Notes

Spring Boot

• Eureka Server is an application that holds the information about all client-service applications. Every Micro service will register into the Eureka server and Eureka server knows all the client applications running on each port and IP address. Eureka Server is also known as Discovery Server.

@SpringBootApplication
@EnableEurekaServer
public class EurekaserverApplication {
   public static void main(String[] args) {
      SpringApplication.run(EurekaserverApplication.class, args);
   }
}

Service Registration with Eureka

@SpringBootApplication
@EnableEurekaClient
@RestController
public class EurekaclientApplication {
   public static void main(String[] args) {
      SpringApplication.run(EurekaclientApplication.class, args);
   }
   @RequestMapping(value = "/")
   public String home() {
      return "Eureka Client application";
   }
}

Spring REST with a Zuul Proxy

• Zuul API Gateway: Zuul is an L7 application gateway that provides capabilities for dynamic routing, monitoring, resiliency, security, and more.

@EnableZuulProxy
@SpringBootApplication
public class UiApplication extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(UiApplication.class, args);
    }
}

Circuit Breaker: Hystrix Clients

Netflix APIs natively

• Hystrix [Hystrix is a library from Netflix. Hystrix isolates the points of access between the services, stops cascading failures across them and provides the fallback options.]

@SpringBootApplication
@EnableHystrix
@RestController
public class HystrixappApplication {
   public static void main(String[] args) {
      SpringApplication.run(HystrixappApplication.class, args);
   }
   
   @RequestMapping(value = "/")
   @HystrixCommand(fallbackMethod = "fallback_hello", commandProperties = {
      @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000")
   })
   public String hello() throws InterruptedException {
      Thread.sleep(3000);
      return "Welcome Hystrix";
   }
   private String fallback_hello() {
      return "Request fails. It takes long time to response";
   }
}