This illustration shows two spaces, the Oracle process space and the external process space.
The Oracle process space includes the Oracle database and database instance, and possibly user-written PL/SQL scripts (that is, stored procedures, functions, or triggers).
The external process space contains the COM feature in which the external procedures reside. The external process space also contains the Oracle listener and external procedure handler.
In the Oracle process space, the PL/SQL script accesses the database, and in the external process space, the script starts the Oracle listener, which activates the external procedure handler.
Once the external procedure handler is activated, it activates the COM feature.
The COM feature communicates with a COM Automation server by COM or DCOM and returns a result to the COM feature. The COM feature then passes the result to the external procedure handler, which then communicates back to the database.