OpenCalais developer Richard Hancock wrote up an informative blog article Understanding the OpenCalais RDF Response summarizing the RDF output.

Others should find his clear explanation, which includes an example article and output, helpful in understanding OpenCalais RDF output.

This sample code shows how to use Markup entities and Disambiguated entities and how to use the Linked Data to get additional info on entities (how to retrieve information from the Linked Data end point).

Basically, the code sends a document to OpenCalais with RDF output format, and then analyzes the Companies, Geographies, Products, marked-up Companies, and the relevant disambiguated company URIs in the Linked Data. It outputs an xml file containing simplified data gathered from OpenCalais and Linked Data.

The application sends a document to OpenCalais with RDF output format. It analyzes the entities and outputs an xml file containing simplified data gathered from OpenCalais and Linked Data.

If you want to drill a little deeper into the RDF structure, the group at Salzburg Research has created a nice desktop RDF explorer called RDF-Gravity.

This PHP code (server and client) demonstrates how to use Calais with PHP. We offer both the raw representation of the Internet browser and a document viewer  representation highlighting all the entities in the text. Download the attached file, which contains documentation as well as source files.

To enable your PHP demo in Safari and Firefox, see this posting from Pete Warden. 

The example of a JSON wrapper – code that runs on the server and converts the RDF into JSON format - is also presented. We will be releasing (soon) a much simpler JSON wrapper (based on RDF) and another format is based in Simple Output Format, as well as a Java application controlling the Calais Web Service.

Stay tuned.

The best place to start is with the Calais Document Viewer. The document viewer allows you to paste sample text and receive that text back with all entities, facts and events highlighted and navigable. You can also view the native RDF output and capture it for analysis in other tools.

RDF may be a beautiful thing for the representation of semantic content - but it is most definitely not a lot of fun to read. We've built a small (windows) application that will allow you to browse a folder of processed documents and see the types of semantic metadata extracted. You can download the installer here. The document viewer requires a current installation of the .NET framework.