diff --git a/services/operation.go b/dag/operation.go
similarity index 99%
rename from services/operation.go
rename to dag/operation.go
index 45b0f0b..91da8c3 100644
--- a/services/operation.go
+++ b/dag/operation.go
@@ -1,4 +1,4 @@
-package services
+package dag
 
 import (
 	"context"
diff --git a/dag/operations.go b/dag/operations.go
new file mode 100644
index 0000000..4ca8aac
--- /dev/null
+++ b/dag/operations.go
@@ -0,0 +1,32 @@
+package dag
+
+import (
+	"sync"
+
+	"github.com/oarkflow/mq"
+)
+
+type Operations struct {
+	mu       *sync.RWMutex
+	Handlers map[string]func(string) mq.Processor
+}
+
+var ops = &Operations{mu: &sync.RWMutex{}, Handlers: make(map[string]func(string) mq.Processor)}
+
+func AddHandler(key string, handler func(string) mq.Processor) {
+	ops.mu.Lock()
+	ops.Handlers[key] = handler
+	ops.mu.Unlock()
+}
+
+func GetHandler(key string) func(string) mq.Processor {
+	return ops.Handlers[key]
+}
+
+func AvailableHandlers() []string {
+	var op []string
+	for opt := range ops.Handlers {
+		op = append(op, opt)
+	}
+	return op
+}
diff --git a/dag/task_manager.go b/dag/task_manager.go
index 70304ca..a91704e 100644
--- a/dag/task_manager.go
+++ b/dag/task_manager.go
@@ -92,6 +92,11 @@ func (tm *TaskManager) getConditionalEdges(node *Node, result mq.Result) []Edge
 }
 
 func (tm *TaskManager) handleNextTask(ctx context.Context, result mq.Result) mq.Result {
+	if result.Ctx != nil {
+		if headers, ok := mq.GetHeaders(ctx); ok {
+			ctx = mq.SetHeaders(result.Ctx, headers.AsMap())
+		}
+	}
 	defer func() {
 		tm.wg.Done()
 		mq.RecoverPanic(mq.RecoverTitle)
diff --git a/examples/dag.go b/examples/dag.go
index 16004f4..d5b4514 100644
--- a/examples/dag.go
+++ b/examples/dag.go
@@ -6,11 +6,9 @@ import (
 	"fmt"
 	"log"
 
-	"github.com/oarkflow/mq/examples/tasks"
-	"github.com/oarkflow/mq/services"
-
 	"github.com/oarkflow/mq"
 	"github.com/oarkflow/mq/dag"
+	"github.com/oarkflow/mq/examples/tasks"
 )
 
 func main() {
@@ -19,14 +17,14 @@ func main() {
 
 func setup(f *dag.DAG) {
 	f.
-		AddNode("Email Delivery", "email:deliver", &tasks.EmailDelivery{Operation: services.Operation{Type: "process"}}).
-		AddNode("Prepare Email", "prepare:email", &tasks.PrepareEmail{Operation: services.Operation{Type: "process"}}).
-		AddNode("Get Input", "get:input", &tasks.GetData{Operation: services.Operation{Type: "input"}}, true).
-		AddNode("Iterator Processor", "loop", &tasks.Loop{Operation: services.Operation{Type: "loop"}}).
-		AddNode("Condition", "condition", &tasks.Condition{Operation: services.Operation{Type: "condition"}}).
-		AddNode("Store data", "store:data", &tasks.StoreData{Operation: services.Operation{Type: "process"}}).
-		AddNode("Send SMS", "send:sms", &tasks.SendSms{Operation: services.Operation{Type: "process"}}).
-		AddNode("Notification", "notification", &tasks.InAppNotification{Operation: services.Operation{Type: "process"}}).
+		AddNode("Email Delivery", "email:deliver", &tasks.EmailDelivery{Operation: dag.Operation{Type: "process"}}).
+		AddNode("Prepare Email", "prepare:email", &tasks.PrepareEmail{Operation: dag.Operation{Type: "process"}}).
+		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"}).
 		AddEdge("Get input to loop", "get:input", "loop").
 		AddIterator("Loop to prepare email", "loop", "prepare:email").
diff --git a/examples/tasks/operations.go b/examples/tasks/operations.go
index acd3996..4713842 100644
--- a/examples/tasks/operations.go
+++ b/examples/tasks/operations.go
@@ -6,11 +6,11 @@ import (
 	"github.com/oarkflow/json"
 
