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Semantic Microformats. Uche Ogbuji. [email protected]. About the presenter. XML expert since 1997 RDF/Semantic Web expert since 1999 Web services/SOA expert since 1999 Heavy work with XML and RDF/SemWeb/SOA best practices Lead developer of key open specs and OSS, e.g. - PowerPoint PPT Presentation
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Semantic MicroformatsSemantic Microformats
Uche OgbujiUche [email protected]@zepheira.com
About the presenterAbout the presenter
XML expert since 1997
RDF/Semantic Web expert since 1999
Web services/SOA expert since 1999
Heavy work with XML and RDF/SemWeb/SOA best practices
Lead developer of key open specs and OSS, e.g.
Versa RDF query language
4Suite XML/RDF processing toolkit
Amara XML toolkit
XML expert since 1997
RDF/Semantic Web expert since 1999
Web services/SOA expert since 1999
Heavy work with XML and RDF/SemWeb/SOA best practices
Lead developer of key open specs and OSS, e.g.
Versa RDF query language
4Suite XML/RDF processing toolkit
Amara XML toolkit
About Zepheira, LLCAbout Zepheira, LLC
Firm offering Semantic technologies solutions bridging technology and business
Team of leaders in next generation Web technology and business applications
Founded in 2007, already featured in MIT Tech Review and BusinessWeek
If you see me in the halls later, ask me about “Zepheira 3D”
Firm offering Semantic technologies solutions bridging technology and business
Team of leaders in next generation Web technology and business applications
Founded in 2007, already featured in MIT Tech Review and BusinessWeek
If you see me in the halls later, ask me about “Zepheira 3D”
AgendaAgenda
A brief intro to microformatsThe basic concepts
The Good, the bad and the ugly
Bringing Semantic Technology to microformatsSemantic transparency
GRDDL
Leapfrogging microformats altogetherXML or even JSON with Semantic schema
RDF/A
A brief intro to microformatsThe basic concepts
The Good, the bad and the ugly
Bringing Semantic Technology to microformatsSemantic transparency
GRDDL
Leapfrogging microformats altogetherXML or even JSON with Semantic schema
RDF/A
A brief intro to microformatsA brief intro to microformats
In their own words...In their own words...
“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”
—microformats.org
Basic ideaBasic idea
Start with a base schema such as XHTML, or Atom
Define specialized variations
Conventions for use of, say, attribute values already defined by the base schema
Modest set of extensions to the base schema
Start with a base schema such as XHTML, or Atom
Define specialized variations
Conventions for use of, say, attribute values already defined by the base schema
Modest set of extensions to the base schema
Embed minor, specialized variations within established vocabularies
It’s just JargonIt’s just Jargon
Jargon is not inventing a completely new language
Start with an existing language
Come up with variations: specialized syntax or specialized vocabulary (mostly the latter)
Establishing and propagating conventions in the language variation
Formal terms and definitions (professional glossaries)
Informally shared trends
Jargon is not inventing a completely new language
Start with an existing language
Come up with variations: specialized syntax or specialized vocabulary (mostly the latter)
Establishing and propagating conventions in the language variation
Formal terms and definitions (professional glossaries)
Informally shared trends
Elemental microformat examples
Elemental microformat examples
<p>Nice blog. Buy your medz <a href='http://medz.com' rel='nofollow'>here</a></p>
<div class='blogroll'>
<a href="http://chimezie.ogbuji.net/" rel="brother met">Chimezie</a>
</div>
<p>We decided not to implement <a rev="vote-against" href="http://www.w3.org/TR/xquery/" title="way too complex">XQuery</a>...</p>
Compound microformat example
Compound microformat example
<ol class='xoxo'> <li>Subject 1 <ol> <li>subpoint a</li> <li>subpoint b</li> </ol> </li> <li>Subject 2 <ol compact="compact"> <li>subpoint c</li> <li>subpoint d</li> </ol> </li></ol>
XOXO is a microformat for “outline”, which can be anything from “Blogrolls” to presentations
A seriously mixed bagA seriously mixed bag
The good: Rough consensus is good, even for minor syntactic details
The bad: It’s very easy for microformats to clash, because of the lack of Semantic grounding (yes, this is biting people in practice already)
The ugly: Putting it bluntly, have you ever seen an format as horrid as XOXO? That’s what you get when you try to tunnel one set of semantics into another.
(OK granted OPML might be even uglier, but we can create a far more humane format)Note: XOXO was inspired by desire to avoid the horrid macro-format OPML
The Ugly: Absurd markup indirection
The Ugly: Absurd markup indirection
A condition where the attempt to fit a microformat into a host leads to unnaturally indirect markup design
<product> <property> <name>ID</name> <value>xyz123</value> </property></product>
<element tagname='description'> My favorite Weblog</element>
<dl> <dt>description</dt> <dd>My favorite Weblog</dd></dl>
<product xml:id='xyz123'> <name>Widget wonder</name></product>
<description> My favorite Weblog<description>
What to do about the uglyWhat to do about the ugly
Elemental microformats minimize syntactic footprint, and are thus harmless.
