+------------------------------------------------+ | | | Client Server | | | | --------- Q4S READY 1 -----------> | | <-------- Q4S 200 OK ------------- | | | | --------- Q4S BWIDTH -----------> | | <-------- Q4S BWIDTH ------------ | | --------- Q4S BWIDTH -----------> | | <-------- Q4S BWIDTH ------------ | | ... | | | +------------------------------------------------+