Nacos 2.x版本增加了GRPC服务接口和客户端，极大的提升了Nacos的性能，本文将简单介绍grpc-java的使用方式以及Nacos中集成GRPC的方式。

grpc-java

GRPC是google开源的、以protobuf作为序列化方式、以http2作为通信协议的高性能rpc框架。

grpc-java是grpc对java语言的实现，使用Netty/Okhttp作为通信组件。

使用方式

添加依赖

<dependency>
  <groupId>io.grpc</groupId>
  <artifactId>grpc-netty-shaded</artifactId>
  <version>1.56.0</version>
  <scope>runtime</scope>
</dependency>
<dependency>
  <groupId>io.grpc</groupId>
  <artifactId>grpc-protobuf</artifactId>
  <version>1.56.0</version>
</dependency>
<dependency>
  <groupId>io.grpc</groupId>
  <artifactId>grpc-stub</artifactId>
  <version>1.56.0</version>
</dependency>
<dependency> <!-- necessary for Java 9+ -->
  <groupId>org.apache.tomcat</groupId>
  <artifactId>annotations-api</artifactId>
  <version>6.0.53</version>
  <scope>provided</scope>
</dependency>

生成代码

需要将.proto文件放到src/main/proto或src/test/proto目录下。

然后添加生成代码使用的插件：

For protobuf-based codegen integrated with the Maven build system, you can use protobuf-maven-plugin (Eclipse and NetBeans users should also look at os-maven-plugin's IDE documentation):

<build>
  <extensions>
    <extension>
      <groupId>kr.motd.maven</groupId>
      <artifactId>os-maven-plugin</artifactId>
      <version>1.7.1</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:3.22.3:exe:${os.detected.classifier}</protocArtifact>
        <pluginId>grpc-java</pluginId>
        <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.56.0:exe:${os.detected.classifier}</pluginArtifact>
        <outputDirectory>${project.basedir}/src/main/java</outputDirectory>
        <clearOutputDirectory>false</clearOutputDirectory>
        <skip>false</skip>
      </configuration>
      <executions>
        <execution>
          <goals>
            <goal>compile</goal>
            <goal>compile-custom</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

生成代码：

mvn clean compile

High-level组件

At a high level there are three distinct layers to the library: Stub, Channel, and Transport.

Stub

The Stub layer is what is exposed to most developers and provides type-safe bindings to whatever datamodel/IDL/interface you are adapting. gRPC comes with a plugin to the protocol-buffers compiler that generates Stub interfaces out of .proto files, but bindings to other datamodel/IDL are easy and encouraged.

Channel

The Channel layer is an abstraction over Transport handling that is suitable for interception/decoration and exposes more behavior to the application than the Stub layer. It is intended to be easy for application frameworks to use this layer to address cross-cutting concerns such as logging, monitoring, auth, etc.

T