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Practical RDF Chapter 3. The Basic Elements Within the RDF/XML Syntax

Practical RDF Chapter 3. The Basic Elements Within the RDF/XML Syntax. Shelley Powers, O’Reilly SNU IDB Lab. Hyewon Kim. Outline. Serializing RDF to XML RDF Blank Nodes URI References Representing Structured Data with rdf:value The rdf:type Property RDF/XML Shortcuts

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Practical RDF Chapter 3. The Basic Elements Within the RDF/XML Syntax

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  1. Practical RDFChapter 3. The Basic Elements Within the RDF/XML Syntax Shelley Powers, O’Reilly SNU IDB Lab. HyewonKim

  2. Outline • Serializing RDF to XML • RDF Blank Nodes • URI References • Representing Structured Data with rdf:value • The rdf:type Property • RDF/XML Shortcuts • More on RDF Data Types

  3. Introduction • Serialization converts an RDF model in a text-based format using XML RDF model http://burningbird.net/postcon/elements/1.0/author http://burningbird.net/articles/monsters3.htm Shelly Powers Serialization Text-based format using XML <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:author>Shelly Powers</pstcn:author> </rdf:Description> </rdf:RDF>

  4. Serializing RDF to XMLExample (1/5) The article on giant squids, titled “Architeuthis Dux,” at http://burningbird.net/articles/monsters3.htm, written by Shelly Powers, explores the giant’s squid’s mythological representation as the legendary Kraken as well as describing current efforts to capture images of a live specimen. In addition, the article also provides descriptions of a giant squid’s physical characteristics. It is part of a four-part series, described at http://burningbird.net/articles/monsters.htm and entitled “A Tale of Two Monsters.” • Identified by • http://burningbird.net/articles/monster3.htm • Series member • http://burningbird.net/articles/monsters.htm • Written by • Shelley Powers • Title • A tale of Two Monsters Article • Title • Architeuthis Dux • Provides • Physical description of giant squid • Associates • Kraken and giant squid

  5. Serializing RDF to XMLExample (2/5) • RDF • Starting small, we’ll take a look at mapping the article and the author and title, only into RDF • pstcn • Created prefix for the example <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:author>Shelly Powers</pstcn:author> <pstcn:title> Architeuthis Dux</pstcn:title> </rdf:Description> </rdf:RDF> • Predicate– Author • Object – Shelly Powers Subject http://burningbird.net/articles/monsters3.htm • Predicate – Title • Object – Architeuthis Dux

  6. Serializing RDF to XMLExample (3/5) • Expanded version of the example <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:author>Shelly Powers</pstcn:author> <pstcn:title> Architeuthis Dux</pstcn:title> <pstcn:seriesrdf:resource=“http://burningbird.net/articles/monsters.htm /”> <pstcn:contains> Physical description of giant squids </pstcn:contains> <pstcn:alsoContains> Tale of the Legendary Kraken </pstcn:alsoContains> </rdf:Description> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster.htm”> <pstcn:seriesTitle>A Tale of Two Monsters</pstcn:seriesTitle> </rdf:Description> </rdf:RDF> • Series member • http://burningbird.net/articles/monsters.htm Article • Title • A tale of Two Monsters

  7. Serializing RDF to XMLExample (4/5) • Expanded RDF modified to use nested resources <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:author>Shelly Powers </pstcn:author> <pstcn:title> Architeuthis Dux</pstcn:title> <pstcn:series > <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monsters.htm”> <pstcn:SeriesTitle>A Tale of Two Monsters </pstcn:seriesTitle> </rdfDescription> <pstcn:series> <pstcn:contains> Physical description of giant squids </pstcn:contains> <pstcn:alsoContains> Tale of the Legendary Kraken </pstcn:alsoContains> </rdf:Description> </rdf:RDF>

  8. Serializing RDF to XMLExample (5/5) • RDF graph http://burningbird.net/postcon/elements/1.0/author Shelley Powers http://burningbird.net/postcon/elements/1.0/title Architeuthis Dux http://burningbird.net/postcon/elements/1.0/series http://burningbird.net/postcon/elements/1.0/seriesTitle <rdfDescriptionxmins.rdf=“http://www.w3.org/199/02/22-rdf-syntax-ns#... http://burningbird.net/articles/monsters.com A Tale of Two Monsters http://burningbird.net/postcon/elements/1.0/contains Physical description of giant squid http://burningbird.net/postcon/elements/1.0/alsoContains Tale of the legendary Kraken

