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This material was developed with financial help of the WUSA fund of Austria. Semantic Web. Content. Markup Languages. XML (eXtended Markup Language). RDF (Resource Description Framework). OWL (Ontology Web Language). OWL-S (OWL for Services). Semantic Search. Markup Languages. - PowerPoint PPT Presentation
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by Miloš Micić, mailto: [email protected]/65
Content
• RDF (Resource Description Framework)• OWL (Ontology Web Language)• OWL-S (OWL for Services)
• Semantic Search
• Markup Languages
Semantic WebSemantic Web
• XML (eXtended Markup Language)
by Miloš Micić, mailto: [email protected]/65
The text contained within the documents were “marked up” using textual commands, explaining how to print the document.
text based software applications requirement
development of GML (Generalized Markup Language)
Integrated text editing
Separated formatting from the document’s text
Formatting and information retrieval
History of Markup LanguagesHistory of Markup Languages
by Miloš Micić, mailto: [email protected]/65
development of SGML (Standard GML)
Text description language (structure and content)
History of Markup LanguagesHistory of Markup Languages
development of XML (eXtended Markup Language)
Data description language (structure)
International standard in 1986
Base for other markup languages (HTML, XML…)
Enables data exchange on a global basis
by Miloš Micić, mailto: [email protected]/65
History of Markup LanguagesHistory of Markup Languages
1970 1990 2000 2010
SGML
HTML
XML
RDF
OWL
by Miloš Micić, mailto: [email protected]/65
Parts of SGML DocumentParts of SGML Document Declaration
specifies which characters and delimiters may appear
DTD (Document Type Definition)
syntax of markup constructsdocument elementselement hierarchy possible sequence of tags
required number of element occurrences
Specificationdescribes the semantic to be ascribed to the markup
Document Instancescontain data and markup
contain a reference to the DTD to be used for interpretation
by Miloš Micić, mailto: [email protected]/65
Pieces of Electronic DocumentPieces of Electronic Document
content
markup
by Miloš Micić, mailto: [email protected]/65
Data Exchange
Semantics+reasoning
Relational Data
???
???
???
Markup Language PyramidMarkup Language Pyramid
by Miloš Micić, mailto: [email protected]/65
The Relationship between The Relationship between SGML, HTML and XMLSGML, HTML and XML
complete document language
can define other markup languages
subset of SGML
also can define other markup languages
work with Web data
XML
SGML
display data
HTML
specific DTD of SGML
GML
SGML
XML HTML
by Miloš Micić, mailto: [email protected]/65
Developing Semantic WebDeveloping Semantic Web XML enables data exchange but says nothing about meaning
Goal is to provide reasoning rules
Development roadmap, stepping stone:
knowledge representation
Inference
ontology
search
by Miloš Micić, mailto: [email protected]/65
OntologyOntologyPrograms have to know that two terms have the same meaning. Solution is collection of information called ontology.
Ontology = document that defines the relations between terms.
Ontology=<taxonomy, inference rules>Taxonomy=<{classes},{relations}>
Example: “If a city code is associated with a state code, and an address uses that city code, than that address has the associated state code”.
A program could deduce, that an ETF address, being in Belgrade, must be in Serbia which is in the SCG and therefore should be formatted to SCG standards.
by Miloš Micić, mailto: [email protected]/65
Family of XMLFamily of XMLMarkup LanguagesMarkup Languages
by Miloš Micić, mailto: [email protected]/65
XML IntroductionXML Introduction designed to describe data
does not DO anything
Someone must write a piece of software to send, receive or display it.
<note> <to>Toma</to> <from>Suzana</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body>
</note>
cross-platform, software and hardware independent
by Miloš Micić, mailto: [email protected]/65
XML IntroductionXML Introduction
XML tags
XML can separate data from HTML
case-sensitivenot predefined
properly nested hierarchy (without overlapping)
Mayor portions of the XML document (six ingredients)
1. XML Declaration (required)2. Document Type Definition (or XML Schema)
3. Elements (required)4. Attributes5. Entity6. Notations
by Miloš Micić, mailto: [email protected]/65
Namespaces and URIsNamespaces and URIs namespaces provide a method to avoid element name conflicts
xmlns:namespace-prefix="namespaceURI"
URI (Uniform Resource Identifier) is a string of characters which identifies Internet Resource.
