RDF Primer - The Diigo Meta page

• 28 Nov 14
  

  markus_stobbs

  Metadata chrome

• 20 Jan 14
  

  Liang Tian
  • Table of Contents
  • The Resource Description Framework (RDF) is a language for  representing information about resources in the World Wide Web.  It is particularly intended for representing metadata about Web  resources, such as the title, author, and modification date of a  Web page, copyright and licensing information about a Web  document, or the availability schedule for some shared resource.
  • RDF is intended for situations in which this information   needs to be processed by applications, rather than being   only displayed to people.
  • RDF is based on the idea of identifying things using Web  identifiers (called Uniform Resource Identifiers,   or URIs), and describing resources in terms of simple  properties and property values.
  • RDF is based on the idea that the things being described  have properties  which have values, and that resources can be described by  making statements, similar to those above, that specify those  properties and values.
  • RDF is about making  machine-processable statements
  • The Web provides a more general form of identifier for these  purposes, called the Uniform Resource  Identifier (URI).
  • RDF defines a  specific XML markup language, referred to as RDF/XML,  for use in representing RDF information, and for exchanging it  between machines.
  • A URI reference  (or URIref) is a URI, together with an optional  fragment identifier at the end.
  • QName
  • A QName contains a prefix that has  been assigned to a namespace URI, followed by a colon, and then  a local name.
  • Since RDF uses URIrefs instead of words to name things in statements, RDF refers to a set of URIrefs (particularly a set intended for a specific purpose) as a vocabulary.
  • identifying things
  • more precise
  • additional information
  • predicates
  • distinguishes the properties
  • additional  information
  • The result of all this is that RDF provides a way to make  statements that applications can more easily process. An  application cannot actually "understand" such statements, as noted  already, any more than a database system "understands" terms like "employee" or "salary" in processing a query like SELECT NAME FROM EMPLOYEE WHERE SALARY > 35000.     However, if an application is appropriately written,   it can deal with RDF statements in a way that makes it seem  like it does understand them, just as a database system and its applications can do useful work in processing employee and payroll information without understanding "employee" and "payroll".  For example, a user could search the Web for all  book reviews and create an average rating for each book. Then,  the user could put that information back on the Web. Another  Web site could take that list of book rating averages and  create a "Top Ten Highest Rated Books" page. Here, the  availability and use of a shared vocabulary about ratings, and  a shared group of URIrefs identifying the books they apply to,  allows individuals to build a mutually-understood and  increasingly-powerful (as additional contributions are made)  "information base" about books on the Web. The same principle  applies to the vast amounts of information that people create  about thousands of subjects every day on the Web.

  17 more annotations...

• 12 Dec 13
  

  Bada Bing
• 22 Oct 13
  

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• 26 Aug 13
  

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• 25 May 13
  

  Salvatore Larosa

  Shared Semantic Web

• 17 May 13
  

  Lisa Spiro

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• 17 Feb 13
  

  Michel Roland-Guill

  web sémantique

  • RDF is based on the idea that the things being described  have properties  which have values, and that resources can be described by  making statements, similar to those above, that specify those  properties and values. RDF uses a particular terminology for  talking about the various parts of statements. Specifically,  the part that identifies the thing the statement is about (the  Web page in this example) is called the subject.  The part that identifies the property or characteristic of the  subject that the statement specifies (creator, creation-date,  or language in these examples) is called the predicate,  and the part that identifies the value of that property is  called the object.

  • As illustrated earlier, the Web already provides one form of  identifier, the Uniform Resource Locator (URL).   A URL was used in the original example to identify the Web page  that John Smith created. A URL is a character string that  identifies a Web resource by representing its primary access  mechanism (essentially, its network "location"). However, it  is also important to be able to record information about many  things that, unlike Web pages, do not have network locations or  URLs.

      

    The Web provides a more general form of identifier for these  purposes, called the Uniform Resource  Identifier (URI). URLs are a particular kind of URI. All  URIs share the property that different persons or organizations  can independently create them, and use them to identify things.  However, URIs are not limited to identifying things that have  network locations, or use other computer access mechanisms. In  fact, a URI can be created to refer to anything that needs   to be referred to in a statement, including

      
     
    • network-accessible things, such as an electronic  document, an image, a service (e.g., "today's weather report  for Los Angeles"), or a group of other resources.
      
    • things that are not network-accessible, such as human  beings, corporations, and bound books in a library.
      
    • abstract concepts that do not physically exist, such as the  concept of a "creator".
• 22 Jan 13
  

  Laurence Baba

  RDF

• 10 Jan 13
  

  ingridbmason

  resource description framework W3C information standard semantic data sharing

• 27 Dec 12
  

  A Gilmore

  Semantics

• 12 Nov 12
  

  Christopher Günther
  • provides a common framework for expressing this  information so it can be exchanged between applications without  loss of meaning
  • enables RDF to represent  simple statements about resources as a graph of nodes  and arcs representing the resources, and their properties and  values
• 27 Sep 12
  