  9. Serializing RDF to XMLPredicates (1/2) • We can mark the type of property using the rdf:parseType attribute • rdf:parseType=“Literal” • Embed XML within an RDF document <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=http://burningbird.net/postcon/elements/1.0/> <rdf:Descriptionrdf:about=http://burningbird.net/articles/monster3.htm> <pstcn:author>Shelly Powers </pstcn:author> <pstcn:title> Architeuthis Dux</pstcn:title> <pstcn:series > <rdf:Descriptionrdf:about=“http://dynamicearth.com/articles/monsters.htm> <pstcn:SeriesTitle>A Tale of Two Monsters </pstcn:seriesTitle> </rdfDescription> <pstcn:series> <pstcn:contains> Physical description of giant squids </pstcn:contains> <pstcn:alsoContainsrdf:parseType=“Literal”> <h1> Tale of the Legendary Kraken </h1> </pstcn:alsoContains> </rdf:Description> </rdf:RDF>

  10. Serializing RDF to XMLPredicates (2/2) • We can mark the type of property using the rdf:parseTypeattribute • rdf:parseType=“Resource” • Identify the element as a resource without having to use rdf:about or rdf:ID <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:authorrdf:parseType=“Resource” /> </rdf:Description> </rdf:RDF> With no value provided http://burningbird.net/postcon/elements/1.0/author http://burningbird.net/articles/monsters3.htm Genid:ARP107458

  11. Serializing RDF to XMLNamespaces and Qnames(1/2) • The format of namespace • RDF Working Group has allowed some attributes to be non-namespace annotated • ID • bagID • about • resource • parseType • type xmlns:name = “URI of schema” QName XML Local name

  12. Serializing RDF to XMLNamespaces and Qnames(2/2) • Qnames can be used as values for rdf:about or rdf:type <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:bbd=“http://www.burningbird.net/schema#” <rdf:Descriptionrdf:about =“http://www.burningbird.net/identifier/tutorials/xul.htm”> <bbd:bidrdf:resource=“bbd:bio”/> <bbd:relevancyrdf:resource=“bbd:relevancy”/> </rdf:Description> <rdf:Descriptionrdf:about=“bbd:bio”> <bbd:Title> YASD Does Mozilla/Navigator 6.0 </bbd:Title> <bbd:Description> Demonstrations of using XUL for interface development </bbd:Description> <bbd:CreationDate> May 2000 </bbd CreationDate> <bbd:ContentAuthor> Shelly Powers </bbd:ContentAuthor> <bbd:ContentOwner> Shelly Powers </bbd:ContentOwner> <bbd:CurrentLocation> N/A </bbd:CurrentLocation> <rdf:Description> <rdf:Descriptionrdf:about=“bbd:relevancy”> <bbd:CurrentStatus> Inactive </bbd:CurrentStatus> <bbd:RelevancyExpiration> N/A </bbd:RelevancyExpiration> <bbd:Dependencies> None </bbd:Dependencies> </rdf:Description> </rdf:RDF>

  13. RDF Blank Nodes (1/2) • A blank node represents a resource that isn’t currently identified • rdf:nodeID is used to provide a specific identifier • <pstcn:biordf:nodeID=“monsters1”> <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/” xml:base=“http://burningbird.net/articles/”> <rdf:Descriptionrdf:about=“monsters1.htm”> <pstcn:bio> <rdf:Description> <pstcn:title>Tale of Two Monsters :Legends </pstcn:title> <pstcn:descriotion> Part 1 of four-part series on cryptozoology, legends, Nessie the Loch Ness Monster and the giant squid. </pstcn:description> <pstcn:created>1999-08-01T00:00:00-06:00 </pstcn:created> <pstcn:creator> Shelley Powers </pstcn:creator> </rdfDescription> <pstcn:bio> </rdf:Description> </rdf:RDF>

  14. RDF Blank Nodes (2/2) • The RDF Validator has generated a node identifier for the blank node, genid:403 http://burningbird.net/postcon/elements/1.0/title Tale of Two Monsters:Legends http://burningbird.net/postcon/elements/1.0/description Part 1 of four-part series on cryptozoology, legends http://burningbird.net/postcon/elements/1.0/bio monsters1.htm genid:403 http://burningbird.net/postcon/elements/1.0/created 1999-08-01T00:00:00-05:00 Blank node http://burningbird.net/postcon/elements/1.0/creator Shelly Powers

