初始化參數
SERVICE_NAMES
列出實例所屬的服務。在啟動時，每個實例及其屬于相同服務的其他實例，被注冊到所有監聽器。在數據庫操作期間，每個服務的實例將 CPU
使用和當前的連接計數等有關信息， 傳遞給監聽相同服務的所有監聽器。這種通信實現了動態負載平衡和連接的故障轉移
Service Registration：
Service registration is a feature by which the PMON process dynamically registers instance information with a listener, which enables the listener to forward client connection requests to the appropriate service handler. PMON provides the listener with information about thefollowing:
1.Names of the database services provided by the database 2.Name of the database instance associated with the services and its current and maximum load 3.Service handlers (dispatchers and dedicated servers) available for the instance, including their type, protocol addresses, and current and maximum load
Service registration is dynamic and does not require configuration in the listener.ora file. Dynamic registration reduces administrative overhead for multiple databases or instances.
The initialization parameter SERVICE_NAMES lists the services an instance belongs to. On startup, each instance registers with the listeners of other instances belonging to the same services. During database operations, the instances of each service pass information about CPU use and current connection counts to all listeners in the same services. This communication enables dynamic load balancing and connection failover.
