The image shows Shows the basic DBMS_PIPE workflow. On the left, SEND_MESSAGE. User 1 performs PACK_MESSAGE and SEND_MESSAGE, and there is an arrow to the center box, a Database Pipe in Oracle Shared Pool. On the right is RECEIVE_MESSAGE, User 2 runs RECEIVE_MESSAGE and UNPACK_MESSAGE, with an arrow from the center box, the Database Pipe in Oracle Shared Pool.