This is a lecture note #5 for my class of Graduate School of Yonsei University, Korea. It describes Resource Description Framework (RDF).

1. Linked Data &
Semantic Web
Technology
The Semantic Web
Part 5. Resource Description Framework (2)
Dr. Myungjin Lee

2. Typed Node
• Typed Node
– the resources described as instances of specific types or classes
– being classified into different kinds or categories
– by providing a predefined property, rdf:type
1. <rdf:Description rdf:ID="item10245">
2. <rdf:type rdf:resource="http://www.example.com/terms/Tent"/>
3. </rdf:Description>
rdf:type
http://www.example.com/2002/04/products#item10245 http://www.example.com/terms/Tent
an instance of that a resource that represents a
category or class category or class of things
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3. Abbreviation for Describing Typed Nodes
• How to describe abbreviation for typed nodes
– the rdf:type property and its value are removed
– the rdf:Description element is replaced by an element whose name
is the QName corresponding to the value of the removed rdf:type
property
1. <rdf:Description rdf:ID="item10245">
2. <rdf:type rdf:resource="http://www.example.com/terms/Tent"/>
3. </rdf:Description>
replaced
1. <exterms:Tent rdf:ID="item10245" />
rdf:type
http://www.example.com/2002/04/products#item10245 http://www.example.com/terms/Tent
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4. How to Describe Groups
• a need to describe groups of things
– such as,
• a book was created by several authors
• to list the students in a course
• Vocabularies for groups
– RDF Containers
• groups containing the members
• open list
– RDF Collections
• groups containing only the specified members
• closed list
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5. RDF Containers
• RDF Containers
– to describe groups containing the members
• Terms
– Container
• a resource that contains things
– Member
• the contained things
• resources (including blank nodes) or literals
• Three types of RDf Containers
– rdf:Bag
– rdf:Seq
– rdf:Alt
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6. RDF Containers
• Bag
– a resource having type rdf:Bag
– a group of resources or literals, possibly including duplicate members
– no significance in the order of the members
• Sequence
– a resource having type rdf:Seq
– a group of resources or literals, possibly including duplicate members
– the order of the members is significant
• Alternative
– a resource having type rdf:Alt
– a group of resources or literals that are alternatives (typically for a single
value of a property)
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7. How to Describe a Resource of Containers
• to give an rdf:type property whose value is one of the
predefined resources rdf:Bag, rdf:Seq, or rdf:Alt
• to describe each member (item) with the container resource:
– in RDF Graph
• using a container membership property rdf:_n, where n is a decimal integer
greater than one
– in RDF/XML
• using the rdf:li property
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8. Bag Container Description
“Course 6.001 has the students Amy, Mohamed, Johann, Maria, and Phuong”
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:s="http://example.org/students/vocab#">
<rdf:Description rdf:about="http://example.org/courses/6.001">
<s:students>
<rdf:Bag>
<rdf:li rdf:resource="http://example.org/students/Amy"/>
<rdf:li rdf:resource="http://example.org/students/Mohamed"/>
<rdf:li rdf:resource="http://example.org/students/Johann"/>
<rdf:li rdf:resource="http://example.org/students/Maria"/>
<rdf:li rdf:resource="http://example.org/students/Phuong"/>
</rdf:Bag>
</s:students>
</rdf:Description>
</rdf:RDF> 8
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9. Alt Container Description
“The source code for X11 may be found at ftp.example.org, ftp1.example.org, or ftp2.example.org”
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:s="http://example.org/packages/vocab#">
<rdf:Description rdf:about="http://example.org/packages/X11">
<s:DistributionSite>
<rdf:Alt>
<rdf:li rdf:resource="ftp://ftp.example.org"/>
<rdf:li rdf:resource="ftp://ftp1.example.org"/>
<rdf:li rdf:resource="ftp://ftp2.example.org"/>
</rdf:Alt>
</s:DistributionSite>
</rdf:Description>
</rdf:RDF> 9
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10. Seq Container Description
“Schedules of Monday”
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:s="http://www.reminders.org#">
<rdf:Description rdf:about="http://www.reminders.org#MondayMeetings">
<s:activities>
<rdf:Seq>
<rdf:li>Meet with CEO at 10am</rdf:li>
<rdf:li>Luncheon at The Eatery</rdf:li>
<rdf:li>Flight at 3pm</rdf:li>
</rdf:Seq>
</s:activities>
</rdf:Description>
</rdf:RDF>
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11. RDF Collections
• A limitation of the containers
– no way to close resources
• such as, "these are all the members of the container“
– no way to exclude the possibility that there is another graph somewhere
that describes additional members
• RDF Collections
– for describing groups containing only the specified members
– a group of things represented as a list structure in the RDF graph
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12. How to Describe a RDF Collection
• to be constructed using a predefined collection vocabulary
– the predefined type rdf:List
– the predefined properties rdf:first and rdf:rest
– and the predefined resource rdf:nil
"The students in course 6.001 are Amy, Mohamed, and Johann"
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13. How to Describe RDF/XML for a Collection
• rdf:parseType attribute
– to indicate that the contents of an element are to be interpreted in a special
way
• rdf:parseType="Collection" attribute
– a group of nested elements representing the members of the collection
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:s="http://example.org/students/vocab#">
<rdf:Description rdf:about="http://example.org/courses/6.001">
<s:students rdf:parseType="Collection">
<rdf:Description rdf:about="http://example.org/students/Amy"/>
<rdf:Description rdf:about="http://example.org/students/Mohamed"/>
<rdf:Description rdf:about="http://example.org/students/Johann"/>
</s:students>
</rdf:Description>
</rdf:RDF>
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14. RDF Reification
• What is RDF Reifications?
