diff --git a/_documents/rpcx_tech_support.png b/_documents/rpcx_tech_support.png
deleted file mode 100644
index 6d9cd48..0000000
Binary files a/_documents/rpcx_tech_support.png and /dev/null differ
diff --git a/client/client.go b/client/client.go
index d68ec57..170c404 100644
--- a/client/client.go
+++ b/client/client.go
@@ -94,6 +94,8 @@ type RPCClient interface {
 
 	IsClosing() bool
 	IsShutdown() bool
+
+	GetConn() net.Conn
 }
 
 // Client represents a RPC client.
@@ -129,6 +131,11 @@ func (c *Client) RemoteAddr() string {
 	return c.Conn.RemoteAddr().String()
 }
 
+// GetConn returns the underlying conn.
+func (c *Client) GetConn() net.Conn {
+	return c.Conn
+}
+
 // Option contains all options for creating clients.
 type Option struct {
 	// Group is used to select the services in the same group. Services set group info in their meta.
diff --git a/client/xclient.go b/client/xclient.go
index 88ec136..5c8c49c 100644
--- a/client/xclient.go
+++ b/client/xclient.go
@@ -53,6 +53,15 @@ type XClient interface {
 	DownloadFile(ctx context.Context, requestFileName string, saveTo io.Writer, meta map[string]string) error
 	Stream(ctx context.Context, meta map[string]string) (net.Conn, error)
 	Close() error
+
+	RegisterCacheClientBuilder(network string, builder CacheClientBuilder)
+}
+
+type CacheClientBuilder interface {
+	setCachedClient(client RPCClient, k, servicePath, serviceMethod string)
+	findCachedClient(k, servicePath, serviceMethod string) RPCClient
+	deleteCachedClient(client RPCClient, k, servicePath, serviceMethod string)
+	generateClient(k, servicePath, serviceMethod string) (client RPCClient, err error)
 }
 
 // KVPair contains a key and a string.
@@ -84,10 +93,11 @@ type xClient struct {
 	servicePath  string
 	option       Option
 
-	mu        sync.RWMutex
-	servers   map[string]string
-	discovery ServiceDiscovery
-	selector  Selector
+	mu                  sync.RWMutex
+	servers             map[string]string
+	discovery           ServiceDiscovery
+	selector            Selector
+	cacheClientBuilders map[string]CacheClientBuilder
 
 	slGroup singleflight.Group
 
@@ -106,12 +116,13 @@ type xClient struct {
 // NewXClient creates a XClient that supports service discovery and service governance.
 func NewXClient(servicePath string, failMode FailMode, selectMode SelectMode, discovery ServiceDiscovery, option Option) XClient {
 	client := &xClient{
-		failMode:     failMode,
-		selectMode:   selectMode,
-		discovery:    discovery,
-		servicePath:  servicePath,
-		cachedClient: make(map[string]RPCClient),
-		option:       option,
+		failMode:            failMode,
+		selectMode:          selectMode,
+		discovery:           discovery,
+		servicePath:         servicePath,
+		cachedClient:        make(map[string]RPCClient),
+		cacheClientBuilders: make(map[string]CacheClientBuilder),
+		option:              option,
 	}
 
 	pairs := discovery.GetServices()
@@ -171,6 +182,12 @@ func NewBidirectionalXClient(servicePath string, failMode FailMode, selectMode S
 	return client
 }
 
+func (c *xClient) RegisterCacheClientBuilder(network string, builder CacheClientBuilder) {
+	c.mu.Lock()
+	c.mu.Unlock()
+	c.cacheClientBuilders[network] = builder
+}
+
 // SetSelector sets customized selector by users.
 func (c *xClient) SetSelector(s Selector) {
 	c.mu.RLock()
@@ -255,7 +272,7 @@ func (c *xClient) getCachedClient(k string, servicePath, serviceMethod string, a
 	var needCallPlugin bool
 	defer func() {
 		if needCallPlugin {
-			c.Plugins.DoClientConnected((client.(*Client)).Conn)
+			c.Plugins.DoClientConnected(client.GetConn())
 		}
 	}()
 	c.mu.Lock()
@@ -302,20 +319,52 @@ func (c *xClient) getCachedClient(k string, servicePath, serviceMethod string, a
 }
 
