总结
增加、修改一个grpc接口步骤：
1.修改proto文件，新增修改一个service，相应的请求和回复的message
2.使用protoc生成go代码
3.server和cilent分别调用生成的go包里的方法
这个也就是平台中立的体现，没有完全的平台中立，只是从新设计。
thrift和 grpc的优劣：
1.依据网络进行合理选择
2.thrift是Facebook的开源rpc框架,thrift的rpc，一次调用在收到回复之前，占用一个TCP连接的，当并发量很高，而一次调用耗时又很长的时候，thrift会出现连接被占满的情况，导致调用堆积，延时增大.
3.grpc是基于http-2设计的，http-2的一个重要特点是在单个TCP连接上可以复用多个请求.而grpc，多个调用可以复用一个连接，这样显然就比thrift支持的并发调用数量更高。
具体实现（照猫画虎）
- 使用protoc生成 proto文件，类如grpc 提供的example中的helloworld
执行protoc.exe ,发现这个编译器插件支持的大概命令
以及版本，我的是libprotoc 3.6.1
$ protoc.exe
Usage: D:\GO\bin\protoc.exe [OPTION] PROTO_FILES
Parse PROTO_FILES and generate output based on the options given:
-IPATH, --proto_path=PATH Specify the directory in which to search for
imports. May be specified multiple times;
directories will be searched in order. If not
given, the current working directory is used.
--version Show version info and exit.
-h, --help Show this text and exit.
--encode=MESSAGE_TYPE Read a text-format message of the given type
from standard input and write it in binary
to standard output. The message type must
be defined in PROTO_FILES or their imports.
--decode=MESSAGE_TYPE Read a binary message of the given type from
standard input and write it in text format
to standard output. The message type must
be defined in PROTO_FILES or their imports.
--decode_raw Read an arbitrary protocol message from
standard input and write the raw tag/value
pairs in text format to standard output. No
PROTO_FILES should be given when using this
flag.
--descriptor_set_in=FILES Specifies a delimited list of FILES
each containing a FileDescriptorSet (a
protocol buffer defined in descriptor.proto).
The FileDescriptor for each of the PROTO_FILES
provided will be loaded from these
FileDescriptorSets. If a FileDescriptor
appears multiple times, the first occurrence
will be used.
-oFILE, Writes a FileDescriptorSet (a protocol buffer,
--descriptor_set_out=FILE defined in descriptor.proto) containing all of
the input files to FILE.
--include_imports When using --descriptor_set_out, also include
all dependencies of the input files in the
set, so that the set is self-contained.
--include_source_info When using --descriptor_set_out, do not strip
SourceCodeInfo from the FileDescriptorProto.
This results in vastly larger descriptors that
include information about the original
location of each decl in the source file as
well as surrounding comments.
--dependency_out=FILE Write a dependency output file in the format
expected by make. This writes the transitive
set of input file paths to FILE
--error_format=FORMAT Set the format in which to print errors.
FORMAT may be 'gcc' (the default) or 'msvs'
(Microsoft Visual Studio format).
--print_free_field_numbers Print the free field numbers of the messages
defined in the given proto files. Groups share
the same field number space with the parent
message. Extension ranges are counted as
occupied fields numbers.
--plugin=EXECUTABLE Specifies a plugin executable to use.
Normally, protoc searches the PATH for
plugins, but you may specify additional
executables not in the path using this flag.
Additionally, EXECUTABLE may be of the form
NAME=PATH, in which case the given plugin name
is mapped to the given executable even if
the executable's own name differs.
--cpp_out=OUT_DIR Generate C++ header and source.
--csharp_out=OUT_DIR Generate C# source file.
--java_out=OUT_DIR Generate Java source file.
--js_out=OUT_DIR Generate JavaScript source.
--objc_out=OUT_DIR Generate Objective C header and source.
--php_out=OUT_DIR Generate PHP source file.
--python_out=OUT_DIR Generate Python source file.
--ruby_out=OUT_DIR Generate Ruby source file.
@<filename> Read options and filenames from file. If a
relative file path is specified, the file
will be searched in the working directory.
The --proto_path option will not affect how
this argument file is searched. Content of
the file will be expanded in the position of
@<filename> as in the argument list. Note
that shell expansion is not applied to the
content of the file (i.e., you cannot use
quotes, wildcards, escapes, commands, etc.).
