Oracle listener and process

[ram chaitanya muppalla_1]

Hello Shiv,

To answer ur question.

In explicit sense status both are different.

These can be treated as two separate components.

If db is open , the status is said to be open for all operations. (internal user aka sys doesn't need to have listener available to connect and work).

If listener is available, all the users will be able to connect (only if the description from listener and tnsnames.ora incase of c/s techno.. else description provided should match incase of a java client) or the client shall receive the famous tns-12* errors. Which doesn't mean that db is unavailable (problem with configuration etc,.)


listener process => waits for incoming requests from users as specified in listener.ora file located under ${ORACLE_HOME}/network/admin

Listener process is a server side network file used in TNS configuration. On the client side we have java jndi or tnsnames.ora etc,. which contains the description.

If listener process is not running on the server side and client makes a request , then we get TNS- no listener error...

DB Processes: As detailed by other members, these are server side database processes.

That's my two cents and if u need more details.. feel free.

Regards,
Ram

[Rajesh SB]

Hi Shiv,

Oracle database server designed as client server.
On Server Oracle Database instance will be running, is identified by SID.

Locally db user access the database by
setting env ORACLE_SID=
$ sqlplus dbuser/pass@

If db user wants to access the Database across the network, Listener role is important. Listener provides the network tcp service to access the database via Oracle client and tnsnames.ora configuration.

How to check the listener status.

As a oracle user run
$ /oracle/app/ora9i/bin/lsnrctl status
OR
$ /oracle/app/ora9i/bin/lsnrctl status []

How to verify the listner is responding for database access.
As a oracle user
$ tnsping

where sid_name is defined in tnsnames.ora file. DB user connect/access to Database using this sid_name across the network.


Regards,
Rajesh

[morganelan]

The Oracle TNS Listener is the server-based process that provides basic network connectivity for clients, application servers, and other databases to an Oracle database. In addition to databases, the Listener can also be configured to support binary executables.

The Listener can be configured in one of three modes (as configured in listener.ora):
â Database :Provides network access to an Oracle database instance
- PLSExtProc : Method for PL/SQL packages to access operating system executables
- Executable: Provides network access to operating system executables.

The â Databaseâ mode is the most widely used mode and is the standard mode used by every database for connectivity. â PLSExtProcâ allows PL/SQL database packages to access external programs and is configured by default for many instances. â Executableâ mode allows an external program to be defined and accessed through a TNS connection.

[TwoProc]

Just wanted to a note re: James' post:
If you want to search for each listener by name - then use James' posting:
ps -ef | grep LISTEN

but, you can name your listeners (LISTENER is the default name), so searching for all tnslisteners, I use:

ps -ef | grep tns

or for more exact (in case there is a conflict with another program which has the word "tns" in it - but I doubt it)

ps -ef | grep tnslsnr