Relatedto
Keywords daml:range Software
SuperTopic
daml:range daml:domain
daml:domain SubTopic
daml: Topic daml:Class ACMTopic . . . Integrated
Literal SuperTopic Circuits
daml:domain daml:range
SubTopic
SubTopic
daml:range daml:domain SuperTopic
Hardware . . .
SubTopic SuperTopic
SubTopic
SuperTopic Memory
Structures
Figure5:TheOntologiesusedbyITTALKSarerelativelysimple,suchasthetopicsontologyusedtodescribe
talktopicsanduserinterests.
3.4.3 ClassifierAgent
ITTALKS uses a Classifier (or recommender) Agent that is invoked when a user is entering
a new talk. Based on the talk’s abstract, the Classifier returns ACM Classification Hierar-
chy Classification numbers along with a rank, in descending order. Using a local table of
classificationnumbersandnames,ITTALKSsuggeststotheusertenpossibletopics.
3.4.4 MapQuestAgent
TheMapQuestAgentisawrapperagentthatallowsITTALKStomakeuseofexternalservices.
Itinteractsdirectlywithagents(e.g.theITTALKSagent,UserAgents),andacceptsrequestsfor
informationsuchasthedistancebetweentwoknownlocations.Itthenphrasesanappropriate
requesttotheMapQuestsystem[33],parsestheresults,andgeneratesanappropriateresponse.
NotethatthisagentcouldbegenericallynamedaDistanceAgent,andmakeuseofanyexternal
service(orcombinationofseveral,asneeded).
3.5 Ontologies
TheITTALKSsystemisbasedonasetofOntologies 1 thatareusedtodescribetalksandthe
thingsassociatedwiththem,e.g.,people,places,topicsandinterests,schedules,etc.Figure6
showssomeofthedependenciesthatexistamongtheseontologies.Theontologiesareusedin
the representation and processing of DAML descriptions and also as “conceptual schemata”
againstwhichthedatabaseandvarioussoftwareAPIsare built.
We have developed a general ontology for describing the topics of arbitrary talks and
papers.Usingthis,wehaveimplementedanontologytodescribeITrelatedtalksbasedonthe
ACM’s Computer Classification System. In addition, we currently are developing a DAML
ontologyforITtalksbasedonaportionoftheOpenDirectory,andareconsideringadditional
classificationontologies.Figure 5sketchessomeof themajorclassesandpropertiesinthese
ontologies. These topic ontologies are used to describe talks as well as the users’ interests
throughout the system. This includes an automated talk classification, for which we have
obtained a training collection for the ACM CCS and are also generating an Open Directory
training collection to develop the necessary components. In addition, the DAML ontologies
1Seehttp://daml.umbc.edu/ontologies.
Personal
Profile
Ontology
ACM Ontology
Calendar Conversation
Topic Ontology
Ontology Ontology
Open Directory
Ontology
Talk Ontology
Figure6:TherelationshipsamongthevariousontologiesusedbytheITTALKSsystem.
willgivea userthe abilitytoaddadditionalassertionsinDAMLtofurther characterize their
interests.Lastly,wearealsointheprocessofdevelopingacomponentthatcanmaptopicsin
oneontologyintotopicsinanother,bytakingadvantageofthefactthatnodesineachontology
haveanassociatedcollectionoftextaswellasDAMLinformation.
3.6 DataEntry
CurrentlyITTALKSrequiresthatinformationabouttalksbemanuallyenteredviaawebform
interface,orbeavailableinaDAMLdescriptionavailableatagivenURL.Althoughwehave
madethisprocessassimpleaspossible(e.g.,bysupportingautomaticformcompletionusing
informationfromtheknowledgebaseandtheuser’sDAMLprofile)itisstillatimeconsuming
process. Therefore, we are developing a focused web spider to collect talk announcements
from open sources on the web. This spider will identify key information items using a text
extractionsystem,and will automaticallyadd informationto the ITTALKS knowledgebase.
