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RDF / XML 28.04.2005 Marcin
Perkowski Magdalena Kowalik
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• RDF Resource Description Framework
• 1. This ist a Project which schould provide
  metadata infrastructure independence from
  producer and applications. It allows to
  represent information about resources in the WWW
  ,in particular metadata about Web resources
  (for an example title,author ,version
  ,publication date,...)
• Goal allow applications to acces and process
  this specified information
• 2. There are 3 important parts of statement in
  RDF
• subject
• predicate
• object
• 3. Example of a Statement

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• Exactly these parts of statements are represented
  by URI-s
• a subject http//www.uni-hannover.de/in
  dex.html
• a predicate http//purl.org/dc/elements/1.
  1/creator
• an object http//www.uni-hannover.de/st
  affid/88770
• Ressource is identified by a URI .
• URI(Uniform Ressource Identificator) can
  identify
• network-accesable things (image,doc)
• things that are not network-accesable (human
  beeings, corporations)
• abstract concepts that dont physically exist
  (concept of a creator)

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• 4 . Such statement can be described in 3 ways
  by a graph , in XML or by triples
• 4.1 by triples (red is a subject , blue
  is a predicate, green is an object)
• (http//www.w3.org/People/EM/contactme
  ,
• http//www.w3.org/2000/10/swap/pim/contactmailb
  ox,
• em_at_w3.org)
• (http//www.w3.org/People/EM/contactme,
• http//www.w3.org/2000/10/swap/pim/contactperso
  nalTitle, "
• Dr.")
• (http//www.w3.org/People/EM/contactme,
• http//www.w3.org/2000/10/swap/pim/contactfullN
  ame,
• "Eric Miller")
• (http//www.w3.org/People/EM/contactme,
• http//www.w3.org/1999/02/22-rdf-syntax-nstype,
  
• http//www.w3.org/2000/10/swap/pim/contactPerso
  n)

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4.2 by a graph
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4.3 In XML An RDF document is
presented by an XML element with tag rdfRDF
lt?xml version"1.0"?gt ltrdfRDF xmlnsrdf"http//w
ww.w3.org/1999/02/22-rdf-syntax-ns" xmlnscontac
t"http//www.w3.org/2000/10/swap/pim/contact"gt
ltcontactPerson rdfabout"http//www.w3.org/Peopl
e/EM/contactme"gt ltcontactfullNamegtEric
Millerlt/contactfullNamegt
ltcontactmailbox rdfresource"mailtoem_at_w3.org"/gt
ltcontactpersonalTitlegtDr.lt/contactperso
nalTitlegt lt/contactPersongt lt/rdfRDFgt (red
is a subject , blue is a predicate, green is an
object)
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• XML - Extensible Markup Language
• 5. XML its not a new HTML generation !
• Its a system for exchanging information
  general-purpose.
  If we consider it as an
  subset of SGML than well classify it into
  general-purpose meta-language (markup language)
  which is used to create special-purpose markup
  languages (like HTML- HyperText Markup Language )
• SGML (Standard Generalized Markup
  Language)-metalanguage which allows to define
  languages which are used to describing of logical
  structure of a document.
• Differences between XML and HTML
• XML cares about contents ,not about presentation
  
• XML we can define meaning of elements and
  attributs (to produce own markers)

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• 5.1 These formating markers are defined in DTD of
  document or in XML Schema.
• DTD ( Document Type Definition) it allows to
  define restrictions which describe a formal
  structure of document written in XML or SGML.DTD
  is a part of standard XML.
• A DTD specifies, in effect, the syntax of an
  "application" of SGML or XML, such the derivative
  (child) language HTML or XHTML. This syntax is
  usually a less general form of the syntax of SGML
  or XML.
• XML Schema ists a standrad used to define of
  structure of XML document (schema language) .
  Its described by the W3C (producer of XML
  Schema) as the successor of DTDs . Its a
  application of XML.
• 5.2 Basic XML usage
• storing of data
• documents formating (CSS , XSLT, XSL-FO, DOM)
• modelling and cohesionc (homogeneity) controll
  of data (DTD, XML Schema)
• exchange of data between applications (XML-RPC,
  SOAP, WSDL, UDDI)

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6. XML tags in RDF 6.1 Namespaces (xmlns)
ltbnBook xmlnsbn"http//apps.bn
.com/ns"gt
ltbnAuthorgtShakespearelt/bnAuthorgt
lt/bnBookgt xmlns signify if there is
a namespace and the schema .(Schema defines this
namespace which we can find over this URL) bn it
can by any word , its a ( abbreviation ) such
schorter name of namespace When we use
namespaces? When we want to use more than one
dictionary of markers for an example There
is a XML document which describes a bill for a
book.The question is what describe marker AUTHOR
? In one dictionary, marker AUTHOR means autor of
the book , in other dictionary it means autor of
a bill the person which have bought this book.
SOLUTION use namespaces !
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• 6.2 rdfabout , rdfid , rdfDescription
• The Description tag may used to describe a
  triple.The about attribute is used to specify the
  subject in the triple.
• rdfDescription - the content of this element
  is a number of descriptions
• Every description makes a statement about a
  resource three different ways
• rdfabout -referencing to an existing resource
• rdfid creating a new resource
• without a name creating an anonymous resource
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-
  rdf-syntax-ns"
• xmlnsuni"http//www.mydomain.o
  rg/"gt
• ltrdfDescription rdfabout"http//www.mydomain.or
  g/uni-ns/949318"gt
• ltuninamegtDavid Billingtonlt/uninamegt
• ltunititlegtAssociate
  Professorlt/unititlegt
• lt/rdfDescriptiongt