  Ruth M.
  • However, by generalizing the concept of a "Web resource", RDF can  also be used to represent information about things that can be  identified on the Web, even when they cannot be directly  retrieved on the Web.
  • RDF/XML is machine processable and, using  URIs, can link pieces of information across the Web. However,  unlike conventional hypertext, RDF URIs can refer to any  identifiable thing, incl
  • Specifically,  the part that identifies the thing the statement is about (the  Web page in this example) is called the subject.  The part that identifies the property or characteristic of the  subject that the statement specifies (creator, creation-date,  or language in these examples) is called the predicate,  and the part that identifies the value of that property is  called the object.  So, taking the En

  • use them to identify things.  However, URIs are not limited to identifying things that have  network locations, or use other computer access mechanisms. In  fact, a URI can be created to refer to anything that needs   to be referred to in a statement, including

      
     
  • network-accessible things
  • things that are not network-accessible,
  • abstract concepts that do not physically exist
  • Figure 3 illustrates that objects  in RDF statements may be either URIrefs, or constant values (called literals)  represented by character strings, in order to represent certain  kinds of property values.
  • Literals may not be used as subjects or  predicates in RDF statements.
  • Sometimes it is not convenient to draw graphs when  discussing them, so an alternative way of writing down the  statements, called triples,  is also used. In the triples notation, each statement in the  graph is written as a simple triple of subject, predicate, and  object, in that order.

  8 more annotations...

• 30 Aug 12
  

  Erik Alarcón

  RDF Recomendation

  • RDF) is a language for  representing information about resources in the World Wide Web
  • This Primer
  • introduces the basic  concepts of RDF and describes its XML syntax
  • The Resource Description Framework
  • is a language for  representing information about resources in the World Wide Web
  • used to represent information about things that can be  identified on the Web
  • the concept of a "Web resource"
  • RDF is based on the idea of identifying things using Web  identifiers
  • , and their properties and  values.
  • represent  simple statements about resources as a graph of nodes  and arcs representing the resources
  • as well as  properties
  • RDF/XML
  • contains URIs
  • and their respective values
  • a simple  statement such as
  • Parts of this statement are
  • is used to identify it. In addition
  • the Web page's URL
  • the  word "creator" is used to identify the property
  • and the
  • words "John Smith" to identify the thing (a person)  that is the value of this property
  • Other properties of this Web page
  • to identify the page, and words
  • statements
  • of the same general form, using  the URL
  • could be described by writing  additional
  • the  date the page was created, and the language
  • could be described using the additional  statements:
  • RDF is based on the idea that the things
  • described  have properties
  • which have values
  • resources can be described by  making statements
  • the part that identifies the thing the statement is
  • The part that identifies the property or characteristic of the  subject
  • is called the subject.
  • is called the predicate
  • the part that identifies the value of that property is  called the object
  • A URL is a character string that  identifies a Web resource
  • However
  • URLs.
  • information about many  things
  • do not have
  • The Web provides a more general form of identifier
  • called the Uniform Resource  Identifier (URI)
  • All  URIs share the property that different persons or organizations  can independently create them, and use them to identify things
  • URIs are not limited to identifying things that have  network locations, or use other computer access mechanisms. In  fact, a URI can be created to refer to anything that needs   to be referred to in a statement
  • RDF uses URIs as the basis of  its mechanism for identifying the subjects, predicates, and  objects in statements
  • RDF defines a  specific XML markup language
  • each  statement consists of a subject, a predicate, and an object
  • RDF models statements as nodes and arcs in a graph.
  • • a node for the subject
      
    • a node for the object
  • an arc for the predicate
  • using suitable URIrefs to name the properties  "creation-date" and "language"
  • the graph shown
  • constant values (called literals)
  • alternative way of writing down the  statements, called triples
  • it is not convenient to draw graphs
  • subject, predicate, and  object
  • <http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/creator> <http://www.example.org/staffid/85740> .  <http://www.example.org/index.html> <http://www.example.org/terms/creation-date> "August 16, 1999" .  <http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/language> "en" .
  • Each triple corresponds to a single arc in the graph
  • The full triples notation requires that URI references
  • RDF user
  • using named properties and values
  • RDF provides a way to express simple statements about  resources
  • that they are  describing specific kinds or classes of resources
  • need the ability     to define the vocabularies  (terms)
  • to use in those statements, specifically,     to indicate
  • and will use  specific properties in describing those resources

  66 more annotations...

• 18 Jun 12
  

  psicosis

  primer rdf semantic web SemanticWeb w3c

• 22 May 12
  

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  tutorial metadata semantic semanticweb Web delicous

• 10 Oct 11
  

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  rdf lenguajemarca xml agildie Metadatos biblioteca

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  rdf lenguajemarca xml agildie Metadatos delicious

• 05 Oct 11
  

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• 24 Jun 11
  

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• 28 Jun 09
  

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  semanticweb rdf w3c reference primer standards

• 18 Jan 08
  

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• 30 Oct 07
  

  Erin Stalberg

  "The Resource Description Framework (RDF) is a language for representing information about resources in the World Wide Web. This Primer is designed to provide the reader with the basic knowledge required to effectively use RDF."

  metadata rdf delicious

• 14 Oct 06
  

  phersh

  If you don't exactly what rdf is and what it is used for, read this excellent tutorial first.

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• 08 Aug 06
  

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  rdf reference semantic semanticweb w3c web xml

• 09 Jul 06
  

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  article W3C web semanticweb rdf teaching wt-semweb wt-semweb2

• 09 Jan 06
  

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