Stefan and I have been discussing the usage of java.util.UUID to generate a sso identifier similar to that done by tomcat's AuthenticatorBase. Since we wanted to avoid overlap with the random id generated by AuthBase, I suggested the usage of UUID.
So we decided to explore the level1 or time based UUID.
After sometime, Stefan gave up figuring out the way to instantiate level 1 UUID.
We found this mini-FAQ on UUID.
Java UUI Mini FAQ
Level 4 UUID should be sufficient.
An example of UUID usage is here >>>