gRPC相互通信实例
gRPC是一个高性能、开源和通用的RPC框架，面向移动和HTTP 2.0设计，目前支持C++、Go、Java、Python语言版本，目的是使得应用程序之间可以相互通信。接下来将通过Python和Java两种语言的简单实例分别来实现gRPC接口通信。
【Python】
1. 安装gRPC
pip install grpcio
2. 安装gRPC工具
pip install grpcio-tools
3. 通过protobuf定义接口和数据类型文件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;
}4. 使用gRPC protobuf工具生成对应语言的库函数
python -m grpc_tools.protoc --python_out=. --grpc_python_out=. -I. helloworld.proto
此时在该目录下生成两个文件helloworld_pb2.py和helloworld_pb2_grpc.py
5. 创建服务端代码hello_server.py
from concurrent import futures
import grpc
import helloworld_pb2
import helloworld_pb2_grpc
class Greeter(helloworld_pb2_grpc.GreeterServicer):
def SayHello(self, request, context):
return helloworld_pb2.HelloReply(message='Hello, %s!' % request.name)
def serve():
server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
server.add_insecure_port('[::]:50051')
server.start()
server.wait_for_termination()
if __name__ == '__main__':
serve()6. 创建客户端代码hello_client.py
from __future__ import print_function
import grpc
import helloworld_pb2
import helloworld_pb2_grpc
def run():
with grpc.insecure_channel('localhost:50051') as channel:
stub = helloworld_pb2_grpc.GreeterStub(channel)
response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'))
print("Greeter client received: " + response.message)
if __name__ == '__main__':
run()7. 先运行服务器，在运行客户端
python hello_server.py
python hello_client.py
【Java】
1. 用IDEA新建Maven项目grpc-helloworld， 目录结构如下
2. 编写项目pom.xml文件如下
4.0.0
grpc
grpc-helloworld
1.0-SNAPSHOT
com.google.guava
guava
23.6-jre
org.apache.httpcomponents
httpcore
4.4.8
com.google.protobuf
protobuf-java
3.5.1
io.grpc
grpc-all
1.20.0
kr.motd.maven
os-maven-plugin
1.4.1.Final
org.springframework.boot
spring-boot-maven-plugin
org.xolstice.maven.plugins
protobuf-maven-plugin
0.6.1
com.google.protobuf:protoc:3.0.0:exe:${os.detected.classifier}
grpc-java
io.grpc:protoc-gen-grpc-java:0.15.0:exe:${os.detected.classifier}
/home/llh/modules/anaconda3/bin/protoc
compile
compile-custom
注意：
3. 编写helloworld.proto文件，和【Python】版本的第三步helloworld.proto保持一致不变
4. 编译.proto文件，分别执行compile和compile-custom
执行完成后在target目录生成相应的库函数如下
5. 创建服务端代码HelloWorldServer.java如下
package io.grpc.examples.helloworld;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.stub.StreamObserver;
import java.io.IOException;
import java.util.logging.Logger;
/**
* Server that manages startup/shutdown of a {@code Greeter} server.
*/
public class HelloWorldServer {
private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName());
private Server server;
private void start() throws IOException {
/* The port on which the server should run */
int port = 50051;
server = ServerBuilder.forPort(port)
.addService(new GreeterImpl())
.build()
.start();
logger.info("Server started, listening on " + port);
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
// Use stderr here since the logger may have been reset by its JVM shutdown hook.
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();
}
}
//Await termination on the main thread since the grpc library uses daemon threads.
private void blockUntilShutdown() throws InterruptedException {
if (server != null) {
server.awaitTermination();
}
}
//Main launches the server from the command line.
public static void main(String[] args) throws IOException, InterruptedException {
final HelloWorldServer server = new HelloWorldServer();
server.start();
server.blockUntilShutdown();
}
static class GreeterImpl extends GreeterGrpc.GreeterImplBase {
@Override
public void sayHello(HelloRequest req, StreamObserver responseObserver) {
HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
responseObserver.onNext(reply);
responseObserver.onCompleted();
}
}
} 6. 创建客户端代码HelloWorldClient.java如下
package io.grpc.examples.helloworld;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import io.grpc.StatusRuntimeException;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A simple client that requests a greeting from the {@link HelloWorldServer}.
*/
public class HelloWorldClient {
private static final Logger logger = Logger.getLogger(HelloWorldClient.class.getName());
private final ManagedChannel channel;
private final GreeterGrpc.GreeterBlockingStub blockingStub;
/** Construct client connecting to HelloWorld server at {@code host:port}. */
public HelloWorldClient(String host, int port) {
this(ManagedChannelBuilder.forAddress(host, port)
// Channels are secure by default (via SSL/TLS). For the example we disable TLS to avoid
// needing certificates.
.usePlaintext()
.build());
}
/** Construct client for accessing HelloWorld server using the existing channel. */
HelloWorldClient(ManagedChannel channel) {
this.channel = channel;
blockingStub = GreeterGrpc.newBlockingStub(channel);
}
public void shutdown() throws InterruptedException {
channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
}
/** Say hello to server. */
public void greet(String name) {
logger.info("Will try to greet " + name + " ...");
HelloRequest request = HelloRequest.newBuilder().setName(name).build();
HelloReply response;
try {
response = blockingStub.sayHello(request);
} catch (StatusRuntimeException e) {
logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
return;
}
logger.info("Greeting: " + response.getMessage());
}
/**
* Greet server. If provided, the first element of {@code args} is the name to use in the
* greeting.
*/
public static void main(String[] args) throws Exception {
HelloWorldClient client = new HelloWorldClient("localhost", 50051);
try {
/* Access a service running on the local machine on port 50051 */
String user = "world";
if (args.length > 0) {
user = args[0]; /* Use the arg as the name to greet if provided */
}
client.greet(user);
} finally {
client.shutdown();
}
}
}7. 和上面一样，先启动服务器， 再运行客户端
最后最重要一点，不管用哪种语言编写，只要保持.proto文件完全一直（包括package），他们之前可以相互访问，例如本文章的【Python】grpc_client可以访问【Java】的grpc_server，【Java】的grpc_client可以访问【Python】的grpc_server。
参考资料：
grpc官网：https://grpc.io/
grpc-python的github: https://github.com/grpc/grpc/tree/master/examples/python
grpc-java的github： https://github.com/grpc/grpc-java/tree/master/examples/src/main/java/io/grpc/examples