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6.3 rdfresource Its used for recognising
dissimilarity between two objects which look like
the same but they arent the same. To show that
resources are like siblings Problem a same name
might be a coincidence The David Billington who
teaches "Discrete Mathematics" may not be the
same person that is a person with
ID Interpretation of resources (and therefore of
RDF triples) is highly contextual
. ltrdfDescription rdfabout"http//www.mydomai
n.org/uni-ns/949318"gt ltuninamegtDavid
Billingtonlt/uninamegt ltunititlegtAssociate
Professorlt/unititlegt lt/rdfDescriptiongt ltrdfDe
scription rdfabout"http//www.mydomain.org/uni-n
s/CIT1111"gt ltunicourseNamegtDiscrete
Mathematicslt/unicourseNamegt ltuniisTaughtBy
rdfresource"http//www.mydomain.org/uni-ns/9493
18"gt lt/rdfDescriptiongt
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We can identify Staff member David Billington
with ID attribute (hier marked bold ) Red marked
is this problematic object . ltrdfDescription
rdfid"949318gt ltuninamegtDavid
Billingtonlt/uninamegt
ltunititlegtAssociate Professorlt/unititlegt lt/rdfD
escriptiongt ltrdfDescription rdfabout"http//ww
w.mydomain.org/uni-ns/CIT1111"gt
ltunicourseNamegtDiscrete Mathematicslt/unicourse
Namegt ltuniisTaughtBy
rdfresource"http//www.mydomain.org/uni-ns/9493
18"gt lt/rdfDescriptiongt
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6.4 rdfType Sometimes it is useful to be able to
identify what kind of thing a resource is .In RDF
there is rdftype element to express a type. For
example, the Sandra resource might be given a
type of 'Person'. Here we have descriptions
about two categories courses, and
lecturers ltrdfDescription rdfID"949318"gt ltrd
ftype rdfresource"http//www.mydomain.org/uni-n
s/lecturer"/gt ltuninamegtDavid
Billingtonlt/uninamegt
ltunititlegtAssociate Professorlt/unititlegt lt/rdfD
escriptiongt ltrdfDescription rdfabout"http//ww
w.mydomain.org/uni-ns/CIT1111"gt ltrdftype
rdfresource"http//www.mydomain.org/uni-ns/cour
se"/gt ltunicourseNamegtDiscrete
Mathematicslt/unicourseNamegt ltuniisTaughtBy
rdfresource"949318"gt lt/rdfDescriptiongt
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6.5 Abbreviation (shorter name) The namespace
can be abbreviated with "name space
name ltrdfRDF xmlnsrdf"http//www.w3.org/19
99/02/22-rdf-syntax-ns"
xmlnsuni"http//www.mydomain.org/"gt ltrdfDescri
ption rdfID"949318"gt
ltrdftype rdfresourceunilecturer"/gt
ltuninamegtDavid Billingtonlt/uninamegt
ltunititlegtAssociate
Professorlt/unititlegt lt/rdfDescriptiongt
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• 6.6 Abbreviations
• Two rules
• 1)Childless property elements within description
  elements may be replaced by XML attributes (as in
  XML)
• 2)For description elements with a typing element
  we can use the name specied in the rdftype
  element instead of rdfDescription
• ltrdfDescription rdfID"CIT1111"gt
• ltrdftype rdfresource"unicourse"/gt
• ltunicourseNamegt Discrete Mathematicslt/unicourse
  Namegt
• ltuniisTaughtBy rdfresource"949318"gt
• lt/rdfDescriptiongt
• is equivalent to (according to rule 1)
• ltrdfDescription rdfabout"CIT1111
  unicourseName"Discrete Mathematics"gt
• ltrdftype rdfresource"unicourse"/gt
• ltuniisTaughtBy rdfresource"949318"gt
• lt/rdfDescriptiongt

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and is equivalent to (according to rule
2) ltunicourse rdfabout"CIT1111
unicourseName"Discrete Mathematics"gt ltuniisTaug
htBy rdfresource"949318"gt lt/unicoursegt
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6.6 Nested Descriptions descriptions can be
nested ltrdfDescription rdfabout"CIT1111"gt lt
unicourseNamegtDiscrete Mathematicslt/unicourseNam
egt ltuniisTaughtBygt ltrdfDescription
rdfabout"949318"gt
ltuninamegtDavid Billingtonlt/uninamegt
ltunititlegtAssociate
Professorlt/unititlegt lt/rdfDescriptiongt lt/uni
isTaughtBygt lt/rdfDescriptiongt
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Bibliography Semantic Web Lecture
http//www.kbs.uni-hannover.de/henze/semweb04/skr
ipt/slides/17_5_2004.pdf WIKIPEDIA
http//en.wikipedia.org/wiki/Resource_Descrip
tion_Framework RDF Tutorial
http//www710.univ-lyon1.fr/champin/rdf-tutorial/
RDF Guide
http//xulplanet.com/tutorials/mozsdk/rdfstart.php