What should have in equal tnsnames,ora and listener.ora?

Question

Hi forum members again I'm very new in oracle, and I'm trying to create a sucessfull net service name, using oracle net configuration assitant, but when I try to test it I got this error, .***"""ORA-12514: TNS:listener does not currently know of service requested in connect descriptor."""*** And I have read that tnsnames.ora and listener.ora should have some parameters in common, but exactly I don't know, Do you know what parameters should be? or The ORA-12514 problem , doesn't have relation with the tnsnames.ora and listener files?, If doesn't wich is the reason of this message?
By the way I put what contain these files:
---------------------------------------------------------------------------listener.ora
# listener.ora Network Configuration File: /opt/oracle/product/10.1.0.3/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = oracle.gentoo)
(ORACLE_HOME = /opt/oracle/product/10.1.0.3)
(SID_NAME = oracle)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
SAVE_CONFIG_ON_STOP_LISTENER = TRUE
TRACE_LEVEL_LISTENER = USER
/////////////////////////////////////////////////////////////////////////////tnsnames.ora
# tnsnames.ora Network Configuration File: /opt/oracle/product/10.1.0.3/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
NORACLE =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = tux)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = noracle)
By the way what must be the username and the pasword that ask the ORACLE CONFIGURATION ASSINTANT to test the net service name? Must be the user name and password of the system user?
Thanks in advance

Answer 1

OK, here we go ... extra long as I intend to bookmark this and make reference, as this is a very common question ... skip to the bottom if you want my guess to the solution.
Oracle Net Services (formerly SQL*Net, Net8, Oracle Networking) has two parts - the client and the server side. I'll discuss the server first, then the client.
1) Server, and specifically Listener:
The Oracle Listener is a monitor that listens for Oracle service requests on one or more ports. Usually this is on TCP/IP port 1521. When it gets an Oracle request from any network client, it checks whether it's in the list of Oracle Services for which it is monitoring. If found, it will contact that service, request a connection for the client, tell the service and client where and how to connect, and get itself out of the loop.
Notes:
a) It can listen on behalf of any number of services;
b) A service can be a database instance, an EPG service (the DBMS_EPG is the replacement for Apache in the database in 10gR2), an external job, etc;
c) One listener can listen on behalf of multiple database instances;
d) The services can be listed in the LISTENER.ORA or they can self-register;
e) If databases self-register, they use the initialization parameter LOCAL_LISTENER
f) If self-registering, the listener should be up before the database
g) Shutting down the listener will stop future connections, but has no impact on existing ones.
One frequent point of confusion - a connection request on the local machine may loop out to the network and contact the listener, or it may bypass the listener entirely and use a bequeath adapter. The 'beq' connection is the 'normal' connection by "sqlplus / as sysdba" or "sqlplus system/manager" on the local machine (note that no @instance was used ... in *nix, that is derived from the $ORACLE_SID environment variable)
In your listener.ora, you specify global_dbname=oracle.gentoo and sid_name=oracle. I assume therefore you can find an initoracle.ora or spfileoracle.ora somewhere on your system.
2) Client:
A client that wants to connect to an Oracle service uses the client side of the Oracle Net Services. The definition of client includes: any Oracle client utiltiy (SQLPlus, SQLLoad, Forms, Reports, etc.); an Oracle database instance that wants to make a external procedure call or a dblink; third party tools such as ODBC and JDBC.
In SQL*Net version 1 the connection was made by specifying the target in the connect string ("user/password@host:listener_port:sid") and that is also used these days by many JDBC drivers, especially the Oracle Thin JDBC driver. Oracle's Easy connection mechanism uses a similar variant.
Since SQL*Net Version 2, Oracle has supported the concept of alias translation. Basically it's very similar in concept to DNS - give it the name of the service and tell it where to find the translation table. The translation tables include TNSNAMES.ORA, ONAMES servers (deprecated in 10g), LDAP usng Oracle's OiD. The choice of translation table, and alternate order if the lookup fails in one, is stored in the SQLNET.ORA (if one exists).
Assuming TNSNAMES.ORA, the chain of events is:
- get the alias to look up (in your case NORACLE);
- if the SQLNET.ORA has a DEFAULT_DOMAIN setting, (often =WORLD) append a dot and that value to the alias;
- go to the TNANSMES.ORA file pointed by the TNS_ADMIN variable (environment or registry), or (if not set) the one in the $ORACLE_HOME/network/admin directory;
- look up the first occurance of the alias;
- if found, use the protocol specified to request a connection to the host, usin DNS to unravel the host to an IP address if necessary (in your case TCP/IP, to TUX) ;
- if host connection if made, connect to the listener that is configured for that port (in your case 1521);
- if listener is there, ask it for connection to the service (in your case, you are asking for instance 'noracle');
i if the listener knowwss about the service, it will hand off the request.
Your problem appears to be asking for instance 'noracle' in the tnsnames but listeneing for 'oracle' at the listener. Of course, I can not see any auto-registered instances which you would get from "lsnrctl status" on the server.