gRPC初探

资源

[1] gRPC Java Example

关键词

高性能，开源，双向流式，多开发语言支持，Apache 2.0

示例

ProtoBuffer定义

protobuf-maven-plugin编译的默认路径

1566788979168.png

syntax = "proto3";

option java_multiple_files = true;
package com.wjg.grpc.helloworld;

message Person {
  string first_name = 1;
  string last_name = 2;
}

message Greeting {
  string message = 1;
}

service HelloWorldService {
  rpc sayHello (Person) returns (Greeting);
}

使用protobuf-maven-plugin生成stub

源：https://github.com/xolstice/protobuf-maven-plugin

grpc-spring-boot-starter： @GRpcService使应用内嵌一个gRPC server。

os-maven-plugin：生成平台依赖的工程属性，ProtocolBuffer编译器依赖这些信息。即是说，protobuf-maven-plugin需要获取当前平台使用的正确的编译器。

sprint-boot-maven-plugin：可以构建独立可运行的jar。

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.codenotfound</groupId>
  <artifactId>grpc-java-hello-world</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>grpc-java-hello-world</name>
  <description>gRPC Java Example</description>
  <url>https://codenotfound.com/grpc-java-example.html</url>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.0.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
  </parent>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <grpc-spring-boot-starter.version>3.0.0</grpc-spring-boot-starter.version>
    <os-maven-plugin.version>1.6.1</os-maven-plugin.version>
    <protobuf-maven-plugin.version>0.6.1</protobuf-maven-plugin.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>io.github.lognet</groupId>
      <artifactId>grpc-spring-boot-starter</artifactId>
      <version>${grpc-spring-boot-starter.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <extensions>
      <extension>
        <groupId>kr.motd.maven</groupId>
        <artifactId>os-maven-plugin</artifactId>
        <version>${os-maven-plugin.version}</version>
      </extension>
    </extensions>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
      <plugin>
        <groupId>org.xolstice.maven.plugins</groupId>
        <artifactId>protobuf-maven-plugin</artifactId>
        <version>${protobuf-maven-plugin.version}</version>
        <configuration>
          <protocArtifact>com.google.protobuf:protoc:3.5.1-1:exe:${os.detected.classifier}</protocArtifact>
          <pluginId>grpc-java</pluginId>
          <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.16.1:exe:${os.detected.classifier}</pluginArtifact>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>compile</goal>
              <goal>compile-custom</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

mvn compile生成的类

1566788914309.png

server代码示例

GRpcService：自动配置gRPC服务在端口6565上发布。可以使用grpc.port=xxxx进行修改发布端口。

package com.wjg.wjggrpcstart.service;


import com.wjg.grpc.helloworld.Greeting;
import com.wjg.grpc.helloworld.HelloWorldServiceGrpc;
import com.wjg.grpc.helloworld.Person;
import io.grpc.stub.StreamObserver;
import org.lognet.springboot.grpc.GRpcService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * created by jingang.wu on 2019/8/26
 */
@GRpcService
public class HelloWorldServiceImpl
        extends HelloWorldServiceGrpc.HelloWorldServiceImplBase {

    private static final Logger LOGGER =
            LoggerFactory.getLogger(HelloWorldServiceImpl.class);

    @Override
    public void sayHello(Person request,
                         StreamObserver<Greeting> responseObserver) {
        LOGGER.info("server received {}", request);

        String message = "Hello " + request.getFirstName() + " "
                + request.getLastName() + "!";
        Greeting greeting =
                Greeting.newBuilder().setMessage(message).build();
        LOGGER.info("server responded {}", greeting);

        // 使用onNext返回greeting，调用onCompleted告诉gRPC响应写入完成
        responseObserver.onNext(greeting);
        responseObserver.onCompleted();
    }
}

client示例代码

调用gRPC服务，首先需要创建一个stub。stub的类型有：

• 同步stub，阻塞等待server响应
• 异步stub，响应异步返回

gRPC使用http/2传输消息。MessageChannel管理连接，隐藏了复杂性。

建立：

一个应用使用一个channel，并在service stubs中共享。

package com.wjg.wjggrpcstart.service;

import com.wjg.grpc.helloworld.Greeting;
import com.wjg.grpc.helloworld.HelloWorldServiceGrpc;
import com.wjg.grpc.helloworld.Person;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;

/**
 * created by jingang.wu on 2019/8/26
 */
@Component
public class HelloWorldClient {

    private static final Logger LOGGER =
            LoggerFactory.getLogger(HelloWorldClient.class);

    private HelloWorldServiceGrpc.HelloWorldServiceBlockingStub helloWorldServiceBlockingStub;

    @PostConstruct
    private void init() {
        //gRPC默认使用TLS安全连接，需要配置安全组件，这里示例不使用
        ManagedChannel managedChannel = ManagedChannelBuilder
                .forAddress("localhost", 6565).usePlaintext().build();
        
        // 这里使用同步调用
        helloWorldServiceBlockingStub =
                HelloWorldServiceGrpc.newBlockingStub(managedChannel);
        //异步调用HelloWorldServiceGrpc.newFutureStub(managedChannel);
    }

    public String sayHello(String firstName, String lastName) {
        Person person = Person.newBuilder().setFirstName(firstName)
                .setLastName(lastName).build();
        LOGGER.info("client sending {}", person);

        Greeting greeting =
                helloWorldServiceBlockingStub.sayHello(person);
        LOGGER.info("client received {}", greeting);

        return greeting.getMessage();
    }
}

unit test

@RunWith(SpringRunner.class)
@SpringBootTest
public class WjgGrpcStartApplicationTests {

    @Test
    public void contextLoads() {
    }

    @Autowired
    private HelloWorldClient helloWorldClient;

    @Test
    public void testSayHello() {
        assert(helloWorldClient.sayHello("John", "Doe").equals("Hello John Doe!"));
    }
}