Tutorial : Text geotagging with OpenCalais

This tutorial will show how to use version 3.1 of the Calais API to identify geographic references in a text and display them on an OpenLayers map. I am going to use the Calais API with JSON output (which is a new feature of version 3.1), so that all the processing can be done easily in JavaScript entirely inside a web browser.

A running version of the demo application can be found here. The code can be downloaded here.

What is the Calais API?

From the documentation:

The Calais Web Service allows you to automatically annotate your content with rich semantic metadata, including entities such as people and companies and events and facts such as acquisitions and management changes.

Version 3.1, currently in beta, has added information regarding the latitude/longitude of a few types of entities: Cities, provinces/states and countries. It makes it possible to plot those entities on a map, in a way similar to what can be done with the Metacarta GeoTagger API.

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