To access previous blog, click this link: – Tutorial 02 – Spring Cloud – Netflix Eureka Server

Publish Microservice to Eureka Server

Every Microservice must be published/ registered with Eureka Server (R&D Server) by becoming Eureka Client
We must create a microservice using Spring Rest Controller to offer support.

The @EnableEurekaClient annotation is not required anymore from spring 3.x onwards. Simply adding spring-cloud-starter-netflix-eureka-client to dependencies will enable the client. If you want to disable it, set the property value of eureka.client.enabled to false.

Procedure for MS Development and Publishing with Eureka Server

Step 1: –

Make sure one Spring Boot project already developed and running as Eureka Server. Make sure Server is running on default port 8761.  [Watch previous tutorial for creating Eureka Server]

Step 2: –

Create Spring Boot Starter project adding Spring Web, “EurekaDiscoveryClient” Dependencies.

Step 3: –

Place @EnableEurekaClient annotation on the top of Main class.

package com.limit;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class CurrencyExchangeServiceApplication {

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

}

Step 4: –

Add the following entries in application.properties file

spring.application.name=currency-exchange-service
server.port = 8000
spring.cloud.config.enabled=false
eureka.client.service-url.default-zone=http://localhost:8761/eureka

Step 5: –

Develop Rest Controller representing the microservices.

package com.limit.controller;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping(“/api/eureka”)
public class CurrencyExchangeController1 {

public ResponseEntity<String> showMessage() {
return new ResponseEntity<String>(“Welcome to Currency Exchange Microservice”, HttpStatus.OK);
}

}

Step 6: –

Run the Microservice Project as Spring Boot application.

This process automatically publishes microservice to Eureka Server

Step 7: –

Check out the instance section by refreshing the Eureka Server home page at [http://localhost:8761].

This method of successfully publishing microservices on Eureka.

Intra Communication between Microservices

In order for two microservices to communicate with one another, they both need to be published on the Eureka Server.

In this case, before any interaction occurs, the Producer and Consumer services will both be published to Eureka Server.

Through Eureka Server, the Consumer microservice will locate and obtain the Provider microservice’s details by providing its Service ID during intra-microservice communication. The “Client Component” is a unique component that the Consumer microservice needs to use for this.
The Client component or Client type component also helps to choose one instance of Provider MS among the multiple instances based on Load Factor.
The work of Client component is: –

Obtaining a Producer microservice instance from Eureka Server by supplying its Service ID. (If necessary, does Load Balancing).
Gather Producer microservice data such as URL/URI, method type, PATH, and so on from the Service Instance.
Passing the above-mentioned data to the Consumer microservice’s Rest Template to create a Rest Template that sends an HTTP request to the Producer microservice and receives an HTTP response from the Producer microservice.

As of now In Eureka Server environment 3 types of “Client Component” are possible.

Discovery Client Component (Legacy, No support for Load Balancing).
Load Balancer Client Component (Good, Perform Load Balancing).
Feign Client Component (Best, Support all approached and Load Balancing).

The forthcoming tutorial will cover type of Client Component.