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| - | ====== Modeling and using knowledge in RDF ====== | ||
| - | ^ Last verification: | 20160924 | | ||
| - | ^ Tools required for this lab: | -- | | ||
| - | |||
| - | ===== Before the lab ===== | ||
| - | Reading: | ||
| - | * [[http://www.w3.org/TR/rdf-schema/|RDF Schema 1.1]] | ||
| - | * [[#if_you_want_to_know_more|If you want to know more...]] | ||
| - | |||
| - | ===== Lab instructions ===== | ||
| - | |||
| - | <WRAP center round important 100%> | ||
| - | During this lab we will use [[http://any23.org/|Anything to Triples]] website. If it is down, there is also a possibility to download any23 service and run it on your own computer: | ||
| - | * download **Apache Any23 Service (Standalone server embedded) 1.1** file from https://any23.apache.org/download.html (mirror: {{http://home.agh.edu.pl/~kkutt/semweb/apache-any23-service-1.1-server-embedded.tar.gz|apache-any23-service-1.1-server-embedded.tar.gz}}) and unpack the zip somewhere | ||
| - | * execute command to start server with any23 service: <code>[PATH-to-unpacked-archieve]/apache-any23-service-1.1-server-embedded/bin/any23server </code> | ||
| - | * Note: use the any23server.bat file if you are using Windows OS | ||
| - | * Change ''<nowiki>"$REPO"</nowiki>'' into ''%REPO%'' twice (line #79 in any23server.bat file) if ''Error: Unable to access jarfile $REPO/jetty-runner-8.1.4.v20120524.jar.'' message appears | ||
| - | * after few seconds any23 service will appear on [[http://localhost:8080/apache-any23-service/]] address :) | ||
| - | </WRAP> | ||
| - | |||
| - | During this lab, you will create an RDF description (using Turtle syntax) of your multimedia library. | ||
| - | It may contain CDs, DVDs, books etc. | ||
| - | The documents created during this lab will be used in the subsequent labs. | ||
| - | ==== - Modeling knowledge with RDF [15 minutes] ==== | ||
| - | |||
| - | - Create a text document, specify your own base namespace and save file as ''mylibrary.ttl''. <code | mylibrary.ttl> | ||
| - | @base <http://kkutt/mylibrary/> . | ||
| - | @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . | ||
| - | |||
| - | # RDF Body...</code> | ||
| - | * Note the ''<nowiki>http://www.w3.org/1999/02/22-rdf-syntax-ns#</nowiki>'' namespace used in the document. | ||
| - | * Comments in Turtle begins with ''#'' symbol. | ||
| - | - __Add statements about **10 items** from your library__: Add RDF statements about items in your multimedia library. Define some //properties// of the items and fill in their //values// e.g.: <code> | ||
| - | <book-semweb> <author> "Dean Allemang", | ||
| - | "James Hendler"; | ||
| - | <title> "Semantic Web for the Working Ontologist"; | ||
| - | <publisher> <Elsevier>; | ||
| - | <lang> "en". | ||
| - | <cd-rhcp_stadiumarcadium> <artist> "Red Hot Chilli Peppers"; | ||
| - | <title> "Stadium Arcadium"; | ||
| - | <lang> "en". | ||
| - | </code> | ||
| - | * In RDF we are describing something (a subject) and giving it a unique ID, e.g.: ''<nowiki><http://kkutt/mylibrary/book-semweb></nowiki>''. To make notation more compact, we can use [[http://www.w3.org/TR/turtle/#prefixed-name|prefixes]] and/or [[http://www.w3.org/TR/turtle/#relative-iri|base namespace]]. | ||
| - | * 8-) To separate statements we can use dot (.), semicolon (;) and comma (,). What is the difference between them? | ||
| - | |||
| - | ==== - RDF: Containers and Collections [10 minutes] ==== | ||
| - | In RDF there are two ways to describe set or sequences of objects: //[[http://www.w3.org/TR/rdf11-mt/#rdf-containers|Containters]]// and //[[http://www.w3.org/TR/rdf11-mt/#rdf-collections|Collections]]//. | ||