 func (c *xClient) setCachedClient(client RPCClient, k, servicePath, serviceMethod string) {
+	network, _ := splitNetworkAndAddress(k)
+	if builder, ok := c.cacheClientBuilders[network]; ok {
+		builder.setCachedClient(client, k, servicePath, serviceMethod)
+		return
+	}
+
 	c.cachedClient[k] = client
 }
 
 func (c *xClient) findCachedClient(k, servicePath, serviceMethod string) RPCClient {
+	network, _ := splitNetworkAndAddress(k)
+	if builder, ok := c.cacheClientBuilders[network]; ok {
+		return builder.findCachedClient(k, servicePath, serviceMethod)
+	}
+
 	return c.cachedClient[k]
 }
 
 func (c *xClient) deleteCachedClient(client RPCClient, k, servicePath, serviceMethod string) {
+	network, _ := splitNetworkAndAddress(k)
+	if builder, ok := c.cacheClientBuilders[network]; ok && client != nil {
+		builder.deleteCachedClient(client, k, servicePath, serviceMethod)
+		client.Close()
+		return
+	}
+
 	delete(c.cachedClient, k)
 	if client != nil {
 		client.Close()
 	}
 }
 
+func (c *xClient) removeClient(k, servicePath, serviceMethod string, client RPCClient) {
+	c.mu.Lock()
+	cl := c.findCachedClient(k, servicePath, serviceMethod)
+	if cl == client {
+		c.deleteCachedClient(client, k, servicePath, serviceMethod)
+	}
+	c.mu.Unlock()
+
+	if client != nil {
+		client.UnregisterServerMessageChan()
+		client.Close()
+	}
+}
+
 func (c *xClient) generateClient(k, servicePath, serviceMethod string) (client RPCClient, err error) {
 	client = &Client{
 		option:  c.option,
@@ -339,51 +388,45 @@ func (c *xClient) generateClient(k, servicePath, serviceMethod string) (client R
 }
 
 func (c *xClient) getCachedClientWithoutLock(k, servicePath, serviceMethod string) (RPCClient, error) {
-	client := c.cachedClient[k]
+	client := c.findCachedClient(k, servicePath, serviceMethod)
 	if client != nil {
 		if !client.IsClosing() && !client.IsShutdown() {
 			return client, nil
 		}
-		delete(c.cachedClient, k)
-		client.Close()
+		c.deleteCachedClient(client, k, servicePath, serviceMethod)
 	}
 
-	// double check
-	client = c.cachedClient[k]
-	if client == nil || client.IsShutdown() {
-		network, addr := splitNetworkAndAddress(k)
-
-		client = &Client{
-			option:  c.option,
-			Plugins: c.Plugins,
+	var needCallPlugin bool
+	defer func() {
+		if needCallPlugin {
+			c.Plugins.DoClientConnected(client.GetConn())
 		}
-		err := client.Connect(network, addr)
+	}()
+
+	// double check
+	client = c.findCachedClient(k, servicePath, serviceMethod)
+	if client == nil || client.IsShutdown() {
+		generatedClient, err, _ := c.slGroup.Do(k, func() (interface{}, error) {
+			return c.generateClient(k, servicePath, serviceMethod)
+		})
+		c.slGroup.Forget(k)
 		if err != nil {
 			return nil, err
 		}
 
+		client = generatedClient.(RPCClient)
+		if c.Plugins != nil {
+			needCallPlugin = true
+		}
+
 		client.RegisterServerMessageChan(c.serverMessageChan)
 
-		c.cachedClient[k] = client
+		c.setCachedClient(client, k, servicePath, serviceMethod)
 	}
 
 	return client, nil
 }
 
-func (c *xClient) removeClient(k, servicePath, serviceMethod string, client RPCClient) {
-	c.mu.Lock()
-	cl := c.cachedClient[k]
-	if cl == client {
-		delete(c.cachedClient, k)
-	}
-	c.mu.Unlock()
-
-	if client != nil {
-		client.UnregisterServerMessageChan()
-		client.Close()
-	}
-}
-
 func splitNetworkAndAddress(server string) (string, string) {
 	ss := strings.SplitN(server, "@", 2)
 	if len(ss) == 1 {