If the parameter is set to Y , when setting the capture process using the below procedure then the capture process is real time as described here.
BEGIN DBMS_CAPTURE_ADM.SET_PARAMETER( capture_name => 'real_time_capture', parameter => 'downstream_real_time_mine', value => 'Y'); END;
If the parameter is set to N , then instead of the redo-log , archived logs are transported and mined at the downstream site.
In the archived-log downstream capture process , the archived redo log has to be transported to the downstream database using redo transport services,the DBMS_FILE_TRANSFERa package, file transfer protocol (FTP), or some other mechanism. Once the archived redo logs are available at the downstream site then they are mined and applied as per the requirement setup.