– to describe other RDF statements using RDF
– such as,
• to record information about when statements were made, who made them, or
other similar information
Obama says
Northern Ireland requires urgent work.
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15. Reification Quad
• description of a statement, reification
– the type rdf:Statement
– the properties rdf:subject, rdf:predicate, and rdf:object
“Obama says Northern Ireland requires urgent work.”
ex:triple12345 rdf:type rdf:Statement .
ex:triple12345 rdf:subject ex:NorthernIreland .
ex:triple12345 rdf:predicate ex:require .
ex:triple12345 rdf:object ex:UrgentWork .
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16. RDF/XML for RDF Reification
• “Obama says Northern Ireland requires urgent work.”
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:ex="http://www.example.com/">
<rdf:Description rdf:about="http://www.example.com/Obama">
<ex:say>
<rdf:Statement>
<rdf:subject rdf:resource="http://www.example.com/NorthenIreland"/>
<rdf:predicate rdf:resource="http://www.example.com/require"/>
<rdf:object rdf:resource="http://www.example.com/UrgentWork"/>
</rdf:Statement>
</ex:say>
</rdf:Description>
</rdf:RDF>
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17. Notes for RDF Reification
• Why we need RDF Reification?
– Modeling Data Provenance
– Formalizing Statements about Reliability (Trust)
– Definition of Metadata about Statements
• the conventional use of reification
– do not imagine that the vocabulary defines some things that are not
actually defined
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18. Structured Values
This is the decimal value of weight
property using typed literal.
exproduct:item10245 exterms:weight "2.4"^^xsd:decimal .
• rdf:value Property
– to describe the main value (if there is one) of a structured value
• How to add an indication of the unit of measure (kilograms)
exproduct:item10245 exterms:weight _:weight10245 .
_:weight10245 rdf:value "2.4"^^xsd:decimal .
_:weight10245 exterms:units exunits:kilograms .
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19. RDF/XML for Structured Value
exproduct:item10245 exterms:weight _:weight10245 .
_:weight10245 rdf:value "2.4"^^xsd:decimal .
_:weight10245 exterms:units exunits:kilograms .
<?xml version="1.0"?>
<!DOCTYPE rdf:RDF [<!ENTITY xsd "http://www.w3.org/2001/XMLSchema#">]>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:exterms="http://www.example.org/terms/">
<rdf:Description rdf:about="http://www.example.com/2002/04/products#item10245">
<exterms:weight rdf:parseType="Resource">
<rdf:value rdf:datatype="&xsd;decimal">2.4</rdf:value>
<exterms:units rdf:resource="http://www.example.org/units/kilograms"/>
</exterms:weight>
</rdf:Description>
</rdf:RDF>
• rdf:parseType=“Resource” attribute
– to indicate that the contents of an element are to be interpreted as the
description of a new (blank node) resource, without a nested
rdf:Description element
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20. XML Literal
• rdf:parseType=“Literal” attribute
– to indicate that the contents of the element are to be interpreted as an
XML fragment
<?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/"
xml:base="http://www.example.com/books">
<rdf:Description rdf:ID="book12345">
<dc:title rdf:parseType="Literal">
<span xml:lang="en">
The <em>&lt;br /&gt;</em> Element Considered Harmful.
</span>
</dc:title>
</rdf:Description>
</rdf:RDF>
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21. RDF Serialization
• N-Triples
– RDF Test Cases, W3C Recommendation, 10 February 2004
– a line-based, plain text serialization format for storing and transmitting RDF data
• Notation 3 (N3)
– a shorthand non-XML serialization of RDF models, designed with human-
readability in mind
– much more compact and readable than XML RDF notation
• Turtle (Terse RDF Triple Language)
– W3C Candidate Recommendation, 19 February 2013
– a format for expressing data in the Resource Description Framework (RDF) data
model
– a subset of Notation3 (N3) language, and a superset of the minimal N-Triples format
• RDF/XML
– W3C Recommendation, 10 February 2004
– an XML syntax for writing down and exchanging RDF graphs
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22. N-Triple
<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/title> "Tony Benn" .
<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/publisher> "Wikipedia" .
N3
@prefix dc: <http://purl.org/dc/elements/1.1/>.
<http://en.wikipedia.org/wiki/Tony_Benn> dc:title "Tony Benn";
dc:publisher "Wikipedia".
RDF/XML
<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://en.wikipedia.org/wiki/Tony_Benn">
<dc:title>Tony Benn</dc:title>
<dc:publisher>Wikipedia</dc:publisher>
</rdf:Description>
</rdf:RDF>
Turtle
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix ex: <http://example.org/stuff/1.0/> .
<http://www.w3.org/TR/rdf-syntax-grammar>
dc:title "RDF/XML Syntax Specification (Revised)" ;
ex:editor [ ex:fullname "Dave Beckett", "Dave R. Beckett";
ex:homePage <http://purl.org/net/dajobe/>
] .
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23. References
• http://www.w3.org/TR/2004/REC-rdf-primer-20040210/
• http://www.slideshare.net/lysander07/openhpi-24
• http://www.slideshare.net/lysander07/openhpi-25
• http://www.slideshare.net/onlyjiny/linkeddata
• http://en.wikipedia.org/wiki/N-Triples
• http://en.wikipedia.org/wiki/Notation3
• http://en.wikipedia.org/wiki/Turtle_(syntax)
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24. Dr. Myungjin Lee
e-Mail : mjlee@li-st.com
Twitter : http://twitter.com/MyungjinLee
Facebook : http://www.facebook.com/mjinlee
SlideShare : http://www.slideshare.net/onlyjiny/
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