 	"github.com/oarkflow/mq"
-	"github.com/oarkflow/mq/services"
+	"github.com/oarkflow/mq/dag"
 )
 
 type GetData struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *GetData) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -18,7 +18,7 @@ func (e *GetData) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
 }
 
 type Loop struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *Loop) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -26,7 +26,7 @@ func (e *Loop) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
 }
 
 type Condition struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *Condition) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -47,7 +47,7 @@ func (e *Condition) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
 }
 
 type PrepareEmail struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *PrepareEmail) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -62,7 +62,7 @@ func (e *PrepareEmail) ProcessTask(ctx context.Context, task *mq.Task) mq.Result
 }
 
 type EmailDelivery struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *EmailDelivery) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -77,7 +77,7 @@ func (e *EmailDelivery) ProcessTask(ctx context.Context, task *mq.Task) mq.Resul
 }
 
 type SendSms struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *SendSms) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -90,7 +90,7 @@ func (e *SendSms) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
 }
 
 type StoreData struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *StoreData) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
@@ -98,7 +98,7 @@ func (e *StoreData) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
 }
 
 type InAppNotification struct {
-	services.Operation
+	dag.Operation
 }
 
 func (e *InAppNotification) ProcessTask(ctx context.Context, task *mq.Task) mq.Result {
diff --git a/examples/tasks/tasks.go b/examples/tasks/tasks.go
index 52c9879..fd6c371 100644
--- a/examples/tasks/tasks.go
+++ b/examples/tasks/tasks.go
@@ -7,24 +7,24 @@ import (
 	"log"
 
 	"github.com/oarkflow/mq"
-	"github.com/oarkflow/mq/services"
+	"github.com/oarkflow/mq/dag"
 )
 
-type Node1 struct{ services.Operation }
+type Node1 struct{ dag.Operation }
 
 func (t *Node1) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	fmt.Println("Node 1", string(task.Payload))
 	return mq.Result{Payload: task.Payload, TaskID: task.ID}
 }
 
-type Node2 struct{ services.Operation }
+type Node2 struct{ dag.Operation }
 
 func (t *Node2) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	fmt.Println("Node 2", string(task.Payload))
 	return mq.Result{Payload: task.Payload, TaskID: task.ID}
 }
 
-type Node3 struct{ services.Operation }
+type Node3 struct{ dag.Operation }
 
 func (t *Node3) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	var user map[string]any
@@ -39,7 +39,7 @@ func (t *Node3) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	return mq.Result{Payload: resultPayload, Status: status}
 }
 
-type Node4 struct{ services.Operation }
+type Node4 struct{ dag.Operation }
 
 func (t *Node4) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	var user map[string]any
@@ -49,7 +49,7 @@ func (t *Node4) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	return mq.Result{Payload: resultPayload}
 }
 
-type Node5 struct{ services.Operation }
+type Node5 struct{ dag.Operation }
 
 func (t *Node5) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	var user map[string]any
@@ -59,7 +59,7 @@ func (t *Node5) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	return mq.Result{Payload: resultPayload}
 }
 
-type Node6 struct{ services.Operation }
+type Node6 struct{ dag.Operation }
 
 func (t *Node6) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	var user map[string]any
@@ -68,7 +68,7 @@ func (t *Node6) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	return mq.Result{Payload: resultPayload}
 }
 
-type Node7 struct{ services.Operation }
+type Node7 struct{ dag.Operation }
 
 func (t *Node7) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	var user map[string]any
@@ -78,7 +78,7 @@ func (t *Node7) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	return mq.Result{Payload: resultPayload}
 }
 
-type Node8 struct{ services.Operation }
+type Node8 struct{ dag.Operation }
 
 func (t *Node8) ProcessTask(_ context.Context, task *mq.Task) mq.Result {
 	var user map[string]any