How do I see the semantic data for a URL?

Question

Let's say I have an URL for a website. How do I see if there is semantic content (FOAF, RDF, etc) associated? And what the URLs for these are?

I just installed Semantic Radar, a Firefox plugin that will notify of semantic content for a website. E.g. if I go to http://sioc-project.org/firefox in Firefox, it tells me that there that there is some semantic data available and shows their links.

But how does Semantic Radar get to know about this semantic data?

Answer 1

Well, looking for .rdf links within the contents of a given .html page should not be very difficult. For more info: http://www.w3.org/TR/rdf-syntax-grammar/#section-rdf-in-HTML

On the other hand, it is also possible to directly embed RDF encoded semantic data into an HTML page by using RDFa standard: http://en.wikipedia.org/wiki/RDFa. This means a tool can use this information to extract semantic data (and then use this to probably indicate links to other sources of semantic data).

Answer 2

To complete Emre answer, this is the RFDa standard : http://www.w3.org/TR/rdfa-syntax/