Most compound microformats are hopeless cases. In almost all cases its better to Just Use XML.
Who needs hAtom when Atom does the trick, and is thriving?
XBEL is a more humane alternative to XOXO (and even OPML)
BTW “Ugly” is not a negligible problem. Form is Function.
The bad: Semantic wafflingThe bad: Semantic waffling
Microformats have to in effect steal and re-purpose the host format’s Semantics
Some formats make somewhat dodgy use of host language constructs (e.g. a/@rev in vote-links)
Few microformats have even reasonable syntactic schema, let alone semantic
Microformats have to in effect steal and re-purpose the host format’s Semantics
Some formats make somewhat dodgy use of host language constructs (e.g. a/@rev in vote-links)
Few microformats have even reasonable syntactic schema, let alone semantic
Note: Schematron is a great schema language for the likes of microformats, and even for their semantics. Ask me later about Schematron Abstract Patterns
Microformat profilesMicroformat profiles
Microformat advocates have taken a stab at alleviating the “bad” by specifying a “profile” link from the source document to a description of the microformat.
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"> <head profile="http://gmpg.org/xfn/11"> <title>Sample document</title> </head>
XMDP for microformat profiles
XMDP for microformat profiles
Microformats descriptions were originally ad-hoc Wiki pages. Profiles movement has defined a super-simple format based on a subset of XHTML.Called XHTML Meta Data Profile (XMDP)
Example Web view of XMDP
What else to do about the badWhat else to do about the bad
XMDP is all about prose description, and is very non-formal
We can do so much better
Bringing Semantic Technology to microformatsBringing Semantic Technology to microformats
Beyond syntaxBeyond syntax
We know that XML is a useful alphabet, but a library of XML needs a reference section for true advancement
That’s what we’re all at this conference to talk about, right?
Microformats need a reference section even more badly, because they often turn simple alphabets into arcane substitution ciphers
Θe quik βroυν φox jυμπσ oveρ θe λειζy δoγ
Semantic transparencySemantic transparency
Semantic transparency is the ability to share context between systems by accessing resources that can be automatically located from the syntax.
Microformats seek to share context, but in their basic form do not offer the tools for context sharing.
Semantic transparency would add value and longevity to documents using microformats.
Just use RDF?Just use RDF?
RDF does provide for semantic transparency, unlike XML, or microformats. It has very formalized semantic expressiveness, and healthy support in tools and standards
We could just advocate standardizing on RDF representations of such rich data.
Let’s get realLet’s get real
RDF/XML’s syntax is awkward, especially for the sorts of prose/narrative documents that serve as host to microformats
RDF is not popular with many in the XML and Web 2.0 world; this “political” battle distracts from getting useful work done
Practical meetingPractical meeting
Time is finally right for a practical meeting of XML and RDF technology I’ve been personally advocating for seven years
Why not use syntax transform technology to extract Semantic details from whatever conventions we can identify in XML and microformats?
Enter GRDDLEnter GRDDL
W3C draft for using transforms such as XSLT to convert XML to RDF
General conventions for associating XML languages with GRDDL transforms
Piggy-backs off microformats profiles
Rather than XMDP the profile link is to a XHTML page with embedded RDF
You would add transforms to the base GRRDL profile for the host language
W3C draft for using transforms such as XSLT to convert XML to RDF
General conventions for associating XML languages with GRDDL transforms
Piggy-backs off microformats profiles
Rather than XMDP the profile link is to a XHTML page with embedded RDF
You would add transforms to the base GRRDL profile for the host language
Pronounced “Griddle”
Short for “Gleaning Resource Descriptions from Dialects of Languages”
Dublin Core/RDF from XHTMLDublin Core/RDF from XHTML
Part of a theoretical script, dc-from-xhtml.xslt, for generating Dublin Core in RDF/XML from XHTML metadata
W3C hosts a very convoluted implementation of this: dc-extract.xsl
...<xsl:template match='xhtml:title'> <dc:title><xsl:apply-templates/></dc:title></xsl:template>...
