Finding users currently logged in to my app

[cjmckenna]

For some reason I am having a real hard time wrapping my head around something..... We have an application where we need to track who is currently logged in. The application writes a log entry when they login and when they logoff. They can login concurrently from multiple stations as well.

So what I need to figure out is if time of login for that user/station combo is higher than the logout time for that user/station combo then we assume they are still logged. So the outcome will need to be a table that shows the ID, Station and time of the current logged in users.

Here is a sample of the data:

ACTION                  STATION                UID                   au_Time
Login                  1.2                                 123456            2017-10-19 09:15:45.0
Login                  1.3                                 987654            2017-10-19 09:24:35.0
Login                  1.4                                 ABCDEF            2017-10-19 09:40:27.0
Login                  1.3                                 XYZPDQ            2017-10-19 10:10:34.0
Login                  1.6                                 XYZPDQ            2017-10-19 10:11:48.0
Login                  1.5                                 XXX111            2017-10-19 09:40:38.0
Logoff                 1.3                                 987654            2017-10-19 09:44:40.0
Logoff                 1.2                                 123456            2017-10-18 14:57:12.0
Logoff                 1.6                                 XYZPDQ            2017-10-19 10:38:52.0

In the example above you see UID 987654 logged in at 9:24 and logged out at 9:44 so they are not currently logged in
- User 123456 last logout was on the 18th at 14:57 and they logged in again on the 19th at 9:15. So they are currently logged in
- User XYZPDQ logged in to station 1.6 at 10:11 on the 19th and logged of of station 1.6 at 1:38 but this user XYZPDQ is still looed in on station 1.3

I just cant figure out the best way to see if that user and station has a greater time for logout than they do for login to decide if they are currently logged in or not.

Thanks for any help !!!

[richgalloway · Accepted solution]

You can do that by filtering out all but the most recent event for each station/user pair. That will leave either a Login or a Logout for each. Then display just the Logins and you'll have your list of those you are still logged in.

<your search> | dedup STATION UID | where ACTION=Login | table ACTION STATION UID _time

[DalJeanis]

@richgalloway - Put quotes around "Login".

[elliotproebstel]

First, convert the timestamps from strings to epoch time:
| eval _time=strptime(au_Time, "%F %X.%1Q")
Then add a field called latest_time to each event. This field will contain the timestamp of the latest event for that given station:
| eventstats latest(_time) AS latest_time BY STATION
Then search for only events where the timestamp of the entry is the same as the latest timestamp:
| where latest_time=_time
This will give you only the lines containing the latest event for each station. From there, you can manipulate the data to output exactly what you need.

[DalJeanis]

@elliotproebstel - Acceptable, and gets the right result. However, overriding the builtin _time field with different data should be avoided, in my opinion, other than for presentation such as in timechart.

Also, note @richgalloway's answer as slightly more elegant, since dedup will automatically select the first event, which in the default order will be the most recent.