The Package DBMS_PIPE allows various sessions to communicate over the named pipes. (A pipe is a region of memory used by one of the process to pass information to the other.) You can use the procedures pack_message & send_message to pack a message into the pipe, then it send to the other session in the similar instance.
At the other part of the pipe, you can use the procedures receive_message and unpack_message to receive and unpack the message. The Named pipes are helpful in many ways. For illustration, you can write the routines in C which allow an external servers to collect the information, then send it through pipes to the procedures stored in an Oracle database.