* Look at these entries in the 9i r2 net files


TNSNAMES.ORA
---------------------------
EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )


listener.ora
----------------------------
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = VALUED-7B9600FA)(PORT = 1521))
      )
    )
  )

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ENVS="EXTPROC_DLLS=ANY") 
      (ORACLE_HOME = D:\oracle\ora92)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (GLOBAL_DBNAME = phoenix)
      (ORACLE_HOME = D:\oracle\ora92)
      (SID_NAME = phoenix)
    )
  )


* Without configuring this entry
  ENVS="EXTPROC_DLLS=ANY"
  
  you will get "INVALID DLL path" error

* Change the alias 
  EXTPROC_CONNECTION_DATA
  in any way, you get
  ORA-28575: unable to open RPC connection to external procedure agent

  Try this:
1.Replace EXTPROC_CONNECTION_DATA with
          EXTPROC_CONNECTION_DAT
  and try to run external procedure -> error.
2.Fix alias and try again -> OK
3.Change alias and try again -> OK (the connection is cached, looks like)
4.Disconnect, reconnect and try again -> error