Certainly there are niche applications, in taxonomy design for example, but there is no tidal wave of change. Search is the application with most to gain from semantics (because it enables rich snippets), but the major search engines have abandoned RDF in favor of simpler, easier to use technology.

So, what does this mean for publishers? Firstly, semantics are still vitally important – it’s still critical to produce high quality content and metadata. There is no substitute for building a carefully designed XML workflow. This will ensure that semantic markup and metadata can be delivered to search engines and other downstream partners effectively. This also ensures you have the necessary foundation for maximum usability and discoverability for users within your site.

But it also means that we can lay to rest many of the technical questions around RDF, triples, inference engines, OWL and other esoterica. There are some parts of the semantic technology stack that I think are still very interesting and I’ll be talking about these more in a future post. But for now it clear that XML workflows will deliver what you need to participate fully in the the ecology of search. And henceforth we can lay to rest the Web 3.0 which never happened.

Whilst I agree that structure in metadata is important, the complexity of RDF/OWL and triple stores severely limit their utility. The challenges of handling big data have created market opportunities and growth for new breeds of NoSQL data stores. Like triple stores these technologies offer structured, accepting, flexible data models. Unlike triple stores these technologies have practical utility and are easy to implement. [in reply to a comment]

You’re quite mistaken in characterising XML as just an interchange format – it is a data model capable of more expressiveness (think full text/mixed content) than RDF. You must realise this is true since RDF itself can be encoded in XML.

I agree: semantics on the web are alive and well in works such as schema.org. Also wolfram alpha remains very interesting, although I am less convinced of the sustainability of their business model.

RDF and triple stores are still research projects. Without production ready solutions to authentication, provenance, access control, etc these systems are not ready for the big time yet. And the astronaut-grade musings on inference, OWL, description logics etc will mean that these technologies will not gain easy acceptance amongst the majority of developers.

Schema.org in the meantime will provide an easily implemented route to semantics which plays well with both Google and Bing.

The era passed with the recent announcement by Google, Yahoo and Microsoft of the launch of schema.org. Schema.org provides technical documentation on the ways in which the major search engines will recognize structured data in your web pages. It shows how to get rich snippets of content and data from your site directly into search engine results pages. Rich snippets are the next step in the evolution of search, because they allow search engines to read meaningful semantics into content on the web.

If rich snippets sound surprisingly like an application of the semantic web, then it’s for good reason. A huge amount of time and effort has gone into researching how to add layers of machine-readable information to the human-readable web, with the grand view that the machine-readable web would always underpin a new wave of disruptive innovation. Web 3.0 would be the next big thing.

However, Google et al. have chosen not to base the next big thing in search, rich snippets, or semantic web technology. Schema.org eschews RDFa in favor of simpler HTML5 markup.

For years semantic web purists have been preaching that the future is all about RDF and triples. Yet, in the 12 years that theorists have been working on the semantic web, we’ve yet to see many convincing practical uses for the technology. The graph I’ve included above shows the rise and fall of Web 2.0 job postings compared to job posts requiring semantic web technologies. This makes a pretty clear case that the semantic web simply never took off.