Getting Session Information & User credentials using FlexContext

Hi,

I am working with sessions and authentication for the first time.
I need assistance with using FlexContext to read the session attributes and user
Information. I want to know, how and from where FlexContext gets the session
information from? I have a flex login page, the user id and password are
submitted via URLVariables - j_username and j_password. The Tomcat validates it,
using custom JDBCRealm. I now want to capture this user information as well as
the session details, such that it is accessible at both the Flex as well as the
Java side. I have a java class, in which I am trying to access the
HttpServletRequest object and FlexSession object, by doing something like this -

HttpServletRequest req = FlexContext.getHttpRequest();
FlexSession session = FlexContext.getFlexSession();

But both of these throw NullPointerException.

Any pointers on how to resolve this issue, would be highly appreciated.

Thanks & Regards,
Deepa