About

A listener is configured with one or more listening protocol addresses, information about supported services, and parameters that control its run-time behavior. The listener configuration is stored in the configuration file named listener.ora.

Located on the database server, this configuration file may include:

• Protocol addresses it is accepting connection requests on
• Database and nondatabase services it is listening for
• Control parameters used by the listener

Because all of the configuration parameters have default values, it is possible to start and use a listener with no configuration. This default listener has a name of LISTENER, supports no services on startup, and listens on the following TCP/IP protocol address:

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

The listener forwards client requests to supported services. These services can be configured statically in the listener.ora file or they can be dynamically registered with the listener. This dynamic registration feature is called service registration.

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Example and Syntax

The LISTENER entry defines the listening protocol address for a listener named LISTENER, and the SID_LIST_LISTENER entry provides information about the external services statically supported by the listener LISTENER.

LISTENER=
  (DESCRIPTION=
    (ADDRESS_LIST=
      (ADDRESS=(PROTOCOL=tcp)(HOST=sales-server)(PORT=1521))
      (ADDRESS=(PROTOCOL=ipc)(KEY=extproc) (queuesize=50))
    )
   )
SID_LIST_LISTENER=
  (SID_LIST=
    (SID_DESC=
      (SID_NAME=plsextproc)
      (ORACLE_HOME=/oracle11g)
      (PROGRAM=extproc)
     )
     (SID_DESC = 
        (SDU=16384)
        (TDU=16384) 
        (ORACLE_HOME = /.....)
        (SID_NAME = SOLAP)
     ) 
   )

To know more about the parameters, see this page: Oracle Net Listener Parameters (listener.ora)

Example of a listener.ora of an EBS database:

VIS =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = ebs121.gerardnico.com)(PORT = 1521))
    )
  )

SID_LIST_VIS =
  (SID_LIST =
    (SID_DESC =
      (ORACLE_HOME= /d01/oracle/VIS/db/tech_st/11.1.0)
      (SID_NAME = VIS)
    )
  )

STARTUP_WAIT_TIME_VIS = 0
CONNECT_TIMEOUT_VIS = 10
TRACE_LEVEL_VIS = OFF

LOG_DIRECTORY_VIS = /d01/oracle/VIS/db/tech_st/11.1.0/network/admin
LOG_FILE_VIS = VIS
TRACE_DIRECTORY_VIS = /d01/oracle/VIS/db/tech_st/11.1.0/network/admin
TRACE_FILE_VIS = VIS
ADMIN_RESTRICTIONS_VIS = OFF
SUBSCRIBE_FOR_NODE_DOWN_EVENT_VIS = OFF


IFILE=/d01/oracle/VIS/db/tech_st/11.1.0/network/admin/VIS_ebs121/listener_ifile.ora