Ajax development is now often tied to another emerging trend in the application world : Widgets. Carla Mott writes an entry on how to connect widgets using jMaki.
Using topics to communicate across components can be a little confusing so I wanted to cover how jMaki widgets use topics. Almost all widgets that are included in jMaki subscribe to a topic or publish to a topic or both. The topic names are of the form /dojo/table or /lib name/widget name. We're in the process of updating the documentation files to include this information so that it is easily accessible. All topic names can be over written when specifying the widget in the page. This is done using the 'publish' and 'subscribe' attributes on the taglib or function call. Note that a widget can subscribe to multiple topics but publish to only one.
Getting an event, regardless of how you get it, is more meaningful if you also get data and know what to do with it. Therefore we have the ability to pass data along with the event and we have specified the format of the data for the various types of widgets. The data is passed in the payload of the event. The format of the data in the payload is described in detail in the data model pages
Read Carla's complete post : http://weblogs.java.net/blog/carlavmott/archive/2007/10/connecting_widg.html