<h:table xmlns:h="http://www.w3.org/TR/html4/"> <h:tr> <h:td>Apples</h:td> <h:td>Bananas</h:td> </h:tr> </h:table>
using a default namespace<table xmlns="http://www.w3.org/TR/html4/"> <tr> <td>Apples</td> <td>Bananas</td> </tr> </table>
URI ensure that concepts are not just words in a document, but are tied to a unique definition that everyone can find on the Web.
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1 XML Declaration1 XML Declaration
document prolog
<?xml version=“1.0” encoding =“ISO-8859-1”?><note>
<to>Toma</to> <from>Suzana</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body>
</note>
announcement to XML processor that the document is marked up in XML
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2 Document Type Definition2 Document Type Definition(DTD)(DTD)
used for validating XML document
structural description of the XML document
Referring to a DTD is a request that the parser compare the document instance to a document model.
defines a legal building blocks of XML document
or (for internal DTD)<!DOCTYPE root_element [element_declaration]>
<?xml version=“1.0” encoding =“ISO-8859-1”?><!DOCTYPE note SYSTEM "note.dtd"> ... (internal definition)
optional but useful
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2 Internal DTD, Example<?xml version="1.0"?> <!DOCTYPE note [ <!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> ]> <note> <to>Toma</to> <from>Suzana</from> <heading>Reminder</heading> <body>Don't forget me this weekend</body> </note>
by Miloš Micić, mailto: [email protected]/65
2 External DTD, Example<?xml version="1.0"?> <!DOCTYPE note SYSTEM "note.dtd"> <note> <to>Toma</to> <from>Suzana</from> <heading>Reminder</heading> <body>Don't forget me this weekend</body> </note>
<!–- “note.dtd” -->
<!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)>
by Miloš Micić, mailto: [email protected]/65
2 XML Schema Definition (XSD)<!–- “note.xsd” --><?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.w3schools.com" xmlns=http://www.w3schools.com> <xs:element name="note"> <xs:complexType>
<xs:sequence> <xs:element name="to" type="xs:string"/> <xs:element name="from" type="xs:string"/> <xs:element name="heading" type="xs:string"/> <xs:element name="body" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element>
</xs:schema>
Complex element(have attributes orother elements)
Simple elements(contain only text)
elements defined in“note.xsd”came from w3schools
default namespace
decimal, integer,boolean, date,time
by Miloš Micić, mailto: [email protected]/65
<?xml version="1.0"?>
<note xmlns="http://www.w3schools.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.w3schools.com note.xsd"> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body>
</note>
2 XML Schema Definition (XSD)
XML document has a reference to an XML schema
by Miloš Micić, mailto: [email protected]/65
2 XML Schema Restrictions2 XML Schema Restrictions<xs:element name="password"> <xs:simpleType> <xs:restriction base="xs:string"> <xs:pattern value="[a-zA-Z0-9]{8}"/> </xs:restriction> </xs:simpleType></xs:element><xs:element name="age"> <xs:simpleType> <xs:restriction base="xs:integer"> <xs:minInclusive value="0"/> <xs:maxInclusive value="100"/> </xs:restriction> </xs:simpleType></xs:element>
restrictions on a set of values restrictions on a series of values restrictions on length
by Miloš Micić, mailto: [email protected]/65
3 XML Elements3 XML Elements building blocks of a document
nested hierarchy (parent – children relation)
only one root element
names must not start with “xml”, “XML” …
4 XML Attributes4 XML Attributes can be used to give an element a unique ID<note> <date> <day>12</day> <month>11</month> <year>2002</year> </date> <to>Toma</to> <from>Suzana</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
<note date="12/11/2002" to="Toma" from=“Suzana" heading="Reminder" body="Don't forget me this weekend!"> </note>
<note day="12" month="11" year="2002" to="Toma" from=“Suzana" heading="Reminder" body="Don't forget me this weekend!"> </note>
by Miloš Micić, mailto: [email protected]/65
XML Family TreeXML Family TreeXML
Validation Languages
DTDXML
Schema
XML Location
Languages
DOM SAX XPATH XPOINTER& XLINK
XML Display
Languages
XSL
XSLT XSL-FO
XML Web
ServicesLanguages
SOAP WSDL UDDI
by Miloš Micić, mailto: [email protected]/65
Resource Description Resource Description Framework (RDF)Framework (RDF)
by Miloš Micić, mailto: [email protected]/65
by Miloš Micić, mailto: [email protected]/65
XML -> RDF provide extra machine understandable layer
Resource Value
Subject Object
The book War and Peace
Property
Predicate
has the title
<?xml version=“1.0”?><rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:dc=“http://purl.org/dc/elements/1.1/”> <rdf:Description rdf:about=“http://www.amazon.com/books”> <dc:title>War and Peace</dc:title> <rdf:Description>
</rdf:RDF>Subject
PredicateObject
by Miloš Micić, mailto: [email protected]/65
"there is a Person identified by http://www.w3.org/People/EM/contact#me, whose name is Eric Miller, whose email address is [email protected], and whose title is
Dr."
