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The web is getting better and better. Search is getting
smarter. Google's 'rich snippets' and Facebook's Open Graph Protocol are great
examples of how the industry is helping web developers make their
content more machine-readable. Industry-standard
'vocabularies' like FOAF, Dublin Core Terms, Good Relations, and
Schema.org are helping developers ensure that their content just
makes sense. And all of those technologies are based largely upon,
and designed to support other technologies that use, RDF.
What is RDF? RDF stands for "Resource Description Framework",
and an excellent overview of it is in the RDF Primer
the W3C has published. If you don't want to dig that deeply,
just know that RDF is a method for describing in a very standard
way the relationship between x and y. Moreover, it can also
describe the relationship between y and z. And so on and so
on, until you get all the way down to some well-known, standardized
'term' that has absolute meaning to something like the Google
search engine.
How is this useful? Well, it means in part that I can say
something like "Shane McCarron is the author of this article".
And, because the concept of an author is a well-known,
standardized 'term' that has an absolute meaning, and because this
article has a permanent URI, anything that can understand RDF will
immediately *know* this. Further, if I also say "Shane
McCarron" is identified by some other URI (e.g.,
http://blog.halindrome.com) RDF-aware processors will automatically
associate the author with that URI.
That's all great, I hear you saying. But how do I, as a web
developer, *tell* Google things about my web pages? Enter
RDFa. RDFa stands for "RDF in attributes" (some people might
argue about that, but I was in the room and that's what I
remember). It is a way to embed RDF information right into
your web page in a pretty straightforward way. And, if you do
it right, it means that search engines like Google and Facebook
will know *more* about your web site and its information than they
will know about your less-savvy competitors who don't bother to put
this data in.
There are a lot of great resources out on the web that can help you
get your annotations right. I have included a list of some at
the end of this article. However, just to get you started,
here is a simple example.
Let's say you have a picture you want to include on your web site.
You want people to be able to use that picture, but you want
them to know what it is a picture of and who took it. You
could say something like:
<span about="#myPicture">
<img id="myPicture"
alt="Cabin on the lake"
src="http://www.example.com/images/picture.png">
<span property="dc:title">Cabin on the lake</span>
by
<span property="dc:creator">Shane
McCarron</span>
</span>
In that example we use terms from the
"Dublin Core" vocabulary. These are well-known terms.
Any knowledge engine will know exactly what you are talking
about. If you wanted to be more explicit about who the
creator was, you might extend that definition like:
<span about="#myPicture">
<img id="myPicture"
alt="Cabin on the lake"
src="http://www.example.com/images/picture.png">
<span property="dc:title">Cabin on the lake</span>
by
<span rel="dc:creator"
typeof="foaf:Person">
<span rel="foaf:homepage"
href="http://blog.halindrome.com"
property="foaf:name">Shane
McCarron</span>
</span>
</span>
Now we have also
mixed in some terms from the "Friend of a Friend" vocabulary to say
that the dc:creator we talked about before is a "Person" who has a
"homepage" and a "name". These are also well-known terms and
will help the knowledge engines make better inferences about who
"Shane McCarron" is. If there are other things out there for
which a 'foaf:Person' with those attributes is listed as the
'dc:creator', they were likely created by the same "Shane
McCarron".
There are LOTS of ways to use RDFa in your
web pages and articles. I plan to write more on this in the
coming weeks. For now, here are some resources that can help
you get started.
General information on RDFa at http://rdfa.info/
The RDFa Primer
An interactive checker at http://rdfa.info/play/
Google's checker at http://www.google.com/webmasters/tools/richsnippets
Help for creating licenses at http://creativecommons.org/choose/
Information on vocabularies at http://www.schema.org/
Next up: How the W3C is using RDFa to help ensure its own documents
are well annotated.
RDFa
is (still) the best way to improve your SEO by Shane McCarron
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