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Internet Technologies The Resource Description Framework (RDF and RDFa) 95 -733 Internet Technologies Internet Technologies The Resource Description Framework (RDF and RDFa) 95 -733 Internet Technologies

RDF and RDFa Notes from two articles on course schedule: “What is RDF” by RDF and RDFa Notes from two articles on course schedule: “What is RDF” by Tim Bray and Joshua Tauberer and the “RDFa Primer” from W 3 C 95 -733 Internet Technologies

A Knowledge Graph 95 -733 Internet Technologies A Knowledge Graph 95 -733 Internet Technologies

Triples Start Node Edge Label End Node vincent_donofrio starred_in law_&_order_ci is_a tv_show the_thirteenth_floor similar_plot_as Triples Start Node Edge Label End Node vincent_donofrio starred_in law_&_order_ci is_a tv_show the_thirteenth_floor similar_plot_as the_matrix 95 -733 Internet Technologies

Notation 3 (N 3) or Turtle Format @prefix rdf: <http: //www. w 3. org/1999/02/22 Notation 3 (N 3) or Turtle Format @prefix rdf: . @prefix ex: . ex: vincent_donofrio ex: starred_in ex: law_and_order_ci rdf: type ex: tv_show. ex: the_thirteenth_floor ex: similar_plot_as ex: the_matrix. 95 -733 Internet Technologies

RDF/XML <rdf: RDF xmlns: rdf= RDF/XML 95 -733 Internet Technologies

Another RDF/XML <rdf: RDF xmlns: rdf= Another RDF/XML 40. 35 -74. 66 95 -733 Internet Technologies

As A Table Subject Predicate Object --------------- ---- <http: //www. princeton. edu> edu: has. As A Table Subject Predicate Object --------------- ---- edu: has. Dept geo: lat "40. 35" geo: long "-74. 66" dc: title "Department of Computer Science" 95 -733 Internet Technologies

Notation 3 @prefix rdf: <http: //www. w 3. org/1999/02/22 -rdf-syntax-ns#>. @prefix dc: <http: //purl. Notation 3 @prefix rdf: . @prefix dc: . @prefix geo: . @prefix edu: . geo: lat "40. 35" ; geo: long "-74. 66". dc: title "Department of Computer Science". edu: has. Dept . 95 -733 Internet Technologies

From the RDFa W 3 C Primer “When web data meant for humans is From the RDFa W 3 C Primer “When web data meant for humans is augmented with hints meant for computer programs, these programs become significantly more helpful. ” 95 -733 Internet Technologies

XHTML Without and With RDFa All content on this site is licensed under <a XHTML Without and With RDFa All content on this site is licensed under a Creative Commons License All content on this site is licensed under a Creative Commons License . 95 -733 Internet Technologies The rel, in a link, describes the relationship between the current page and the linked page.

A Link with a Flavor 95 -733 Internet Technologies A Link with a Flavor 95 -733 Internet Technologies

Labeling Title and Author <div> <h 2>The trouble with Bob</h 2> <h 3>Alice</h 3>. Labeling Title and Author

The trouble with Bob Alice. . .
RDFa introduces the property attribute. What kind of title? A title of a person or a title to land or a title of a work?
The trouble with Bob Alice. . . 95 -733 Internet Technologies

In RDFa, all property names are, in fact, URLs. 95 -733 Internet Technologies In RDFa, all property names are, in fact, URLs. 95 -733 Internet Technologies

Multiple Items Per Page RDFa provides @about, an attribute for

The trouble with Bob specifying the Alice exact URL to. . . which the
contained RDFa markup
Jo's Barbecue applies
Eve. . .
95 -733 Internet Technologies

As a Diagram 95 -733 Internet Technologies As a Diagram 95 -733 Internet Technologies

The trouble with Bob" src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-17.jpg" alt="Alice Gives Bob Credit

The trouble with Bob" /> Alice Gives Bob Credit
The trouble with Bob The trouble with Bob is that he takes much better photos than I do:
Beautiful Sunset by Bob.
The
inner about overrides the outer about. 95 -733 Internet Technologies