by Miloš Micić, mailto: [email protected]/65
4. Each RDF triple can be joined to other RDF triples, but still retains its own unique meaning, regardless of complexity.
1. Each RDF triple is made up of S, P, O.
2. Each RDF triple is complete and unique fact.
3. Subject is uri reference or blank node (represent a resource that isn’t currently identified). Predicate is uriref. Object is uri reference, blank node or literal.
Four important facts Four important facts about RDF tripletsabout RDF triplets
by Miloš Micić, mailto: [email protected]/65
Container VocabularyContainer Vocabulary
<rdf:Bag>
<rdf:Alt>
<rdf:Seq>
used to describe a list of values that is intended to be unordered.
used to describe a list of values that is intended to be ordered (For example, in alphabetical order)
used to describe a list of alternative values (the user can select only one of the values).
by Miloš Micić, mailto: [email protected]/65
<rdf:Bag> example<rdf:Bag> example
<?xml version="1.0"?><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:cd="http://www.recshop.fake/cd#">
<rdf:Description rdf:about="http://www.recshop.fake/cd/Beatles"> <cd:artist> <rdf:Bag>
<rdf:li>John</rdf:li> <rdf:li>Paul</rdf:li> <rdf:li>George</rdf:li>
<rdf:li>Ringo</rdf:li> </rdf:Bag> </cd:artist> </rdf:Description>
</rdf:RDF>
by Miloš Micić, mailto: [email protected]/65
"Course 6.001 has the students Amy, Mohamed, Johann, Maria, and Phuong" <rdf:Bag> example
by Miloš Micić, mailto: [email protected]/65
<rdf:Alt> example<rdf:Alt> example
<?xml version="1.0"?><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:cd="http://www.recshop.fake/cd#">
<rdf:Description rdf:about="http://www.recshop.fake/cd/Beatles"> <cd:format> <rdf:Alt> <rdf:li>CD</rdf:li> <rdf:li>Record</rdf:li> <rdf:li>Tape</rdf:li> </rdf:Alt> </cd:format> </rdf:Description>
</rdf:RDF>
by Miloš Micić, mailto: [email protected]/65
Serialization (RDF in Serialization (RDF in XML)XML)
RDF/XML is used for transporting, interchange, collection and merging of data from multiple models
RDF/XML parsers does not use DTD or XML Schema to ensure that RDF/XML is valid
There is no way to stop many individuals from independently assigning URIs to represent
There could be many resources that represent the same tree ! ! ! ! ! !
by Miloš Micić, mailto: [email protected]/65
RDF SchemaRDF Schema
can express classes and their relations (subClassOf)
Three most important RDF concepts:
rdfs:Resource
rdfs:Class
rdf:Property
defines properties and associate them with classes
focused on defining taxonomies (class hierarchy)
by Miloš Micić, mailto: [email protected]/65
RDF Schema Class RDF Schema Class ExampleExample
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xml:base="http://example.org/schemas/vehicles"> ... <rdfs:Class rdf:ID="MiniVan"> <rdfs:subClassOf rdf:resource="#Van"/> <rdfs:subClassOf rdf:resource="#PassengerVehicle"/> </rdfs:Class> </rdf:RDF>
by Miloš Micić, mailto: [email protected]/65
RDF Schema Property RDF Schema Property ExampleExample
<rdf:Property rdf:ID="registeredTo"> <rdfs:domain rdf:resource="#MotorVehicle"/> <rdfs:range rdf:resource="#Person"/> </rdf:Property>
<rdf:Property rdf:ID="rearSeatLegRoom"> <rdfs:domain rdf:resource="#PassengerVehicle"/> <rdfs:range rdf:resource="&xsd;integer"/> </rdf:Property>
The registeredTo property applies to any MotorVehicle and its value is a Person
by Miloš Micić, mailto: [email protected]/65
RDF Schema Instance RDF Schema Instance ExampleExample
<?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ex="http://example.org/schemas/vehicles#" xml:base="http://example.org/things">
<ex:PassengerVehicle rdf:ID="johnSmithsCar"> <ex:registeredTo rdf:resource="http://www.example.org/staffid/85740“ /> <ex:rearSeatLegRoom rdf:datatype="&xsd;integer">127</ex:rearSeatLegRoom> </ex:PassengerVehicle>
</rdf:RDF>
Instance is described in a separate document from the schema.
