How to migrate OpenSocial to Elgg?

Hi! At first I have to apologize for my English. Now I will explain my problem:

I'm making my final degree job, an OpenSocial based application. Now that I get used to XML, JavaScript and the OpenSocial API, I'd like to know its possibilities as a future elgg application. When I finish my application is there a way to convert it for its use in an elgg platform?

I know that exists an opensocial widget for elgg but I have a problem. When I write the URL with the XML of the application (a probe one) it doesn't work (Invalid XML document).

Is there another way to make this conversion? If not, is there any tutorial to start getting used with elgg and it's app development world?

Lots of thanks!

Pablo