gRPC是一個(gè)高性能、通用的開源RPC框架，基于ProtoBuf(Protocol Buffers)序列化協(xié)議開發(fā)，且支持眾多開發(fā)語言，目前提供C、Java和Go語言版本，分別是grpc、grpc-java、grpc-go。gRPC提供了一種簡單的方法來精確地定義服務(wù)和為iOS、Android和后臺支持服務(wù)自動生成可靠性很強(qiáng)的客戶端功能庫。gRPC基于HTTP/2標(biāo)準(zhǔn)設(shè)計(jì)，帶來諸如雙向流、流控、頭部壓縮、單TCP連接上的多復(fù)用請求等特性，使得gRPC在移動設(shè)備上表現(xiàn)更好、更省電和節(jié)省空間占用。
創(chuàng)新互聯(lián)建站是一家集網(wǎng)站建設(shè),邕寧企業(yè)網(wǎng)站建設(shè),邕寧品牌網(wǎng)站建設(shè),網(wǎng)站定制,邕寧網(wǎng)站建設(shè)報(bào)價(jià),網(wǎng)絡(luò)營銷,網(wǎng)絡(luò)優(yōu)化,邕寧網(wǎng)站推廣為一體的創(chuàng)新建站企業(yè)，幫助傳統(tǒng)企業(yè)提升企業(yè)形象加強(qiáng)企業(yè)競爭力?？沙浞譂M足這一群體相比中小企業(yè)更為豐富、高端、多元的互聯(lián)網(wǎng)需求。同時(shí)我們時(shí)刻保持專業(yè)、時(shí)尚、前沿，時(shí)刻以成就客戶成長自我，堅(jiān)持不斷學(xué)習(xí)、思考、沉淀、凈化自己，讓我們?yōu)楦嗟钠髽I(yè)打造出實(shí)用型網(wǎng)站。
gRPC優(yōu)點(diǎn)如下：
（1）平臺無關(guān)，語言無關(guān)，可擴(kuò)展；
（2）提供了友好的動態(tài)庫，使用簡單；
（3）解析速度快，比對應(yīng)的XML快約20-100倍；
（4）序列化數(shù)據(jù)非常簡潔、緊湊，與XML相比，其序列化之后的數(shù)據(jù)量約為1/3到1/10。
官方推薦安裝命令：go get google.golang.org/grpc
國內(nèi)網(wǎng)絡(luò)環(huán)境由于GFW原因，不能直接訪問google服務(wù)器，報(bào)錯(cuò)如下：package google.golang.org/grpc: unrecognized import path "google.golang.org/grpc" (https fetch: Get https://google.golang.org/grpc?go-get=1: dial tcp 216.239.37.1:443: i/o timeout)
因此，在國內(nèi)網(wǎng)絡(luò)環(huán)境下推薦直接從GitHub下載相應(yīng)依賴進(jìn)行安裝。
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git clone https://github.com/grpc/grpc-go.git $GOPATH/src/google.golang.org/grpc
git clone https://github.com/golang/net.git $GOPATH/src/golang.org/x/net
git clone https://github.com/golang/text.git $GOPATH/src/golang.org/x/text
go get -u github.com/golang/protobuf/{proto,protoc-gen-go}
git clone https://github.com/google/go-genproto.git $GOPATH/src/google.golang.org/genproto
git clone https://github.com/golang/sys $GOPATH/src/golang.org/x/sys安裝gRPC：go install google.golang.org/grpc
gRPC使用流程如下：
（1）編寫.proto描述文件。
（2）編譯生成.pb.go文件。
（3）服務(wù)端實(shí)現(xiàn)約定的接口并提供服務(wù)。
（4）客戶端按照約定調(diào)用方法請求服務(wù)。
一個(gè)RPC service是一個(gè)能夠通過參數(shù)和返回值進(jìn)行遠(yuǎn)程調(diào)用的方法。由于gRPC通過將數(shù)據(jù)編碼成Protocal Buffer來實(shí)現(xiàn)傳輸，因此，使用者可以通過Protocal Buffers interface definitioin language(IDL)來定義service method，同時(shí)將參數(shù)和返回值也定義成Protocal Buffer message類型。gRPC源碼目錄提供了多個(gè)使用示例，本文使用helloworld示例作為模板，helloworld示例目錄位于google.golang.org/grpc/examples/helloworld。
在$GOPATH/src目錄下創(chuàng)建helloworld目錄，包含proto、server、client子目錄。proto目錄下創(chuàng)建helloworld.proto文件。
helloworld.proto：
syntax = "proto3";
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;