#Person type
by Miloš Micić, mailto: [email protected]/65
"Tell me what wines I should buy to serve with each course of the following menu. And, by the way, I don't like Sauternes."
OWL is not a message format. It is a knowledge representation.
provides three sublanguages
we must go beyond keywords and specify the meaning
by Miloš Micić, mailto: [email protected]/65
OWL SublanguagesOWL Sublanguages OWL Lite
classification hierarchy
simple constraint features
OWL DL (Description Logic)maximum expressiveness and decidability of reasoning system
restrictions such as type separation(a class can not also be an individual or property, a property can not also be an individual or class)
OWL Full
syntactic freedom of RDF
(class can be treated simultaneously as a collection of individuals and as an individual in its own right)
by Miloš Micić, mailto: [email protected]/65
<rdf:RDF xmlns:owl ="http://www.w3.org/2002/07/owl#" xmlns:rdf ="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:xsd =http://www.w3.org/2001/XMLSchema#xmlns:vin ="http://www.w3.org/TR/2004/REC-owl-guide-
20040210/wine#“xmlns:food="http://www.w3.org/TR/2004/REC-owl-guide-
20040210/food#">
<owl:Ontology rdf:about=""> <rdfs:comment>An example OWL ontology</rdfs:comment> <owl:priorVersion rdf:resource= "http://www.w3.org/TR/2003/PR-owl-guide-20031215/wine"/> <owl:imports rdf:resource= "http://www.w3.org/TR/2004/REC-owl-guide-20040210/food"/> <rdfs:label>Wine Ontology</rdfs:label> ...
Ontology HeadersOntology Headers
Importing another ontology brings the entire set of assertions provided by that ontology into the current ontology
by Miloš Micić, mailto: [email protected]/65
ClassesClassesEach user-defined class is implicitly a subclass of owl:Thing.
<owl:Class rdf:ID="Winery"/> <owl:Class rdf:ID="Region"/> <owl:Class rdf:ID="ConsumableThing"/>
Within this document, the Region class can now be referred to using #Region, e.g. rdf:resource="#Region"
<owl:Class rdf:ID="Wine"> <rdfs:subClassOf rdf:resource="food:PotableLiquid"/> <rdfs:label xml:lang="en">wine</rdfs:label> <rdfs:label xml:lang="fr">vin</rdfs:label> ... </owl:Class>
<owl:Class rdf:ID="Pasta"> <rdfs:subClassOf rdf:resource="#EdibleThing" /> ... </owl:Class>
by Miloš Micić, mailto: [email protected]/65
IndividualsIndividuals
<Region rdf:ID="CentralCoastRegion" />
Identical in the meaning to the example below:
<owl:Thing rdf:ID="CentralCoastRegion" /> <owl:Thing rdf:about="#CentralCoastRegion"> <rdf:type rdf:resource="#Region"/> </owl:Thing>
rdf:type is an RDF property that ties an individual to a class of which it is a member
by Miloš Micić, mailto: [email protected]/65
Properties
<owl:ObjectProperty rdf:ID="locatedIn"> <rdfs:domain rdf:resource="http://www.w3.org/2002/07/owl#Thing" /> <rdfs:range rdf:resource="#Region" /> </owl:ObjectProperty>
Two types of properties:• DATATYPE PROPERTIES, relations between instances of classes and RDF literals and XML Schema datatypes
• OBJECT PROPERTIES, relations between instances of two classes
<owl:Class rdf:ID="VintageYear" />
<owl:DatatypeProperty rdf:ID="yearValue"> <rdfs:domain rdf:resource="#VintageYear" /> <rdfs:range rdf:resource="&xsd;positiveInteger"/> </owl:DatatypeProperty>
by Miloš Micić, mailto: [email protected]/65
Properties of Individuals
<VintageYear rdf:ID="Year1998"> <yearValue rdf:datatype="&xsd;positiveInteger">
1998 </yearValue> </VintageYear>
<Region rdf:ID="SantaCruzMountainsRegion"> <locatedIn rdf:resource="#CaliforniaRegion" /> </Region>
