Cross-Domain MQLRead Access with GWT, JSON and JSNI

This MQLRead query application is written in Java and uses GWT's UI widgets (TextArea and Tree). This example, downloaded from this site (www.webcollab.com), runs in Web browser and makes an asynchronous cross-domain MQLRead request using GWT to www.freebase.com. In a nutshell, the example demonstrates:

a cross-domain MQLRead service call,
a JSON service response,
a Javascript callback that bridges back into Java,
an analysis of the JSON response that creates Java-accessible objects such as the GWT tree widget.

Type in a valid MQLRead query and click the "Query" button below. Caveat: During alpha trial, Freebase requires authentication. So, please signin first.

MQLRead Query

MQLRead JSON Result

Download the source code for the example.

The example is adapted from the following information with several caveats:

Caveats:

The GWT cross-site fetch approach is correct but the actual code snippets and code explanation is incorrect.
Each GWT application is loaded in a zero-size iframe. Multiple GWT modules running in a single application do so in separate iframes. As a consequence, the instanceof does not work across windows.