The maintenance window is regulated by ICE. All the details about the maintenance window can be found in the section "8. Feed Availability and Maintenance Window" of the ICE iMpact Multicast Feed Technical Specification.
As the session number is changed after the maintenance window the Handler activates full recovery procedure to refresh the product definitions and the market state.
The Handler doesn't provide any mechanism to notify when the maintenance window starts or ends. A user application should handle this period of inactivity on its own.
After the maintenance window, the number of product definitions may change. The Handler keeps all product definitions downloaded at the beginning, when the Handler::start method is called, and uses this set during market state recovery. This means that if at least one product definition is removed after the maintenance window, the Handler won't be able to complete market state recovery, as it will keep waiting for snapshot messages for product definitions that are no longer available. To avoid this situation a full restart of the Handler is required.
