A few years ago, I wrote a small LDAP gateway that processes LDAP requests from mail clients (Apple Mail, Thunderbird, SquirrelMail, etc) by looking up the results from a relational database. It's mainly used for email address auto-completion, but can also be used by address book software (e.g. Apple AddressBook).
The current soulution works fine, but is based on ruby-ldapserver v0.3. Now I'm looking for a lightweight Java or Grovy based alternative to ruby-ldapserver, because I feel much more at home with Java and Groovy compared to Ruby.
There are many Groovy libraries for coding LDAP clients, e.g. for authentication or lookup against an existing server. However, I haven't found anything suitable for implementing a lightweight LDAP server (ApacheDS looks too heavyweight, since I just need to receive and respond to LDAP queries).
Any ideas would be appreciated. Thanks!