"General comment: Support for notifications
I don’t see support for notifications or is WS‐Notification an interface that implementations of the specification can
 optionally support. As much as possible, it would be good for the specification to reduce the need for client 
roundtrips, e.g. getting a state notification instead of polling the DTI resource to check whether the transfer is done.
 In fact, adding a “callback” EPR in the create DTI call could be a good way to eliminate the need for the client to 
make a second remote call (following the first remote call to create the resource) to set up notifications, if 
notifications are to be supported."