SQL*Net is a version of Oracle Network services that has been deprecated since Oracle 9i.
It is important to understand that there are many different configurations for listeners, and, as the figure below illustrates, many Oracle listeners can exist on the same Oracle server. These include
- SQL*Net version 1 listeners,
- SQL*Net version 2 listeners, and
- Oracle Net listeners.
In addition, a listener can be defined as a dedicated listener or a multi-threaded server listener. Finally, for SQL*Net version 2 and above, you can have separate listeners for different protocols.
- The MTS is commonly used on servers where resources are scarce and there are very high volumes of incoming connections. We will discuss the MTS in detail in the second course in this series.
- Multi-protocol listeners are the separate SQL*Net version 2 or Oracle Net listeners that are defined to handle incoming SNMP, SPX, or other protocols.
Again, it is important to understand that the purpose of the listener process is to establish connections on behalf of the remote transaction. After establishing the connection, the listener disconnects from the process.
The next lesson discusses how to configure the Oracle listener.