XHTML GRDDL profileXHTML GRDDL profile
grrdl-example.xhtml
<html xmlns="http://www.w3.org/1999/xhtml"> <head profile="http://www.w3.org/2003/g/data-view"> <title>Some Document</title> <link rel="transformation" href="http://www.w3.org/2000/06/dc-extract/dc-extract.xsl" />
<meta name="DC.Subject" content="ADAM; Simple Search; Index+; prototype" /> ... </head> ...</html>
RDF/XML resultRDF/XML result
<rdf:RDF xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" > <rdf:Description rdf:about=""> <dc:title>Some Document</dc:title> </rdf:Description></rdf:RDF>
Using GRDDL with microformats
Using GRDDL with microformats
grrdl-xfn-example.xhtml
GRDDL in practiceGRDDL in practice
The main implementation is a Firefox “GreaseMonkey” script
microcontentextractor.user.js applies GRDDL profiles and builds an aggregated model for the user
GRDDL does provide a way of increasing the formality of microformat models, an important step towards semantic transparency
With GRDDL in place the microformats buzz at least offers Webmasters an rough and ready path toward Semantic technology
The main implementation is a Firefox “GreaseMonkey” script
microcontentextractor.user.js applies GRDDL profiles and builds an aggregated model for the user
GRDDL does provide a way of increasing the formality of microformat models, an important step towards semantic transparency
With GRDDL in place the microformats buzz at least offers Webmasters an rough and ready path toward Semantic technology
Leapfrogging microformats altogetherLeapfrogging microformats altogether
Just use XML (or JSON or...)Just use XML (or JSON or...)
Blogroll example in plain XML (compare XOXO)
Blogroll example in plain JSON
<folder> <title>Technology</title> <weblog href="http://weblog.foo"> <title>Example Weblog</title> <webfeed href="http://weblog.foo/atom" type="application/atom+xml"/> <description>That good ole Weblog</description> </weblog></folder>
[ {"blog": "http://example.com/bud/", "feed": "http://example.com/bud/atom", "description": "My buddy's Weblog", "tags": ["buddy"] } ]
Not as ugly, but just as bad, right?
Not as ugly, but just as bad, right?
Semantic technology advocates need to do a better job of building on plain old XML. GRDDL is a good first step, but more is needed.This is my primary space of professional interest.
Again: if you see me later, ask me about Schematron Abstract Patterns
As for JSON. Work is just starting, but let’s not forget the XML lesson:
Collaborate rather than compete with emerging syntax.
RDF/ARDF/A
RDF/A is a system for embedding triples right into documents using ideas similar to microformats.
It eliminates the extra transform step required by GRDDL for extracting RDF
Note: RDF/A predates both microformats and GRDDL
rel-license microformat example
rel-license microformat example
rel-license is a microformat for providing a link specifically to the license for the source document.
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Some Document</title> </head> <body> ... <p>This document is licensed under a<a rel="license" href="http://creativecommons.org/licenses/by-nc/2.5/"> Creative Commons Non-Commercial License</a>. </p> ... </body></html>
RDF/A license exampleRDF/A license example
In RDF/A you would repurpose an existing RDF vocabulary for a license relationship, and just embed this into the host document
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:cc="http://creativecommons.org/licenses/"> <head> <title>Some Document</title> </head> <body> ... <p>This document is licensed under a<a rel="cc:license" href="http://creativecommons.org/licenses/by-nc/2.5/"> Creative Commons Non-Commercial License</a>. </p> ... </body></html>Yes, QNames in content stink, but they’re all over the XML and RDF worlds
Advantage RDF/A?Advantage RDF/A?
Qualification of the license relationship provides for discovery and semantic precision. The namespace can be treated as a link and dereferenced for discovery and hence Semantic transparency.
That fixes the “bad”, but RDF/A is no help with the “ugly”. Stretching RDF to fit an XHTML skeleton gets grungy in a hurry.
Note: RDF/A is not the same as the Talis “RDF in HTML” system used in the GRDDL profile document. Yeah, we need to get our act together, folks.
ResourcesResources
Microformats Microformats homehome http://microformats.org
““Thinking XML” Thinking XML” columncolumn http://uche.ogbuji.net/tech/publications/thinkingxml
““Perspective on Perspective on XML” columnXML” column http://www.adtmag.com/article.asp?id=8515
GRDDLGRDDL http://www.w3.org/2001/sw/grddl-wg/
““Microformats in Microformats in Context”Context” http://www.xml.com/pub/a/2006/04/26/microformats-grddl-rdfa-
nvdl.html
XMDPXMDP http://gmpg.org/xmdp/
More fun linksMore fun links
http://dannyayers.com/archives/2005/08/01/microformats-on-the-grddl/
http://copia.ogbuji.net/blog/2005-11-16/Does_it_co
http://copia.ogbuji.net/blog/2007-05-21/planetatom-information-pipeline
http://www.oasis-open.org/cover/xmlAndSemantics.html
http://theryanking.com/blog/archives/2005/06/10/wordpress-kubrick-hreview-trouble/http://theryanking.com/blog/archives/2005/06/10/wordpress-kubrick-hreview-trouble/