LDAP, ADS and java API for same

Hi buddies,
I am to design a web-page (basically a servlet or JSP page) that accepts a username and pwd. The deal is to authenticate this user against the Active Directory Service which is basically on win 2003 server machine. Now hod do I achieve all this??? With a vision of core java programmer, I have something to ask and something to share...

1. ADS uses LDAP or to be more specific LDAP can be used to use ads services?
2. Are their built in API for LDAP services?
3. If no, does the implementation vary from platform to platform...
4. What is the difference between ADS and LDAP, will I be wrong if I say ADS is platform dependent and LDAP is much a protocol implementation?

Any ideas??? And I apologise to the moderators if my question is in the wrong thread for I am really unaware under which thread this should go in. Please channelise it in the right path.
[ April 20, 2006: Message edited by: Akhilesh Trivedi ]

The Java Authentication and Authorization Service is a set of APIs that enable services to authenticate and enforce access controls upon users. Weblogic supports JAAS to LDAP and Active Directory servers (among others) and I'd think most application servers do the same. Consult your server's documentation for details on configuration and implementation.
If you want the bare-bones approach, one can directly access LDAP and AD trees using JNDI.

Sorry to bring up an old post, but I was wondering if you have found an answer to your problem? I am still working on mine, and I want to know the exact same thing. If you figured this out, please post!!

Hi Heather, We had windows 2003 server and I did the page-designing work with .Net framework then, keeping the abstractions as is. All that was needed was a simple login page.
On the go I remember browsing around OpenLDAP but could not take it to work for me, there is one from Novell as well. I suspect if they both are same.