Session key expiration

Please forgive my ignorance, but do session keys expire?

We're currently having a website developed and I've seen the following behaviour:-

  • New session key is obtained
  • SetVariable method is called (we're in a consortium)
  • Login to an existing constituent
  • Call constituent details into a form (i.e. a 'My Account' screen)
  • Do nothing for a while
  • Click on a 'My Basket' link, triggering the allocation of a new session key

When I queried the allocation of a new session key with the developer, I was told that the previous session expired due to inactivity.

I know there's a definite expiration time for the seat server, but the basket was empty, so I didn't think the seat server was a factor here.

Am I missing something? If session keys do expire after inactivity, where is the time limit set?

Ian