As A Graph 95 -733 Internet Technologies As A Graph 95 -733 Internet Technologies

[email protected]" src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-19.jpg" alt="Blog Contact Info

Alice Birpemswick

Email: [email protected]" /> Blog Contact Info

This is mainly useful for viewing. 95 -733 Internet Technologies

Blog w/FOAF Contact Info

Alice Birpemswick

Email: The Dublin core has no vocabulary for describing friendships. But foaf does. The typeof is an [email protected] com RDFa attribute that is

specifically meant to

declare a new data Phone: +1 617. 555. 7332 a certain

type.
95 -733 Internet Technologies

As A Graph Alice didn't specify @about like she did when adding blog entry As A Graph Alice didn't specify @about like she did when adding blog entry metadata. What is she associating these properties with, then? In fact, the @typeof on the enclosing div implicitly sets the subject of the properties marked up within that div. The name, email address, and phone number are associated with a 95 -733 Internet Technologies foaf: Person. This new node of type node has no URL to identify it, so it is called a blank node.

Bob Eve" src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-22.jpg" alt="Social Networks

  • Bob
  • Eve" /> Social Networks
    friends of Alice and she Includes them in her 95 -733 Internet Technologiesnormal HTML blog.

    " src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-23.jpg" alt="Adding RDFa First, describe these as Persons.
      " /> Adding RDFa First, describe these as Persons. 95 -733 Internet Technologies

    " src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-24.jpg" alt="Add Homepages Use rel for the link relationships.

    " /> Add Homepages Use rel for the link relationships. 95 -733 Internet Technologies

    • " src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-25.jpg" alt="Describe Text as Names
      • " /> Describe Text as Names
        95 -733 Internet Technologies

      Claim in Primer “Alice is ecstatic that, with so little additional markup, she's able Claim in Primer “Alice is ecstatic that, with so little additional markup, she's able to fully express both a pleasant human-readable page and a machine-readable dataset. ” 95 -733 Internet Technologies

          Using foaf: knows Alice knows these people with these names and homepages. 95 -733 Internet Technologies

      95 -733 Internet Technologies 95 -733 Internet Technologies

      Building Custom Vocabularies 1. Selecting a URL where the vocabulary will reside, e. g. Building Custom Vocabularies 1. Selecting a URL where the vocabulary will reside, e. g. http: //example. com/photos/vocab#. 2. Distributing an RDF document, at that URL, which defines the classes and properties that make up the vocabulary. For example, Alice may want to define classes Photo and Camera, as well as the property taken. With that relates a photo to the camera with which it was taken. 3. Using the vocabulary in XHTML+RDFa with the usual prefix declaration mechanism, e. g. xmlns: photo="http: //example. com/photos/vocab#", and typeof="photo: Camera". 95 -733 Internet Technologies

      Microformats Compete with RDFa h. Card Business card data XFN Friends and contacts h. Microformats Compete with RDFa h. Card Business card data XFN Friends and contacts h. Calendar Events h. Review movies, books, etc. . “When web data meant for humans is augmented with hints meant for computer programs, these programs become significantly more helpful. ” But, perhaps we will use microformats rather than RDFa. 95 -733 Internet Technologies

      Microformats Compete with RDFa As an exercise, visit http: //microformats. org and build an Microformats Compete with RDFa As an exercise, visit http: //microformats. org and build an h. Card an h. Calendar. Use h. Card creator and h. Calendar creator. 95 -733 Internet Technologies

      RDF On Its Own • RDFa is RDF in XHTML. • The Resource Description RDF On Its Own • RDFa is RDF in XHTML. • The Resource Description Framework (RDF) is a W 3 C recommendation for an XML encoding of metadata. • A standard for encoding metadata is important for finding and describing resources. A “resource” is anything with a URI. This would include people, books, devices and so on. • Card catalogs, for example, have been used for years to record metadata about the collection of materials in libraries. Is Google the card catalogue for the web? Are we done? 95 -733 Internet Technologies

