Add support for querying session's by a specific user identifier

[rwinch]

In some situations it may be nice to be able to query sessions by a user identifier (i.e. a username). This would be useful for displaying all the active sessions of a particular user.

[cemo]

Definitely +1

[fieder]

+1

[rwinch]

Related to #17

[ptahchiev]

+1

[shanewow]

Hi, I would like to create a wrapper or extend the RedisOperationsSessionRepository in order to save each session to a second RedisTemplate using the username instead of sessionId as the hash. I hit a brick wall with trying to call or override the save method as RedisSession is private. Can this class be made public? Or is there another way to filter/inject logic when the session is created and deleted? Essentially how would I delete and create from a second RedisTemplate at the same time the RedisOperationsSessionRepository does? Thanks.

[rwinch]

@shanewow Right now I'm not sure there is a good answer as to how to do that. We'd really like to keep the RedisSession private so that we can modify it as necessary without causing users any passivity issues.

The best solution I can come up with is to ensure that the username is populated in the session attributes. Then, anytime the HttpServletRequest.getUserPrincipal() changes ensure to save using another RedisTemplate a mapping of the username to the session id (which might contain multiple ids). This could all be done in a separate Filter and interacting with the generic HttpSession and HttpServletRequest API's.

The problem is to figure out how to clean up expired sessions from the username. I'm not quite sure how to properly go about this.

[rwinch]

This is now supported with the Redis implementation. See http://docs.spring.io/spring-session/docs/current-SNAPSHOT/reference/html5/guides/findbyusername.html (will be deployed in next 30 min or so). Also see http://spring-session-kill.cfapps.io/ for the deployed sample.