All you should know about Semantic Web as an app developer

I have basic technical knowledge. Tell me what the Semantic Web is.

The Semantic Web is a vision, that hopes to join together dispersed bits of data on the internet, very much like web pages are currently joined (linked) together. As with the current web of pages, anyone can create data on the Semantic Web, and anyone can “join” one bit of data to another.

Data isn’t forced into using a specific structure (like web pages are with HTML), so the data can be about anything; people, weather, books, movies, currency exchange rates or the distribution of geese in Europe.

Put simply, it’s like installing a huge relational database on the internet, where anyone can add tables to the database, and anyone can add data to a table. Tables and data can map to one another if you want, like foreign and primary keys.

Note that the Semantic Web (capital S, capital W) is often differentiated from the semantic web (small s, small w), which is basically a smaller-scale vision of making the current web more ’semantic’ (e.g. marking-up the ‘meaning’ of words on a page, rather than how they should look).

What’s the point of that?

If you’ve ever used a relational database — such as MySQL or SQL Server — you’ll know how useful they are, which is why relational databases are used ‘behind the scenes’ on most websites today. By storing distinct data-sets that inter-relate (for example, books, authors, and sales), you can very quickly find data that matches certain rules, such as books by a particular author, the top five best selling books, or top five best selling authors. Although each data-set can be maintained separately, they become increasingly powerful as they are joined together.

Imagine the possibilities if these data-sets were not just inter-related inside one database, but each database in the world was also inter-related. The authors table from a bookstore could be mapped to a birth records table in a government department (so, for example, you could get top five best selling books by nationality of the author). A historical database of world conflict could then be included to show the top five best selling books by authors who had been born in a country during time of war. And so on.

By treating the many large sets of data on the web as a single database, we’ll be able to create some incredibly powerful and valuable tools. The current trend of ‘mash-ups’ goes some way towards exploring this idea (usually mixing the data from only two data sets).

Read more at O'Reilly XML.com