Three easy ways to get into the Semantic Web

So, you’ve been curious about this whole Semantic Web thing. Perhaps you would like search engines to put useful things up next to your links when someone searches for you. Maybe you’re interested by the possibility that smart bots could track down information from across the web via Linked Data to provide Internet users with the most up-to-date information possible from its original source.

Whatever the reason — getting started with the Semantic Web is a mental stretch. Thankfully, there are ways to make your information useful to machines without needing to know OWL, ontology or the rest of the jargon. Each of these three methods simply extends the HTML code that you already know.

RSS

RSS feeds have always been sematically great. In fact, by using RSS, you’re publishing your content as RDF, the Resource Description Framework. RDF is the main way that machines resolve resources’ ambiguity. They use URIs to do that. There are many Tims in the world, but only one lives at timmcnamara.co.nz.

Open Graph Protocol

The Open Graph Protocol is a way to get your data to completely simplify everything. Pushed by Facebook, it’s bound to get a greater following in the months to come as it’s simplicity to implement. One of the problems it immediately resolves is displaying your information correctly when it is shared on Facebook.

Take a look at this HTML snippet, representing the move The Rock:

<html xmlns:og="http://ogp.me/ns#">
<head>
  <title>The Rock (1996)</title>
  <meta property="og:title" content="The Rock" />
  <meta property="og:type" content="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>

What we’ve done here is define an og namespace, and then use it within meta tags. Pretty simple. Facebook has done something great here, making <meta> tags is now one of the easiest ways to get started with the Semantic Web.

Common Tag

Common Tag is an effort to make data able to be included into massive Linked Data stores, such as Freebase. It focuses specifically on tagging content. That is, for authors to add categories and topics to their content.

The idea behind Common Tag is to reconcile the problem of using different tags for the same thing. For example, if you’re looking for images in Flickr from New York, NY, they’re probably tagged nyc, new_york, newyorkcity and so on. Common Tag avoids this by providing a single, unambiguous reference.

Here’s a snippet representing the band U2.

<body xmlns:ctag="http://commontag.org/ns#"
          rel="ctag:tagged">
  <span typeof="ctag:Tag" 
        rel="ctag:means" 
        resource="http://rdf.freebase.com/ns/en.u2" 
        property="ctag:label" 
        content="U2"/>
    U2
  </span>
</body>

Under the hood, we’re using a technology you may have heard of - RDFa. The most important part of this snippet is the resource section. It is the unambiguous reference to the content that you’re talking about. However, the process is very similar to the Open Graph Protocol above. First, we define a namespace, then we use it in our HTML. There are several interesting things you can do with Common Tag, including declaring whether content has been tagged by authors or by users. You should read the Common Tag Getting Started Guide to learn more.

Three easy ways to use hard tools

Each of the tools we’ve described here allows you to use a different piece of the Semantic Web pie in bit sized pieces. By using the simple tools above, you’re actually using the very scary tools you’ve been avoiding:

RSS means you’re using RDF
Open Graph Protocol means you’re adding usable metadata to your meta tags
Common Tag exposes RDFa to User-Agents

Tim McNamara