Beeing able to generate files on the client is a common requirement and a usefull feature for a webapplication .
In one of our applications for example we have users generating reports every 30-45 seconds. By beeing able to do that on the client we do not need to scale our servers when the number of users grows.
Gwt4Air (http://code.google.com/p/gwt4air/) introduced in version 2.1 a File API that uses Flex and let u create files(PDF , Excel, Text, PNG, JPEG...) on the client by adding a Flex widget into your GWT application. The problem with that approach is that you needed to load an entire instance of the Flex framework just to be able to read/write files on the client
Gwt4air 2.2 will introcude a more lightweigt solution that does not require Flex(Flash is still needed dough). Please take a minute to visit: