Go语言版本的Protobuf-RPC基本算完成了. 现在简单说下使用方法.
安装测试环境
先下载代码(不支持go get):
hg clone https://bitbucket.org/chai2010/gopath
然后下载后的目录设置为GOPATH, 并添加$GOPATH/bin到PATH环境变量.
在$GOPATH/bin中已经包含了Windows下的2.4.1版本的protoc.exe. 如果是Linux等系统, 请自行下载并安装protoc程序.
安装protoc.exe的Go语言插件:
go install encoding/protobuf/protoc-gen-go
该插件是基于code.google.com/p/goprotobuf/protoc-gen-go实现, 主要增加了encoding/protobuf/protoc-gen-go/generator/service.go文件, 用于RPC的代码生成. 生成的RPC代码依赖net/rpc/protorpc, 这个包是Protobuf-RPC的底层实现, 可以单独使用.
现在可以运行一下测试程序:
C:\>go test net/rpc/protorpc/service.pb
ok net/rpc/protorpc/service.pb 2.123s
测试通过, 继续.
编译 proto 文件
创建一个名为pbrpc的工作目录, 再创建pbrpc/arith.pb的子目录.
将net/rpc/protorpc/service.pb/service.proto文件复制到pbrpc/arith.pb的子目录.
包名字改为arith, 文件arith.proto的内容如下:
package arith;
option cc_generic_services = true;
option java_generic_services = true;
option py_generic_services = true;
message ArithRequest {
optional int32 a = 1;
optional int32 b = 2;
}
message ArithResponse {
optional int32 c = 1;
}
service ArithService {
rpc add (ArithRequest) returns (ArithResponse);
rpc mul (ArithRequest) returns (ArithResponse);
rpc div (ArithRequest) returns (ArithResponse);
rpc error (ArithRequest) returns (ArithResponse);
}
主要是定义了一个ArithService接口. 要注意的是cc_generic_services/java_generic_services, py_generic_services几个选项.
我前提提到的protoc-gen-go在生成代码的时候, 这3个选项至少要有一个为true, 才会生成RPC的代码.
当然, 如果不生成RPC代码的话, 也是可以单独使用net/rpc/protorpc包的. 不过protoc-gen-go生成的代码会简便很多.
进入pbrpc/arith.pb的子目录, 编译arith.proto文件:
protoc --go_out=. arith.proto
生成 arith.pb.go 文件, 其中RPC的代码主要是下面这些:
type ArithService interface {
Add(in *ArithRequest, out *ArithResponse) error
Mul(in *ArithRequest, out *ArithResponse) error
Div(in *ArithRequest, out *ArithResponse) error
Error(in *ArithRequest, out *ArithResponse) error
}
// RegisterArithService publish the given ArithService implementation on the server.
func RegisterArithService(srv *rpc.Server, x ArithService) error {
if err := srv.RegisterName("ArithService", x); err != nil {
return err
}
return nil
}
// ServeArithService serves the given ArithService implementation on conn.
func ServeArithService(conn io.ReadWriteCloser, x ArithService) error {
srv := rpc.NewServer()
if err := srv.RegisterName("ArithService", x); err != nil {
return err
}
srv.ServeCodec(protorpc.NewServerCodec(conn))
return nil
}
// ListenAndServeArithService listen announces on the local network address laddr
// and serves the given ArithService implementation.
func ListenAndServeArithService(network, addr string, x ArithService) error {
clients, err := net.Listen(network, addr)
if err != nil {
return err
}
srv := rpc.NewServer()
if err := srv.RegisterName("ArithService", x); err != nil {
return err
}
for {
conn, err := clients.Accept()
if err != nil {
return err
}
go srv.ServeCodec(protorpc.NewServerCodec(conn))
}
panic("unreachable")
}
type rpcArithServiceStub struct {
*rpc.Client
}
func (c *rpcArithServiceStub) Add(in *ArithRequest, out *ArithResponse) error {
return c.Call("ArithService.Add", in, out)
}
func (c *rpcArithServiceStub) Mul(in *ArithRequest, out *ArithResponse) error {
return c.Call("ArithService.Mul", in, out)
}
func (c *rpcArithServiceStub) Div(in *ArithRequest, out *ArithResponse) error {
return c.Call("ArithService.Div", in, out)
}
func (c *rpcArithServiceStub) Error(in *ArithRequest, out *ArithResponse) error {
return c.Call("ArithService.Error", in, out)
}
// DialArithService connects to an ArithService at the specified network address.
