diff --git a/backends/etcd/client.go b/backends/etcd/client.go
index 7953ffc..5bfd296 100644
--- a/backends/etcd/client.go
+++ b/backends/etcd/client.go
@@ -244,7 +244,7 @@ func (c *Client) internalSync(prefix string, store store.Store, stopChan chan bo
 				time.Sleep(time.Duration(1000) * time.Millisecond)
 				continue
 			}
-			store.SetBulk("/", val)
+			store.PutBulk("/", val)
 			inited = true
 		}
 
@@ -267,7 +267,7 @@ func processSyncChange(prefix string, store store.Store, resp *client.Response)
 	case "delete":
 		store.Delete(nodePath)
 	default:
-		store.Set(nodePath, false, resp.Node.Value)
+		store.Put(nodePath, resp.Node.Value)
 	}
 }
 
diff --git a/backends/etcdv3/client.go b/backends/etcdv3/client.go
index f02d9e7..59044ea 100644
--- a/backends/etcdv3/client.go
+++ b/backends/etcdv3/client.go
@@ -206,7 +206,7 @@ func (c *Client) internalSync(prefix string, store store.Store, stopChan chan bo
 				time.Sleep(time.Duration(1000) * time.Millisecond)
 				continue
 			}
-			store.SetBulk("/", val)
+			store.PutBulk("/", val)
 			inited = true
 		}
 		for resp := range watchChan {
@@ -224,12 +224,12 @@ func processSyncChange(prefix string, store store.Store, resp *client.WatchRespo
 		log.Debug("process sync change, event_type: %s, prefix: %v, nodePath:%v, value: %v ", event.Type, prefix, nodePath, value)
 		switch event.Type {
 		case mvccpb.PUT:
-			store.Set(nodePath, false, value)
+			store.Put(nodePath, value)
 		case mvccpb.DELETE:
 			store.Delete(nodePath)
 		default:
 			log.Warning("Unknow watch event type: %s ", event.Type)
-			store.Set(nodePath, false, value)
+			store.Put(nodePath, value)
 
 		}
 	}
diff --git a/store/store.go b/store/store.go
index 7228146..b5113ed 100644
--- a/store/store.go
+++ b/store/store.go
@@ -1,19 +1,25 @@
 package store
 
 import (
+	"fmt"
 	"github.com/yunify/metadata-proxy/util"
 	"github.com/yunify/metadata-proxy/util/flatmap"
 	"path"
+	"reflect"
 	"strings"
 	"sync"
 )
 
 type Store interface {
+	// Get
+	// return a string (nodePath is a leaf node) or
+	// a map[string]interface{} (nodePath is dir)
 	Get(nodePath string) (interface{}, bool)
-	Set(nodePath string, dir bool, value string)
-	Sets(nodePath string, values map[string]interface{})
+	// Put value can be a map[string]interface{} or string
+	Put(nodePath string, value interface{})
 	Delete(nodePath string)
-	SetBulk(nodePath string, value map[string]string)
+	// PutBulk value should be a flatmap
+	PutBulk(nodePath string, value map[string]string)
 }
 
 type store struct {
@@ -48,35 +54,27 @@ func (s *store) Get(nodePath string) (interface{}, bool) {
 	return nil, false
 }
 
-// Set creates or replace the node at nodePath, return old value
-func (s *store) Set(nodePath string, dir bool, value string) {
+// Put creates or update the node at nodePath, value should a map[string]interface{} or a string
+func (s *store) Put(nodePath string, value interface{}) {
 	nodePath = path.Clean(path.Join("/", nodePath))
 
 	s.worldLock.Lock()
 	defer s.worldLock.Unlock()
-	s.internalSet(nodePath, dir, value)
-}
-
-func (s *store) SetBulk(nodePath string, values map[string]string) {
-	s.worldLock.Lock()
-	defer s.worldLock.Unlock()
-	s.internalSetBulk(nodePath, values)
-}
-
-func (s *store) internalSetBulk(nodePath string, values map[string]string) {
-	for k, v := range values {
-		key := util.AppendPathPrefix(k, nodePath)
-		s.internalSet(key, false, v)
+	switch t := value.(type) {
+	case map[string]interface{}, map[string]string, []interface{}:
+		flatValues := flatmap.Flatten(t)
+		s.internalPutBulk(nodePath, flatValues)
+	case string:
+		s.internalPut(nodePath, t)
+	default:
+		panic(fmt.Sprintf("Unsupport type: %s", reflect.TypeOf(t)))
 	}
 }
 
-func (s *store) Sets(nodePath string, values map[string]interface{}) {
-	nodePath = path.Clean(path.Join("/", nodePath))
-
+func (s *store) PutBulk(nodePath string, values map[string]string) {
 	s.worldLock.Lock()
 	defer s.worldLock.Unlock()
-	flatValues := flatmap.Flatten(values)
-	s.internalSetBulk(nodePath, flatValues)
+	s.internalPutBulk(nodePath, values)
 }
 
