Has anyone implemented security and authentication in a Struts app?

[Davina and Mac]

Has anybody out there implemented a roles-based security system in a Struts
application? If so, did you use an existing class library or write your own?
It seems to me that relying on container providers for security schemes
makes it almost impossible to write portable applications, and Struts/MVC,
with its single point of access and clearly defined actions would be an
ideal place to implement security...
thoughts anyone?

Mac Ferguson