}helloworld.proto文件中定義了一個(gè)Greeter Service，服務(wù)包含一個(gè)SayHello方法，同時(shí)聲明了HelloRequest和HelloReply消息結(jié)構(gòu)用于請求和響應(yīng)?？蛻舳耸褂肏elloRequest參數(shù)調(diào)用SayHello方法請求服務(wù)端，服務(wù)端響應(yīng)HelloReply消息。
根據(jù)定義的RPC service，利用protocal buffer compiler，即protoc生成相應(yīng)的服務(wù)器端和客戶端的Go代碼，生成的代碼中包含了客戶端能夠進(jìn)行RPC的方法以及服務(wù)器端需要進(jìn)行實(shí)現(xiàn)的接口。
在$GOPATH/src/helloworld/proto目錄下生成gRPC對應(yīng)的Go代碼的命令如下：protoc --go_out=plugins=grpc:. helloworld.proto
將在目錄下生成helloworld.pb.go文件，內(nèi)容如下：
// Code generated by protoc-gen-go. DO NOT EDIT.
// source: helloworld.proto
package helloworld
import (
context "context"
fmt "fmt"
proto "github.com/golang/protobuf/proto"
grpc "google.golang.org/grpc"
math "math"
)
// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf
// This is a compile-time assertion to ensure that this generated file
// is compatible with the proto package it is being compiled against.
// A compilation error at this line likely means your copy of the
// proto package needs to be updated.
const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
// The request message containing the user's name.
type HelloRequest struct {
Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
XXX_NoUnkeyedLiteral struct{} `json:"-"`
XXX_unrecognized []byte `json:"-"`
XXX_sizecache int32 `json:"-"`
}
func (m *HelloRequest) Reset() { *m = HelloRequest{} }
func (m *HelloRequest) String() string { return proto.CompactTextString(m) }
func (*HelloRequest) ProtoMessage() {}
func (*HelloRequest) Descriptor() ([]byte, []int) {
return fileDescriptor_17b8c58d586b62f2, []int{0}
}
func (m *HelloRequest) XXX_Unmarshal(b []byte) error {
return xxx_messageInfo_HelloRequest.Unmarshal(m, b)
}
func (m *HelloRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
return xxx_messageInfo_HelloRequest.Marshal(b, m, deterministic)
}
func (m *HelloRequest) XXX_Merge(src proto.Message) {
xxx_messageInfo_HelloRequest.Merge(m, src)
}
func (m *HelloRequest) XXX_Size() int {
return xxx_messageInfo_HelloRequest.Size(m)
}
func (m *HelloRequest) XXX_DiscardUnknown() {
xxx_messageInfo_HelloRequest.DiscardUnknown(m)
}
var xxx_messageInfo_HelloRequest proto.InternalMessageInfo
func (m *HelloRequest) GetName() string {
if m != nil {
return m.Name
}
return ""
}
// The response message containing the greetings
type HelloReply struct {
Message string `protobuf:"bytes,1,opt,name=message,proto3" json:"message,omitempty"`
XXX_NoUnkeyedLiteral struct{} `json:"-"`
XXX_unrecognized []byte `json:"-"`
XXX_sizecache int32 `json:"-"`
}
func (m *HelloReply) Reset() { *m = HelloReply{} }
func (m *HelloReply) String() string { return proto.CompactTextString(m) }
