gRPC是由Google主导开发的RPC框架，使用HTTP/2协议并用ProtoBuf作为序列化工具。其客户端提供Objective-C、Java接口，服务器侧则有Java、Golang、C++等接口，从而为移动端（iOS/Androi）到服务器端通讯提供了一种解决方案。 当然在当下的环境下，这种解决方案更热门的方式是RESTFull API接口。该方式需要自己去选择编码方式、服务器架构、自己搭建框架（JSON-RPC）。gRPC官方对REST的声音是：
和REST一样遵循HTTP协议(明确的说是HTTP/2)，但是gRPC提供了全双工流
和传统的REST不同的是gRPC使用了静态路径，从而提高性能
用一些格式化的错误码代替了HTTP的状态码更好的标示错误
至于是否要选择用gRPC。对于已经有一套方案的团队，可以参考下。如果是从头来做，可以考虑下gRPC提供的从客户端到服务器的整套解决方案，这样不用客户端去实现http的请求会话，JSON等的解析，服务器端也有现成的框架用。从15年3月到现在gRPC也发展了一年了，慢慢趋于成熟。下面我们就以gRPC的Golang版本看下其在golang上面的表现。至于服务端的RPC，感觉golang标准库的RPC框架基本够用了,没必要再去用另一套方案。
最近google发布了grpc1.0，之前一直关注过grpc，数据交互使用了protocol buffer,相比之前使用的hession和json序列化方式性能应该提升不少，所有先搞一个grpc的hello world跑一下,项目使用maven搭建，并使用idea开发。
使用idea创建maven项目，添加pom配置
<a name="t2"></a>添加grpc1.0 maven依赖
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-netty</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-protobuf</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-stub</artifactId>
<version>1.0.0</version>
</dependency>
配置protobuf maven插件
配置了protobuf 插件后，可以自动将.proto文件生成对应的java代码
<build>
<extensions>
<extension>
<groupId>kr.motd.maven</groupId>
<artifactId>os-maven-plugin</artifactId>
<version>1.4.1.Final</version>
</extension>
</extensions>
<plugins>
<plugin>
<groupId>org.xolstice.maven.plugins</groupId>
<artifactId>protobuf-maven-plugin</artifactId>
<version>0.5.0</version>
<configuration>
<protocArtifact>com.google.protobuf:protoc:3.0.0:exe:${os.detected.classifier}</protocArtifact>
<pluginId>grpc-java</pluginId>
<pluginArtifact>io.grpc:protoc-gen-grpc-java:1.0.0:exe:${os.detected.classifier}</pluginArtifact>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>compile-custom</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
编写proto文件 helloworld.proto
syntax = "proto3";
option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";
option objc_class_prefix = "HLW";
package helloworld;
// The greeting service definition.
service Greeter {
// Sends a greeting
rpc SayHello (HelloRequest) returns (HelloReply) {}
}
// The request message containing the user's name.
message HelloRequest {
string name = 1;
}
// The response message containing the greetings
message HelloReply {
string message = 1;
}
编写grpc 服务端HelloWorldServer.java
package com;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.examples.helloworld.GreeterGrpc;
import io.grpc.examples.helloworld.HelloReply;
import io.grpc.examples.helloworld.HelloRequest;
import io.grpc.stub.StreamObserver;
import java.io.IOException;
public class HelloWorldServer {
private int port = 50051;
private Server server;
private void start() throws IOException {
server = ServerBuilder.forPort(port)
.addService(new GreeterImpl())
.build()
.start();
System.out.println("service start...");
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
System.err.println("*** shutting down gRPC server since JVM is shutting down");
HelloWorldServer.this.stop();
System.err.println("*** server shut down");
}
});
}
private void stop() {
if (server != null) {
server.shutdown();
}
}
// block 一直到退出程序
private void blockUntilShutdown() throws InterruptedException {
if (server != null) {
server.awaitTermination();
}
}
public static void main(String[] args) throws IOException, InterruptedException {
final HelloWorldServer server = new HelloWorldServer();
server.start();
server.blockUntilShutdown();
}
// 实现 定义一个实现服务接口的类
private class GreeterImpl extends GreeterGrpc.GreeterImplBase {
public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
System.out.println("service:"+req.getName());
HelloReply reply = HelloReply.newBuilder().setMessage(("Hello: " + req.getName())).build();
responseObserver.onNext(reply);
responseObserver.onCompleted();
}
}
}
编写grpc 客户端 HelloWorldClient.java
package com;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import io.grpc.examples.helloworld.GreeterGrpc;
import io.grpc.examples.helloworld.HelloReply;
import io.grpc.examples.helloworld.HelloRequest;
import java.util.concurrent.TimeUnit;
public class HelloWorldClient {
private final ManagedChannel channel;
private final GreeterGrpc.GreeterBlockingStub blockingStub;
public HelloWorldClient(String host,int port){
channel = ManagedChannelBuilder.forAddress(host,port)
.usePlaintext(true)
.build();
blockingStub = GreeterGrpc.newBlockingStub(channel);
}
public void shutdown() throws InterruptedException {
channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
}
public void greet(String name){
HelloRequest request = HelloRequest.newBuilder().setName(name).build();
HelloReply response = blockingStub.sayHello(request);
System.out.println(response.getMessage());
}
public static void main(String[] args) throws InterruptedException {
HelloWorldClient client = new HelloWorldClient("127.0.0.1",50051);
for(int i=0;i<5;i++){
client.greet("world:"+i);
}
}
}
