The return from createTimespan(days, hours, minutes, seconds) is a double numeric value representing a number of days. For example, createTimespan(2, 6, 0, 0) is 2.25, meaning two and a quarter days. The resolution of the function is one second, which is 1/86400th or 0.000011574074074 of a day.

Interestingly, the ColdFusion Application class/component/whatever is configured with timeout values using this createTimespan function. For example, if I want a session to timeout after 30 minutes, I would set do this.sessionTimeout = createTimespan(0, 0, 30, 0). However, if at a later time in the application I evaluate this.sessionTimeout, the value is expressed in seconds, as a signed 32-bit integer. The implication is that the longest timeout value for a ColdFusion application is 2147483647 seconds, or about 68 years.

None of this has any significance to the problem on which I've been working this morning. I am trying to demonstrate that it is/is not possible to set the session timeout per client. So far, using both JEE and native ColdFusion sessions, my testing shows that the sessionTimeout set during application startup cannot be altered. I've set a whole bunch of Application.cfc event logging to watch when events are fired, and ColdFusion 9.0.1 ignores (mocks, even) my attempts to alter session creation/timeout.

Hat tip to Ben Nadel, as usual.