       • RDF Is All About Making Statements An RDF Document contains Statements. • • RDF Is All About Making Statements An RDF Document contains Statements. • A statement can be thought of as an ordered triple composed of three items: (resource, property-type, property-value) • A Resource is anything that can be identified. • A Predicate is a property name that has a URI. The Predicate may or may not actually be resolvable. • A Value is another Resource or a literal • Statements may be represented in RDF XML, abbreviated RDF XML, NTriples or graphs. 95 -733 Internet Technologies

      RDF Triples It is required that each resource have a URI. http: //www. andrew. RDF Triples It is required that each resource have a URI. http: //www. andrew. cmu. edu/~mm 6/my. xml#root(). child(1) mailto: mm [email protected] cmu. edu urn: isbn: 0764532367 (resource, property-type, property-value) A property is a specific characteristic, attribute or relationship of a resource. Each property has a specific meaning that can be identified by the property’s name and the associated schema. The schema must actually be pointed to by the property’s namespace. Using RDF Schema we can describe the property names, values and value ranges that are permitted for the property. 95 -733 Internet Technologies

      property value property value" src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-35.jpg" alt="A Simple Description <RDF> <Description about = "Some URI"> <creator>property value </creator> <title>property value" /> A Simple Description <RDF> <Description about = "Some URI"> <creator>property value </creator> <title>property value 95 -733 Internet Technologies

      Resource Valued Property Mike Mc. Carthy 95 -733 Internet Technologies

      property value property value " src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-37.jpg" alt="Making Many Statements property value property value " /> Making Many Statements property value property value : : 95 -733 Internet Technologies

      Joe Smith [email protected] com" src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-38.jpg" alt="Blank Nodes Joe Smith [email protected] com" /> Blank Nodes Joe Smith [email protected] com 95 -733 Internet Technologies

      " src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-39.jpg" alt="XML Valued Property " /> XML Valued Property 95 -733 Internet Technologies

      A Type Property 95 -733 Internet Technologies

      property value " src="http://present5.com/presentation/e54774b46c3ae1d0314b0bb731c594b6/image-41.jpg" alt="An Abbreviated Type Property property value " /> An Abbreviated Type Property property value property value 95 -733 Internet Technologies

      RDF Notations • English • RDF XML • Abbreviated RDF XML • N-Triples • RDF Notations • English • RDF XML • Abbreviated RDF XML • N-Triples • Graph 95 -733 Internet Technologies

      Another RDF Application Composite Capabilities/Preference Profiles • The CC/PP working group was formed in Another RDF Application Composite Capabilities/Preference Profiles • The CC/PP working group was formed in August 1999. • Its mission was to develop an RDF-based framework for the management of device profile information. • Now under W 3 C’s Ubiquitous Web Applications Working Group (UWAWG) 95 -733 Internet Technologies

      An RDF Application CC/PP A composite capability/preference profile is a collection of information which An RDF Application CC/PP A composite capability/preference profile is a collection of information which describes the capabilities, hardware, system software and applications used by someone accessing the web. Information might include: • Preferred language (Spanish, French, etc. ) • Sound (on/off) • Images (on/off) • Class of device (phone, PC, printer, etc. ) • Screen size • Available bandwidth • Version of HTML supported, and so on. 95 -733 Internet Technologies

      Composite Capability/Preference Profiles (CC/PP) DEVICE PROFILE CC/PP RDF XML CC/PP provides the equivalent of Composite Capability/Preference Profiles (CC/PP) DEVICE PROFILE CC/PP RDF XML CC/PP provides the equivalent of database fields and associated model formalizing the device profiles RDF is language which provides a standard way for using XML to represent metadata in the form of properties and relationships of items on the Web. The device profile and user preferences might be stored in a CC/PP repository. CC/PP is in turn an RDF application. 95 -733 Internet Technologies

      Composite Capability/Preference Profiles (CC/PP) • The location of the device profile is sent with Composite Capability/Preference Profiles (CC/PP) • The location of the device profile is sent with a request for a Web page. • The CC/PP data is accessed and on the basis of the profile, a Web server can choose the right content. This might be a certain XHTML file or perhaps a suitable document would be generated on the fly. • A document on the server may refer to its own document profile-describing the required capabilities of its client. • The server might match and send or generate and send. 95 -733 Internet Technologies

