IDL defines cross-language services

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

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>
       <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>
   

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("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();
      }
   }
   

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

11. 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!"