How is an Oracle shared server configured?

How is an Oracle shared server configured?

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To configure an Oracle shared server, the following processes must be set to run on the server:

Listener process: A listener process contains the addresses of all the dispatchers in the Oracle shared server. The job of a listener is to constantly look out for user requests. Whenever it finds a user request, it returns the address of the least heavily loaded dispatcher to which the user process can connect. A listener process is configured by using a centralized listener configuration file called listener.ora.

Dispatcher process: At least one dispatcher process must be running on an Oracle server in order to make it behave as an Oracle shared server. However, there must be a minimum of one dispatcher process configured for each network protocol used for a connection with the Oracle shared server. The job of a dispatcher process is to send user requests to a pool of Oracle server processes. After an Oracle server process has executed a request, the process sends the result back to the dispatcher that had sent the request. Consequently, the dispatcher sends the result to the user process.

Configuring the DISPATCHERS initialization parameter in the initialization parameter file starts the preset number of dispatcher processes when an Oracle instance is started. The maximum number of dispatchers process that can be started is determined by the MAX_DISPATCHERS initialization parameter.

Shared server process: At least one shared server process must be running on an Oracle server in order to make it behave as an Oracle shared server. In an Oracle shared server configuration, Oracle starts a fixed number of shared server processes when an Oracle instance starts. These server processes work in a round-robin fashion to serve requests from multiple user processes. Shared server processes terminate when the associated Oracle instance is terminated.

The number of shared server processes to be started at the instance startup is determined by the SHARED_SERVERS initialization parameter. The maximum number of shared server processes that can be started is determined by the MAX_SHARED_SERVERS initialization parameter.

Note: In order to configure an Oracle shared server, Oracle requires Oracle Net Services or SQL*Net version 2. Also, to use an Oracle shared server, a user process must connect through Oracle Net Services or SQL*Net version 2, even if the user process and the shared server process are running on the same computer.

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