diff --git a/codec/codec.go b/codec/codec.go
index 92ee8d4..a61f0b5 100644
--- a/codec/codec.go
+++ b/codec/codec.go
@@ -5,9 +5,9 @@ import (
 	"context"
 	"encoding/binary"
 	"net"
-	"sync"
 
 	"github.com/oarkflow/mq/consts"
+	"github.com/oarkflow/mq/internal/bpool"
 )
 
 type Message struct {
@@ -45,33 +45,28 @@ func Deserialize(data []byte) (*Message, error) {
 	return &msg, nil
 }
 
-var byteBufferPool = sync.Pool{
-	New: func() interface{} {
-		return make([]byte, 0, 4096)
-	},
-}
-
 func SendMessage(ctx context.Context, conn net.Conn, msg *Message) error {
 	data, err := msg.Serialize()
 	if err != nil {
 		return err
 	}
 	totalLength := 4 + len(data)
-	buffer := byteBufferPool.Get().([]byte)
-	if cap(buffer) < totalLength {
-		buffer = make([]byte, totalLength)
+	buffer := bpool.Get()
+	defer bpool.Put(buffer)
+	buffer.Reset()
+	if cap(buffer.B) < totalLength {
+		buffer.B = make([]byte, totalLength)
 	} else {
-		buffer = buffer[:totalLength]
+		buffer.B = buffer.B[:totalLength]
 	}
-	defer byteBufferPool.Put(buffer)
-	binary.BigEndian.PutUint32(buffer[:4], uint32(len(data)))
-	copy(buffer[4:], data)
+	binary.BigEndian.PutUint32(buffer.B[:4], uint32(len(data)))
+	copy(buffer.B[4:], data)
 	writer := bufio.NewWriter(conn)
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
-		if _, err := writer.Write(buffer); err != nil {
+		if _, err := writer.Write(buffer.B[:totalLength]); err != nil {
 			return err
 		}
 	}
@@ -84,20 +79,26 @@ func ReadMessage(ctx context.Context, conn net.Conn) (*Message, error) {
 		return nil, err
 	}
 	length := binary.BigEndian.Uint32(lengthBytes)
-	data := byteBufferPool.Get().([]byte)[:length]
-	defer byteBufferPool.Put(data)
+	buffer := bpool.Get()
+	defer bpool.Put(buffer)
+	buffer.Reset()
+	if cap(buffer.B) < int(length) {
+		buffer.B = make([]byte, length)
+	} else {
+		buffer.B = buffer.B[:length]
+	}
 	totalRead := 0
 	for totalRead < int(length) {
 		select {
 		case <-ctx.Done():
 			return nil, ctx.Err()
 		default:
-			n, err := conn.Read(data[totalRead:])
+			n, err := conn.Read(buffer.B[totalRead:])
 			if err != nil {
 				return nil, err
 			}
 			totalRead += n
 		}
 	}
-	return Deserialize(data[:length])
+	return Deserialize(buffer.B[:length])
 }
diff --git a/dag/dag.go b/dag/dag.go
index 4fac96e..9559bd4 100644
--- a/dag/dag.go
+++ b/dag/dag.go
@@ -234,7 +234,7 @@ func (tm *DAG) Start(ctx context.Context, addr string) error {
 	return http.ListenAndServe(addr, nil)
 }
 
-func (tm *DAG) AddDAGNode(name string, key string, dag *DAG, firstNode ...bool) {
+func (tm *DAG) AddDAGNode(name string, key string, dag *DAG, firstNode ...bool) *DAG {
 	dag.AssignTopic(key)
 	tm.mu.Lock()
 	defer tm.mu.Unlock()
@@ -247,6 +247,7 @@ func (tm *DAG) AddDAGNode(name string, key string, dag *DAG, firstNode ...bool)
 	if len(firstNode) > 0 && firstNode[0] {
 		tm.startNode = key
 	}
+	return tm
 }
 
 func (tm *DAG) AddNode(name, key string, handler mq.Processor, firstNode ...bool) *DAG {
diff --git a/examples/dag.go b/examples/dag.go
index d5b4514..03d927b 100644
--- a/examples/dag.go
+++ b/examples/dag.go
@@ -15,6 +15,16 @@ func main() {
 	aSync()
 }
 
