diff --git a/external/external.go b/external/external.go
new file mode 100644
index 0000000..5aa384c
--- /dev/null
+++ b/external/external.go
@@ -0,0 +1,11 @@
+package external
+
+import "git.loafle.net/overflow/member_gateway_rest/external/grpc"
+
+func InitPackage() {
+	grpc.InitPackage()
+}
+
+func DestroyPackage() {
+	grpc.DestroyPackage()
+}
diff --git a/external/grpc/grpc.go b/external/grpc/grpc.go
new file mode 100644
index 0000000..502514e
--- /dev/null
+++ b/external/grpc/grpc.go
@@ -0,0 +1,53 @@
+package grpc
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"sync"
+
+	"git.loafle.net/commons/logging-go"
+	oci "git.loafle.net/overflow/central_api/golang"
+	"google.golang.org/grpc"
+)
+
+var grpcClient oci.OverflowApiServerClient
+
+func InitPackage() {
+	conn, err := grpc.Dial("192.168.1.50:50006", grpc.WithInsecure())
+	if nil != err {
+		logging.Logger().Panic(err)
+	}
+	grpcClient = oci.NewOverflowApiServerClient(conn)
+
+}
+
+func DestroyPackage() {
+
+}
+
+var execMtx sync.RWMutex
+
+func Exec(ctx context.Context, method string, params ...string) (string, error) {
+	if nil == grpcClient {
+		return "", fmt.Errorf("GRPC Client is not initialized")
+	}
+
+	var err error
+
+	sm := strings.Split(method, ".")
+	si := &oci.ServerInput{
+		Target: sm[0],
+		Method: sm[1],
+		Params: params,
+	}
+
+	execMtx.Lock()
+	defer execMtx.Unlock()
+	so, err := grpcClient.(oci.OverflowApiServerClient).Exec(ctx, si)
+	if nil != err {
+		return "", err
+	}
+
+	return so.Result, nil
+}
diff --git a/glide.yaml b/glide.yaml
index abeed13..6bb6de0 100644
--- a/glide.yaml
+++ b/glide.yaml
@@ -2,3 +2,6 @@ package: git.loafle.net/overflow/member_gateway_rest
 import:
 - package: git.loafle.net/commons/server-go
 - package: git.loafle.net/commons/rpc-go
+- package: git.loafle.net/overflow/central_api
+- package: google.golang.org/grpc
+  version: ^1.11.2
diff --git a/main.go b/main.go
index d3b2cbe..8b07efa 100644
--- a/main.go
+++ b/main.go
@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"git.loafle.net/commons/logging-go"
+	"git.loafle.net/overflow/member_gateway_rest/external"
 	"git.loafle.net/overflow/member_gateway_rest/server"
 )
 
@@ -19,6 +20,11 @@ func init() {
 func main() {
 	s := server.NewServer()
 
+	external.InitPackage()
+	defer func() {
+		external.DestroyPackage()
+	}()
+
 	go func() {
 		err := s.ListenAndServe()
 		if nil != err {
diff --git a/service/member-service.go b/service/member-service.go
index f9824da..51752dd 100644
--- a/service/member-service.go
+++ b/service/member-service.go
@@ -1,7 +1,10 @@
 package service
 
 import (
+	"context"
+
 	"git.loafle.net/commons/server-go"
+	"git.loafle.net/overflow/member_gateway_rest/external/grpc"
 	"github.com/valyala/fasthttp"
 )
 
@@ -10,7 +13,13 @@ type MemberService struct {
 
 func (ms *MemberService) Signin(servletCtx server.ServletCtx, ctx *fasthttp.RequestCtx, id string, pw string) (string, error) {
 
-	return "dkfksddfk", nil
+	gRPCCtx := context.Background()
+	r, err := grpc.Exec(gRPCCtx, "MemberService.signin", id, pw)
+	if nil != err {
+		return "", err
+	}
+
+	return r, nil
 }
 
 func (ms *MemberService) Register(servletCtx server.ServletCtx, ctx *fasthttp.RequestCtx, id string, pw string) (string, error) {
diff --git a/servlet/rest-servlet.go b/servlet/rest-servlet.go
index 434fa06..47bf65b 100644
--- a/servlet/rest-servlet.go
+++ b/servlet/rest-servlet.go
@@ -72,7 +72,7 @@ func (s *RESTServlet) HandleGet(servletCtx server.ServletCtx, ctx *fasthttp.Requ
 
 	reply, err := s.RPCInvoker.Invoke(reqCodec, servletCtx, ctx)
 
-	buf, err := reqCodec.NewResponse(reply, err)
+	buf, err := reqCodec.NewResponseWithString(reply.(string), err)
 	if nil != err {
 		return csw.NewError(fasthttp.StatusInternalServerError, err)
 	}
@@ -95,7 +95,7 @@ func (s *RESTServlet) HandlePost(servletCtx server.ServletCtx, ctx *fasthttp.Req
 
 	reply, err := s.RPCInvoker.Invoke(reqCodec, servletCtx, ctx)
 
-	buf, err = reqCodec.NewResponse(reply, err)
+	buf, err = reqCodec.NewResponseWithString(reply.(string), err)
 	if nil != err {
 		return csw.NewError(fasthttp.StatusInternalServerError, err)
 	}