I have seen that, as for now, there is not support for LDAP in Activiti. I have also seen, that there are some posts about this topic in the forum, and either an opened task: http://jira.codehaus.org/browse/ACT-116. However, this task is about adding support to Spring security, and is not exactly what I am looking for.
I would like that the engine could be configured to query an LDAP directory to obtain information about users, groups, and how they are related, instead of having that information in a relational DB. I have some experience with LDAP queries in Java, so I could code it. For that, I would need some context information about identity service, identity sessions, etc, as I don't know these details about Activiti. Where can I find that information?.
If the LDAP access was of interest for others users, I could send the code to be added to the main project.
In the meantime, we figured out that Spring security is not an abstraction for managing/retrieving identity information from various data sources. So we'll need to build our LDAP support through either spring ldap or directly with JNDI. I added that comment to ACT-116