Openfire logging question

I have been trying to figure out where a newly authenticated user shows up in the logs and or database? An example of what I am looking for is if a user is already logged into Openfire using the Spark client, and another user logs in the already logged in user receives a broadcast the newly authenticated user has signed in. I would like to utilize that mechanism for a future project and or a custom plugin. If anyone could shed some light that would be great. Thanks!