Duration (for registration and subscriptions)

Default duration

If you don't specify a duration in registerContext, subscribeContext or subscribeContextAvailability a default of 24 hours is used. You will get a confirmation of the duration in these cases in the response, e.g. for a registerContext:

  "duration": "PT24H",
     "registrationId": "52f38a64261c371af12b8565"

Extending duration

We have seen that registrations and subscriptions (both context and context availability ones) have a duration. The expiration date is calculated using the following formula:

  • expiration = current-time + duration

The behavior of the broker regarding expired elements is the following:

  • For registrations: an expired registration is not taken into account in discoverContextAvailability request processing, but it is still updatable.
  • For subscriptions: an expired subscription is not taken into account to send new notifications based on it, but it is still updatable (using updateContextSubscription/updateContextSubscriptionAvailability) and it can be canceled (using unsubscribeContext/unsubscribeContextAvailability).

Note that Orion Context Broker doesn't remove expired elements from the database, but that they can be easily deleted as described in the administration manual.

Finally, take into account that the expiration is recalculated on updates, not expanded. Let's clarify this with an example. Let's suppose that at 18:30 you do a subscription with PT1H duration (i.e. one hour). Thus, it will expire at 19:30. Next, at 19:00 you do an update using again PT1H as duration. So, that hour period is not added to 19:30 (the previous expiration limit) but added to the 19:00 (the current time). Thus, the new expiration time is 20:00.