SSO and authorization between java and ABAP systems

Hello all

Issue is:

We are building NW 7.11 JAVA based system. It has to be integrated with ABAP based system serving some RFC/WS/BAPI services.

How to configure and which techniques/components use to achieve SSO?

BTW: on this ABAP system users have accounts independent from LDAP - no mapping or SSO is provided, so they use just login/passwd logon method. Is there any way to map (in which part of this landscape?) MS AD logins (which will be used in SSO to this new JAVA-based system) to those ABAP logins users have?

Any suggestions ?

Thank you in advance

Regards

Maciej