With the development of the Internet, distributed system architecture has attracted more and more attention and application. In a distributed architecture, the number and complexity of services will increase significantly. In order to ensure high availability and high performance of the system, service governance and current limiting have become one of the issues that must be solved. This article will introduce the service governance and current limiting implementation method based on Spring Boot.
1. Service Governance
Service governance is a very important part of the distributed architecture, and it is even more essential in the microservice architecture. Spring Cloud, as a microservice framework based on Spring Boot, provides a complete solution for service governance.
When a service is called by multiple clients, how to spread the requests to multiple service instances to achieve load balancing. Spring Cloud provides a Ribbon load balancing component, which can obtain a list of service instances in the service registration center and use a specific load balancing algorithm to send requests to each service instance.
In a distributed system, some services need to call other services, so a centralized service registration and discovery mechanism is needed. Spring Cloud provides Eureka components, which can realize automated service registration and discovery functions. Developers only need to introduce the Eureka client dependency, register the service in the Eureka server, and then discover and call it through the service name.
In the microservice architecture, communication between services can be implemented using various protocols such as HTTP, TCP, and AMQP. Spring Cloud provides the Feign component, which can implement inter-service communication by defining annotations on the interface. The specific implementation is as follows:
Define Feign client:
@FeignClient(name = "user-service") public interface UserService { @GetMapping("/user/{id}") User findUserById(@PathVariable("id") Long id); }
Call the service:
@Autowired private UserService userService; public User getUserById(Long id) { return userService.findUserById(id); }
Through the above method, you can use Feign to implement calls between services.
2. Current Limiting
In the microservice architecture, current limiting is a very necessary measure, which can avoid system collapse caused by service overload. Spring Cloud provides a variety of current limiting solutions.
Hystrix is a fault-tolerant framework open sourced by Netflix, which can realize service degradation, fault isolation, circuit breaker and other functions. In Spring Cloud, current limiting can be achieved by using Hystrix components.
Code example:
@RequestMapping("/getUser/{id}") @HystrixCommand(fallbackMethod = "getUserFallback") public User getUser(@PathVariable("id") Long id) { return userService.getUserById(id); } // fallback回调方法 private User getUserFallback(Long id) { return new User(id, "defaultUsername", "defaultPassword"); }
By adding the @HystrixCommand annotation on the requested method and specifying the fallback callback method, when the service call fails or times out, the fallback method will be called to return the default value. Avoided service crash.
Spring Cloud Gateway provides a way to implement current limiting through annotations. You can implement interface limiting by adding the @RequestRateLimiter annotation on the route. Flow, the specific implementation method is as follows:
Define the current limiter:
@Bean RedisRateLimiter redisRateLimiter() { return new RedisRateLimiter(1, 1); }
Add the current limiting annotation to the route:
@Bean public RouteLocator customRouteLocator(RouteLocatorBuilder builder) { return builder.routes() .route(r -> r.path("/user/**") .filters(f -> f.requestRateLimiter(c -> c.setRateLimiter(redisRateLimiter()))) .uri("lb://user-service")) .build(); }
By adding the @RequestRateLimiter annotation on the route, you can Limit the current flow on the interface to avoid service overload.
To sum up, Spring Cloud provides a complete service governance and current limiting solution. Developers can choose appropriate components to implement service governance and current limiting according to the actual situation.
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