GWT Communication strategies

I am newbie to GWT. I am currently doing a feasibility study on GWT to decide whether to include it in our product or not. I went through various docs and I have some open questions. Whether can I use RPC( java-servlets) to get data from other server as well- means cross site access. I could see that I can get it via JSON or JSONP, but just wanted to confirm on that.

May be this question sounds bad . I am not well-versed in Web technologies as well. Web Engines do a load balancing, it that case it means that the browser gets the reply and he need not worry about the server from which it gets the result. How is this different from cross-site access? Why java-script is not stopping it from accessing different servers in this?

Then which communication strategy would be better to implement? I know this is a tricky question and it is requirement specific. But in general which some one can proceed with.

I get to see many docs 开发者_如何学运维saying its fine to go only with GWT and no need to have GXT in place. What benefit would I get when I use GXT? I have not worked on any. I have just worked on examples provided in the GWT tutorial. Now needed to know the border-line between GXT and GWT ...

It will be great if I some one can clarify the above doubts.

--Priya.

GWT is primariy a client-side technology. It does have some server-side related stuff related to its RPC mechanism (there may be some more server-side tech in the 2.x versions, I was a 1.7 user).

GWT's RPC allows you to write your server-side logic in Java and call those services directly via Java code (rather that making a request to a page that returns JSON or other data and then parsing that data), and is one of the big plusses to GWT. Of course, on the server side of things, you can do whatever you want (including making connections to servers on other domains). GWT manages RPC completely internally using a proprietary binary format, but in the end it's just fancy Ajax. :)

GXT is a UI library for GWT, giving you some fancy widgets and layouts, etc. The demos will give you a better idea of what it can do.