Oracle listner

Oracle Net listener is a process which acts like a service provider and which takes all the request that are requested by the client . Oracle Net Listener is called an interface between the client and Server Engine(which helps to display the JSP page).

Whenever a client submits a request from the client tier and submitted to the application tier and to database tier to fetch the data,actually the very first thing that we have to check whether our listener is up and running or not .

If listener is not up and running then the request send by the client can not be processed and not to be submitted to the application tier. SO it's very important to be up the listener of oracle apps always.

Listener mainly listen the webserver and request send by the client and manages te traffic of  these requests to the database server . It is like a servant for webserver.

The configuration of the listener is stored in the configuration file listener.ora.

The default listener has a name of listener ,supports no service on startup, and listens on the following TCP/IP protocol address.

(ADDRESS=(PROTOCOL=tcp)(HOST=host_name)(PORT=1521))

The listener forwards the client requests to supported services. These services are 

configured statically in the  listener.ora file or they can be directly registered 

with the listener. This dynamic registration feature is called service registration. 

A listener can be set up for a single instance 'database' or it can be setup to 

handle all instances "database"  if more then instances are installed in your server.

 We will get confusion that what is the difference between listener.ora with the tnsname.ora?

Don't confusion!!!
Listener.ora is a container for services . It handles all the client request but tnsname.ora is a file which is located in the ORACLE_HOME/network/admin contains information regarding the instances that have a listener running for them. It mainly helped to connect to the instances in the server.

The tnsnames style is required for connecting to an Oracle RAC cluster.

To determine the host, port, service name, and/or SID, execute the following command as the user running Oracle. (By default, the user is "oracle"):

lsnrctl status   (a utility called lsnrctl is used to manage the listener process.)

Example of listener.ora file

LISTENER=
  (DESCRIPTION=
    (ADDRESS_LIST=
      (ADDRESS=(PROTOCOL=tcp)(HOST=mills-server)(PORT=1521))
      (ADDRESS=(PROTOCOL=ipc)(KEY=examprc) (queuesize=100))))
SID_LIST_LISTENER=
  (SID_LIST=
    (SID_DESC=
      (SID_NAME=plzextprc)
      (ORACLE_HOME=/oracle11g)
      (PROGRAM=extproc))

 Oracle Net Manager can be used to customize the listener.ora file.

Oracle supports a number of protocols TCP, SDP, TCP with secure sockets and named pipes. There are two ways to connect to oracle dedicated or Shared Server, both could be running at the same time on the same server. There are 4 connection types

• Dedicated - direct handoff (client and server are on the same computer)
• Dedicated - redirect (client and server are on different computers)
• Shared server - direct handoff (client and server are on the same computer)
• Shared server - redirect (client and server are on different computers)

We can do the below activities on the lsnrctl command

 Please refer the below link to know more about the configuration and administration of oracle listener

http://oracle.su/docs/11g/network.112/e10836/listenercfg.htm


 Thanks....