diff --git a/async-server-rooms/CMakeLists.txt b/async-server-rooms/CMakeLists.txt
index 97411e7..05e5812 100644
--- a/async-server-rooms/CMakeLists.txt
+++ b/async-server-rooms/CMakeLists.txt
@@ -21,8 +21,8 @@ add_library(${project_name}-lib
 
 ## link libs
 
-find_package(oatpp              0.19.11 REQUIRED)
-find_package(oatpp-websocket    0.19.11 REQUIRED)
+find_package(oatpp              0.19.12 REQUIRED)
+find_package(oatpp-websocket    0.19.12 REQUIRED)
 
 target_link_libraries(${project_name}-lib
         PUBLIC oatpp::oatpp
diff --git a/async-server-rooms/src/rooms/Peer.cpp b/async-server-rooms/src/rooms/Peer.cpp
index b5e5990..95b349c 100644
--- a/async-server-rooms/src/rooms/Peer.cpp
+++ b/async-server-rooms/src/rooms/Peer.cpp
@@ -53,7 +53,7 @@ oatpp::async::CoroutineStarter Peer::onClose(const std::shared_ptr<AsyncWebSocke
   return nullptr; // do nothing
 }
 
-oatpp::async::CoroutineStarter Peer::readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) {
+oatpp::async::CoroutineStarter Peer::readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) {
 
   if(size == 0) { // message transfer finished
 
@@ -63,7 +63,7 @@ oatpp::async::CoroutineStarter Peer::readMessage(const std::shared_ptr<AsyncWebS
     m_room->sendMessage(m_nickname + ": " + wholeMessage);
 
   } else if(size > 0) { // message frame received
-    m_messageBuffer.write(data, size);
+    m_messageBuffer.writeSimple(data, size);
   }
 
   return nullptr; // do nothing
diff --git a/async-server-rooms/src/rooms/Peer.hpp b/async-server-rooms/src/rooms/Peer.hpp
index 80570d1..9138202 100644
--- a/async-server-rooms/src/rooms/Peer.hpp
+++ b/async-server-rooms/src/rooms/Peer.hpp
@@ -77,7 +77,7 @@ class Peer : public oatpp::websocket::AsyncWebSocket::Listener {
   CoroutineStarter onPing(const std::shared_ptr<AsyncWebSocket>& socket, const oatpp::String& message) override;
   CoroutineStarter onPong(const std::shared_ptr<AsyncWebSocket>& socket, const oatpp::String& message) override;
   CoroutineStarter onClose(const std::shared_ptr<AsyncWebSocket>& socket, v_word16 code, const oatpp::String& message) override;
-  CoroutineStarter readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) override;
+  CoroutineStarter readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) override;
 
 };
 
diff --git a/async-server/CMakeLists.txt b/async-server/CMakeLists.txt
index c4f2663..ec348d9 100644
--- a/async-server/CMakeLists.txt
+++ b/async-server/CMakeLists.txt
@@ -17,8 +17,8 @@ add_library(${project_name}-lib
 
 ## link libs
 
-find_package(oatpp              0.19.11 REQUIRED)
-find_package(oatpp-websocket    0.19.11 REQUIRED)
+find_package(oatpp              0.19.12 REQUIRED)
+find_package(oatpp-websocket    0.19.12 REQUIRED)
 
 target_link_libraries(${project_name}-lib
         PUBLIC oatpp::oatpp
diff --git a/async-server/src/websocket/WSListener.cpp b/async-server/src/websocket/WSListener.cpp
index cfe4e5d..1102051 100644
--- a/async-server/src/websocket/WSListener.cpp
+++ b/async-server/src/websocket/WSListener.cpp
@@ -22,7 +22,7 @@ oatpp::async::CoroutineStarter WSListener::onClose(const std::shared_ptr<AsyncWe
   return nullptr; // do nothing
 }
 
-oatpp::async::CoroutineStarter WSListener::readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) {
+oatpp::async::CoroutineStarter WSListener::readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) {
 
   if(size == 0) { // message transfer finished
 
@@ -35,7 +35,7 @@ oatpp::async::CoroutineStarter WSListener::readMessage(const std::shared_ptr<Asy
     return socket->sendOneFrameTextAsync( "Hello from oatpp!: " + wholeMessage);
 