Each line corresponds to a single argument,
even if it contains spaces.
$ protoc.exe --version
libprotoc 3.6.1
- 自带的列子中helloworld.proto 的内容：
syntax = "proto3";
option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";
package helloworld; //包名
// The greeting service definition. 服务器调用的方法
service Greeter {
// Sends a greeting
rpc SayHello (HelloRequest) returns (HelloReply) {}
}
// The request message containing the user's name.//请求消息中的格式字段
message HelloRequest {
string name = 1;
}
// The response message containing the greetings//响应消息中的格式字段
message HelloReply {
string message = 1;
}
解释如下：
syntax = “proto3” 指定proto版本
package helloworld protoc命令生成的go代码的包名，客户端服务器程序都要引用这个包，所在路径同名
service 定义了这个远程调用的服务，服务请求者调用SayHello方法，请求中携带HelloRequest格式的信息，服务提供者则返回HelloReply格式的回复
message 这个就是定义请求和回复的格式
- 生成对应的go语言代码，这里终于要用到我们最开始安装的protoc了，命令如下：
protoc.exe --go_out=plugins=grpc:. helloworld.proto
liu@liu-PC MINGW64 /d/GO/GO_WORKSPACE/src/google.golang.org/grpc/examples/helloworld/helloworld (master)
$ ls
helloworld.pb.go helloworld.proto
liu@liu-PC MINGW64 /d/GO/GO_WORKSPACE/src/google.golang.org/grpc/examples/helloworld/helloworld (master)
$
liu@liu-PC MINGW64 /d/GO/GO_WORKSPACE/src/google.golang.org/grpc/examples/helloworld/helloworld (master)
$ rm helloworld.pb.go
liu@liu-PC MINGW64 /d/GO/GO_WORKSPACE/src/google.golang.org/grpc/examples/helloworld/helloworld (master)
$ ls
helloworld.proto
liu@liu-PC MINGW64 /d/GO/GO_WORKSPACE/src/google.golang.org/grpc/examples/helloworld/helloworld (master)
$ protoc.exe --go_out=plugins=grpc:. helloworld.proto
2020/04/18 22:17:11 WARNING: Missing 'go_package' option in "helloworld.proto", please specify:
option go_package = ".;helloworld";
A future release of protoc-gen-go will require this be specified.
See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.
liu@liu-PC MINGW64 /d/GO/GO_WORKSPACE/src/google.golang.org/grpc/examples/helloworld/helloworld (master)
$ ls
helloworld.pb.go helloworld.proto
- 编写服务器、客户端的代码，记得 import pb"google.golang.org/grpc/examples/helloworld/helloworld"
“google.golang.org/grpc”
“context”
客户端代码：
package main
import (
"context"
"log"
"os"
"time"
"google.golang.org/grpc" //grpc 的包
pb "google.golang.org/grpc/examples/helloworld/helloworld" //生产的中间文件
)
const (
address = "localhost:50051" //ip + port
defaultName = "world"
)
func main() {
// Set up a connection to the server.
conn, err := grpc.Dial(address, grpc.WithInsecure(), grpc.WithBlock())
if err != nil {
log.Fatalf("did not connect: %v", err)
}
defer conn.Close()
c := pb.NewGreeterClient(conn)
// Contact the server and print out its response.
name := defaultName
if len(os.Args) > 1 {
name = os.Args[1]
}
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
r, err := c.SayHello(ctx, &pb.HelloRequest{Name: name})
if err != nil {
log.Fatalf("could not greet: %v", err)
}
log.Printf("Greeting: %s", r.GetMessage())
}
服务器代码：
/*
*
* Copyright 2015 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
//go:generate protoc -I ../helloworld --go_out=plugins=grpc:../helloworld ../helloworld/helloworld.proto
// Package main implements a server for Greeter service.
package main
import (
"context"
"log"
"net"
"google.golang.org/grpc"
pb "google.golang.org/grpc/examples/helloworld/helloworld"
)
const (
port = ":50051"
)
// server is used to implement helloworld.GreeterServer.
type server struct {
pb.UnimplementedGreeterServer
}
// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
log.Printf("Received: %v", in.GetName())
return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}
func main() {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
s := grpc.NewServer()
pb.RegisterGreeterServer(s, &server{})
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
运行结果：
客户端：2020/04/18 22:37:57 Received: world
服务端：2020/04/18 22:37:57 Received: world
