cross auth between jportal and dwr/servlet better solution t

[je.a.le]

I convert a project from "form" submit based to dwr (ajax) submit. both work fine together.
At the top security(login, portlet access) level i will use jboss.
Like in any project :-) some actions must be valid only to some users. Since dwr is just servet, i must check user right here too.

From the dwr servlet i succesfully have access to user and role module, but to know who is logged in, the only solution I found so far is by storing the user name into a session attribute.

in portlet with admin/secure op :

// somewhere in the doView
String ruser = request.getRemoteUser();
 if (ruser != null) {
 PortletSession sss = request.getPortletSession(true);
 if (sss != null) {
 sss.setAttribute("ruser", ruser, PortletSession.APPLICATION_SCOPE);
 }
 }

from a dwr class function

WebContext ctx = WebContextFactory.get();
HttpServletRequest req = ctx.getHttpServletRequest();
HttpSession sss = req.getSession(false);
if (sss != null) {
 String ruser = (String)sss.getAttribute("ruser");
 if( ruser !=null ){
 // user auth
 // now check againt jboss through role module etc.....
 }
}

So, yes it's working. when loggin out, jboss clean the session too.
But i have 2 questions :
1) is it really secure ?? can an exploit might hack into my dwr function ??? (there's always a risk, I meet hack easily ...)
2) Is there a better solution, to get who's loggin in, direclty by asking jbossportal ???

what I really need, is to have acces to the roles list of the logged in user making the request; that's all (I'm using ejb to external db and jackrabbit)

Thks