func DialArithService(network, addr string) (*rpc.Client, ArithService, error) {
conn, err := net.Dial(network, addr)
if err != nil {
return nil, nil, err
}
c, srv := NewArithServiceClient(conn)
return c, srv, nil
}
// NewArithServiceClient returns a ArithService rpc.Client and stub to handle
// requests to the set of ArithService at the other end of the connection.
func NewArithServiceClient(conn io.ReadWriteCloser) (*rpc.Client, ArithService) {
c := rpc.NewClientWithCodec(protorpc.NewClientCodec(conn))
return c, &rpcArithServiceStub{c}
}
// NewArithServiceStub returns a ArithService stub to handle rpc.Client.
func NewArithServiceStub(c *rpc.Client) ArithService {
return &rpcArithServiceStub{c}
}
其中生成的服务器端的代码有: ListenAndServeArithService, ServeArithService, RegisterArithService.
生成的客户端的接口有: DialArithService, NewArithServiceClient, NewArithServiceStub.
其中RPC接口对应ArithService接口.
编写测试代码
在pbrpc目录创建rpc_server.go文件, 代码如下:
package main
import (
"encoding/protobuf/proto"
"errors"
"./arith.pb"
)
type Arith int
func (t *Arith) Add(args *arith.ArithRequest, reply *arith.ArithResponse) error {
reply.C = proto.Int32(args.GetA() + args.GetB())
return nil
}
func (t *Arith) Mul(args *arith.ArithRequest, reply *arith.ArithResponse) error {
reply.C = proto.Int32(args.GetA() * args.GetB())
return nil
}
func (t *Arith) Div(args *arith.ArithRequest, reply *arith.ArithResponse) error {
if args.GetB() == 0 {
return errors.New("divide by zero")
}
reply.C = proto.Int32(args.GetA() / args.GetB())
return nil
}
func (t *Arith) Error(args *arith.ArithRequest, reply *arith.ArithResponse) error {
return errors.New("ArithError")
}
func main() {
arith.ListenAndServeArithService("tcp", ":1234", new(Arith))
}
最关键的是arith.ListenAndServeArithService("tcp", ":1234", new(Arith)). 当然, 也可以使用RegisterArithService或ServeArithService等接口进行定制.
然后在pbrpc创建rpc_client.go对应客户端, 代码如下:
package main
import (
"encoding/protobuf/proto"
"log"
"./arith.pb"
)
func main() {
// client
client, stub, err := arith.DialArithService("tcp", "127.0.0.1:1234")
if err != nil {
log.Fatalf(`arith.DialArithService("tcp", "127.0.0.1:1234"): %v`, err)
}
defer client.Close()
var args arith.ArithRequest
var reply arith.ArithResponse
// Add
args.A = proto.Int32(1)
args.B = proto.Int32(2)
if err = stub.Add(&args, &reply); err != nil {
log.Fatalf(`arith.Add: %v`, err)
}
if reply.GetC() != 3 {
log.Fatalf(`arith.Add: expected = %d, got = %d`, 3, reply.GetC())
}
// Mul
args.A = proto.Int32(2)
args.B = proto.Int32(3)
if err = stub.Mul(&args, &reply); err != nil {
log.Fatalf(`arith.Mul: %v`, err)
}
if reply.GetC() != 6 {
log.Fatalf(`arith.Mul: expected = %d, got = %d`, 6, reply.GetC())
}
// Div
args.A = proto.Int32(13)
args.B = proto.Int32(5)
if err = stub.Div(&args, &reply); err != nil {
log.Fatalf(`arith.Div: %v`, err)
}
if reply.GetC() != 2 {
log.Fatalf(`arith.Div: expected = %d, got = %d`, 2, reply.GetC())
}
// Div zero
args.A = proto.Int32(1)
args.B = proto.Int32(0)
if err = stub.Div(&args, &reply); err.Error() != "divide by zero" {
log.Fatalf(`arith.Error: expected = %s, got = %s`, "divide by zero", err.Error())
}
// Error
args.A = proto.Int32(1)
args.B = proto.Int32(2)
if err = stub.Error(&args, &reply); err.Error() != "ArithError" {
log.Fatalf(`arith.Error: expected = %s, got = %s`, "ArithError", err.Error())
}
log.Printf("Done")
}
然后就可以启动服务, 并测试客户端了.
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