Set up for calling external procedures from Pl/SQL

Oracle8 has provided a coll new feature called "External procedures". Which in simple terms gives you ability to call any program on Operating system from within a stored program unit. Prior to this, only way to do this was to use deamons & pipes or Pro*C. Fot this to work DBA needs to do following setup.

Create a separate listener for external procedures. Add following entries to your listener.ora
EXTERNAL_PROC_LISTENER =
(ADDRESS_LIST =
(ADDRESS= (PROTOCOL= TCP)(Host= machine)(Port= 1526))
)
SID_LIST_EXTERNAL_PROC_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = external)
(ORACLE_HOME = /oracle/app/oracle/product/8.0.5)
(PROGRAM = /oracle/app/oracle/product/8.0.5/bin/extproc)
)
)
Thing to take care is that SID should not clash with a valid database SID
Then add an alias in tnsnames.ora for this connection
extproc_connection_data.world =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(Host=machine)(Port=1526))
(CONNECT_DATA = (SID = external))
)