Oracle RAC study note-- Node Applications

Node Applications

A number of node applications are automatically configured on each RAC instance.
If the node applications are enabled they will be automatically started when the node is booted. they can also be stared and stopped using the SRVCTL utility.

Listener
--The listener process runs on each node and listens for incoming connection requests from clients that are then redirected to an appropriate instance.
--The Listener process is responsible for managing connections for both dedicated and shared servers. It also behaves as an intermediary in the workload-balancing mechanism
--In a single-instance environment, the listener process runs as a daemon process and is usually started using the LSNCTL utiliy.
--In a RAC environment, the listener process is configured to run as a node application within the OCR. while the listener can still be started , stopped, and refreshed using teh LSNRCTL utility, it is normally managed with the other node applications using the SRVCTL utility.

Oracle Notification Service(ONS)
Oracle Notification Service(ONS) is used by Oracle Clusterware to propagatec传播 messages both within the RAC cluster and to clients and application-tier systems. ONS uses a publish-and-subscribe method to generate and deliver event messages to both local and remote consumers.

ONS provides the foundation for Fast Application Notification(FAN) , which in turn provides the basis for Fast Connection Failover(FCF)


Virtual IP(VIP)

Global Services Daemon(GSD)