diff --git a/servlet/rpc-servlet.go b/servlet/rpc-servlet.go
index 64b4184..9dee116 100644
--- a/servlet/rpc-servlet.go
+++ b/servlet/rpc-servlet.go
@@ -6,7 +6,6 @@ import (
 
 	logging "git.loafle.net/commons/logging-go"
 	crp "git.loafle.net/commons/rpc-go/protocol"
-	crpj "git.loafle.net/commons/rpc-go/protocol/json"
 	"git.loafle.net/commons/server-go"
 	css "git.loafle.net/commons/server-go/socket"
 	cssw "git.loafle.net/commons/server-go/socket/web"
@@ -23,7 +22,8 @@ type RPCServlet interface {
 type RPCServlets struct {
 	cssw.Servlets
 
-	UseSession bool
+	RPCServerCodec crp.ServerCodec
+	UseSession     bool
 
 	sessions sync.Map
 }
@@ -72,7 +72,6 @@ func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
 		replyBuff []byte
 		err       error
 	)
-	sc := crpj.NewServerCodec()
 
 	_clientType := servletCtx.GetAttribute(og.SessionClientTypeKey)
 	_sessionID := servletCtx.GetAttribute(og.SessionIDKey)
@@ -95,7 +94,7 @@ func (s *RPCServlets) Handle(servletCtx server.ServletCtx,
 				return
 			}
 			// grpc exec method call
-			src, err = sc.NewRequest(msg)
+			src, err = s.RPCServerCodec.NewRequest(msg)
 			if nil != err {
 				logging.Logger().Error(err)
 				break