How is the Next_Alert_TimeStamp updated in the YFS_SHIPMENT table by shipment monitor agent or when the shipment is modified?

Answer

The logic behind Next_Alert_TimeStamp field is that the shipment monitor agent should process the shipment if Next_Alert_TimeStamp is less than or eaqual to the current time. Any time shipment entity changes we set the Next_Alert_TimeStamp to low date (so that the shipment monitor agent picks this shipment). When the monitor runs, this shipment is picked up and the Next_Alert_TimeStamp is modified accordingly. If as per the monitoe rule, the system should look into the shipment after 1 hour, then the NextAlertTimeStamp will be set to current time + 1 Hour. If the shipment does not require an alert, the Next_Alert_TimeStamp is set to a high date.

For eg.
Create a shipment. The Next_Alert_TimeStamp will be set low date.

Now, lets says as per the monitor rule, if the shipment lies in Created status for 1 hour then raise an alert.
If the shipment agent monitor is run, it will pick this shipment, will process it and see that the shipment is not in Created status for more than 1 hour. So, the monitor agent will update the Next_Alert_TimeStamp to current time + 1 hour.

Now, if we add a shipment line to the shipment (or modify the quantity; the basic idea is to modify the shipment); then the Next_Alert_TimeStamp will again be modified to low date (so that the shipment monitor picks this shipment for processing).

Again the monitor agent will pick this shipment (as the Next_Alert_TimeStamp is low date (time less than current time)) and set the Next_Alert_TimeStamp accordingly (time when the monitor will again pick this shipment for processing).

Now, lets say that teh shipment moved to Sent To Node status. As the shipment has been modified, the Next_Alert_TimeStamp will gain be updated to low date.

Now when the monitor again picks up this shipment, it sees that the shipment has moved from Created status to Sent To Node status and hence does not require further processing, so the Next_Alert_TimeStamp will then be updated to high date.