ch4-06: 增加rest内容

2025-05-24 12:32:21 +00:00 · 2018-07-15 07:41:27 +08:00 · 2018-07-15 07:41:27 +08:00 · 903e87b09b
commit 903e87b09b
parent 00a6238fb1
7 changed files with 680 additions and 3 deletions
--- a/ch4-rpc/ch4-06-grpc-ext.md
+++ b/ch4-rpc/ch4-06-grpc-ext.md
@ -148,11 +148,122 @@ func (this *Message) Validate() error {

 通过生成的验证函数，并结合GRPC的截取器，我们可以很容易为每个方法的输入参数和返回值进行验证。

-<!--
-
 ## REST接口

-TODO
+GRPC服务一般用于集群内部通信，如果需要对外暴露服务一般会提供等价的REST接口。通过REST接口比较方便前端JavaScript和后端交互。开源社区中的grac-gateway项目就实现了将GRPC服务转为REST服务的能力。
+
+grpc-gateway的工作原理如下图：
+
+![](../images/ch4-06-grpc-gateway.png)
+
+通过在Protobuf文件中添加路由相关的元信息，通过自定义的代码插件生成路由相关的处理代码，最终将Rest请求转给更后端的Grpc服务处理。
+
+路由扩展元信息也是通过Protobuf的元数据扩展用法提供：
+
+```protobuf
+syntax = "proto3";
+
+package main;
+
+import "google/api/annotations.proto";
+
+message StringMessage {
+  string value = 1;
+}
+
+service RestService {
+	rpc Get(StringMessage) returns (StringMessage) {
+		option (google.api.http) = {
+			get: "/get/{value}"
+		};
+	}
+	rpc Post(StringMessage) returns (StringMessage) {
+		option (google.api.http) = {
+			post: "/post"
+			body: "*"
+		};
+	}
+}
+```
+
+我们首先为GRPC定义了Get和Post方法，然后通过元扩展语法在对应的方法后添加路由信息。其中“/get/{value}”路径对应的是Get方法，`{value}`部分对应参数中的value成员，结果通过json格式返回。Post方法对应“/post”路径，body中包含json格式的请求信息。
+
+然后通过以下命令安装protoc-gen-grpc-gateway插件：
+
+```
+go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway
+```
+
+再通过插件生成grpc-gateway必须的路由处理代码：
+
+```
+$ protoc -I/usr/local/include -I. \
+	-I$GOPATH/src \
+	-I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
+	--grpc-gateway_out=. \
+	hello.proto
+```
+
+插件会为RestService服务生成对应的RegisterRestServiceHandlerFromEndpoint函数：
+
+```go
+func RegisterRestServiceHandlerFromEndpoint(
+	ctx context.Context, mux *runtime.ServeMux, endpoint string,
+	opts []grpc.DialOption,
+) (err error) {
+	...
+}
+```
+
+RegisterRestServiceHandlerFromEndpoint函数用于将定义了Rest接口的请求转发到真正的GRPC服务。注册路由处理函数之后就可以启动Web服务了：
+
+```go
+func main() {
+	ctx := context.Background()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	mux := runtime.NewServeMux()
+
+	err := RegisterRestServiceHandlerFromEndpoint(
+		ctx, mux, "localhost:5000",
+		grpc.WithInsecure(),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	http.ListenAndServe(":8080", mux)
+}
+```
+
+首先通过runtime.NewServeMux()函数创建路由处理器，然后通过RegisterRestServiceHandlerFromEndpoint函数将RestService服务相关的REST接口导到后面的GRPC服务。grpc-gateway提供runtime.ServeMux类似同时也实现了http.Handler接口，因此可以标准库中的相关函数配置使用。
+
+档GRPC和REST服务全部启动之后，就可以用curl请求REST服务了：
+
+```
+$ curl localhost:8080/get/gopher
+{"value":"Get: gopher"}
+
+$ curl localhost:8080/post -X POST --data '{"value":"grpc"}'
+{"value":"Post: grpc"}
+```
+
+在对外公布REST接口时，我们一般还会提供一个Swagger格式的文件用于描述这个接口规范。
+
+```
+$ go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-swagger
+
+$ protoc \
+	-I=. -I=../../../github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
+	--swagger_out=. \
+	hello.proto
+```
+
+然后会生成一个hello.swagger.json文件。这样的话就可以通过swagger-ui这个项目，在网页中提供REST接口的文档和测试等功能。
+
+<!--
+

 ## Nginx代理

--- a/vendor/gobook.examples/ch4-06-grpc-ext/rest/Makefile
+++ b/vendor/gobook.examples/ch4-06-grpc-ext/rest/Makefile
@ -0,0 +1,21 @@
+
+run:
+	@go build -o a.out && ./a.out
+	-@rm ./a.out
+
+gen:
+	protoc \
+		-I=. -I=../../../github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
