registry

注册中心
Eureka

Eureka自我保护机制

springcloud服务已经关但是Eureka还是显示up，该状态持续很久，访问该服务也返回错误，但在注册中心界面，该服务却一直存在，且为UP状态，并且在大约十分钟后，出现一行红色大字：EMERGENCY! EUREKA MAY BE INCORRECTLY CLAIMING INSTANCES ARE UP WHEN THEY’RE NOT. RENEWALS ARE LESSER THAN THRESHOLD AND HENCE THE INSTANCES ARE NOT BEING EXPIRED JUST TO BE SAFE.
原因：自我保护机制。Eureka Server在运行期间，会统计心跳失败的比例在15分钟之内是否低于85%，如果出现低于的情况（在单机调试的时候很容易满足，实际在生产环境上通常是由于网络不稳定导致），Eureka Server会将当前的实例注册信息保护起来，同时提示这个警告。

进程间通信

Feign

负载均衡

客户端负载均衡
Ribbon

分布式配置中心

Spring Cloud Config
动态刷新
http://blog.didispace.com/springcloud4-2/
消息总线

dependency

动态刷新

使用限制

@RefreshScope @Configuration 不能同时在一个类上使用
原因说明：

@RefreshScope works (technically) on an @Configuration class, but it might lead to surprising behaviour: e.g. it does not mean that all the @Beans defined in that class are themselves @RefreshScope. Specifically, anything that depends on those beans cannot rely on them being updated when a refresh is initiated, unless it is itself in @RefreshScope (in which it will be rebuilt on a refresh and its dependencies re-injected, at which point they will be re-initialized from the refreshed @Configuration).

参考：
https://stackoverflow.com/questions/45137555/refreshscope-not-working-spring-boot
http://projects.spring.io/spring-cloud/spring-cloud.html#_refresh_scope