Connections without listener

We have an application that connects to an Oracle 10g instance via jdbc.
Something is happening such that it appears the connections are being made even though the listener is down.
Can this be so?
How so?
xoxomosAsked:
Who is Participating?
 
schwertnerCommented:
No, it is not possible to connect Oracle instance on other machine
without using the Listener.

As Linuxo said it is possible to connect
from the same machine but if only there is one instance or possibly
(I am not sure) to the instance located by ORACLE_SID variable.

But after the Listener made the connection normally it redirects
to created socket connection to other ports of the machine and
also creates Oracle Process thar serves the connection.
So the created connections do need the Listener. It could be down,
but this will make impossible further new connections, not the allready
established.
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mohammadzahidCommented:
Listener is only used if connect_descriptor field used when logging in database.

sqlplus> abc/abc@server1111  will invoke listener in DEDICATED and SHARED SERVER mode

sqlplus > abc/abc  will not invoke listener. Oracle uses Net8 connectivity in this case.

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xoxomosAuthor Commented:
Ok.  I'm talking about an applications server on one machine and database server on another so the sqlplus abc/abc would not suffice here would it?
I see a lot about jdbc in listener log.  
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konektorCommented:
when you are on server, where database is, it's enough to have set oracle variables (ORACLE_BASE, ORACLE_HOME) and you can connect to database only using username and pasword, listener can be down, because is not used.
but if your application is on different server than database, you need to go through listener as i know. isn't there any other listener on database server (there might be more than one)?
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linuxoCommented:
Hi,

No need for listiner to connect from the same PC where database is located, Lisener used for remote Call ...

thanks
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Docteur_ZCommented:
Connect to the database and issue a "show parameter local_listener"

Check the adress of the listed listener, if it's not the one you were thinking about.

If nothing is listed, then it's using the listener on default port (1521).
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xoxomosAuthor Commented:
From the docs Listener Architecture:
"The database server receives an initial connection from a client application through the listener. The listener is an application positioned on top of the Oracle Net foundation layer. "
From the results of some testing here, it seems once that initial connection is made, queries can be made to the database even after listener is shut down at least with JDBC.  TOAD would not do it, but a Cold Fusion program program continued to return results from queries as does an application called Blackboard. (Learning system).  If I try to make a new connection without listener, it does not work.
So I'm wondering if that coincides with what schwertner says here:
"But after the Listener made the connection normally it redirects
to created socket connection to other ports of the machine and
also creates Oracle Process thar serves the connection.
So the created connections do need the Listener. It could be down,
but this will make impossible further new connections, not the allready
established."
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mohammadzahidCommented:
yes, queries can be made to the listener after listener is down. Listener function is to authenticate new connections to the server or dispatcher. Connection that are connected to the database after listener is down or stopped are not effected.

You need to check what session is running SQL statements. This information can be pulling from library cache and by linking those SQL statement with the session id of the SQL executed those SQL.

You can get all this information from V$session, V$SQLtext, V$sqlarea. First get the Session id of user connected thru Coldfusion application.

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