+		--go_out=plugins=grpc:. \
+		helloworld.proto
+	protoc \
+		-I=. -I=../../../github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
+		--grpc-gateway_out=. \
+		helloworld.proto
+	protoc \
+		-I=. -I=../../../github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
+		--swagger_out=. \
+		helloworld.proto
+
+clean:
+	-rm *.pb.go
--- a/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.pb.go
+++ b/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.pb.go
@ -0,0 +1,190 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: helloworld.proto
+
+package main
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+import _ "google.golang.org/genproto/googleapis/api/annotations"
+
+import (
+	context "golang.org/x/net/context"
+	grpc "google.golang.org/grpc"
+)
+
+// 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.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type StringMessage struct {
+	Value                string   `protobuf:"bytes,1,opt,name=value,proto3" json:"value,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *StringMessage) Reset()         { *m = StringMessage{} }
+func (m *StringMessage) String() string { return proto.CompactTextString(m) }
+func (*StringMessage) ProtoMessage()    {}
+func (*StringMessage) Descriptor() ([]byte, []int) {
+	return fileDescriptor_helloworld_b65656966bdaa93a, []int{0}
+}
+func (m *StringMessage) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_StringMessage.Unmarshal(m, b)
+}
+func (m *StringMessage) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_StringMessage.Marshal(b, m, deterministic)
+}
+func (dst *StringMessage) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_StringMessage.Merge(dst, src)
+}
+func (m *StringMessage) XXX_Size() int {
+	return xxx_messageInfo_StringMessage.Size(m)
+}
+func (m *StringMessage) XXX_DiscardUnknown() {
+	xxx_messageInfo_StringMessage.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_StringMessage proto.InternalMessageInfo
+
+func (m *StringMessage) GetValue() string {
+	if m != nil {
+		return m.Value
+	}
+	return ""
+}
+
+func init() {
+	proto.RegisterType((*StringMessage)(nil), "main.StringMessage")
+}
+
+// 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
+
+// RestServiceClient is the client API for RestService service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
+type RestServiceClient interface {
+	Get(ctx context.Context, in *StringMessage, opts ...grpc.CallOption) (*StringMessage, error)
+	Post(ctx context.Context, in *StringMessage, opts ...grpc.CallOption) (*StringMessage, error)
+}
+
+type restServiceClient struct {
+	cc *grpc.ClientConn
+}
+
+func NewRestServiceClient(cc *grpc.ClientConn) RestServiceClient {
+	return &restServiceClient{cc}
+}
+
+func (c *restServiceClient) Get(ctx context.Context, in *StringMessage, opts ...grpc.CallOption) (*StringMessage, error) {
+	out := new(StringMessage)
+	err := c.cc.Invoke(ctx, "/main.RestService/Get", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *restServiceClient) Post(ctx context.Context, in *StringMessage, opts ...grpc.CallOption) (*StringMessage, error) {
+	out := new(StringMessage)
+	err := c.cc.Invoke(ctx, "/main.RestService/Post", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// RestServiceServer is the server API for RestService service.
