How to detect disconnection of flash client from php server?

How can the disconnection or Closure of the flash client be detected while using a php backend which ensures that only active client usernames are present in the datbase. My approaches were to use some polling method - where the client sends some message to the server periodically else the server deletes the client's name from the DB assuming it is closed - or to use some augmenting javascript code that informs the backend of a closure event. This won't help in case of an abrupt, improper closing wher开发者_JAVA技巧e the script won't run. Are there any other more efficient methods for doing this?

the poller method is how i addressed this issue in the past. set flash to poll a php heartbeat script at a set interval which will up date the last access time of the users session. Then if the heartbeats stop the session clean up can clear out any expired sessions