用户问题 ：

Does Nacos only support polling for querying service online offline status Can Nacos provide a watch mechanism similar to Zookeeper

---

专家官方解答 ：

Nacos does offer a mechanism beyond simple polling for tracking the online/offline status of services, akin to the watch mechanism in Zookeeper. While the provided knowledge doesn’t directly discuss this feature in depth, Nacos does have capabilities that align with your query.

Understanding Your Inquiry: You’re essentially asking if Nacos can provide real-time notifications or updates when a service’s status changes (goes online or offline), similar to how Zookeeper facilitates watches on nodes for changes, instead of relying solely on periodic polling.

Nacos’ Capability: Nacos indeed supports a more efficient way to monitor service status changes without the need for continuous polling. It achieves this through its event-driven model and subscription mechanism. When a service instance’s status alters, Nacos can push these changes to the subscribed clients immediately, which is a more reactive approach compared to periodic polling.

How It Works in Practice:

1. Service Subscription: Clients (your applications or microservices) can subscribe to Nacos for service instance list changes. This subscription model includes registering listeners for service instances’ status updates like coming online or going offline.

2. Event Notification: Upon any change in the registered services (like a new instance being added or an existing one removed), Nacos triggers an event and notifies all the subscribed clients almost instantly.

3. Implementation Hint: To leverage this feature in your application, you would typically use Nacos’ SDKs or client libraries, configuring them to subscribe to the desired service changes. The exact implementation details would depend on the language and framework you’re using, but the Nacos documentation provides guidance for various environments.

While the specific steps for setup are not detailed here due to the nature of the provided knowledge, I encourage referring to the official Nacos documentation for the most up-to-date instructions on how to set up event listening or subscription mechanisms for service status changes.

For a deeper dive into Nacos features and configurations, including dynamic service discovery and management, refer to the official documentation at https://nacos.io/docs/latest/. This will provide comprehensive guides tailored to different use cases and development environments.

---------------

参考链接 ：

*专家经验：Nacos “status”:501,“error”:“Not Implemented”,“message”:“no such api:…”,“path”:“…

*专家经验：Nacos 欢迎你

*专家经验：Nacos 介绍

---------------

答疑服务说明：

本内容经由技术专家审阅的用户问答的镜像生成，我们提供了专家智能答疑服务，在页面的右下的浮窗”专家答疑“。您也可以访问 : 全局专家答疑 。 咨询其他产品的的问题

反馈

如问答有错漏，欢迎点：差评给我们反馈。