# Dubbo Microservice Registration and Discovery

# Local Application Development

# Prerequisites

Before using Spring Boot to develop Dubbo microservice applications, please confirm that you have done the following:

Download Maven (opens new window) and set environment variables.
Download the latest Nacos Server (opens new window).
Follow the steps below to start Nacos server.
1. Unzip the Nacos server package.
2. Go to the nacos/bin directory and start Nacos server.

Tips

Linux/Unix/Mac system: sh startup.sh -m standalone
Windows system: double-click the file startup.cmd

# Create a Service Provider

Create a Maven project named spring-boot-dubbo-provider.

Add dependencies in the pom.xml file. Here takes Spring Boot 2.1.6.RELEASE as an example.

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.1.6.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>io.terminus.boot.rpc</groupId>
            <artifactId>dubbo-light-provider</artifactId>
            <version>2.1.6-RELEASE</version>
        </dependency>
    </dependencies>

Develop Dubbo service providers. Dubbo services are provided as interfaces.

Create package: io.terminus.erda.trial.demo.hellodubbo under the path src/main/java.

Create an interface EchoService under io.terminus.erda.trial.demo.hellodubbo which contains an echo method.

package io.terminus.erda.trial.demo.hellodubbo;

public interface EchoService {
    String echo(String name);
}

Create a class EchoServiceImpl under io.terminus.erda.trial.demo.hellodubbo to implement this interface.

package io.terminus.erda.trial.demo.hellodubbo;

import org.apache.dubbo.config.annotation.Service;;


import java.util.concurrent.TimeUnit;

@Service
public class EchoServiceImpl implements EchoService {

    public String echo(String name) {
        long start = System.currentTimeMillis();

        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
        }

        long end = System.currentTimeMillis();
        return "\r\n\t" + start + " Provider received." +
                "\r\n\t\tProvider processed after sleep 1 second! Echo String: \"" + name + "\"" +
                "\r\n\t" + end + " Provider Return";

    }
}

Tips

The service annotation here is an annotation class provided by Dubbo. The full name of the class is org.apache.dubbo.config.annotation.Service.

Configure Dubbo service.
- Create application.properties or application.yml file under the path src/main/resources and open it.
- Add the following configuration in application.properties or application.yml:
```
spring:
  application.name: dubbo-spring-boot-provider
dubbo:
  application.name: dubbo-spring-boot-provider
  protocol:
    name: dubbo
    port: 20880
  registry:
    address: nacos://${NACOS_ADDRESS:127.0.0.1:8848}?namespace=${NACOS_TENANT_ID:}
  scan:
    base-packages: io.terminus.erda.trial.demo.hellodubbo
```
  Tips
  - There is no default value for the configuration above and specific configuration must be provided.
  - The value prefix of dubbo.registry.address must start with nacos://, and the IP address and port are the Nacos server address. In the code sample, it is the local address. If the Nacos server is deployed on other machines, please change it to the actual IP address.
  - The value of dubbo.scan.base-packages needs to be exposed to external calls in the code. When there are multiple packages with @Service annotated classes, separate them by commas.

Develop and start the Spring Boot entry class DubboProvider.

package io.terminus.erda.trial.demo.hellodubbo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

Log in to the Nacos console http://127.0.0.1:8848, and in the left navigation bar select Service List > Provider List, which already contains io.terminus.erda.trial.demo.hellodubbo.EchoService, and you can query the service group and provider IP of the service.

# Create a Service Consumer

Create a Maven project named spring-boot-dubbo-consumer.

Add dependencies in the pom.xml file. Here takes Spring Boot 2.1.6.RELEASE as an example.

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.1.6.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>io.terminus.boot.rpc</groupId>
            <artifactId>dubbo-light-consumer</artifactId>
            <version>2.1.6-RELEASE</version>
        </dependency>
    </dependencies>

Develop Dubbo consumers.

Create package: io.terminus.erda.trial.demo.hellodubbo under the path src/main/java.

Create an interface EchoService under io.terminus.erda.trial.demo.hellodubbo which contains an echo method.

package io.terminus.erda.trial.demo.hellodubbo;

public interface EchoService {
    String echo(String name);
}

Develop Dubbo service calls. For example, to call a remote Dubbo service in the controller, the code sample is as follows:

package io.terminus.erda.trial.demo.hellodubbo;

import org.apache.dubbo.config.annotation.Reference;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoConsumerController {
    @Reference
    private EchoService demoService;

    @RequestMapping(value = "/ping", method = RequestMethod.GET)
    public Boolean ping() {
        try {
            String pong = demoService.echo("ping");

            System.out.println("Service returned: " + pong);
            return pong.contains("ping");
        } catch (Throwable t) {
            t.printStackTrace();
            return false;
        }
    }
    @RequestMapping(value = "/consumer-echo/{str}", method = RequestMethod.GET)
    public String feign1(@PathVariable String str) {
        long start = System.currentTimeMillis();

        String result = demoService.echo(str);

        long end = System.currentTimeMillis();
        return "" + start + " Consumer received." +
                "\t" + result +
                "\r\n" + end + " Consumer Return";
    }
}

Tips

The reference annotation here is org.apache.dubbo.config.annotation.Reference.

Add the following configuration in application.properties or application.yml:
```
spring:
  application.name: dubbo-spring-boot-consumer
dubbo:
  application.name: dubbo-spring-boot-consumer
  registry:
    address: nacos://${NACOS_ADDRESS:127.0.0.1:8848}?namespace=${NACOS_TENANT_ID:}
```
Tips
- There is no default value for the configuration above and specific configuration must be provided.
- The value prefix of dubbo.registry.address must start with nacos://, and the IP address and port are the Nacos server address. In the code sample, it is the local address. If the Nacos server is deployed on other machines, please change it to the actual IP address.

Develop and start the Spring Boot entry class DubboConsumer.

package io.terminus.erda.trial.demo.hellodubbo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

Log in to the Nacos console http://127.0.0.1:8848, and in the left navigation bar select Service List > Consumer List, which already contains io.terminus.erda.trial.demo.hellodubbo.EchoService, and you can query the service group and consumer IP of the service.

# Verification Results

`curl http://localhost:8088/ping`
true

# Deploy the Application to Erda

When deploying an application to Erda, note that Erda will inject the following variables of application.yml:

spring:
  application.name: dubbo-spring-boot-provider
dubbo:
  application.name: dubbo-spring-boot-provider
  protocol:
    name: dubbo
    port: 20880
  registry:
    address: nacos://${NACOS_ADDRESS:127.0.0.1:8848}?namespace=${NACOS_TENANT_ID:}
  scan:
    base-packages: io.terminus.erda.trial.demo.hellodubbo

spring:
  application.name: dubbo-spring-boot-consumer
dubbo:
  application.name: dubbo-spring-boot-consumer
  registry:
    address: nacos://${NACOS_ADDRESS:127.0.0.1:8848}?namespace=${NACOS_TENANT_ID:}

Modify dice.yml and add the dependency of register v2.0.

After the service is deployed, Erda will automatically inject two environment variables:

NACOS_ADDRESS
NACOS_TENANT_ID

Click on the registration center to view the registered services.

# Local Connection to the Registration Center

When using Nacos, configure the following environment variables:

NACOS_ADDRESS
NACOS_TENANT_ID

When using ZooKeeper, configure the following environment variables:

ZOOKEEPER_DUBBO
DUBBO_TENANT_ID