diff --git a/integration/rabbus_integration_test.go b/integration/rabbus_integration_test.go
index 3dd6c97..9d1430a 100644
--- a/integration/rabbus_integration_test.go
+++ b/integration/rabbus_integration_test.go
@@ -80,7 +80,7 @@ func testRabbusPublishSubscribe(t *testing.T) {
 
 	messages, err := r.Listen(rabbus.ListenConfig{
 		Exchange: "test_ex",
-		Kind:     "direct",
+		Kind:     rabbus.ExchangeDirect,
 		Key:      "test_key",
 		Queue:    "test_q",
 	})
@@ -101,7 +101,7 @@ func testRabbusPublishSubscribe(t *testing.T) {
 
 	msg := rabbus.Message{
 		Exchange:     "test_ex",
-		Kind:         "direct",
+		Kind:         rabbus.ExchangeDirect,
 		Key:          "test_key",
 		Payload:      []byte(`foo`),
 		DeliveryMode: rabbus.Persistent,
@@ -167,7 +167,7 @@ func benchmarkEmitAsync(b *testing.B) {
 	for n := 0; n < b.N; n++ {
 		msg := rabbus.Message{
 			Exchange:     "test_bench_ex" + strconv.Itoa(n%10),
-			Kind:         "direct",
+			Kind:         rabbus.ExchangeDirect,
 			Key:          "test_key",
 			Payload:      []byte(`foo`),
 			DeliveryMode: rabbus.Persistent,
diff --git a/internal/amqp/amqp.go b/internal/amqp/amqp.go
index d2e45cb..445c7f9 100644
--- a/internal/amqp/amqp.go
+++ b/internal/amqp/amqp.go
@@ -2,12 +2,14 @@ package amqp
 
 import "github.com/streadway/amqp"
 
-// Amqp interpret (implement) Amqp interface definition
-type Amqp struct {
-	conn            *amqp.Connection
-	ch              *amqp.Channel
-	passiveExchange bool
-}
+type (
+	// Amqp interpret (implement) Amqp interface definition
+	Amqp struct {
+		conn            *amqp.Connection
+		ch              *amqp.Channel
+		passiveExchange bool
+	}
+)
 
 // New returns a new Amqp configured, or returning an non-nil err
 // if an error occurred while creating connection or channel.
diff --git a/rabbus.go b/rabbus.go
index 1145da2..a3fe8a7 100644
--- a/rabbus.go
+++ b/rabbus.go
@@ -17,10 +17,16 @@ const (
 	Transient uint8 = 1
 	// Persistent messages will be restored to durable queues and lost on non-durable queues during server restart.
 	Persistent uint8 = 2
-	// ContentTypeJSON define json content type
+	// ContentTypeJSON define json content type.
 	ContentTypeJSON = "application/json"
-	// ContentTypePlain define plain text content type
+	// ContentTypePlain define plain text content type.
 	ContentTypePlain = "plain/text"
+	// ExchangeDirect indicates the exchange is of direct type.
+	ExchangeDirect = "direct"
+	// ExchangeFanout indicates the exchange is of fanout type.
+	ExchangeFanout = "fanout"
+	// ExchangeTopic indicates the exchange is of topic type.
+	ExchangeTopic = "topic"
 
 	contentEncoding = "UTF-8"
 )
diff --git a/rabbus_test.go b/rabbus_test.go
index c7edebe..9510ef9 100644
--- a/rabbus_test.go
+++ b/rabbus_test.go
@@ -153,7 +153,7 @@ func testCreateNewListener(t *testing.T) {
 	durable := true
 	config := ListenConfig{
 		Exchange: "exchange",
-		Kind:     "direct",
+		Kind:     ExchangeDirect,
 		Key:      "key",
 		Queue:    "queue",
 	}
@@ -210,7 +210,7 @@ func testFailToCreateNewListenerWhenCreateConsumerReturnsError(t *testing.T) {
 
 	_, err = r.Listen(ListenConfig{
 		Exchange: "exchange",
-		Kind:     "direct",
+		Kind:     ExchangeDirect,
 		Key:      "key",
 		Queue:    "queue",
 	})
@@ -222,7 +222,7 @@ func testFailToCreateNewListenerWhenCreateConsumerReturnsError(t *testing.T) {
 func testEmitAsyncMessage(t *testing.T) {
 	msg := Message{
 		Exchange: "exchange",
-		Kind:     "direct",
+		Kind:     ExchangeDirect,
 		Key:      "key",
 		Payload:  []byte(`foo`),
 	}
@@ -291,7 +291,7 @@ outer:
 func testEmitAsyncMessageFailToDeclareExchange(t *testing.T) {
 	msg := Message{
 		Exchange: "exchange",
-		Kind:     "direct",
+		Kind:     ExchangeDirect,
 		Key:      "key",
 		Payload:  []byte(`foo`),
 	}
@@ -337,7 +337,7 @@ outer:
 func testEmitAsyncMessageFailToPublish(t *testing.T) {
 	msg := Message{
 		Exchange: "exchange",
-		Kind:     "direct",
+		Kind:     ExchangeDirect,
 		Key:      "key",
 		Payload:  []byte(`foo`),
 	}
@@ -384,7 +384,7 @@ func testEmitAsyncMessageEnsureBreaker(t *testing.T) {
 	threshold := uint32(1)
 	msg := Message{
 		Exchange: "exchange",
-		Kind:     "direct",
+		Kind:     ExchangeDirect,
 		Key:      "key",
 		Payload:  []byte(`foo`),
 	}