      Each variant of the document has a document profile describing the browser support it Each variant of the document has a document profile describing the browser support it needs to display it DEVICE PROFILES DOCUMENT PROFILES NEGOTIATE CORRECT CONTENT FOR DEVICES If none of the document variants are suitable, existing document may be transformed by style sheet or tool for the purpose, or new document generated DEVICES RECEIVE RIGHT MARK-UP 95 -733 Internet Technologies

      Processing RDF in Java • • • XSLT? DOM? SAX? St. AX? Open source Processing RDF in Java • • • XSLT? DOM? SAX? St. AX? Open source Jena from HP Research provides another approach 95 -733 Internet Technologies

      Jena Example 1 // Modified from HP's Jena Tutorial // ~/mm 6/www/95 -733/examples/Jena import Jena Example 1 // Modified from HP's Jena Tutorial // ~/mm 6/www/95 -733/examples/Jena import com. hpl. jena. rdf. model. *; import com. hpl. jena. vocabulary. *; public class Tutorial 01 extends Object { // some definitions static String person. URI static String full. Name = "http: //somewhere/John. Smith"; = "John Smith"; 95 -733 Internet Technologies

      public static void main (String args[]) { // create an empty model (An empty public static void main (String args[]) { // create an empty model (An empty RDF graph) Model model = Model. Factory. create. Default. Model(); // create the resource Resource john. Smith = model. create. Resource(person. URI); // add the property john. Smith. add. Property(VCARD. FN, full. Name); model. write(System. out); } } 95 -733 Internet Technologies

      D: Mc. Carthywww95 -733examplesJena>java Tutorial 01 <rdf: RDF xmlns: rdf= D: Mc. Carthywww95 -733examplesJena>java Tutorial 01 John Smith 95 -733 Internet Technologies

      A Resource Valued Predicate // Modified from HP's Jena Tutorial import com. hpl. jena. A Resource Valued Predicate // Modified from HP's Jena Tutorial import com. hpl. jena. rdf. model. *; import com. hpl. jena. vocabulary. *; public class Tutorial 03 extends Object { public static void main (String args[]) { String person. URI = "http: //somewhere/John. Smith"; String given. Name = "John"; String family. Name = "Smith"; String full. Name = given. Name + " " + family. Name; // create an empty model Model model = Model. Factory. create. Default. Model(); 95 -733 Internet Technologies

      // create the resource // and add the properties cascading style Resource john. Smith // create the resource // and add the properties cascading style Resource john. Smith = model. create. Resource(person. URI). add. Property(VCARD. FN, full. Name). add. Property(VCARD. N, model. create. Resource(). add. Property(VCARD. Given, given. Name). add. Property(VCARD. Family, family. Name)) 95 -733 Internet Technologies

      // list the statements in the graph Stmt. Iterator iter = model. list. Statements(); // list the statements in the graph Stmt. Iterator iter = model. list. Statements(); // print out the predicate, subject and object of each statement while (iter. has. Next()) { Statement stmt = iter. next. Statement(); // get next statement Resource subject = stmt. get. Subject(); // get the subject Property predicate = stmt. get. Predicate(); // get the predicate RDFNode object = stmt. get. Object(); // get the object System. out. print(subject. to. String()); System. out. print(" " + predicate. to. String() + " "); 95 -733 Internet Technologies

      if (object instanceof Resource) { System. out. print(object. to. String()); } else { // if (object instanceof Resource) { System. out. print(object. to. String()); } else { // object is a literal System. out. print(" "" + object. to. String() + """); } System. out. println(". "); } // end while System. out. println("=========="); model. write(System. out); } } 95 -733 Internet Technologies

