communication between GWT application and LifeRay portal

I'm developing a GWT application which will be linked with LifeRay portal just as a link. What I want to get from LifeRay is a user and roles management (from LifeRay) so user logged in LifeRay and then he gets access to开发者_运维问答 my application link.

What is the best way to share the current logged in user between LifeRay and my GWT application?

Thanks

If it is possible the LifeRay should be able to provide the link of the GWT application with a single sign on token which can be used by the filter in the server of the GWT application to a verify the sign on in the background.

The link from the LifeRay portal should be like http://gwt.application.url/appName?user=1293129fidsi3493k.

The server for the GWT app should pick up the token and verify the login credentials with the LifeRay server and set the details in the session and cookie of the GWT app.