+type RestServiceServer interface {
+	Get(context.Context, *StringMessage) (*StringMessage, error)
+	Post(context.Context, *StringMessage) (*StringMessage, error)
+}
+
+func RegisterRestServiceServer(s *grpc.Server, srv RestServiceServer) {
+	s.RegisterService(&_RestService_serviceDesc, srv)
+}
+
+func _RestService_Get_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(StringMessage)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(RestServiceServer).Get(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/main.RestService/Get",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(RestServiceServer).Get(ctx, req.(*StringMessage))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _RestService_Post_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(StringMessage)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(RestServiceServer).Post(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/main.RestService/Post",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(RestServiceServer).Post(ctx, req.(*StringMessage))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+var _RestService_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "main.RestService",
+	HandlerType: (*RestServiceServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "Get",
+			Handler:    _RestService_Get_Handler,
+		},
+		{
+			MethodName: "Post",
+			Handler:    _RestService_Post_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "helloworld.proto",
+}
+
+func init() { proto.RegisterFile("helloworld.proto", fileDescriptor_helloworld_b65656966bdaa93a) }
+
+var fileDescriptor_helloworld_b65656966bdaa93a = []byte{
+	// 192 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, 0x62, 0xc9, 0x4d,
+	0xcc, 0xcc, 0x93, 0x92, 0x49, 0xcf, 0xcf, 0x4f, 0xcf, 0x49, 0xd5, 0x4f, 0x2c, 0xc8, 0xd4, 0x4f,
+	0xcc, 0xcb, 0xcb, 0x2f, 0x49, 0x2c, 0xc9, 0xcc, 0xcf, 0x2b, 0x86, 0xa8, 0x51, 0x52, 0xe5, 0xe2,
+	0x0d, 0x2e, 0x29, 0xca, 0xcc, 0x4b, 0xf7, 0x4d, 0x2d, 0x2e, 0x4e, 0x4c, 0x4f, 0x15, 0x12, 0xe1,
+	0x62, 0x2d, 0x4b, 0xcc, 0x29, 0x4d, 0x95, 0x60, 0x54, 0x60, 0xd4, 0xe0, 0x0c, 0x82, 0x70, 0x8c,
+	0x66, 0x30, 0x72, 0x71, 0x07, 0xa5, 0x16, 0x97, 0x04, 0xa7, 0x16, 0x95, 0x65, 0x26, 0xa7, 0x0a,
+	0xb9, 0x72, 0x31, 0xbb, 0xa7, 0x96, 0x08, 0x09, 0xeb, 0x81, 0xac, 0xd0, 0x43, 0x31, 0x41, 0x0a,
+	0x9b, 0xa0, 0x92, 0x48, 0xd3, 0xe5, 0x27, 0x93, 0x99, 0xf8, 0x84, 0x78, 0xf4, 0xd3, 0x53, 0x4b,
+	0xf4, 0xab, 0xc1, 0xa6, 0xd6, 0x0a, 0x39, 0x71, 0xb1, 0x04, 0xe4, 0x17, 0x93, 0x62, 0x8e, 0x00,
+	0xd8, 0x1c, 0x2e, 0x25, 0x56, 0xfd, 0x82, 0xfc, 0xe2, 0x12, 0x2b, 0x46, 0xad, 0x24, 0x36, 0xb0,
+	0x47, 0x8c, 0x01, 0x01, 0x00, 0x00, 0xff, 0xff, 0x75, 0x88, 0x64, 0x8b, 0x00, 0x01, 0x00, 0x00,
+}
--- a/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.pb.gw.go
+++ b/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.pb.gw.go
@ -0,0 +1,180 @@
+// Code generated by protoc-gen-grpc-gateway. DO NOT EDIT.
+// source: helloworld.proto
+
+/*
+Package main is a reverse proxy.
+
+It translates gRPC into RESTful JSON APIs.