   } else if(size > 0) { // message frame received
-    m_messageBuffer.write(data, size);
+    m_messageBuffer.writeSimple(data, size);
   }
 
   return nullptr; // do nothing
diff --git a/async-server/src/websocket/WSListener.hpp b/async-server/src/websocket/WSListener.hpp
index 7c5b964..a855974 100644
--- a/async-server/src/websocket/WSListener.hpp
+++ b/async-server/src/websocket/WSListener.hpp
@@ -39,7 +39,7 @@ class WSListener : public oatpp::websocket::AsyncWebSocket::Listener {
   /**
    * Called on each message frame. After the last message will be called once-again with size == 0 to designate end of the message.
    */
-  CoroutineStarter readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) override;
+  CoroutineStarter readMessage(const std::shared_ptr<AsyncWebSocket>& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) override;
 
 };
 
diff --git a/client-binance.com/CMakeLists.txt b/client-binance.com/CMakeLists.txt
index aef0b06..5eb1930 100644
--- a/client-binance.com/CMakeLists.txt
+++ b/client-binance.com/CMakeLists.txt
@@ -20,9 +20,9 @@ add_library(${project_name}-lib
 
 ## link libs
 
-find_package(oatpp              0.19.11 REQUIRED)
-find_package(oatpp-websocket    0.19.11 REQUIRED)
-find_package(oatpp-mbedtls      0.19.11 REQUIRED)
+find_package(oatpp              0.19.12 REQUIRED)
+find_package(oatpp-websocket    0.19.12 REQUIRED)
+find_package(oatpp-mbedtls      0.19.12 REQUIRED)
 
 target_link_libraries(${project_name}-lib
         PUBLIC oatpp::oatpp
diff --git a/client-binance.com/src/WSListener.cpp b/client-binance.com/src/WSListener.cpp
index 45f1def..3c7c20d 100644
--- a/client-binance.com/src/WSListener.cpp
+++ b/client-binance.com/src/WSListener.cpp
@@ -20,7 +20,7 @@ void WSListener::onClose(const WebSocket& socket, v_word16 code, const oatpp::St
   OATPP_LOGD(TAG, "onClose code=%d", code);
 }
 
-void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) {
+void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) {
 
   if(size == 0) { // message transfer finished
 
@@ -29,7 +29,7 @@ void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 da
     onCompleteMessage(wholeMessage);
 
   } else if(size > 0) { // message frame received
-    m_messageBuffer.write(data, size);
+    m_messageBuffer.writeSimple(data, size);
   }
 
 }
diff --git a/client-binance.com/src/WSListener.hpp b/client-binance.com/src/WSListener.hpp
index f008f72..24cbeb8 100644
--- a/client-binance.com/src/WSListener.hpp
+++ b/client-binance.com/src/WSListener.hpp
@@ -39,7 +39,7 @@ class WSListener : public oatpp::websocket::WebSocket::Listener {
   /**
    * Called on each message frame. After the last message will be called once-again with size == 0 to designate end of the message.
    */
-  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) override;
+  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) override;
 
 public:
 
diff --git a/client-mbedtls/CMakeLists.txt b/client-mbedtls/CMakeLists.txt
index 3ec3c83..25da02e 100644
--- a/client-mbedtls/CMakeLists.txt
+++ b/client-mbedtls/CMakeLists.txt
@@ -15,9 +15,9 @@ add_library(${project_name}-lib
 
 ## link libs
 
-find_package(oatpp              0.19.11 REQUIRED)
-find_package(oatpp-websocket    0.19.11 REQUIRED)
-find_package(oatpp-mbedtls      0.19.11 REQUIRED)
+find_package(oatpp              0.19.12 REQUIRED)
+find_package(oatpp-websocket    0.19.12 REQUIRED)
+find_package(oatpp-mbedtls      0.19.12 REQUIRED)
 
 target_link_libraries(${project_name}-lib
         PUBLIC oatpp::oatpp
diff --git a/client-mbedtls/src/WSListener.cpp b/client-mbedtls/src/WSListener.cpp
index 78d8744..ca645a6 100644
--- a/client-mbedtls/src/WSListener.cpp
+++ b/client-mbedtls/src/WSListener.cpp
@@ -21,7 +21,7 @@ void WSListener::onClose(const WebSocket& socket, v_word16 code, const oatpp::St
   OATPP_LOGD(TAG, "onClose code=%d", code);
 }
 
-void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) {
+void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) {
 
   if(size == 0) { // message transfer finished
 
@@ -35,7 +35,7 @@ void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 da
     //socket.sendOneFrameText( "Hello from oatpp!: " + wholeMessage);
 
   } else if(size > 0) { // message frame received
-    m_messageBuffer.write(data, size);
+    m_messageBuffer.writeSimple(data, size);
   }
 
