On 11/11/11 8:04 AM, John F. Sowa wrote:
In an earlier note, I claimed that
JFS
Twitter, Facebook, and LinkedIn have
huge graph databases, but none of them use RDF.
And I received an offline reply:
Anonymous
I was under the impression that Facebook's OpenGraph is based on RDFa
(http://ogp.me/)
[OGP wrote] To turn your web pages into graph objects, you need to
add basic metadata to your page. We've based the initial version of
the protocol on RDFa <http://en.wikipedia.org/wiki/RDFa>...
As I have said many times, the only relationship between RDF and RDFa
is in the three letters R D F. If you follow that pointer to ogp.me,
you'll find the following example in HTML.
OGP
John,
Facebook support and publish Linked Data. Of course, Linked Data !=
RDF (and its family of syntaxes and serialization formats) as sole
implementation mechanism.
Facebook does publish Linked Data using both JSON and Turtle (a
syntax and serialization format from the RDF family).
I explained Facebook's approach to Linked Data in an old post [1]
published a month or so ago.
<html prefix="og: http://ogp.me/ns#">
<head>
<title>The Rock (1996)</title>
<meta property="og:title" content="The Rock" />
<meta property="og:type" content="video.movie" />
<meta property="og:url" content="http://www.imdb.com/title/tt0117500/" />
<meta property="og:image" content="http://ia.media-imdb.com/images/rock.jpg" />
...
</head>
...
</html>
Just above that example is the following explanation:
OGP
The four required properties for every page are:
og:title - The title of your object as it should appear within the graph.
og:type - The type of your object, e.g., "video.movie".
og:image - An image URL which should represent your object within the graph.
og:url - The canonical URL of your object that will be used as its permanent ID
Given that explanation, you could write a program in _javascript_
or any other language to generate JSON, CLIF, CGIF, or SQL.
If you follow the links in the following URLs, you'll find that
the native language for the Facebook API is JSON.
Yes. They publish Linked Data by default using JSON. Their graphs
are fine-grained and follow-your-nose friendly, subject to OAuth
based access controls which are scoped to personal social graphs.
Anonymous
Indeed, these two posts
http://lists.w3.org/Archives/Public/public-lod/2011Oct/0032.html
http://www.readwriteweb.com/archives/w3c_pleased_with_semantic_web_adoption.php
seem to indicate that they are using some version of RDFs and RDFa.
Note that those are W3C web sites, which follow the party line.
When a project X is failing, management will resort to CYA measures.
A typical response is to rename something successful with the name X
so that they can tell the board of directors and the investors that
the money poured into X was not wasted.
In this case, they took a minor extension to HTML and called it RDFa.
Then they used RDFS to specify a mapping to RDF. But nobody actually
uses that mapping to RDF. What they use is JSON, which is a subset
of _javascript_ that the W3C could have adopted 15 years ago.
Syntax agnostic Linked Data is the way forward. Which is why its
wrong to conflate Linked Data (a concept) and RDF (syntax).
Hopefully, the W3C will come to understand this critical fact.
Links:
1. http://goo.gl/y7Gq4 --
What Facebook Can Teach Us about Bootstrapping Linked Data at
InterWeb Scales
2. http://goo.gl/tyqyM -- note about distributed data
objects
3. http://goo.gl/Ez3CC -- note about data objects
.
John
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