func (*HelloReply) ProtoMessage() {}
func (*HelloReply) Descriptor() ([]byte, []int) {
return fileDescriptor_17b8c58d586b62f2, []int{1}
}
func (m *HelloReply) XXX_Unmarshal(b []byte) error {
return xxx_messageInfo_HelloReply.Unmarshal(m, b)
}
func (m *HelloReply) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
return xxx_messageInfo_HelloReply.Marshal(b, m, deterministic)
}
func (m *HelloReply) XXX_Merge(src proto.Message) {
xxx_messageInfo_HelloReply.Merge(m, src)
}
func (m *HelloReply) XXX_Size() int {
return xxx_messageInfo_HelloReply.Size(m)
}
func (m *HelloReply) XXX_DiscardUnknown() {
xxx_messageInfo_HelloReply.DiscardUnknown(m)
}
var xxx_messageInfo_HelloReply proto.InternalMessageInfo
func (m *HelloReply) GetMessage() string {
if m != nil {
return m.Message
}
return ""
}
func init() {
proto.RegisterType((*HelloRequest)(nil), "helloworld.HelloRequest")
proto.RegisterType((*HelloReply)(nil), "helloworld.HelloReply")
}
func init() { proto.RegisterFile("helloworld.proto", fileDescriptor_17b8c58d586b62f2) }
var fileDescriptor_17b8c58d586b62f2 = []byte{
// 175 bytes of a gzipped FileDescriptorProto
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x12, 0xc8, 0x48, 0xcd, 0xc9,
0xc9, 0x2f, 0xcf, 0x2f, 0xca, 0x49, 0xd1, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x42, 0x88,
0x28, 0x29, 0x71, 0xf1, 0x78, 0x80, 0x78, 0x41, 0xa9, 0x85, 0xa5, 0xa9, 0xc5, 0x25, 0x42, 0x42,
0x5c, 0x2c, 0x79, 0x89, 0xb9, 0xa9, 0x12, 0x8c, 0x0a, 0x8c, 0x1a, 0x9c, 0x41, 0x60, 0xb6, 0x92,
0x1a, 0x17, 0x17, 0x54, 0x4d, 0x41, 0x4e, 0xa5, 0x90, 0x04, 0x17, 0x7b, 0x6e, 0x6a, 0x71, 0x71,
0x62, 0x3a, 0x4c, 0x11, 0x8c, 0x6b, 0xe4, 0xc9, 0xc5, 0xee, 0x5e, 0x94, 0x9a, 0x5a, 0x92, 0x5a,
0x24, 0x64, 0xc7, 0xc5, 0x11, 0x9c, 0x58, 0x09, 0xd6, 0x25, 0x24, 0xa1, 0x87, 0xe4, 0x02, 0x64,
0xcb, 0xa4, 0xc4, 0xb0, 0xc8, 0x14, 0xe4, 0x54, 0x2a, 0x31, 0x38, 0x19, 0x70, 0x49, 0x67, 0xe6,
0xeb, 0xa5, 0x17, 0x15, 0x24, 0xeb, 0xa5, 0x56, 0x24, 0xe6, 0x16, 0xe4, 0xa4, 0x16, 0x23, 0xa9,
0x75, 0xe2, 0x07, 0x2b, 0x0e, 0x07, 0xb1, 0x03, 0x40, 0x5e, 0x0a, 0x60, 0x4c, 0x62, 0x03, 0xfb,
0xcd, 0x18, 0x10, 0x00, 0x00, 0xff, 0xff, 0x0f, 0xb7, 0xcd, 0xf2, 0xef, 0x00, 0x00, 0x00,
}
// Reference imports to suppress errors if they are not otherwise used.
var _ context.Context
var _ grpc.ClientConn
// This is a compile-time assertion to ensure that this generated file
// is compatible with the grpc package it is being compiled against.
const _ = grpc.SupportPackageIsVersion4
// GreeterClient is the client API for Greeter service.
