How real-time apply works in logical standby oracle? I am a little bit confused about real-time apply services.
I've read a documentation about the services and I still have a question.
Does archived redo logs required for logical standby or not?
I've configure logical standby and there are 3 destination for db_recovery_file dest.
1st is local storage, 2nd transmits logs on standby and the 3d is for switchover.
But still I do not purely understand how it works.
Please, clarify or give some useful links.
Does archived redo logs required for logical standby or not? 
  Yes, it does. 


https://docs.oracle.com/cd/B19306_01/server.102/b14239/create_ls.htm#g105412

The archived redo logs (archivelogs, commonly) contain SQL statements to apply the changes being made to the database, as well as SQL statements to undo the work if a rollback occurs later on the primary's activity.