How To Register Listener In Oracle

Oracle Database Service Listener Registration and Oracle Service Names (KBA5885)

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Issue

The premise backside this commodity is to wait at how Oracle performs its registration of databases services within Oracle listeners and how these facilitate SQLNet based connections (network based connections) to Oracle databases.

Applicable Delphix Versions

Click hither to view the versions of the Delphix engine to which this article applies

Major Release	All Sub Releases
six.0	6.0.0.0, six.0.ane.0, 6.0.1.1, 6.0.two.0
5.iii	five.three.0.0, 5.three.0.i, v.3.0.two, v.3.0.3, 5.3.ane.0, five.iii.1.1, v.3.1.2, v.three.ii.0, 5.3.three.0, 5.iii.3.i, 5.3.4.0, v.3.5.0 5.3.vi.0, v.3.7.0, v.iii.7.ane, v.iii.8.0, 5.three.eight.1, five.iii.9.0
5.2	five.two.ii.0, v.ii.two.1, 5.ii.3.0, v.2.four.0, 5.2.v.0, 5.2.5.1, 5.ii.half-dozen.0, 5.2.half dozen.i
5.one	v.1.0.0, 5.1.1.0, v.1.two.0, 5.1.3.0, 5.1.4.0, 5.one.5.0, 5.i.5.one, 5.ane.six.0, 5.1.7.0, 5.1.8.0, v.i.8.1, 5.1.9.0, 5.one.10.0
5.0	5.0.one.0, 5.0.1.1, 5.0.2.0, 5.0.2.one, 5.0.2.2, v.0.ii.three, five.0.3.0, v.0.3.1, v.0.4.0, 5.0.4.1 ,v.0.5.0, 5.0.5.1, 5.0.5.two, v.0.five.iii, 5.0.5.4
4.three	iv.3.ane.0, 4.three.2.0, 4.3.2.i, iv.3.3.0, 4.iii.iv.0, 4.3.4.1, 4.3.five.0
4.ii	4.2.0.0, four.2.0.3, four.2.1.0, 4.two.one.ane, iv.2.2.0, 4.ii.2.1, 4.ii.3.0, 4.2.iv.0 , 4.2.five.0, 4.2.v.ane
four.one	four.1.0.0, 4.1.2.0, four.1.3.0, 4.1.3.i, 4.1.3.2, 4.1.4.0, 4.1.5.0, 4.1.six.0

Resolution

TO PROVIDE INSIGHT INTO HOW ORACLE DATABASES REGISTER THEMSELVES IN ORACLE LISTENERS, this includes Delphix Virtualised Oracle Databases (VDB's) and Oracle sources (dSources) used past Delphix. The database parameter settings that influence the database behaviour around service registration and the commands that can be used to examine both the database and listener configuration are detailed and explained to ensure that the correct Oracle database services are registered in an appropriate Oracle listener.

How does an Oracle database register itself and its services in an Oracle Listener?

The Oracle Database uses a combination of database parameters and an Oracle background process to perform what is termed service registration.  When a database starts Oracle uses the background process PMON (older versions 11.2 and earlier) or LREG (12c and college) to perform the registration of all services defined by the service_names parameter in a specific listener.  Oracle uses the local_listener parameter to locate a specific listener to perform the registration and in the absence of the local_listener parameter a default listener would exist used (a listener utilizing listener port 1521).  For Oracle RAC databases the remote_listener parameter comes into play and services are cross registered against all SCAN listeners that may be running beyond up to iii of the nodes in the cluster.  In that location is likewise the listener_networks parameter that can be used to control listener registration in a more complex style, yet this is not often used and will not be discussed hither.  Oracle RAC Database service registration volition be examined in a carve up article.

Parameters used for listener registration.

• db_name - the proper name the database was given when it was created.
• db_unique_name - a unique name that allows the database to be globally recognized across the organization.
• db_domain - a domain name used by the database in registering services that is appended to the db_unique_name for uniquely identifying a database.
• service_names - a comma separated listing of service names that the database will register confronting its listener(south).
• local_listener - A TNS alias or Oracle SQLNet address string used to locate a specific listener or set of listeners that the databases services will be registered within.

Listener Registration Process Diagram.

By default an Oracle Database will register a default service using the db_unique_name and db_domain parameter settings in the format db_unique_name.db_domain.  If neither of these is specified then db_unique_name will default to db_name and this will be used.  This default service can be used without effect nonetheless Oracle recommends that not-default services be used for stop user and applications.  Given this, Oracle DBA's will frequently set there own services via the service_names parameter and these would be registered in the listener pointed to by the local_listener parameter setting.

