push synchronization request status indicator: synchronizeStatus method option
Push synchronization (cn.synchronize, mn.updateSystemMetadata) involves an end-user that might want to have an idea of how long until the queued action is going to take to complete. Something as simple as returning the place in line of the sync request might suffice as the indicator, or a more complete data packet, including the place in line and the queue velocity, could be attempted.
The real-world analogy for this kind of indictor is taking a number at the deli-counter: You don't know when you will be served, but you know how many people are in front of you.
This option is a separate call to the CN to check the status of the sync request, so that the current place in line is returned. The advantage of this is that if the velocity of synchronization changes, the interested party can call again and get an updated value - it has more diagnostic and monitoring power. This could lead to over-use, however.