| - | |||
| - | The container and collection are resources that contain things. The contained things are members. | ||
| - | RDF defines three types of containers: | ||
| - | * ''rdf:Bag'', | ||
| - | * ''rdf:Seq'', | ||
| - | * ''rdf:Alt'', | ||
| - | and one type of collection: | ||
| - | * ''rdf:List''. | ||
| - | While "a //container// only says that certain identified resources are members; it does not say that other members do not exist." with a //Collection// we can describe groups containing __only__ the specified members. | ||
| - | |||
| - | [[http://www.w3.org/TR/rdf11-mt/#rdf-containers|Read about them]] and then: | ||
| - | - 8-) Describe shortly what is the difference between different types of containers. | ||
| - | - Create a container called ''MyFavouriteBooks'' and fill it with the URIs of the books you like the most. | ||
| - | - In your RDF file describe a book/CD/DVD which has multiple authors or actors playing in it. Use the //RDF Collection//. For hint and examples see the [[http://www.w3.org/TR/turtle/#collections|recommendation]]. | ||
| - | |||
| - | ==== - RDF: Datatypes [10 minutes] ==== | ||
| - | Add the references to [[http://www.w3.org/TR/xmlschema-2/|XML Schema datatypes]] to chosen information in your RDF file, e.g.: | ||
| - | <code> | ||
| - | # ... | ||
| - | @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . | ||
| - | # ... | ||
| - | |||
| - | # ... | ||
| - | <cd-rhcp_stadiumarcadium> <artist> "Red Hot Chilli Peppers"^^xsd:string; | ||
| - | <title> "Stadium Arcadium"^^xsd:string; | ||
| - | <lang> "en". | ||
| - | # ... | ||
| - | </code> | ||
| - | Use at least 3 different datatypes! | ||
| - | |||
| - | ==== - RDF Visualization [10 minutes] ==== | ||
| - | |||
| - | We are in the middle, so let's visualize our RDF files. | ||
| - | |||
| - | - Using <wrap caution>[[http://any23.org/|Anything to Triples]]</wrap> service convert your file to RDF/XML (''rdfxml'') format. Do not analyze resulting code. Simply copy it :) | ||
| - | - Go to the [[http://www.w3.org/RDF/Validator/|RDF Validator]] page and simply paste generated code into ''Check by Direct Input'' field. Select ''Graph only'' from dropdown list and click ''Parse RDF'' | ||
| - | - Analyze the results: | ||
| - | - 8-) How containers are represented in the graph? | ||
| - | - 8-) How collections are represented in the graph? | ||
| - | |||
| - | ==== - Semantic vocabularies: Dublin Core [10 minutes] ==== | ||
| - | |||
| - | Semantic vocabularies are sets of predefined properties for describing some domains. Examples include: | ||
| - | * [[http://semanticweb.org/wiki/Dublin_Core|Dublin Core]] | ||
| - | * [[http://semanticweb.org/wiki/FOAF|FOAF]] | ||
| - | * [[http://semanticweb.org/wiki/SIOC|SIOC]] | ||
| - | * etc. | ||
| - | |||
| - | - Have a look at [[http://dublincore.org/documents/dc-rdf/|Expressing Dublin Core metadata using the Resource Description Framework]]. | ||
| - | - Modify your RDF file to use the properties from Dublin Core vocabulary, e.g.: | ||
| - | <code> | ||
| - | # ... | ||
| - | @prefix dc: <http://purl.org/dc/elements/1.1/>. | ||
| - | @prefix dcterms: <http://purl.org/dc/terms/> . | ||
| - | # ... | ||
| - | |||
| - | # ... | ||
| - | <book-semweb> <author> "Dean Allemang", | ||
| - | "James Hendler"; | ||
| - | dc:title "Semantic Web for the Working Ontologist"; | ||
| - | dc:publisher <Elsevier>; | ||
| - | dc:language "en". | ||
| - | # ... | ||
| - | </code> | ||
| - | * Hint: comprehensive list of ''dcterms:'' and ''dc:'' elements is [[http://dublincore.org/documents/dcmi-terms/|here]] ("Section 2: Properties in the /terms/ namespace" = ''dcterms:'', "Properties in the /elements/1.1/ namespace" = ''dc:'') | ||