      D: Mc. Carthywww95 -733examplesJena>java Tutorial 03 16 fa 474: fd 074695 f 6: -8000 D: Mc. Carthywww95 -733examplesJena>java Tutorial 03 16 fa 474: fd 074695 f 6: -8000 http: //www. w 3. org/2001/vcard-rdf/3. 0#Given "John". http: //somewhere/John. Smith http: //www. w 3. org/2001/vcard-rdf/3. 0#FN "John Smith". 16 fa 474: fd 074695 f 6: -8000 http: //www. w 3. org/2001/vcard-rdf/3. 0#Family "Smith". http: //somewhere/John. Smith http: //www. w 3. org/2001/vcard-rdf/3. 0#N 16 fa 474: fd 074695 f 6: -8000. ========== 16 fa… is a blank node with family John and given Smith properties. The main resource has a blank node as the value John Smith of the N property. The main resource also has a FN property with a value. 95 -733 Internet Technologies

      Reading OWL with Jena import com. hpl. jena. rdf. model. *; import com. hpl. Reading OWL with Jena import com. hpl. jena. rdf. model. *; import com. hpl. jena. ontology. *; import java. io. *; import java. net. *; public class Read. Wine. Ontology extends Object { public static void main (String args[]) throws Exception { // create an empty model Ont. Model model = Model. Factory. create. Ontology. Model(); 95 -733 Internet Technologies

      // read the wine. xml file either way model. read( // read the wine. xml file either way model. read("file: D: /Mc. Carthy/www/95 -733/examples/Jena/wine. xml"); //model. read("http: //www. andrew. cmu. edu/user/mm 6/ontology/wine. xml"); // write it to standard out model. write(System. out); } } The next step is to use Jena to make or verify deductions. 95 -733 Internet Technologies

      The Semantic Web These notes are from an article entitled “The Semantic Web” by The Semantic Web These notes are from an article entitled “The Semantic Web” by Tim Berners-Lee, James Hendler and Ora Lassila appearing in Scientific American, May 2001 By augmenting web pages with data directed at computers and by adding documents solely for computers, we will transform the web into the Semantic Web. Intuitive software will be developed that will allow anyone to create Semantic Web Pages. For the semantic web to function, computers must have access to structured collections of information and sets of inference rules that can be used to conduct automated reasoning. XML has no built-in mechanism to convey the meaning of the user’s new tags to other users. 95 -733 Internet Technologies

      The Semantic Web The challenge of the Semantic Web is to provide a language The Semantic Web The challenge of the Semantic Web is to provide a language that expresses both data and rules for reasoning about the data and that allows rules from an existing knowledge-representation system to be exported unto the Web. Ontologies: Collections of statements written in a language such as RDF that define the relations between concepts and specify logical rules for reasoning about them. Computers will “understand” the meaning of semantic data on a web page by following links to specified ontologies. Consider the statement “a hex-head bolt is a type of machine bolt”. We could encode this in RDF. When writing code against traditional XML data, the programmer must know what the document author uses each tag for. Meaning is expressed by RDF, which encodes it in a set of triples. 95 -733 Internet Technologies

      The Semantic Web An RDF document makes assertions that particular things (people, web pages, The Semantic Web An RDF document makes assertions that particular things (people, web pages, or whatever) have properties (such as “is sister of”, “is the author of”) with certain values (another person, another Web page). We can remove ambiguity by associating each of the three parts with a URI. For example: “(filed 5 in database A) (is a field of type) (zip code)” could be replaced with three URI’s. An ontology is a document or file that formally defines the relations among terms. An ontology may express a rule “If a city code is associated with a state code, and an address uses that city code, then that address has the associated state code. ” A program can then draw conclusions. The meaning of terms or XML codes can be defined by pointers from the page to an ontology. 95 -733 Internet Technologies

      The Semantic Web Many automated web based services already exist without semantics, but other The Semantic Web Many automated web based services already exist without semantics, but other programs such as agents have no way to locate one that will perform a specific function. Service Discovery will happen only when there is a common language to describe a service in a way that lets other agents “understand” both the function offered and how to take advantage of it. Services can advertise their functions in directories analogous to the Yellow Pages. Devices can advertise their abilities with RDF. 95 -733 Internet Technologies