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This article introduces how Ribbon consumes microservice-provider-user in a load-balanced manner. The content is very detailed. Interested friends can use it for reference. I hope it will be helpful to you.

To consume microservice-provider-user services is easy, we just need to use RestTemplate, or http tools such as HttpClient can be used. But in a cluster environment, we must deploy multiple instances per service, so what about load balancing when service consumers consume service providers?

1. Preparatory work

Start the registry: microservice-discovery-eureka

Startup provider: microservice-provider-user

Modify the port of microservice-provider-user to 8001, and start another instance

At this point, visit http://discovery:8761

You can see that there are two instances of microservice-provider-user running in Eureka.

Let's create a new microservice (microservice-consumer-movie-*) that consumes microservice-provider-user 's services in a load-balanced manner.

2.Ribbon introduction

Ribbon is an open source project released by Netflix, and its main function is to provide software load balancing algorithms on the client side to connect the middle-tier services of Netflix. The Ribbon client component provides a complete set of configuration items such as connection timeout, retry, etc. To put it simply, all the machines behind Load Balancer are listed in the configuration file, and Ribbon will automatically help you connect these machines based on certain rules (such as simple polling, immediate connection, etc.). We can also easily implement custom load balancing algorithms using Ribbon. Simply put, Ribbon is a client-side load balancer. Ribbon is divided into two steps: the first step is to select Eureka Server, which gives priority to the Server; with the same Zone and less load, and then, according to the policy specified by the user, select an address from the service registration list obtained from Server. Ribbon provides three strategies: polling, circuit breaker, and weighting based on response time.

3. Development

Create a Maven project and add the following to pom.xml:

Xsi:schemaLocation= "http://maven.apache.org/POM/4.0.0 http://m

Aven.apache.org/xsd/maven-4.0.0.xsd ">

4.0.0

Microservice-consumer-movie-ribbon

Jar

Com.itmuch.cloud

Spring-cloud-microservice-study

0.0.1-SNAPSHOT

Org.springframework.cloud

Spring-cloud-starter-eureka

Org.springframework.cloud

Spring-cloud-starter-ribbon

Org.springframework.boot

Spring-boot-starter-actuator

Startup class: MovieRibbonApplication.java. Use the @ LoadBalanced annotation to enable load balancing for RestTemplate.

@ SpringBootApplication

@ EnableDiscoveryClient

Public class MovieRibbonApplication {

/ * *

* instantiate RestTemplate and enable load balancing capacity through @ LoadBalanced annotation.

* @ return restTemplate

* /

@ Bean

@ LoadBalanced

Public RestTemplate restTemplate () {

Return new RestTemplate ()

}

Public static void main (String [] args) {

SpringApplication.run (MovieRibbonApplication.class, args)

}

}

Entity class: User.java

Public class User {

Private Long id

Private String username

Private Integer age

...

/ / getters and setters

}

Test class for Ribbon: RibbonService.java

@ Service

Public class RibbonService {

@ Autowired

Private RestTemplate restTemplate

Public User findById (Long id) {

/ / serviceId/url of the http:// service provider

Return this.restTemplate.getForObject ("http://microservice-p"

Rovider-user/ "+ id, User.class)

} Wuxi × × Hospital https://yyk.familydoctor.com.cn/20612/

}

Controller:RibbonController.java

@ RestController

Public class RibbonController {

@ Autowired

Private RibbonService ribbonService

@ GetMapping ("/ ribbon/ {id}")

Public User findById (@ PathVariable Long id) {

Return this.ribbonService.findById (id)

}

}

Application.yml

Server:

Port: 8010

Spring:

Application:

Name: microservice-consumer-movie-ribbon

Eureka:

Client:

ServiceUrl:

Instance:

PreferIpAddress: true

After startup, visit http://localhost:8010/ribbon/1 multiple times and return the result:

{

"id": 1

"username": "Tom"

"age": 12

}

Then open the console of the two microservice-provider-user instances and find that both instances output log contents similar to the following:

Hibernate: select user0_.id as id1_0_0_, user0_.age as age2_0_0_

User0_.username as username3_0_0_ from user user0_ where user0_.id=?

2016-09-13 21 o.h.type.descriptor.sql.BasicBinder 38 o.h.type.descriptor.sql.BasicBinder 56.719 TRACE 17404-[nio-8000-exec-1]

Binding parameter [1] as [BIGINT]-[1]

2016-09-13 21 o.h.type.descriptor.sql.BasicExtractor 38 o.h.type.descriptor.sql.BasicExtractor 56.720 TRACE 17404-[nio-8000-exec-1]

Extracted value ([age2_0_0_]: [INTEGER])-[12]

2016-09-13 21 o.h.type.descriptor.sql.BasicExtractor 38 o.h.type.descriptor.sql.BasicExtractor 56.720 TRACE 17404-[nio-8000-exec-1]

Extracted value ([username3_0_0_]: [VARCHAR])-[Tom]

2016-09-13 21 c.n.d.s.r.aws.ConfigClusterResolver 39 c.n.d.s.r.aws.ConfigClusterResolver 10.588 INFO 17404-[trap-executor-0]

Resolving eureka endpoints

Via configuration

So far, we have achieved load balancing on the client side through Ribbon.

So much for sharing about how Ribbon consumes microservice-provider-user in a load-balanced manner. I hope the above content can be of some help and learn more knowledge. If you think the article is good, you can share it for more people to see.

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