locatedIn is object property defined for Region instances
yearValue is datatype property defined for VintageYear instances
by Miloš Micić, mailto: [email protected]/65
Property Characteristics
<owl:ObjectProperty rdf:ID="locatedIn"> <rdf:type rdf:resource="owl:TransitiveProperty" /> <rdfs:domain rdf:resource="owl:Thing" /> <rdfs:range rdf:resource="#Region" /> </owl:ObjectProperty>
<Region rdf:ID="SantaCruzMountainsRegion"> <locatedIn rdf:resource="#CaliforniaRegion" /> </Region>
<Region rdf:ID="CaliforniaRegion"> <locatedIn rdf:resource="#USRegion" /> </Region>
1. Transitive property
P(x,y) and P(y,z) implies P(x,z)
locatedIn is transitive property
by Miloš Micić, mailto: [email protected]/65
Property Characteristics
<owl:ObjectProperty rdf:ID="adjacentRegion"> <rdf:type rdf:resource="&owl;SymmetricProperty" /> <rdfs:domain rdf:resource="#Region" /> <rdfs:range rdf:resource="#Region" /> </owl:ObjectProperty>
<Region rdf:ID=“SumadijaRegion"> <locatedIn rdf:resource="#SerbiaRegion" /> <adjacentRegion rdf:resource="#PomoravljeRegion" /> </Region>
2. Symmetric Property
P(x,y) iff P(y,x)
adjacentRegion is symmetric property
by Miloš Micić, mailto: [email protected]/65
Property Property CharacteristicsCharacteristics
<owl:Class rdf:ID="VintageYear" /> <owl:ObjectProperty rdf:ID="hasVintageYear"> <rdf:type rdf:resource="owl:FunctionalProperty" /> <rdfs:domain rdf:resource="#Vintage" /> <rdfs:range rdf:resource="#VintageYear" /> </owl:ObjectProperty>
3. Functional Property
P(x,y) and P(x,z) implies y=z
hasVintageYear is functional property
One individual of Vintage must have strictly one value of VintageYear.
by Miloš Micić, mailto: [email protected]/65
Property Characteristics
<owl:ObjectProperty rdf:ID="hasMaker"> <rdf:type rdf:resource="&owl;FunctionalProperty" /> </owl:ObjectProperty>
<owl:ObjectProperty rdf:ID="producesWine"> <owl:inverseOf rdf:resource="#hasMaker" /> </owl:ObjectProperty>
4. InverseOf Property
P(x,y) iff P(y,x)
by Miloš Micić, mailto: [email protected]/65
Ontology MappingOntology Mapping
merging ontologies
hardest part of ontology development
tool support is necessary
Some important OWL primitives:
equivalentClass, equivalentProperty, sameAs,differentFrom, AllDifferent
by Miloš Micić, mailto: [email protected]/65
Equivalent Classes and Equivalent Classes and PropertiesProperties
combined ontologies must not be contradictory
<owl:Class rdf:ID=“o1:caffe"> <owl:equivalentClass rdf:resource=“o2:bar"/>
</owl:Class>
entailments from two ontologies are combined
indicate that two classes have precisely the same instances
To tie together properties in a similar fashion, we use owl:equivalentProperty.
We can use owl:sameAs between two classes to indicate that they are identical in every way (in OWL Full), treating them as individuals.
by Miloš Micić, mailto: [email protected]/65
Identity between Identity between IndividualsIndividuals
sameAs – declaring two individuals to be the same
<Wine rdf:ID="MikesFavoriteWine"> <owl:sameAs rdf:resource="#StGenevieveTexasWhite" /> </Wine>
differentFrom – opposite to sameAs
<WineSugar rdf:ID="Dry" />
<WineSugar rdf:ID="Sweet"> <owl:differentFrom rdf:resource="#Dry"/> </WineSugar>
<WineSugar rdf:ID="OffDry"> <owl:differentFrom rdf:resource="#Dry"/> <owl:differentFrom rdf:resource="#Sweet"/> </WineSugar>
If we erred, and asserted that a wine was both Dry and Sweet, without the differentFrom elements above, this would
imply that Dry and Sweet are identical – contradiction.
