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

Create project

  1. 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
    
  2. Switch to the project directory

    $ cd tri-stub-demo
    
  3. 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>
    </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>3.0.8</version>
       </dependency>
       <dependency>
        <groupId>org.apache.dubbo</groupId>
        <artifactId>dubbo-dependencies-zookeeper-curator5</artifactId>
        <type>pom</type>
        <version>3.0.8</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>0.0.4.1-SNAPSHOT</version>
                            <mainClass>org.apache.dubbo.gen.tri.Dubbo3TripleGenerator</mainClass>
                        </protocPlugin>
                    </protocPlugins>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
    
  4. 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);
    }
    
  5. 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
    
  6. 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();
       }
    }
    
  7. 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("multicast://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();
       }
    }
    
  8. 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);
        }
    }
    
  9. Compile the code

    $ mvn clean install
    
  10. 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
  1. 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 January 2, 2023: Enhance en docs (#1798) (95a9f4f6c)