 }
diff --git a/client-mbedtls/src/WSListener.hpp b/client-mbedtls/src/WSListener.hpp
index 1d06070..c010c43 100644
--- a/client-mbedtls/src/WSListener.hpp
+++ b/client-mbedtls/src/WSListener.hpp
@@ -44,7 +44,7 @@ class WSListener : public oatpp::websocket::WebSocket::Listener {
   /**
    * Called on each message frame. After the last message will be called once-again with size == 0 to designate end of the message.
    */
-  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) override;
+  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) override;
 
 };
 
diff --git a/client/CMakeLists.txt b/client/CMakeLists.txt
index dc5341f..f09efdc 100644
--- a/client/CMakeLists.txt
+++ b/client/CMakeLists.txt
@@ -15,8 +15,8 @@ add_library(${project_name}-lib
 
 ## link libs
 
-find_package(oatpp              0.19.11 REQUIRED)
-find_package(oatpp-websocket    0.19.11 REQUIRED)
+find_package(oatpp              0.19.12 REQUIRED)
+find_package(oatpp-websocket    0.19.12 REQUIRED)
 
 target_link_libraries(${project_name}-lib
         PUBLIC oatpp::oatpp
diff --git a/client/src/WSListener.cpp b/client/src/WSListener.cpp
index 78d8744..ca645a6 100644
--- a/client/src/WSListener.cpp
+++ b/client/src/WSListener.cpp
@@ -21,7 +21,7 @@ void WSListener::onClose(const WebSocket& socket, v_word16 code, const oatpp::St
   OATPP_LOGD(TAG, "onClose code=%d", code);
 }
 
-void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) {
+void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) {
 
   if(size == 0) { // message transfer finished
 
@@ -35,7 +35,7 @@ void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 da
     //socket.sendOneFrameText( "Hello from oatpp!: " + wholeMessage);
 
   } else if(size > 0) { // message frame received
-    m_messageBuffer.write(data, size);
+    m_messageBuffer.writeSimple(data, size);
   }
 
 }
diff --git a/client/src/WSListener.hpp b/client/src/WSListener.hpp
index 1d06070..c010c43 100644
--- a/client/src/WSListener.hpp
+++ b/client/src/WSListener.hpp
@@ -44,7 +44,7 @@ class WSListener : public oatpp::websocket::WebSocket::Listener {
   /**
    * Called on each message frame. After the last message will be called once-again with size == 0 to designate end of the message.
    */
-  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) override;
+  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) override;
 
 };
 
diff --git a/server/CMakeLists.txt b/server/CMakeLists.txt
index 3d8ae60..b7b08c2 100644
--- a/server/CMakeLists.txt
+++ b/server/CMakeLists.txt
@@ -17,8 +17,8 @@ add_library(${project_name}-lib
 
 ## link libs
 
-find_package(oatpp              0.19.11 REQUIRED)
-find_package(oatpp-websocket    0.19.11 REQUIRED)
+find_package(oatpp              0.19.12 REQUIRED)
+find_package(oatpp-websocket    0.19.12 REQUIRED)
 
 target_link_libraries(${project_name}-lib
         PUBLIC oatpp::oatpp
diff --git a/server/src/websocket/WSListener.cpp b/server/src/websocket/WSListener.cpp
index 9bffed7..37b0112 100644
--- a/server/src/websocket/WSListener.cpp
+++ b/server/src/websocket/WSListener.cpp
@@ -20,7 +20,7 @@ void WSListener::onClose(const WebSocket& socket, v_word16 code, const oatpp::St
   OATPP_LOGD(TAG, "onClose code=%d", code);
 }
 
-void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) {
+void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) {
 
   if(size == 0) { // message transfer finished
 
@@ -33,7 +33,7 @@ void WSListener::readMessage(const WebSocket& socket, v_word8 opcode, p_char8 da
     socket.sendOneFrameText( "Hello from oatpp!: " + wholeMessage);
 
   } else if(size > 0) { // message frame received
-    m_messageBuffer.write(data, size);
+    m_messageBuffer.writeSimple(data, size);
   }
 
 }
diff --git a/server/src/websocket/WSListener.hpp b/server/src/websocket/WSListener.hpp
index cf83052..9aaeb3f 100644
--- a/server/src/websocket/WSListener.hpp
+++ b/server/src/websocket/WSListener.hpp
@@ -39,7 +39,7 @@ class WSListener : public oatpp::websocket::WebSocket::Listener {
   /**
    * Called on each message frame. After the last message will be called once-again with size == 0 to designate end of the message.
    */
-  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::data::v_io_size size) override;
+  void readMessage(const WebSocket& socket, v_word8 opcode, p_char8 data, oatpp::v_io_size size) override;
 
 };