auth0/express-jwt — pull request #25 by ilijamt (2014-08-19 09:15:13+00:00)
Title: Using custom callback to fetch data from a persistent location

In my case it allows me easily to connect to redis, get the data from there, compare it, and then replace
**req.user** with the data from the redis store.

Also this enables you the ability to invalidate the token easily, just delete the record from the redis store and you are done, you no longer have access to the system.