IDL defines cross-language services

Demo from zero how to define Dubbo service based on IDL and use Triple protocol

Using IDL to define services has better cross-language friendliness. For new users of Dubbo3, we recommend this method. However, the Triple protocol is not strongly bound to IDL. You can also use Java Interface + Pojo to define services and enable the Triple protocol. For details, see Example.

For more usage of Triple and IDL, please refer to official samples

precondition

JDK version >= 8
Installed Maven

Create project

First create an empty maven project

$ mvn archetype:generate \
    -DgroupId=org.apache.dubbo \
    -DartifactId=tri-stub-demo \
    -DarchetypeArtifactId=maven-archetype-quickstart \
    -DarchetypeVersion=1.4 \
    -DarchetypeGroupId=org.apache.maven.archetypes \
    -Dversion=1.0-SNAPSHOT

Switch to the project directory
```
$ cd tri-stub-demo
```

Set JDK version in pom.xml, add Dubbo dependencies and plugins

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <dubbo.version>3.1.7</dubbo.version>
</properties>

<dependencies>
   <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.13</version>
       <scope>test</scope>
   </dependency>
   <dependency>
       <groupId>org.apache.dubbo</groupId>
       <artifactId>dubbo</artifactId>
       <version>${dubbo.version}</version>
   </dependency>
   <dependency>
    <groupId>org.apache.dubbo</groupId>
    <artifactId>dubbo-dependencies-zookeeper-curator5</artifactId>
    <type>pom</type>
    <version>${dubbo.version}</version>
   </dependency>
    <dependency>
        <groupId>com.google.protobuf</groupId>
        <artifactId>protobuf-java</artifactId>
        <version>3.19.4</version>
    </dependency>
</dependencies>

<build>
    <extensions>
        <extension>
            <groupId>kr.motd.maven</groupId>
            <artifactId>os-maven-plugin</artifactId>
            <version>1.6.1</version>
        </extension>
    </extensions>
    <plugins>
        <plugin>
            <groupId>org.xolstice.maven.plugins</groupId>
            <artifactId>protobuf-maven-plugin</artifactId>
            <version>0.6.1</version>
            <configuration>
                <protocArtifact>com.google.protobuf:protoc:3.19.4:exe:${os.detected.classifier}</protocArtifact>
                <protocPlugins>
                    <protocPlugin>
                        <id>dubbo</id>
                        <groupId>org.apache.dubbo</groupId>
                        <artifactId>dubbo-compiler</artifactId>
                        <version>${dubbo.version}</version>
                        <mainClass>org.apache.dubbo.gen.tri.Dubbo3TripleGenerator</mainClass>
                    </protocPlugin>
                </protocPlugins>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Add the interface definition file src/main/proto/hello.proto, Dubbo uses Protobuf as IDL

syntax = "proto3";

option java_multiple_files = true;
option java_package = "org.apache.dubbo.hello";
option java_outer_classname = "HelloWorldProto";
option objc_class_prefix = "HLW";

package helloworld;

message HelloRequest {
    string name = 1;
}

message HelloReply {
    string message = 1;
}
service Greeter{
    rpc greet(HelloRequest) returns (HelloReply);
}

Compile the IDL

$ mvn clean install

After the compilation is successful, you can see that the code file is generated in the target/generated-sources/protobuf/java directory

$ ls org/apache/dubbo/hello/
DubboGreeterTriple.java HelloReply.java HelloRequest.java HelloWorldProto.java
Greeter.java HelloReplyOrBuilder.java HelloRequestOrBuilder.java

Add server interface implementation src/main/java/org/apache/dubbo/GreeterImpl.java

package org.apache.dubbo;

import org.apache.dubbo.hello.DubboGreeterTriple;
import org.apache.dubbo.hello.HelloReply;
import org.apache.dubbo.hello.HelloRequest;

public class GreeterImpl extends DubboGreeterTriple. GreeterImplBase {
   @Override
   public HelloReply greet(HelloRequest request) {
      return HelloReply.newBuilder()
      .setMessage("Hello," + request.getName() + "!")
      .build();
   }
}

Add server startup class src/main/java/org/apache/dubbo/MyDubboServer.java

package org.apache.dubbo;

import org.apache.dubbo.common.constants.CommonConstants;
import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.ProtocolConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.config.ServiceConfig;
import org.apache.dubbo.config.bootstrap.DubboBootstrap;
import org.apache.dubbo.hello.Greeter;

import java.io.IOException;

public class MyDubboServer {

   public static void main(String[] args) throws IOException {
       ServiceConfig<Greeter> service = new ServiceConfig<>();
       service.setInterface(Greeter.class);
       service.setRef(new GreeterImpl());

       DubboBootstrap bootstrap = DubboBootstrap.getInstance();
       bootstrap.application(new ApplicationConfig("tri-stub-server"))
               .registry(new RegistryConfig("zookeeper://127.0.0.1:2181"))
               .protocol(new ProtocolConfig(CommonConstants.TRIPLE, 50051))
               .service(service)
               .start();
       System.out.println("Dubbo triple stub server started");
       System.in.read();
   }
}

Add the client startup class src/main/java/org/apache/dubbo/MyDubboClient.java

package org.apache.dubbo;

import org.apache.dubbo.common.constants.CommonConstants;
import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.ReferenceConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.config.bootstrap.DubboBootstrap;
import org.apache.dubbo.hello.Greeter;
import org.apache.dubbo.hello.HelloReply;
import org.apache.dubbo.hello.HelloRequest;

public class MyDubboClient {
   public static void main(String[] args) {
      DubboBootstrap bootstrap = DubboBootstrap.getInstance();
      ReferenceConfig<Greeter> ref = new ReferenceConfig<>();
      ref.setInterface(Greeter.class);
      ref.setProtocol(CommonConstants.TRIPLE);
      ref.setProxy(CommonConstants.NATIVE_STUB);
      ref.setTimeout(3000);
      bootstrap.application(new ApplicationConfig("tri-stub-client"))
         .registry(new RegistryConfig("zookeeper://127.0.0.1:2181"))
         .reference(ref)
         .start();

      Greeter greeter = ref.get();
      HelloRequest request = HelloRequest.newBuilder().setName("Demo").build();
      HelloReply reply = greeter.greet(request);
      System.out.println("Received reply:" + reply);
    }
}

Compile the code
```
$ mvn clean install
```
Start the server

$ mvn org.codehaus.mojo:exec-maven-plugin:3.0.0:java -Dexec.mainClass="org.apache.dubbo.MyDubboServer"
Dubbo triple stub server started

Open a new terminal and start the client

$ mvn org.codehaus.mojo:exec-maven-plugin:3.0.0:java -Dexec.mainClass="org.apache.dubbo.MyDubboClient"
Received reply: message: "Hello, Demo!"

Last modified August 9, 2024: Fix code style in demo code (#3015) (e6205fa5322)

IDL defines cross-language services

precondition

Create project

Feedback