13.10. Triple 协议_Dubbo 教程

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

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;
}

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>

构建/ 编译生成 Protobuf Message 类
```
$ mvn clean install
```

Unary 方式

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);
}

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();
    }

创建 Consumer

public static void main(String[] args) throws IOException {
    ReferenceConfig<IGreeter> ref = new ReferenceConfig<>();
    ref.setInterface(IGreeter.class);
    ref.setCheck(false);
    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();
}

运行 Provider 和 Consumer ,可以看到请求正常返回了

Reply:message: “name”

stream 方式

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);
}

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();
            }
        };
    }
}

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();
   }
}

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();
   }
}

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。

示例程序

本文的示例程序可以在 triple-samples 找到