Hi,
The idea of OperationTimeout is that you can provide a timeout for specific operation separately and Connection Timeout is a global connection timeout for any SSH protocol operation.
After looking at a code of SFTP I probably did not do the best job of separating it so might need to looked at it again. But the way it works now is if you specify Operation Timeout 15s and Connection timeout 30s then if you performing any SFTP operation and no response were received for request sent within 15 sec it will throw an exception but connection still be active since.
I guess the best way where OperationTimeout used in SshClient where you can specify timeout for each command you execute seperatly so this way if you have long running operation you can specify different timeout and I think I just tried apply same principles to SFTP operations.
Hope it somewhat explains it. If you have any suggestions on how to improve it please let me know.
Thanks,
Oleg