Ribbon load balancing principle and some source codes

Black horse programmer -Ribbon Load balancing source code

Premise ： Service providers have multiple service clusters , Otherwise, if there is only one service , Also load balancing a hammer ！
Ribbon Basic principles of load balancing ：
1、Ribbon Will intercept Eureka Client From the client http request , Get service name （userservice）
2、 from Eureka Pull the dynamic service list from （8081、8082.....）
3、 Choose a service from it （ Such as 8081） come out （ polling 、 Random equal algorithm ）
4、 To call this service

The detailed steps ：

1、 Client initiated http request , For example, use RestTemplate launch ;
2、LoadBalancerInterceptor Load balancing interceptors , It will block all initiated by this client http request , To analyze , Access to services ID（ Instance name example ：userservice）;

3、 Through this instance name , from Eureka Pull the dynamic service list from ;
4、Eureka Back to the list of services , here LoadBalancerInterceptor The load balancing interceptor gets all the service instances ;

5、 Use IRule Interface for load balancing ,IRule Rule interfaces include ： Client custom rules 、 polling 、 Random 、 Retry and other load balancing algorithms ：
6、 Use the one specified by the client , Or the default load balancing algorithm , Select one from the list of services , Return to RibbonLoadBanlancerClient（Ribbon Load balancer client ）

7、RibbonLoadBanlancerClient（Ribbon Load balancer client ） Use real ip And port （http://127.0.0.1:8080/user/1） Replace The original “ service name + route ”(http://userservice/user/1), And make a request
8、 Final , Request to the corresponding server selected after load balancing

When using @LoadBalanced When the annotation , Automatically called spring-cloud Medium Ribbon Components are load balanced , We just need to configure Ribbon Our algorithm can be used as we like