To achieve these objectives, we expand UDT in the following four directions.
The first and the most important is to allow users to directly tune the sending rate, either through the congestion window size or inter-packet time.
The second is to use callback functions to tune the sending rate once certain events occurs. Users can redefine the event handlers such as when an ACK is received, when packet loss is detected, and so on.
Users can also read and set many protocol parameters, including RTT, RTO, loss rate, and many other performance statistics.
Finally, when necessary, users can define their own control packets.