| - | |||
| - | |||
| - | ==== - RDF Schema: classes [10 minutes] ==== | ||
| - | RDF Schema allows to organize objects into classes and define simple taxonomies. | ||
| - | |||
| - | - Define classes of items in you multimedia library, e.g. | ||
| - | <code> | ||
| - | @base <http://kkutt/mylibrary/> . | ||
| - | @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . | ||
| - | @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . | ||
| - | |||
| - | <MultimediaItem> rdf:type rdfs:Class . | ||
| - | |||
| - | <MusicCD> rdf:type rdfs:Class ; | ||
| - | rdfs:subClassOf <MultimediaItem> . | ||
| - | |||
| - | <Book> rdf:type rdfs:Class ; | ||
| - | rdfs:subClassOf <MultimediaItem> . | ||
| - | </code> | ||
| - | |||
| - | Add the ''rdf:type'' statements to your RDF file, e.g.: | ||
| - | <code> | ||
| - | <cd-rhcp_stadiumarcadium> <artist> "Red Hot Chilli Peppers"^^xsd:string; | ||
| - | dc:title "Stadium Arcadium"^^xsd:string; | ||
| - | dc:language "en"; | ||
| - | rdf:type <MusicCD>. | ||
| - | </code> | ||
| - | |||
| - | Note that ''a'' is an alias for ''rdf:type'' so two statements: <code><cd-rhcp_stadiumarcadium> rdf:type <MusicCD>.</code><code><cd-rhcp_stadiumarcadium> a <MusicCD>.</code> are equivalent. | ||
| - | |||
| - | ==== - RDF Schema: properties [10 minutes] ==== | ||
| - | |||
| - | RDF Schema also provides a way to define Properties as well as their domains and ranges. | ||
| - | |||
| - | - In your file identify properties that are not defined in external dictionaries (e.g. Dublin Core), e.g. in this code:<code> | ||
| - | <cd-rhcp_stadiumarcadium> <artist> "Red Hot Chilli Peppers"^^xsd:string; | ||
| - | dc:title "Stadium Arcadium"^^xsd:string; | ||
| - | dc:language "en"; | ||
| - | rdf:type <MusicCD>. | ||
| - | </code> ''<artist>'' is not defined in external dictionary -- it is defined in our own namespace. | ||
| - | - Describe each such property using RDF Schema capabilities:<code> | ||
| - | @base <http://kkutt/mylibrary/> . | ||
| - | @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . | ||
| - | @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . | ||
| - | |||
| - | <artist> rdf:type rdfs:Property ; | ||
| - | rdfs:domain <MusicCD> ; | ||
| - | rdfs:range rdfs:Literal. | ||
| - | </code> | ||
| - | |||
| - | You may find [[http://www.w3.org/TR/rdf-schema/|RDF Schema 1.1]] recommendation useful. | ||
| - | |||
| - | ==== - RDF Schema: Non-modeling properties [10 minutes] ==== | ||
| - | |||
| - | RDF Schema also provides some handful properties that are not used in inference process. These are: | ||
| - | * ''rdfs:label'' -- used by convention to provide a human-readable name that is displayed by semantic web agents, | ||
| - | * ''rdfs:seeAlso'' -- cross-referencing; provide links to supplementary information, | ||
| - | * ''rdfs:isDefinedBy'' -- subPropertyOf rdfs:seeAlso; provides a link to the primary source of information, | ||
| - | * ''rdfs:comment'' -- for everything you want :) . | ||
| - | |||
| - | - Use each of them in your RDF file. | ||
| - | - 8-) Include final RDF **Turtle** file in the report archive. | ||
| - | * Check if your Turtle file passes validation on <wrap caution>[[http://any23.org/|Anything to Triples]]</wrap>! | ||
| - | ===== Control questions ===== | ||
| - | * What container elements are available in RDF? | ||
| - | * What is RDF Schema? | ||
| - | * What are core RDF Schema Classes and properties? | ||
| - | * How constraints on domain and range of properties are added? | ||
| - | |||
| - | ===== Materials ===== | ||
| - | |||
| - | {{section>.:rdfmodel#if_you_want_to_know_more}} | ||