by Miloš Micić, mailto: [email protected]/65
Set OperatorsSet Operators intersectionOf<owl:Class rdf:ID="WhiteWine"> <owl:intersectionOf rdf:parseType="Collection"> <owl:Class rdf:about="#Wine" /> <owl:Restriction> <owl:onProperty rdf:resource="#hasColor" /> <owl:hasValue rdf:resource="#White" /> </owl:Restriction> </owl:intersectionOf> </owl:Class>
required element
unionOf<owl:Class rdf:ID="Fruit"> <owl:unionOf rdf:parseType="Collection"> <owl:Class rdf:about="#SweetFruit" /> <owl:Class rdf:about="#NonSweetFruit" /> </owl:unionOf> </owl:Class>
includes both the extensionsSweetFruit & NonSweetFruit
defining members of new class
complementOfselects all individuals that do not belong to a certain class
by Miloš Micić, mailto: [email protected]/65
Web Service is a software system identified by a URI
it uses public interfaces and bindings described by Markup Language
definition and function can be discovered by other software systems
software agents exchange information in the form of messages (Request Receive MEP – Message Exchange Pattern)
by Miloš Micić, mailto: [email protected]/65
OWL-S PrimerOWL-S Primer OWL-S uses OWL to define a set of classes and properties specific to the description of a service
OWL-S is designed to perform next tasks:
Task Description
Discovery Locating Web Services.
Invocation Execution of service by an agent or other service.
Interoperation Breaking down interoperability barriers and automatic insertion of message parameter translations.
Composition New services through automatic selection, composition and interoperation of existing services.
Verification Verify service properties.
Execution monitoring
Tracking the execution of composite tasks and identifying failure cases of different exe-traces.
by Miloš Micić, mailto: [email protected]/65
Upper Ontology for Upper Ontology for ServicesServices
OWS-S define a set of classes and properties specific to the description of services.
Service
ServiceModelServiceProfile ServiceGrounding
presentsdescribed by
supports
What does the service provide for and require of agents?
How does it work? How to access to service?
by Miloš Micić, mailto: [email protected]/65
Creating Ontology for Web Creating Ontology for Web ServiceService
1. Describe individual programsDescribe the individual programs that comprise the service. The process model provides a declarative description of a program’s properties.
2. Describe the grounding for each atomic process
3. Describe compositions of the atomic processes Describe the composite process which is a composition of its atomic processes
4. Describe a simple process for a service (optional)
5. Profile descriptionProvide a declarative advertisement for the service.It is partially populated by the process model.
by Miloš Micić, mailto: [email protected]/65
Designing a Search Designing a Search AgentAgent
four main phases
1. Initialization agent should setup all variables, structures, and
arrays, method of searching
2. Perceptioncentered on using the knowledge provided to contact a site and
retrieve the information from that location. It should identify if
the target is present and identify paths to other URL 3. Actiondetermines if the goal has been met. If it is not it
has to determine the next step – this is the intelligence of
the agent 4. Effect
by Miloš Micić, mailto: [email protected]/65
Search AlgorithmsSearch Algorithms uniformthose that have no information about number of steps
or the path cost from the current state to the goal – breadth first, depth first… informed
heuristic searches have the information about the goal (estimated path cost to it or step away) best-first, hill-climbing, A*...
How much can we trust that search engine understand what we want ? ?
by Miloš Micić, mailto: [email protected]/65
Using RDF and OWL for Using RDF and OWL for Search EnginesSearch Engines
ontologies are mapping semantically same things
text categorization based on ontology mapping
Comparing each element of an ontology with each element of the other ontology, and than determines a similarity metric.
Example of similarity metric:
),(),(),(
),(
)(
)(),(
BAPBAPBAP
BAP
BAP
BAPBAJaccardsim
Instance is randomly chosen from the universe (A,B).P(A,B) is the probability that the instance belongs to A and B...
similarity with relational databases leads to a global semantic web database
by Miloš Micić, mailto: [email protected]/65
Related links http://www.w3schools.com/default.asp http://www.w3.org