  15. URI ReferencesResolving Relative URIs and xml:base • With xml:base, we can specify a base document that’s used to generate full URIs when given relative URI references <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/” xml:base=“http://burningbird.net/articles/”> <rdf:Descriptionrdf:about=“monsters3.htm”> <pstcn:authorrdf:parseType=“Literal” /> </rdf:Description> </rdf:RDF> A relative URI reference A base document Full URI → http://burningbird.net/articles/monsters3.htm

  16. URI ReferencesResolving References with rdf:ID <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=http://burningbird.net/postcon/elements/1.0/> <rdf:Descriptionrdf:ID=“monsters3.htm”> <pstcn:author>Shelly Powers </pstcn:author> <pstcn:title> Architeuthis Dux</pstcn:title> <pstcn:series > <rdf:Descriptionrdf:ID=“monsters.htm”> <pstcn:SeriesTitle>A Tale of Two Monsters </pstcn:seriesTitle> </rdfDescription> <pstcn:series> <pstcn:contains> Physical description of giant squids </pstcn:contains> <pstcn:alsoContainsrdf:parseType=“Literal”> <h1> Tale of the Legendary Kraken</h1> </pstcn:alsoContains> </rdf:Description> </rdf:RDF> http://burningbird.net/index.htm#monsters3.htm http://burningbird.net/index.htm#monsters.htm • Enclosing document • http://burningbird.net/index.htm

  17. Representing Structured Data with rdf:value • Some data values have both a value and additional information The last modified date : 18 July RDF <pstcn:lastEdited> 18 </pstcn:lastEdited> Ambiguous!Is it 18 days? Months? Hours? <pstcn:lastEdited> 18 days </pstcn:lastEdited> It should be split ! <pstcn:lastEdited> 18 </pstcn:lastEdited> <pstcn:lastEditedUnit> day </pstcn:lastEditedUnit> There is a disconnectbetween the value and the unit <pstcn:lastEditedrdf:parseType=“Resource”> <rdf:value> 18 </rdf:value> <pstcn:lastEditedUnit> day </pstcn:lastEditedUnit> </pstcn:lastEdited> • rdf:value • When dealing with structured data, the rdf:value predicate includes the actual value of the structure

  18. The rdf:type Property • rdf:type • Explicitly define the resource type • Is associated at the same level of granularity as the other properties <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:Author>Shelly Powers</pstcn:Author> <pstcn:Title>Architeuthis Dux</pstcn:Title> <rdf:typerdf:resource=“http://burningbird.net/postcon/elements/1.0/Article/”> </rdf:Description> </rdf:RDF> Abbreviated syntax <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <pstcn:Articlerdf:about=“http://burningbird.net/articles/monster3.htm”> <pstcn:Author>Shelly Powers</pstcn:Author> <pstcn:Title>Architeuthis Dux</pstcn:Title> </pstcn:Article> </rdf:RDF>

  19. RDF/XML Shortcuts • RDF/XML Shortcut is an abbreviated technique • Separate predicates can be enclosed within the same resource block • Nonrepeating properties can be created as resource attributes • Empty resource properties do not have to be formally defined with description block <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <pstcn:Article pstcn:author = “Shelly Powers” pstcn:title= “Architeuthis Dux” rdf:about=“http://dynamicearth.com/articles/monsters3.htm”> <pstcn:relatedrdf:resource=“http://burningbird.net/articles/monsters1.htm” pstcn:reason=“First in the series” /> </pstcn:Article> </rdf:RDF>

  20. More on RDF Data Types • Within RDF/XML, the data type is specified as an attribute of the element, using the rdf:datatype attribute <?xml version=“1.0”?> <rdf:RDF xmlns:rdf=“http://www.w3.org/1999/02/22-rdf-syntax-ns#” xmlns:pstcn=“http://burningbird.net/postcon/elements/1.0/”> <rdf:Descriptionrdf:about=“http://burningbird.net/articles/monsters3.htm”> <pstcn:authorrdf:datatype = “http://www.w3.org/2001/XMLSchema#string”> Shelley Powers </pstcn:author> <pstcn:titlerdf:datatype = “http://www.w3.org/2001/XMLSchema#string”> Architeuthis Dux </pstcn:title> </rdf:Description> </rdf:RDF>

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