Am I abusing SubjectDAO?

[Nolan Darilek]

Another design question:

I'm working on storing my account data into MongoDB. For a while, I've 
had two Subject objects--Shiro's, and my own.

This is getting ugly fast. I just refactored such that my app's primary 
principal is the MongoDB ObjectId of the subject, and this vastly 
simplifies many of my use cases. I no longer need my own Subject class 
to reference subjects from other documents, and can just stash the 
primary principal or use it for record lookups. My one remaining case is 
modifying subjects to create a new account or change principal values, 
then saving the subject to the database.

I see there is a SubjectDAO with basic save and delete methods. 
DefaultSubjectDAO appears to persist subjects in sessions though, and 
I'm wondering if this DAO isn't intended to be modified for saving 
subjects in a database?

I was thinking of calling 
getSecurityManager().getSubjectDAO().save(subject) rather than my 
Mongo-specific code. Then my app wouldn't really care what persisted its 
subjects, and I could potentially migrate to something else in the 
future. Is this not what SubjectDAO was intended for, though?