Dubbo3实践系列：使用 IDL 定义跨语言服务

从零演示如何基于 IDL 方式来定义 Dubbo 服务并使用 Triple 协议

使用 IDL 定义服务具有更好的跨语言友好性，对于 Dubbo3 新用户而言，我们推荐使用这种方式。
然而 Triple 协议并不是和 IDL 强绑定的，也可以使用 Java Interface + Pojo 的方式定义服务并启用 Triple 协议，具体可参见示例。

更多 Triple 和 IDL 使用方式，请参考官方示例

前置条件

• JDK 版本 >= 8
• 已安装 Maven

创建工程

1. 首先创建一个空的 maven 工程

   $ 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. 切换到工程目录

   $ cd tri-stub-demo

3. 在 pom.xml 中设置 JDK 版本，添加 Dubbo 依赖和插件

   <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. 添加接口定义文件src/main/proto/hello.proto，Dubbo 使用 Protobuf 作为 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. 编译 IDL

   $ mvn clean install

   编译成功后，可以看到target/generated-sources/protobuf/java 目录下生成了代码文件

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

6. 添加服务端接口实现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. 添加服务端启动类 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. 添加客户端启动类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. 编译代码

   $ mvn clean install

10. 启动服务端

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

11. 打开新的终端，启动客户端

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