diff --git a/rpc/plugins/push/prosumer.go b/rpc/plugins/push/prosumer.go
index 7a9d312..8b28c46 100644
--- a/rpc/plugins/push/prosumer.go
+++ b/rpc/plugins/push/prosumer.go
@@ -56,6 +56,24 @@ func NewProsumer(client *core.Client, id ...string) *Prosumer {
 	return p
 }
 
+func (p *Prosumer) onError(err error) {
+	if p.OnError != nil {
+		p.OnError(err)
+	}
+}
+
+func (p *Prosumer) onSubscribe(topic string) {
+	if p.OnSubscribe != nil {
+		p.OnSubscribe(topic)
+	}
+}
+
+func (p *Prosumer) onUnsubscribe(topic string) {
+	if p.OnUnsubscribe != nil {
+		p.OnUnsubscribe(topic)
+	}
+}
+
 func (p *Prosumer) Client() *core.Client {
 	return p.client
 }
@@ -99,14 +117,19 @@ func (p *Prosumer) call(callback Callback, message Message) {
 	default:
 		v := reflect.ValueOf(callback)
 		t := v.Type()
-		switch t.NumIn() {
-		case 1:
-			if data, err := io.Convert(message.Data, t.In(0)); err != nil {
-				v.Call([]reflect.Value{reflect.ValueOf(data)})
+		if n := t.NumIn(); n >= 1 {
+			data, err := io.Convert(message.Data, t.In(0))
+			if err != nil {
+				p.onError(err)
+				return
 			}
-		case 2:
-			if data, err := io.Convert(message.Data, t.In(0)); err != nil {
+			switch n {
+			case 1:
+				v.Call([]reflect.Value{reflect.ValueOf(data)})
+			case 2:
 				v.Call([]reflect.Value{reflect.ValueOf(data), reflect.ValueOf(message.From)})
+			default:
+				panic("invalid callback: " + t.String())
 			}
 		}
 	}
@@ -120,9 +143,7 @@ func (p *Prosumer) message() {
 				if p.RetryInterval != 0 {
 					<-time.After(p.RetryInterval)
 				}
-				if p.OnError != nil {
-					p.OnError(err)
-				}
+				p.onError(err)
 			}
 			continue
 		}
@@ -138,9 +159,7 @@ func (p *Prosumer) Subscribe(topic string, callback Callback) (result bool, err
 		p.callbacks.Store(topic, callback)
 		result, err = p.proxy.subscribe(topic)
 		go p.message()
-		if p.OnSubscribe != nil {
-			p.OnSubscribe(topic)
-		}
+		p.onSubscribe(topic)
 	}
 	return
 }
@@ -149,9 +168,7 @@ func (p *Prosumer) Unsubscribe(topic string) (result bool, err error) {
 	if p.ID() != "" {
 		result, err = p.proxy.unsubscribe(topic)
 		p.callbacks.Delete(topic)
-		if p.OnUnsubscribe != nil {
-			p.OnUnsubscribe(topic)
-		}
+		p.onUnsubscribe(topic)
 	}
 	return
 }
diff --git a/rpc/rpc_test.go b/rpc/rpc_test.go
index 04b0e21..dfa8e32 100644
--- a/rpc/rpc_test.go
+++ b/rpc/rpc_test.go
@@ -779,8 +779,11 @@ func TestPush(t *testing.T) {
 	time.Sleep(time.Millisecond * 5)
 
 	client1 := rpc.NewClient("tcp://127.0.0.1/")
-	client1.Use(log.Plugin.IOHandler)
+	//client1.Use(log.Plugin.IOHandler)
 	prosumer1 := push.NewProsumer(client1, "1")
+	prosumer1.OnError = func(e error) {
+		fmt.Println(e.Error())
+	}
 	prosumer1.OnSubscribe = func(topic string) {
 		fmt.Println(topic, "is subscribed.")
 	}
@@ -788,10 +791,10 @@ func TestPush(t *testing.T) {
 		fmt.Println(topic, "is unsubscribed.")
 	}
 	client2 := rpc.NewClient("tcp://127.0.0.1/")
-	client2.Use(log.Plugin.IOHandler)
+	//client2.Use(log.Plugin.IOHandler)
 	prosumer2 := push.NewProsumer(client2, "2")
-	prosumer1.Subscribe("test", func(data string) {
-		fmt.Println(data)
+	prosumer1.Subscribe("test", func(data int, from string) {
+		fmt.Printf("%v from %v\n", data, from)
 	})
 	prosumer1.Subscribe("test2", func(message push.Message) {
 		fmt.Println(message)