In reply to shanthi:
Sending back responses is more easy as you are saying. It simply
seq_item_port.item_done(rsp);
sending back data to the sequence using seq_item_port.
The lines
seq_item_port.put_response(rsp);
rsp_port.write(rsp);
are 2 alternatives sending back data.
The last one needs an additional connection to the sequencer.