协议使用方式

Triple 协议是 Dubbo3 的主力协议，完整兼容 gRPC over HTTP/2，并在协议层面扩展了负载均衡和流量控制相关机制。本文档旨在指导用户正确的使用 Triple 协议。

在开始前，需要决定服务使用的序列化方式，如果为新服务，推荐使用 protobuf 作为默认序列化，在性能和跨语言上的效果都会更好。如果是原有服务想进行协议升级，Triple 协议也已经支持其他序列化方式，如 Hessian / JSON 等

Protobuf 方式

1. 编写 IDL 文件

   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;
   
   // The request message containing the user's name.
   message HelloRequest {
     string name = 1;
   }
   
   // The response message containing the greetings
   message HelloReply {
     string message = 1;
   }
   

2. 添加编译 protobuf 的 extension 和 plugin (以 maven 为例)

      <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:3.7.1:exe:${os.detected.classifier}</protocArtifact>
                       <pluginId>triple-java</pluginId>
                       <outputDirectory>build/generated/source/proto/main/java</outputDirectory>
                   </configuration>
                   <executions>
                       <execution>
                           <goals>
                               <goal>compile</goal>
                               <goal>test-compile</goal>
                           </goals>
                       </execution>
                   </executions>
               </plugin>
           </plugins>
   

3. 构建/ 编译生成 protobuf Message 类

   mvn clean install
   

Unary 方式

4. 编写 Java 接口

   import org.apache.dubbo.hello.HelloReply;
   import org.apache.dubbo.hello.HelloRequest;
   
   public interface IGreeter {
       /**
        * <pre>
        *  Sends a greeting
        * </pre>
        */
       HelloReply sayHello(HelloRequest request);
   
   }
   

5. 创建 Provider

       public static void main(String[] args) throws InterruptedException {
           ServiceConfig<IGreeter> service = new ServiceConfig<>();
           service.setInterface(IGreeter.class);
           service.setRef(new IGreeter1Impl());
           // 这里需要显示声明使用的协议为triple 
           service.setProtocol(new ProtocolConfig(CommonConstants.TRIPLE, 50051));
           service.setApplication(new ApplicationConfig("demo-provider"));
           service.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
           service.export();
           System.out.println("dubbo service started");
           new CountDownLatch(1).await();
       }
   

6. 创建 Consumer

   public static void main(String[] args) throws IOException {
       ReferenceConfig<IGreeter> ref = new ReferenceConfig<>();
       ref.setInterface(IGreeter.class);
       ref.setCheck(false);
       ref.setProtocol(CommonConstants.TRIPLE);
       ref.setLazy(true);
       ref.setTimeout(100000);
       ref.setApplication(new ApplicationConfig("demo-consumer"));
       ref.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
       final IGreeter iGreeter = ref.get();
   
       System.out.println("dubbo ref started");
       try {
           final HelloReply reply = iGreeter.sayHello(HelloRequest.newBuilder()
                   .setName("name")
                   .build());
           TimeUnit.SECONDS.sleep(1);
           System.out.println("Reply:" + reply);
       } catch (Throwable t) {
           t.printStackTrace();
       }
       System.in.read();
   }
   

7. 运行 Provider 和 Consumer ,可以看到请求正常返回

   > Reply:message: "name"
   

stream 方式

8. 编写 Java 接口

   import org.apache.dubbo.hello.HelloReply;
   import org.apache.dubbo.hello.HelloRequest;
   
   public interface IGreeter {
       /**
    	* <pre>
    	*  Sends greeting by stream
    	* </pre>
   	 */
       StreamObserver<HelloRequest> sayHello(StreamObserver<HelloReply> replyObserver);
   
   }
   

9. 编写实现类

   public class IStreamGreeterImpl implements IStreamGreeter {
   
       @Override
       public StreamObserver<HelloRequest> sayHello(StreamObserver<HelloReply> replyObserver) {
   
           return new StreamObserver<HelloRequest>() {
               private List<HelloReply> replyList = new ArrayList<>();
   
               @Override
               public void onNext(HelloRequest helloRequest) {
                   System.out.println("onNext receive request name:" + helloRequest.getName());
                   replyList.add(HelloReply.newBuilder()
                       .setMessage("receive name:" + helloRequest.getName())
                       .build());
               }
   
               @Override
               public void onError(Throwable cause) {
                   System.out.println("onError");
                   replyObserver.onError(cause);
               }
   
               @Override
               public void onCompleted() {
                   System.out.println("onComplete receive request size:" + replyList.size());
                   for (HelloReply reply : replyList) {
                       replyObserver.onNext(reply);
                   }
                   replyObserver.onCompleted();
               }
           };
       }
   }
   

10. 创建 Provider

    public class StreamProvider {
        public static void main(String[] args) throws InterruptedException {
            ServiceConfig<IStreamGreeter> service = new ServiceConfig<>();
            service.setInterface(IStreamGreeter.class);
            service.setRef(new IStreamGreeterImpl());
            service.setProtocol(new ProtocolConfig(CommonConstants.TRIPLE, 50051));
            service.setApplication(new ApplicationConfig("stream-provider"));
            service.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
            service.export();
            System.out.println("dubbo service started");
            new CountDownLatch(1).await();
        }
    }
    

11. 创建 Consumer

    public class StreamConsumer {
        public static void main(String[] args) throws InterruptedException, IOException {
            ReferenceConfig<IStreamGreeter> ref = new ReferenceConfig<>();
            ref.setInterface(IStreamGreeter.class);
            ref.setCheck(false);
            ref.setProtocol(CommonConstants.TRIPLE);
            ref.setLazy(true);
            ref.setTimeout(100000);
            ref.setApplication(new ApplicationConfig("stream-consumer"));
            ref.setRegistry(new RegistryConfig("zookeeper://mse-6e9fda00-p.zk.mse.aliyuncs.com:2181"));
            final IStreamGreeter iStreamGreeter = ref.get();
    
            System.out.println("dubbo ref started");
            try {
    
                StreamObserver<HelloRequest> streamObserver = iStreamGreeter.sayHello(new StreamObserver<HelloReply>() {
                    @Override
                    public void onNext(HelloReply reply) {
                        System.out.println("onNext");
                        System.out.println(reply.getMessage());
                    }
    
                    @Override
                    public void onError(Throwable throwable) {
                        System.out.println("onError:" + throwable.getMessage());
                    }
    
                    @Override
                    public void onCompleted() {
                        System.out.println("onCompleted");
                    }
                });
    
                streamObserver.onNext(HelloRequest.newBuilder()
                    .setName("tony")
                    .build());
    
                streamObserver.onNext(HelloRequest.newBuilder()
                    .setName("nick")
                    .build());
    
                streamObserver.onCompleted();
            } catch (Throwable t) {
                t.printStackTrace();
            }
            System.in.read();
        }
    }
    

12. 运行 Provider 和 Consumer ,可以看到请求正常返回了

    > onNext\
    > receive name:tony\
    > onNext\
    > receive name:nick\
    > onCompleted
    

其他序列化方式

省略上文中的 1-3 步，指定 Provider 和 Consumer 使用的协议即可完成协议升级。

本文的示例可以在 triple-samples 找到