authentication with ajax pages

[Allen Gilliland]

So, I've been playing a bit with struts2 and some of its ajax support 
and the cool thing is that we can get a pretty good amount of ajax 
goodies for minimal effort, but the drawback is that we are going to 
really have to revise some of the way the application works, beginning 
with authentication.

The first major issue that I've seen with my ajax testing is that when a 
users session expires and the first thing they try to do after that is 
done via an ajax widget, then how to properly handle logins is tricky. 
Currently if I have any component of a page which is rendered 
asynchronously using ajax and it fails an authentication check then the 
login page is returned in place of that component, which is not going to 
work :/

So I'm interested in hearing what folks have to say about how to solve 
this problem.  I have code which enables some bits and pieces of ajax 
functionality, but I'm hesitant to really commit to it until this 
problem is solved.

Thoughts?

-- Allen