+func subDAG() *dag.DAG {
+	f := dag.NewDAG("Sub DAG", "sub-dag", mq.WithCleanTaskOnComplete(), mq.WithSyncMode(true))
+	f.
+		AddNode("Store data", "store:data", &tasks.StoreData{Operation: dag.Operation{Type: "process"}}, true).
+		AddNode("Send SMS", "send:sms", &tasks.SendSms{Operation: dag.Operation{Type: "process"}}).
+		AddNode("Notification", "notification", &tasks.InAppNotification{Operation: dag.Operation{Type: "process"}}).
+		AddEdge("Store Data to send sms and notification", "store:data", "send:sms", "notification")
+	return f
+}
+
 func setup(f *dag.DAG) {
 	f.
 		AddNode("Email Delivery", "email:deliver", &tasks.EmailDelivery{Operation: dag.Operation{Type: "process"}}).
@@ -22,14 +32,11 @@ func setup(f *dag.DAG) {
 		AddNode("Get Input", "get:input", &tasks.GetData{Operation: dag.Operation{Type: "input"}}, true).
 		AddNode("Iterator Processor", "loop", &tasks.Loop{Operation: dag.Operation{Type: "loop"}}).
 		AddNode("Condition", "condition", &tasks.Condition{Operation: dag.Operation{Type: "condition"}}).
-		AddNode("Store data", "store:data", &tasks.StoreData{Operation: dag.Operation{Type: "process"}}).
-		AddNode("Send SMS", "send:sms", &tasks.SendSms{Operation: dag.Operation{Type: "process"}}).
-		AddNode("Notification", "notification", &tasks.InAppNotification{Operation: dag.Operation{Type: "process"}}).
-		AddCondition("condition", map[dag.When]dag.Then{"pass": "email:deliver", "fail": "store:data"}).
+		AddDAGNode("Persistent", "persistent", subDAG()).
+		AddCondition("condition", map[dag.When]dag.Then{"pass": "email:deliver", "fail": "persistent"}).
 		AddEdge("Get input to loop", "get:input", "loop").
 		AddIterator("Loop to prepare email", "loop", "prepare:email").
-		AddEdge("Prepare Email to condition", "prepare:email", "condition").
-		AddEdge("Store Data to send sms and notification", "store:data", "send:sms", "notification")
+		AddEdge("Prepare Email to condition", "prepare:email", "condition")
 }
 
 func sendData(f *dag.DAG) {
diff --git a/examples/subdag.go b/examples/subdag.go
index 87ea254..55d9d4d 100644
--- a/examples/subdag.go
+++ b/examples/subdag.go
@@ -2,11 +2,7 @@ package main
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
-	"github.com/oarkflow/mq/consts"
-	"io"
-	"net/http"
 
 	"github.com/oarkflow/mq/examples/tasks"
 
@@ -42,64 +38,8 @@ func main() {
 	d.AddCondition("C", map[dag.When]dag.Then{"PASS": "D", "FAIL": "E"})
 	d.AddEdge("Label 1", "B", "C")
 
-	// Classify edges
-	// d.ClassifyEdges()
 	fmt.Println(d.ExportDOT())
 
-	requestHandler := func(requestType string) func(w http.ResponseWriter, r *http.Request) {
-		return func(w http.ResponseWriter, r *http.Request) {
-			if r.Method != http.MethodPost {
-				http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
-				return
-			}
-			var payload []byte
-			if r.Body != nil {
-				defer r.Body.Close()
-				var err error
-				payload, err = io.ReadAll(r.Body)
-				if err != nil {
-					http.Error(w, "Failed to read request body", http.StatusBadRequest)
-					return
-				}
-			} else {
-				http.Error(w, "Empty request body", http.StatusBadRequest)
-				return
-			}
-			ctx := r.Context()
-			if requestType == "request" {
-				ctx = mq.SetHeaders(ctx, map[string]string{consts.AwaitResponseKey: "true"})
-			}
-			// ctx = context.WithValue(ctx, "initial_node", "E")
-			rs := d.Process(ctx, payload)
-			if rs.Error != nil {
-				http.Error(w, fmt.Sprintf("[DAG Error] - %v", rs.Error), http.StatusInternalServerError)
-				return
-			}
-			w.Header().Set("Content-Type", "application/json")
-			json.NewEncoder(w).Encode(rs)
-		}
-	}
-
-	http.HandleFunc("POST /publish", requestHandler("publish"))
-	http.HandleFunc("POST /request", requestHandler("request"))
-	http.HandleFunc("/pause-consumer/{id}", func(writer http.ResponseWriter, request *http.Request) {
-		id := request.PathValue("id")
-		if id != "" {
-			d.PauseConsumer(request.Context(), id)
-		}
-	})
-	http.HandleFunc("/resume-consumer/{id}", func(writer http.ResponseWriter, request *http.Request) {
-		id := request.PathValue("id")
-		if id != "" {
-			d.ResumeConsumer(request.Context(), id)
-		}
-	})
-	http.HandleFunc("/pause", func(writer http.ResponseWriter, request *http.Request) {
-		d.Pause(request.Context())
-	})
-	http.HandleFunc("/resume", func(writer http.ResponseWriter, request *http.Request) {
-		d.Resume(request.Context())
-	})
 	err := d.Start(context.TODO(), ":8083")
 	if err != nil {
 		panic(err)
diff --git a/sio/socket.go b/sio/socket.go
index f6148b2..9a93204 100644
--- a/sio/socket.go
+++ b/sio/socket.go
@@ -4,14 +4,15 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
-	"github.com/oarkflow/mq/internal/bpool"
-	"github.com/oarkflow/mq/storage"
-	"github.com/oarkflow/mq/storage/memory"
 	"log/slog"
 	"net/http"
 	"sync"
 	"time"
 
+	"github.com/oarkflow/mq/internal/bpool"
+	"github.com/oarkflow/mq/storage"
+	"github.com/oarkflow/mq/storage/memory"
+
 	"github.com/gorilla/websocket"
 )