官方：
https://github.com/alibaba/Sentinel/wiki/%E4%BB%8B%E7%BB%8D
As microservices become popular, the stability of service calls is becoming increasingly important. Sentinel takes “flow” as the breakthrough point, and works on multiple fields including flow control, circuit breaking and load protection to protect service reliability. —[摘自官网]
官方：https://nacos.io/zh-cn/index.html
英文缩写：Name Configurations 表示注册中心和配置中心
Nacos 致力于帮助您发现、配置和管理微服务。Nacos 提供了一组简单易用的特性集，帮助您快速实现动态服务发现、服务配置、服务元数据及流量管理。
官方：https://spring.io/projects/spring-cloud-alibaba
Spring Cloud Alibaba provides a one-stop solution for distributed application development. It contains all the components required to develop distributed applications, making it easy for you to develop your applications using Spring Cloud.
With Spring Cloud Alibaba, you only need to add some annotations and a small amount of configurations to connect Spring Cloud applications to the distributed solutions of Alibaba, and build a distributed application system with Alibaba middleware.