In the diagram below local_listener is set up to a complete address cord ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.125)(PORT=1521)).

This aligns with the listener endpoint for the listener named "LISTENER" where its listening endpoint is (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oelsiasm1)(PORT=1521))).  The host oelsiasm1 resolves to the IP address 192.168.0.125.

Database Parameters relevant to Listener Service Registration.

To view the database side settings linked to service names and service registration execute the following SQL.

SQL> ready pages 500 SQL> set lines 300 SQL> col proper noun format a20 SQL> col value format a80 SQL> col isdefault format a10 SQL> select proper noun,value,isdefault from 5$parameter       where lower(name) in ('db_name','db_unique_name','db_domain','instance_name','service_names','local_listener')       order past proper name;       NAME                 VALUE                                                     ISDEFAULT -------------------- --------------------------------------------------------- ---------- db_domain                                                                      Simulated db_name              src121                                                    FALSE db_unique_name       src121                                                    FALSE instance_name        src121                                                    TRUE local_listener       (Accost=(PROTOCOL=TCP)(HOST=192.168.0.125)(PORT=1521))   TRUE service_names        src121,plb121_svc                                         FALSE                  

Listener Listening Endpoints.

To view the listeners endpoint configuration.

Notation:

The output below has been edited to highlight simply the listener endpoint information and where its configuration file, the listener.ora, is held.

[oracle@oelsiasm1 ~]$ lsnrctl status listener  LSNRCTL for Linux: Version 12.ii.0.i.0 - Product on 15-MAY-2020 ten:26:28  Copyright (c) 1991, 2016, Oracle. All rights reserved.  Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521)) Status of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 18.0.0.0.0 - Production Starting time Appointment 14-MAY-2020 17:41:54 Uptime 0 days 16 hr. 44 min. 35 sec Trace Level off Security ON: Local Os Authentication SNMP OFF Listener Parameter File /u01/app/grid/18c/network/admin/listener.ora Listener Log File /u01/app/grid/diag/tnslsnr/oelsiasm1/listener/alert/log.xml  Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oelsiasm1)(PORT=1521)))                  

The unix control nslookup can be used to map the hostname oelsiasm1 to and IP Address, in this case, 192.168.0.125.

[oracle@oelsiasm1 ~]$ nslookup oelsiasm1  Server:  192.168.0.111 Address: 192.168.0.111#53  Name: oelsiasm1.plb.internal Accost: 192.168.0.125                  

What is now in play given the configuration of the listener and the database?

Given the configuration in play, the local_listener parameter (local_listener='(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.125)(PORT=1521))')  is telling the database src121 (db_name=src121, db_unique_name=src121) to register the services src121,plb121_svc (service_names=src121,plb121_svc) against the listener whose endpoint is (Description=(ADDRESS=(PROTOCOL=tcp)(HOST=oelsiasm1)(PORT=1521))).

Listener Service Registration Details

To check the services are correctly registered with the Oracle listener LISTENER and endpoint(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oelsiasm1)(PORT=1521))) on the target host execute the following control.

Note:

The control output has been edited for clarity.

[oracle@oelsiasm1 ~]$ lsnrctl services listener  LSNRCTL for Linux: Version 12.two.0.1.0 - Production on 15-MAY-2020 10:46:01  Copyright (c) 1991, 2016, Oracle. All rights reserved.  Connecting to (Accost=(PROTOCOL=tcp)(HOST=)(PORT=1521)) Services Summary... .. Service "plb121_svc" has 1 instance(south).    Instance "src121", condition READY, has i handler(southward) for this service...      Handler(south):         "Defended" established:15 refused:0 state:ready            LOCAL SERVER Service "src121" has 1 instance(s).    Instance "src121", status READY, has 1 handler(s) for this service...      Handler(s):         "Dedicated" established:15 refused:0 land:ready           LOCAL SERVER .. The command completed successfully                  

This services summary tells you the Service plb121_svc is registered in the listener named LISTENER. The listener,  when a new connexion request comes in with this service_name plb121_svc in its connect string will be redirect the connection to the database instance src121where a new database session volition be established.

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Source: https://support.delphix.com/Continuous_Data_Engine_(formerly_Virtualization_Engine)/Oracle/Oracle_Database_Service_Listener_Registration_and_Oracle_Service_Names_(KBA5885)

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