Oracle Database - Service Handler

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Service handlers act as connection points from the listener to an Oracle database.

A service handler can be a:

You can configure it for a client connection in the connect descriptor with the SERVER parameter.

How to see which service handler is configured?

To see which service handler is configured for a service, enter this command:

lsnrctl SERVICES [listener_name]

The SERVICES command lists the services supported by the database, along with at least one available service handler. In the example belwo, it's a dedicated server process.

[oracle@oel11g tmp]$ lsnrctl SERVICES listener

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 23-JUL-2010 13:16:34

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=oel11g.localdomain)(PORT=1521)))
Services Summary...
Service "oel11g.localdomain" has 1 instance(s).
  Instance "oel11g", status READY, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:0 refused:0 state:ready
         LOCAL SERVER
Service "oel11gXDB.localdomain" has 1 instance(s).
  Instance "oel11g", status READY, has 1 handler(s) for this service...
    Handler(s):
      "D000" established:0 refused:0 current:0 max:1022 state:ready
         DISPATCHER <machine: oel11g.localdomain, pid: 11508>
         (ADDRESS=(PROTOCOL=tcp)(HOST=oel11g.localdomain)(PORT=42593))
The command completed successfully

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