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RDFa, Microformats, RDFa, Microformats, and Atom and Atom Semantic Web Presented by: Anuradha Kandula Instructor: Steven Seida
RDFa, Microformats, and RDFa, Microformats, and AtomAtomSemantic Web
Presented by: Anuradha Kandula
Instructor: Steven Seida
BackgroundBackgroundWhy do we need semantic
markup?
To an English-speaking person, the same information could be represented as:
“The title of this resource, published by Wikipedia, is ‘Tony Benn’ ”
The purpose of RDF is to provide an encoding and interpretation mechanism so that resources can be described in a way that particular software can understand it
RDFaRDFaRDFa (or Resource Description
Framework - in - attributes) is a W3C Recommendation that adds a set of attribute level extensions to XHTML for embedding rich metadata within Web documents.
EssenceEssenceThe essence of RDFa is to
provide a set of attributes that can be used to carry metadata in an XML language (hence the 'a' in RDFa).
These attributes are:
o about – a URI or CURIE specifying the resource the metadata is about; in its absence it defaults to the current document
Essence (cont.)Essence (cont.)
o rel and rev – specifying a relationship or reverse-relationship with another resource
o href, src and resource – specifying the partner resource
o property – specifying a property for the content of an element
o content – optional attribute that overrides the content of the element when using the property attribute
o datatype – optional attribute that specifies the datatype of text specified for use with the property attribute
o typeof – optional attribute that specifies the RDF type(s) of the subject (the resource that the metadata is about).
Examples of RDFaExamples of RDFa(FOAF profile using RDFa)(FOAF profile using RDFa)
1.<html xmlns:foaf="http://xmlns.com/foaf/0.1/">2. <head>3. <title>Mark Birbeck's profile</title>4. <link rel="foaf:primaryTopic foaf:maker" href="#me"/>5. </head>6. <body>7. <div about=“#me" typeof=foaf:Person">8. <span property="foaf:name">"Mark Birbeck</span>9. <a rel="foaf:weblog" href="http://internet-apps.blogspot.com/">XForms and Internet Applications</a>10. <a rel="foaf:knows" href="http://www.w3.org/People/Ivan/#me">Ivan Herman</a>11. <span rel="foaf:img">12. <img src="http://www.formsplayer.com/files/pictures/picture-11.jpg"/>13. </span> 14. <span rel="foaf:holdsAccount">15. <span typeof="foaf:OnlineAccount">16. <a rel="foaf:accountServiceHomepage" ref="http://twitter.com/">Twitter</a>17. <span property="foaf:accountName">markbirbeck</span>18. </span>19. </span>20. </div>21. </body>22.</html>
Publisher Independence - each site can use its own standards
Data Reuse - data is not duplicated. Separate XML and HTML sections are not required for the same content.
Schema Modularity - The attributes are reusable
Benefits of RDFaBenefits of RDFa
Evolvability - additional fields can be added and XML transforms can extract the semantics of the data from an XHTML file
MicroformatMicroformatA microformat is a web-based
approach to semantic markup that seeks to re-use existing XHTML and HTML tags to convey metadata and other attributes. This approach allows information intended for end-users (such as contact information, geographic coordinates, calendar events, and the like) to also be automatically processed by software.
Designed for humans first and machines second, microformats are a set of simple, open data formats built upon existing and widely adopted standards. Instead of throwing away what works today, microformats intend to solve simpler problems first by adapting to current behaviors and usage patterns (e.g. XHTML, blogging).
The microformats The microformats principlesprinciplesSolve a specific problemStart as simple as possibleDesign for humans first, machines
second Reuse building blocks from widely
adopted standardsModularity / embeddabilityEnable and encourage decentralized
development, content, services
hCard microformat hCard microformat markupmarkup
Browser supportBrowser supportOperator for FirefoxOomph for Internet ExplorerhCard exported to formats
compatible with contact management
hCalendar exported to formats compatible with calander utilities
geographical coordinates to Google Maps
AtomAtomAtom is an XML-based document format
that describes lists of related information known as "feeds". Feeds are composed of a number of items, known as "entries", each with an extensible set of attached metadata. For example, each entry has a title.
The primary use case that Atom addresses is the syndication of Web content such as weblogs and news headlines to Web sites as well as directly to user agents.
Atom is a simple way to read and write information on the web, allowing you to easily keep track of more sites in less time, and to seamlessly share your words and ideas by publishing to the web.
Web feeds allow software programs to check for updates published on a website. To provide a web feed, a site owner may use specialized software (such as a content management system) that publishes a list (or "feed") of recent articles or content in a standardized, machine-readable format.
A feed contains entries, which may be headlines, full-text articles, excerpts, summaries, and/or links to content on a website, along with various metadata.
UsageUsage Web feeds are used by the blogging
community to share recent entries' headlines, full text, and even attached multimedia files. These providers allow other websites to incorporate the blog's "syndicated" headline or headline-and-short-summary feeds under various usage agreements. Atom and other web syndication formats are now used for many purposes, including journalism, marketing, bug-reports, or any other activity involving periodic updates or publications. Atom also provides a standard way to export an entire blog, or parts of it, for backup or for importing into other blogging systems.
It is common to find web feeds on major Web sites, as well as many smaller ones. Some websites let people choose between RSS or Atom formatted web feeds; others offer only RSS or only Atom. In particular, many blog and wiki sites offer their web feeds in the Atom format.
Feed readerFeed reader
A feed reader or "aggregator" program can be used to check feeds and display new articles. Client-side readers may also be designed as standalone programs or as extensions to existing programs like web browsers. Browsers are moving toward integrated feed reader functions.
Single-entry Atom Feed Single-entry Atom Feed DocumentDocument<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title>Example Feed</title>
<link href="http://example.org/"/>
<updated>2003-12-13T18:30:02Z</updated>
<author>
<name>John Doe</name>
</author>
<id>urn:uuid:60a76c80-d399-11d9-b93C-0003939e0af6</id>
<entry>
<title>Atom-Powered Robots Run Amok</title>
<link href="http://example.org/2003/12/13/atom03"/>
<id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
<updated>2003-12-13T18:30:02Z</updated>
<summary>Some text.</summary>
</entry>
</feed>
The "atom:feed" ElementThe "atom:feed" Element atom:feed elements MUST contain one or more
atom:author elements, unless all of the atom:feed element's child atom:entry elements contain at least one atom:author element.
atom:feed elements MAY contain any number of atom:category elements.
atom:feed elements MAY contain any number of atom:contributor elements.
atom:feed elements MUST NOT contain more than one atom:generator element.
atom:feed elements MUST NOT contain more than one atom:icon element.
atom:feed elements MUST NOT contain more than one atom:logo element.
atom:feed elements MUST contain exactly one atom:id element.
More information on atoms at:
http://www.ietf.org/rfc/rfc4287
Queries?
Thank You !