+*/
+package main
+
+import (
+	"io"
+	"net/http"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/grpc-ecosystem/grpc-gateway/runtime"
+	"github.com/grpc-ecosystem/grpc-gateway/utilities"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/status"
+)
+
+var _ codes.Code
+var _ io.Reader
+var _ status.Status
+var _ = runtime.String
+var _ = utilities.NewDoubleArray
+
+func request_RestService_Get_0(ctx context.Context, marshaler runtime.Marshaler, client RestServiceClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq StringMessage
+	var metadata runtime.ServerMetadata
+
+	var (
+		val string
+		ok  bool
+		err error
+		_   = err
+	)
+
+	val, ok = pathParams["value"]
+	if !ok {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "missing parameter %s", "value")
+	}
+
+	protoReq.Value, err = runtime.String(val)
+
+	if err != nil {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", "value", err)
+	}
+
+	msg, err := client.Get(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
+	return msg, metadata, err
+
+}
+
+func request_RestService_Post_0(ctx context.Context, marshaler runtime.Marshaler, client RestServiceClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq StringMessage
+	var metadata runtime.ServerMetadata
+
+	if err := marshaler.NewDecoder(req.Body).Decode(&protoReq); err != nil {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := client.Post(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
+	return msg, metadata, err
+
+}
+
+// RegisterRestServiceHandlerFromEndpoint is same as RegisterRestServiceHandler but
+// automatically dials to "endpoint" and closes the connection when "ctx" gets done.
+func RegisterRestServiceHandlerFromEndpoint(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) (err error) {
+	conn, err := grpc.Dial(endpoint, opts...)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if err != nil {
+			if cerr := conn.Close(); cerr != nil {
+				grpclog.Printf("Failed to close conn to %s: %v", endpoint, cerr)
+			}
+			return
+		}
+		go func() {
+			<-ctx.Done()
+			if cerr := conn.Close(); cerr != nil {
+				grpclog.Printf("Failed to close conn to %s: %v", endpoint, cerr)
+			}
+		}()
+	}()
+
+	return RegisterRestServiceHandler(ctx, mux, conn)
+}
+
+// RegisterRestServiceHandler registers the http handlers for service RestService to "mux".
+// The handlers forward requests to the grpc endpoint over "conn".
+func RegisterRestServiceHandler(ctx context.Context, mux *runtime.ServeMux, conn *grpc.ClientConn) error {
+	return RegisterRestServiceHandlerClient(ctx, mux, NewRestServiceClient(conn))
+}
+
+// RegisterRestServiceHandler registers the http handlers for service RestService to "mux".
+// The handlers forward requests to the grpc endpoint over the given implementation of "RestServiceClient".
+// Note: the gRPC framework executes interceptors within the gRPC handler. If the passed in "RestServiceClient"
+// doesn't go through the normal gRPC flow (creating a gRPC client etc.) then it will be up to the passed in
+// "RestServiceClient" to call the correct interceptors.
+func RegisterRestServiceHandlerClient(ctx context.Context, mux *runtime.ServeMux, client RestServiceClient) error {
+
+	mux.Handle("GET", pattern_RestService_Get_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(ctx)
+		defer cancel()
+		if cn, ok := w.(http.CloseNotifier); ok {
+			go func(done <-chan struct{}, closed <-chan bool) {
+				select {
+				case <-done:
+				case <-closed:
+					cancel()
+				}
+			}(ctx.Done(), cn.CloseNotify())
+		}
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		rctx, err := runtime.AnnotateContext(ctx, mux, req)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := request_RestService_Get_0(rctx, inboundMarshaler, client, req, pathParams)
+		ctx = runtime.NewServerMetadataContext(ctx, md)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_RestService_Get_0(ctx, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
+	mux.Handle("POST", pattern_RestService_Post_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(ctx)
+		defer cancel()
+		if cn, ok := w.(http.CloseNotifier); ok {
+			go func(done <-chan struct{}, closed <-chan bool) {
+				select {
+				case <-done:
+				case <-closed:
+					cancel()
+				}
+			}(ctx.Done(), cn.CloseNotify())
+		}
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		rctx, err := runtime.AnnotateContext(ctx, mux, req)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := request_RestService_Post_0(rctx, inboundMarshaler, client, req, pathParams)