WeareworkingwiththeLockheed-Martinresearchgroupontheabovetask,andwillusetheir
AeroTextinformationextractionsystem[1].
3.7 Architecture
The current implementation of ITTALKS uses a relational database, in combination with a
web server, to provide user access to the system. To enable agents to access the system, the
ITTALKSprovidesaninterface foragent-basedcommunication.
3.7.1 Database
ThemainsoftwarepackagesthatareusedintheITTALKSsystemaretheMySQLrelational
database software and a combination of Apache and Tomcat as the web portal servers. The
contents of the ITTALKS knowledge base are stored in a database whose schema is closely
mapped to our ontologies describing events, people, topics and locations. We have chosen
MySQLbecauseofitsknownreliability,andbecausewerequiredsoftwarewithalicensethat
allows us to make the ITTALKS package available to additional academic and commercial
institutions.
3.7.2 WebServer
As stated above, for our web, we have chosen a combination of Apache and Tomcat. This
enables us to present the IT talk descriptions to the user using Java servlets and JSP files,
whichdynamicallygeneraterequestedinformationinDAML,XML,HTML,RSS,andWML
formats.ThecurrentITTALKSimplementationcanprovideinformationsuitableforviewing
oneitherastandard,computer-basedoraWAP-enabledcellularphone.
3.7.3 Extensions
Inaddition,wearecurrentlyemployingtheJackalagentcommunicationinfrastructuredevel-
opedatUMBCandtheLockheed-Martin’sAeroTextinformationextractionsysteminorderto
facilitateITTALKS-useragentinteractionandtheautomatedtextextraction,respectively.We
areintheprocessofmodifyingJackaltoprovidesupportforFIPAACLinteroperability.Also,
we are consideringthe possiblereplacement of MySQL with nativeXML database software
suchasdbXML.
4 Scenarios
We describe here a couple of typical interactions that illustrate some of the features of
ITTALKS. The first involves direct use by a human user, and the second, advanced features
providedthroughtheuseofagents.
4.1 HumanInteraction
Inthisfirstscenario,auser,Jim,learnsfromhiscolleaguesabouttheexistenceoftheITTALKS
webportalasasourceofITrelatedeventsinhisarea;JimisaffiliatedwithStanfordUniversity.
Jimdirectshisbrowsertothewww.ittalks.orgmainpage.SeeingalinktoaStanford
ITTALKSdomain(stanford.ittalks.org),heselectsit,andispresentedwitha new
page listing upcoming talks that are scheduled at Stanford, SRI and other locations within a
15-mileradius(thedefaultdistancefortheStanforddomain).
Jimbrowsesthewebsite,viewingannouncementsforvarioustalksmatchinghisinterests
andpreferredlocations(asprovidedinhisexplicitsearchqueries).Heisimpressedthathecan
seethetalkinformationnotonlyinHTML,butalsoinDAML,RSSandWMLformats.Finding
atalkofpotentialinteresttoacolleague,Jimtakesadvantageoftheinvitationfeature,which
allowshimtosendaninvitationale-mailtoanyofhisfriendsforanyofthelistedtalks.Finally,
usingthepersonalizelinkonthebottomofthepage,Jimcreateshisownittalks.orgmainpage,
byprovidingtheURLofhisDAML-encodedprofile.Thiscustomizedpage,listingtalksbased
onhispreferences, willbeJim’sentrancetotheITTALKSsitewheneverher returns.
4.2 AgentInteraction
This scenario assumes that user Jim has already registered with ITTALKS, and has left in-
structionswiththesystemtobenotifiedoftheoccurrence ofcertaintypesoftalks.
In the course of operation, ITTALKS discovers that there is an upcoming talk that may
interestJim,andofwhichJimhasnotbeennotified.BasedoninformationinJim’spreferences,
which have been obtained from his online, DAML-encoded profile and from information
