plz tell me in which situation we will be using docheckin() and docheckout().could u give some simple scenario. where this methods will be available?
This explained in the DFC development guide.
How about you write a test TBO object, override the methods as detailed in the DFC development guide and numerous examples on the web, then add some prints out to see what is happening...
System.out.println("doCheckin called");
DfLogger.debug.(this, "doCheckin called", null,null);
System.out.println("doCheckout called");
DfLogger.debug.(this, "doCheckout called", null,null);