//
// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
type GreeterClient interface {
// Sends a greeting
SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error)
}
type greeterClient struct {
cc *grpc.ClientConn
}
func NewGreeterClient(cc *grpc.ClientConn) GreeterClient {
return &greeterClient{cc}
}
func (c *greeterClient) SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error) {
out := new(HelloReply)
err := c.cc.Invoke(ctx, "/helloworld.Greeter/SayHello", in, out, opts...)
if err != nil {
return nil, err
}
return out, nil
}
// GreeterServer is the server API for Greeter service.
type GreeterServer interface {
// Sends a greeting
SayHello(context.Context, *HelloRequest) (*HelloReply, error)
}
func RegisterGreeterServer(s *grpc.Server, srv GreeterServer) {
s.RegisterService(&_Greeter_serviceDesc, srv)
}
func _Greeter_SayHello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
in := new(HelloRequest)
if err := dec(in); err != nil {
return nil, err
}
if interceptor == nil {
return srv.(GreeterServer).SayHello(ctx, in)
}
info := &grpc.UnaryServerInfo{
Server: srv,
FullMethod: "/helloworld.Greeter/SayHello",
}
handler := func(ctx context.Context, req interface{}) (interface{}, error) {
return srv.(GreeterServer).SayHello(ctx, req.(*HelloRequest))
}
return interceptor(ctx, in, info, handler)
}
var _Greeter_serviceDesc = grpc.ServiceDesc{
ServiceName: "helloworld.Greeter",
HandlerType: (*GreeterServer)(nil),
Methods: []grpc.MethodDesc{
{
MethodName: "SayHello",
Handler: _Greeter_SayHello_Handler,
},
},
Streams: []grpc.StreamDesc{},
Metadata: "helloworld.proto",
}生成文件包含服務(wù)端接口GreeterServer描述，客戶端greeterClient接口及實(shí)現(xiàn)，以及HelloRequest、HelloResponse結(jié)構(gòu)體。
在server子目錄下創(chuàng)建server.go文件：
package main
import (
"context"
"net"
"google.golang.org/grpc"
pb "helloworld/proto"
"google.golang.org/grpc/reflection"
"google.golang.org/grpc/grpclog"
)
const (
// Address gRPC服務(wù)地址
port = ":50051"
)
// server is used to implement helloworld.GreeterServer.
type server struct{}
// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}
func main() {
lis, err := net.Listen("tcp", port)
if err != nil {
grpclog.Fatalf("failed to listen: %v", err)
}
// 實(shí)例化gRPC Server
s := grpc.NewServer()
// 注冊服務(wù)
pb.RegisterGreeterServer(s, &server{})
// Register reflection service on gRPC server.
reflection.Register(s)
if err := s.Serve(lis); err != nil {
grpclog.Fatalf("failed to serve: %v", err)
}
}服務(wù)端引入編譯后的proto包，實(shí)現(xiàn)約定的SayHello接口方法，接口描述可以查看helloworld.pb.go文件中的GreeterServer接口描述。實(shí)例化grpc Server并注冊GreeterService，開始提供服務(wù)。
客戶端使用gRPC訪問服務(wù)端：
package main
import (
"context"
"os"
"time"
"google.golang.org/grpc"
pb "helloworld/proto"
"log"
)
const (
address = "localhost:50051"
defaultName = "world"
)
func main() {
// Set up a connection to the server.
conn, err := grpc.Dial(address, grpc.WithInsecure())
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.Message)
}
// output:
// 2018/12/17 19:57:47 Greeting: Hello world客戶端初始化連接后直接調(diào)用聲明的方法，即可向服務(wù)端發(fā)起請求。
在server目錄下啟動Server：go run main.go
在client目錄下啟動客戶端：go run main.go
客戶端接收到服務(wù)端的響應(yīng)：2018/12/17 20:03:44 Greeting: Hello world
