Tns and Listener in oracle

LISTENER IN ORACLE:-

1. The Oracle Database Listener is the server process that provides basic network connectivity for clients,application servers, and other databases to an Oracle database.
2. The Listener can also be configured to execute custom and/or third party binary executables in the operating system.

Examples of Listener.

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = sakthidbtech.com)(PORT = 1521))
    )
  )

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = orcl.example.com)
      (ORACLE_HOME = /u01/app/oracle/product/11.2.0.4/db_1)
      (SID_NAME = orcl)
    )
  )


TNS:-Transparent network substrate.

• This file will also be present on the server if client style connections are used on the server itself.
• The transparent network substrate a proprietary oracle computer network in technology,
•  supports homogeneous peer-to-peer connectivity on top of other  networking technologies such as  tcp/ip and named pipes.
• Tns operates mainly for connection to oracle databases.

TNS EXAMPLES:-

LISTENER = (ADDRESS = (PROTOCOL = TCP)(HOST = sakthidbtech.com)(PORT = 1521))

ORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = sakthidbtech.com)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = orcl)
    )
  )

$ # Restart
$ lsnrctl stop
$ lsnrctl start

$ # Or Reload.
$ lsnrctl reload

LISTENER DETAILS

The relevant files for the Listener are as follows –
$ORACLE_HOME/bin/lsnrctl                                  Listener control program
$ORACLE_HOME/network/admin/listener.ora       Configuration file for the Listener
$ORACLE_HOME/network/admin/sqlnet.ora         Configuration file for the Listener
$ORACLE_HOME/bin/tnslnsr                                 Server Listener process



The "listerner.ora" file contains server side network configuration parameters.
The "sqlnet.ora" file contains client side network configuration parameters.
The "tnsnames.ora" file contains client side network configuration parameters.

The lsnrctl program is the mechanism for starting and stopping the listener process (tnslsnr).
Tnslnsr starts and reads the listener.ora and sqlnet.ora files for configuration information, such as port numbers and
              database service names.



SELECT NETWORK_SERVICE_BANNER FROM V$SESSION_CONNECT_INFO;