 // Delete deletes the node at the given path.
@@ -120,7 +118,7 @@ func (s *store) walk(nodePath string, walkFunc func(prev *node, component string
 	return curr
 }
 
-func (s *store) internalSet(nodePath string, dir bool, value string) *node {
+func (s *store) internalPut(nodePath string, value string) *node {
 
 	dirName, nodeName := path.Split(nodePath)
 
@@ -130,26 +128,23 @@ func (s *store) internalSet(nodePath string, dir bool, value string) *node {
 
 	// force will try to replace an existing file
 	if n != nil {
-		if dir {
-			n.AsDir()
-		}
 		n.value = value
 		return n
 	}
 
-	if !dir { // create file
-
-		n = newKV(s, nodePath, value, d)
-	} else { // create directory
-
-		n = newDir(s, nodePath, d)
-	}
-
+	n = newKV(s, nodePath, value, d)
 	d.Add(n)
 
 	return n
 }
 
+func (s *store) internalPutBulk(nodePath string, values map[string]string) {
+	for k, v := range values {
+		key := util.AppendPathPrefix(k, nodePath)
+		s.internalPut(key, v)
+	}
+}
+
 // InternalGet gets the node of the given nodePath.
 func (s *store) internalGet(nodePath string) *node {
 
diff --git a/store/store_test.go b/store/store_test.go
index c523b6e..33035f1 100644
--- a/store/store_test.go
+++ b/store/store_test.go
@@ -14,7 +14,7 @@ func TestStoreBasic(t *testing.T) {
 	assert.False(t, ok)
 	assert.Nil(t, val)
 
-	store.Set("/foo", false, "bar")
+	store.Put("/foo", "bar")
 
 	val, ok = store.Get("/foo")
 	assert.True(t, ok)
@@ -30,17 +30,14 @@ func TestStoreBasic(t *testing.T) {
 func TestStoreDir(t *testing.T) {
 	store := New()
 
-	store.Set("/foo", true, "")
+	store.Put("/foo/foo1", "")
 
-	store.Set("/foo/foo1", true, "")
-
-	val, ok := store.Get("/foo/foo1")
+	val, ok := store.Get("/foo")
 	assert.True(t, ok)
-	mapVal, mok := val.(map[string]interface{})
+	_, mok := val.(map[string]interface{})
 	assert.True(t, mok)
-	assert.Equal(t, 0, len(mapVal))
 
-	store.Set("/foo/foo1/key1", false, "val1")
+	store.Put("/foo/foo1/key1", "val1")
 	val, ok = store.Get("/foo/foo1/key1")
 	assert.True(t, ok)
 	assert.Equal(t, "val1", val)
@@ -62,7 +59,7 @@ func TestStoreBulk(t *testing.T) {
 		values[fmt.Sprintf("/clusters/%v/ip", i)] = fmt.Sprintf("192.168.0.%v", i)
 		values[fmt.Sprintf("/clusters/%v/name", i)] = fmt.Sprintf("cluster-%v", i)
 	}
-	store.SetBulk("/", values)
+	store.PutBulk("/", values)
 
 	val, ok := store.Get("/clusters/10")
 	assert.True(t, ok)
@@ -83,7 +80,7 @@ func TestStoreSets(t *testing.T) {
 			"name": fmt.Sprintf("cluster-%v", i),
 		}
 	}
-	store.Sets("/clusters", values)
+	store.Put("/clusters", values)
 
 	val, ok := store.Get("/clusters/10")
 	assert.True(t, ok)
@@ -97,9 +94,9 @@ func TestStoreSets(t *testing.T) {
 func TestStoreNodeToDirPanic(t *testing.T) {
 	store := New()
 	// first set a node value.
-	store.Set("/nodes/6", false, "node6")
+	store.Put("/nodes/6", "node6")
 	// create pre node's child's child, will cause panic.
-	store.Set("/nodes/6/label/key1", false, "value1")
+	store.Put("/nodes/6/label/key1", "value1")
 
 	v, _ := store.Get("/nodes/6")
 	_, mok := v.(map[string]interface{})
@@ -113,8 +110,8 @@ func TestStoreRemoveEmptyParent(t *testing.T) {
 	store := New()
 
 	// if dir has children, dir's text value will be hidden.
-	store.Set("/nodes/6", false, "node6")
-	store.Set("/nodes/6/label/key1", false, "value1")
+	store.Put("/nodes/6", "node6")
+	store.Put("/nodes/6/label/key1", "value1")
 
 	store.Delete("/nodes/6/label/key1")
 
@@ -127,7 +124,7 @@ func TestStoreRemoveEmptyParent(t *testing.T) {
 	assert.Equal(t, "node6", v)
 
 	// when delete leaf node, empty parent dir will been auto delete.
-	store.Set("/nodes/7/label/key1", false, "value1")
+	store.Put("/nodes/7/label/key1", "value1")
 	store.Delete("/nodes/7/label/key1")
 
 	_, ok = store.Get("/nodes/7")