How to write an SQL update trigger with 5 minute delay? (with a jsp websevice)

I am writing a SOAP webservice with java-axis which is interacting with an Android app and will set the status of the user as available or not.

I plan to implement a simple mechanism: Any request sent to the webservice will mark the user as available.

Also, after five minu开发者_运维百科tes of inactivity, the user shall be marked as offline.

How can i achieve this. I thought of writing an always running service which shall do this or an trigger which will run after five minutes of the user being marked available.

Any tips or solutions?

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Why not have a column called LastSeenDateTime that is checked by subsequent activities to determine if use if "on line" within the last 5 minutes.

You could make this computed so you get true or false based on a DATEADD calculation

You'd need a scheduled task to search for "last on-line" values and set according which isn't ideal. A trigger in the SQL sense would keep a transaction open which is bad

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If you wish to maintain state then you should have server side sessions and a session manager.
SessionManager could be a daemon or a cron job.
Calling an SQL trigger from JSP is not such a good idea.