j_security_check

[Boudreau, Mike]

I have a requirement to implement security via LDAP and RDBMS.  
 
I was planning on using Form Based Authentication utilizing the
j_sucurity_check.
 
I see that you can use a JDBC Realm, but can I implement an LDAP realm or
some custom solution and take advantage of the web.xml security
declarations?
 
Does the JDBC realm use connection pooling?    
 
Is there a standard way to extend the j_security_check in a way that will
work in other Servlet Containers (e.g. WebSphere, WebLogic)?
 
Thanks,
Mike