Make GWT interact with ASP.NET Web Service

Question

Does anyone know of a good article or tutorial on the Internet demonstrating the use of GWT leveraging a (ASP.NET) web service cross domain?

To my knowledge, interacting with either XML or JSON should be possible from GWT, but becomes a lot more difficult when the web service is on a different domain. I've tried finding an article that demonstrates this setup, but without any luck.

Answer 1

There are a few options available:

• use the Cross Site linker - it should make cross domain request easier, simply add <set-linker name="xs"/> in your module file (*.gwt.xml)
• window.name hack :) Be sure to read the post with the original dojo proposal
• JSONP
• many others ;)

But first I recommend reading http://code.google.com/webtoolkit/tutorials/1.6/Xsite.html - it should get you going :)

Answer 2

I was initially going for a JSONP approach (as suggested by Google), in order to do cross site AJAX calls in JavaScript, but ended up with too many hacks that I had to incorporate into the ASP.NET web service in order for it to work.

The solution, in my case, was instead to use GWT RPC to a JAVA servlet, acting as a proxy, which then would call the ASP.NET Web Service using SOAP. The SOAP Java classes was generated using the wslist tool that is part of JAX-WS project (as demonstrated here).

Using the GWT RPC, I was still able to call the JAVA servlet asynchronously, giving the user a seamless experience.