+		ctx = runtime.NewServerMetadataContext(ctx, md)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_RestService_Post_0(ctx, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
+	return nil
+}
+
+var (
+	pattern_RestService_Get_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 1, 0, 4, 1, 5, 1}, []string{"get", "value"}, ""))
+
+	pattern_RestService_Post_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0}, []string{"post"}, ""))
+)
+
+var (
+	forward_RestService_Get_0 = runtime.ForwardResponseMessage
+
+	forward_RestService_Post_0 = runtime.ForwardResponseMessage
+)
--- a/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.proto
+++ b/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.proto
@ -0,0 +1,23 @@
+syntax = "proto3";
+
+package main;
+
+import "google/api/annotations.proto";
+
+message StringMessage {
+  string value = 1;
+}
+
+service RestService {
+	rpc Get(StringMessage) returns (StringMessage) {
+		option (google.api.http) = {
+			get: "/get/{value}"
+		};
+	}
+	rpc Post(StringMessage) returns (StringMessage) {
+		option (google.api.http) = {
+			post: "/post"
+			body: "*"
+		};
+	}
+}
--- a/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.swagger.json
+++ b/vendor/gobook.examples/ch4-06-grpc-ext/rest/helloworld.swagger.json
@ -0,0 +1,79 @@
+{
+  "swagger": "2.0",
+  "info": {
+    "title": "helloworld.proto",
+    "version": "version not set"
+  },
+  "schemes": [
+    "http",
+    "https"
+  ],
+  "consumes": [
+    "application/json"
+  ],
+  "produces": [
+    "application/json"
+  ],
+  "paths": {
+    "/get/{value}": {
+      "get": {
+        "operationId": "Get",
+        "responses": {
+          "200": {
+            "description": "",
+            "schema": {
+              "$ref": "#/definitions/mainStringMessage"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "name": "value",
+            "in": "path",
+            "required": true,
+            "type": "string"
+          }
+        ],
+        "tags": [
+          "RestService"
+        ]
+      }
+    },
+    "/post": {
+      "post": {
+        "operationId": "Post",
+        "responses": {
+          "200": {
+            "description": "",
+            "schema": {
+              "$ref": "#/definitions/mainStringMessage"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/mainStringMessage"
+            }
+          }
+        ],
+        "tags": [
+          "RestService"
+        ]
+      }
+    }
+  },
+  "definitions": {
+    "mainStringMessage": {
+      "type": "object",
+      "properties": {
+        "value": {
+          "type": "string"
+        }
+      }
+    }
+  }
+}
--- a/vendor/gobook.examples/ch4-06-grpc-ext/rest/main.go
+++ b/vendor/gobook.examples/ch4-06-grpc-ext/rest/main.go
@ -0,0 +1,73 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+	"net/http"
+
+	"github.com/golang/glog"
+	"github.com/grpc-ecosystem/grpc-gateway/runtime"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+)
+
+var (
+	port         = ":5000"
+	echoEndpoint = flag.String("echo_endpoint", "localhost"+port, "endpoint of YourService")
+)
+
+type myGrpcServer struct{}
+
+func (s *myGrpcServer) Get(ctx context.Context, in *StringMessage) (*StringMessage, error) {
+	return &StringMessage{Value: "Get: " + in.Value}, nil
+}
+func (s *myGrpcServer) Post(ctx context.Context, in *StringMessage) (*StringMessage, error) {
+	return &StringMessage{Value: "Post: " + in.Value}, nil
+}
+
+func run() error {
+	ctx := context.Background()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	mux := runtime.NewServeMux()
+	opts := []grpc.DialOption{grpc.WithInsecure()}
+	err := RegisterRestServiceHandlerFromEndpoint(ctx, mux, *echoEndpoint, opts)
+	if err != nil {
+		return err
+	}
+
+	return http.ListenAndServe(":8080", mux)
+}
+
+// $ curl localhost:8080/get/gopher
+// {"value":"Get: gopher"}
+
+// $ curl localhost:8080/post -X POST --data '{"value":"grpc"}'
+// {"value":"Post: grpc"}
+
+func main() {
+	flag.Parse()
+	defer glog.Flush()
+
+	go startGrpcServer()
+
+	if err := run(); err != nil {
+		glog.Fatal(err)
+	}
+}
+
+func startGrpcServer() {
+	server := grpc.NewServer()
+	RegisterRestServiceServer(server, new(myGrpcServer))
+
+	lis, err := net.Listen("tcp", port)
+	if err != nil {
+		log.Panicf("could not list on %s: %s", port, err)
+	}
+
+	if err := server.Serve(lis); err != nil {
+		log.Panicf("grpc serve error: %s", err)
+	}
+}