Three months ago, Paul Ramsey created a tutorial that builds an example census mapping application using OpenGeo Suite. Since then, we’ve released OpenGeo Suite 4.0, which includes early access to OpenLayers 3, and we’ve updated the tutorial to use OpenLayers 3 instead of GeoExt.
A Different Approach
GeoExt, a combination of ExtJS and OpenLayers 2, allows one to create web applications without writing any HTML and CSS, which was useful back when all browsers behaved differently. However, with HTML5 and CSS3 available in all modern browsers, a more modular stack adds flexibility.