diff --git a/vendor/ch4-04/01/client/main.go b/vendor/ch4-04/01/client/main.go
new file mode 100644
index 0000000..c603c40
--- /dev/null
+++ b/vendor/ch4-04/01/client/main.go
@@ -0,0 +1,24 @@
+package main
+
+import (
+	hs "ch4-04/01/helloservice"
+	"context"
+	"fmt"
+	"google.golang.org/grpc"
+	"log"
+)
+
+func main() {
+	conn, err := grpc.Dial("localhost:1234", grpc.WithInsecure())
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer conn.Close()
+
+	client := hs.NewHelloServiceClient(conn)
+	reply, err := client.Hello(context.Background(), &hs.String{Value: "hello"})
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(reply.GetValue())
+}
diff --git a/vendor/ch4-04/01/helloservice/hello.pb.go b/vendor/ch4-04/01/helloservice/hello.pb.go
new file mode 100644
index 0000000..b2e90a0
--- /dev/null
+++ b/vendor/ch4-04/01/helloservice/hello.pb.go
@@ -0,0 +1,151 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: hello.proto
+
+package helloservice
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+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 String 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 *String) Reset()         { *m = String{} }
+func (m *String) String() string { return proto.CompactTextString(m) }
+func (*String) ProtoMessage()    {}
+func (*String) Descriptor() ([]byte, []int) {
+	return fileDescriptor_hello_c1f637c850550ef7, []int{0}
+}
+func (m *String) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_String.Unmarshal(m, b)
+}
+func (m *String) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_String.Marshal(b, m, deterministic)
+}
+func (dst *String) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_String.Merge(dst, src)
+}
+func (m *String) XXX_Size() int {
+	return xxx_messageInfo_String.Size(m)
+}
+func (m *String) XXX_DiscardUnknown() {
+	xxx_messageInfo_String.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_String proto.InternalMessageInfo
+
+func (m *String) GetValue() string {
+	if m != nil {
+		return m.Value
+	}
+	return ""
+}
+
+func init() {
+	proto.RegisterType((*String)(nil), "helloservice.String")
+}
+
+// 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
+
+// HelloServiceClient is the client API for HelloService service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
+type HelloServiceClient interface {
+	Hello(ctx context.Context, in *String, opts ...grpc.CallOption) (*String, error)
+}
+
+type helloServiceClient struct {
+	cc *grpc.ClientConn
+}
+
+func NewHelloServiceClient(cc *grpc.ClientConn) HelloServiceClient {
+	return &helloServiceClient{cc}
+}
+
+func (c *helloServiceClient) Hello(ctx context.Context, in *String, opts ...grpc.CallOption) (*String, error) {
+	out := new(String)
+	err := c.cc.Invoke(ctx, "/helloservice.HelloService/Hello", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// HelloServiceServer is the server API for HelloService service.
+type HelloServiceServer interface {
+	Hello(context.Context, *String) (*String, error)
+}
+
+func RegisterHelloServiceServer(s *grpc.Server, srv HelloServiceServer) {
+	s.RegisterService(&_HelloService_serviceDesc, srv)
+}
+
+func _HelloService_Hello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(String)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(HelloServiceServer).Hello(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/helloservice.HelloService/Hello",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(HelloServiceServer).Hello(ctx, req.(*String))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+var _HelloService_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "helloservice.HelloService",
+	HandlerType: (*HelloServiceServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "Hello",
+			Handler:    _HelloService_Hello_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "hello.proto",
+}
+
+func init() { proto.RegisterFile("hello.proto", fileDescriptor_hello_c1f637c850550ef7) }
+
+var fileDescriptor_hello_c1f637c850550ef7 = []byte{
+	// 108 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0xe2, 0xce, 0x48, 0xcd, 0xc9,
+	0xc9, 0xd7, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0xe2, 0x01, 0x73, 0x8a, 0x53, 0x8b, 0xca, 0x32,
+	0x93, 0x53, 0x95, 0xe4, 0xb8, 0xd8, 0x82, 0x4b, 0x8a, 0x32, 0xf3, 0xd2, 0x85, 0x44, 0xb8, 0x58,
+	0xcb, 0x12, 0x73, 0x4a, 0x53, 0x25, 0x18, 0x15, 0x18, 0x35, 0x38, 0x83, 0x20, 0x1c, 0x23, 0x67,
+	0x2e, 0x1e, 0x0f, 0x90, 0xfa, 0x60, 0x88, 0x7a, 0x21, 0x63, 0x2e, 0x56, 0x30, 0x5f, 0x48, 0x44,
+	0x0f, 0xd9, 0x1c, 0x3d, 0x88, 0x21, 0x52, 0x58, 0x45, 0x93, 0xd8, 0xc0, 0x36, 0x1b, 0x03, 0x02,
+	0x00, 0x00, 0xff, 0xff, 0xf7, 0x6b, 0x07, 0xff, 0x88, 0x00, 0x00, 0x00,
+}
diff --git a/vendor/ch4-04/01/helloservice/hello.proto b/vendor/ch4-04/01/helloservice/hello.proto
new file mode 100644
index 0000000..48ee47f
--- /dev/null
+++ b/vendor/ch4-04/01/helloservice/hello.proto
@@ -0,0 +1,13 @@
+syntax = "proto3";
+
+package helloservice;
+
+message String {
+	string value = 1;
+}
+
+service HelloService {
+	rpc Hello (String) returns (String);
+}
+
+//protoc --go_out=plugins=grpc:. hello.proto
\ No newline at end of file
diff --git a/vendor/ch4-04/01/server/main.go b/vendor/ch4-04/01/server/main.go
new file mode 100644
index 0000000..8618613
--- /dev/null
+++ b/vendor/ch4-04/01/server/main.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"context"
+	"log"
+	"net"
+
+	"google.golang.org/grpc"
+
+	hs "ch4-04/01/helloservice"
+)
+
+type HelloServiceImpl struct{}
+
+func (p *HelloServiceImpl) Hello(
+	ctx context.Context, args *hs.String,
+) (*hs.String, error) {
+	reply := &hs.String{Value: "hello:" + args.GetValue()}
+	return reply, nil
+}
+
+func main() {
+	grpcServer := grpc.NewServer()
+	hs.RegisterHelloServiceServer(grpcServer, new(HelloServiceImpl))
+
+	lis, err := net.Listen("tcp", ":1234")
+	if err != nil {
+		log.Fatal(err)
+	}
+	grpcServer.Serve(lis)
+}
diff --git a/vendor/ch4-04/03/server/server.go b/vendor/ch4-04/03/server/main.go
similarity index 100%
rename from vendor/ch4-04/03/server/server.go
rename to vendor/ch4-04/03/server/main.go