diff --git a/bin/enum_gen b/bin/enum_gen
index 2332792..a9661e7 100755
Binary files a/bin/enum_gen and b/bin/enum_gen differ
diff --git a/lib/tres/controller.ex b/lib/tres/controller.ex
index 92d962e..ee48dbb 100644
--- a/lib/tres/controller.ex
+++ b/lib/tres/controller.ex
@@ -4,6 +4,7 @@ defmodule Tres.Controller do
       import Tres.SwitchRegistry,
         only: [
           send_message: 2,
+          blocking_send_message: 2,
           get_current_xid: 1
         ]
 
diff --git a/lib/tres/message_helper.ex b/lib/tres/message_helper.ex
index b9b1655..dcb1a02 100644
--- a/lib/tres/message_helper.ex
+++ b/lib/tres/message_helper.ex
@@ -17,7 +17,7 @@ defmodule Tres.MessageHelper do
           instructions: options[:instructions] || []
         }
 
-        send_message(flow_mod, datapath_id)
+        send_message(flow_mod, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_flow_mod_modify(datapath_id, options \\ []) do
@@ -36,7 +36,7 @@ defmodule Tres.MessageHelper do
           instructions: options[:instructions] || []
         }
 
-        send_message(flow_mod, datapath_id)
+        send_message(flow_mod, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_flow_mod_delete(datapath_id, options \\ []) do
@@ -53,7 +53,7 @@ defmodule Tres.MessageHelper do
           match: options[:match] || Openflow.Match.new()
         }
 
-        send_message(flow_mod, datapath_id)
+        send_message(flow_mod, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_packet_out(datapath_id, options \\ []) do
@@ -65,7 +65,7 @@ defmodule Tres.MessageHelper do
           data: options[:data] || ""
         }
 
-        send_message(packet_out, datapath_id)
+        send_message(packet_out, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_group_mod_add(datapath_id, options \\ []) do
@@ -78,7 +78,7 @@ defmodule Tres.MessageHelper do
             buckets: options[:buckets] || []
           )
 
-        send_message(group_mod, datapath_id)
+        send_message(group_mod, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_group_mod_delete(datapath_id, options \\ []) do
@@ -89,7 +89,7 @@ defmodule Tres.MessageHelper do
             group_id: options[:group_id] || :all
           )
 
-        send_message(group_mod, datapath_id)
+        send_message(group_mod, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_group_mod_modify(datapath_id, options \\ []) do
@@ -102,7 +102,7 @@ defmodule Tres.MessageHelper do
             buckets: options[:buckets] || []
           )
 
-        send_message(group_mod, datapath_id)
+        send_message(group_mod, datapath_id, Keyword.get(options, :blocking, false))
       end
 
       defp send_role_request(datapath_id, options) do
@@ -113,7 +113,7 @@ defmodule Tres.MessageHelper do
             generation_id: options[:generation_id] || 0
           )
 
-        send_message(role_request, datapath_id)
+        send_message(role_request, datapath_id, Keyword.get(options, :blocking, false))
       end
     end
   end
diff --git a/lib/tres/secure_channel.ex b/lib/tres/secure_channel.ex
index eb835ac..f6671ba 100644
--- a/lib/tres/secure_channel.ex
+++ b/lib/tres/secure_channel.ex
@@ -369,7 +369,8 @@ defmodule Tres.SecureChannel do
     XACT_KV.delete(state_data.xact_kv_ref, xid)
   end
   defp process_xact_entry({:xact_entry, xid, message, _orig, from}, state_data) when is_tuple(from) do
-    unless is_nil(message), do: :gen_statem.reply(from, message)
+    reply = if is_nil(message), do: :noreply, else: message
+    _ = :gen_statem.reply(from, {:ok, reply})
     XACT_KV.delete(state_data.xact_kv_ref, xid)
   end
 
diff --git a/lib/tres/switch_registry.ex b/lib/tres/switch_registry.ex
index 78823b7..7849058 100644
--- a/lib/tres/switch_registry.ex
+++ b/lib/tres/switch_registry.ex
@@ -18,6 +18,13 @@ defmodule Tres.SwitchRegistry do
     lookup_pid({datapath_id, 0})
   end
 
+  def send_message(message, dpid, _blocking = true) do
+    blocking_send_message(message, dpid)
+  end
+  def send_message(message, dpid, _blocking) do
+    send_message(message, dpid)
+  end
+
   def send_message(message, {_dpid, _aux_id} = datapath_id) do
     Registry.dispatch(__MODULE__, datapath_id, &do_send_message(&1, message))
   end
diff --git a/src/tres_xact_kv.erl b/src/tres_xact_kv.erl
index fdbf225..2924dfe 100644
--- a/src/tres_xact_kv.erl
+++ b/src/tres_xact_kv.erl
@@ -3,13 +3,16 @@
 -include_lib("stdlib/include/ms_transform.hrl").
 
 -export([create/0, drop/1]).
--export([insert/3, update/3, get/2, delete/2, is_exists/2, is_empty/1]).
+-export([insert/3, insert/4,
+         update/3, get/2,
+         delete/2, is_exists/2,
+         is_empty/1]).
 
 -define(TABLE, xact_kv).
 -define(ENTRY, xact_entry).
 -define(TABLE_OPTS, [set, protected, {keypos, #?ENTRY.xid}]).
 
--record(?ENTRY, {xid = 0, pending = nil, orig = nil}).
+-record(?ENTRY, {xid = 0, pending = nil, orig = nil, from = nil}).
 
 -spec create() -> reference().
 create() ->
@@ -23,6 +26,10 @@ drop(Tid) ->
 insert(Tid, Xid, Orig) ->
     ets:insert(Tid, #?ENTRY{xid = Xid, orig = Orig}).
 
+-spec insert(reference(), integer(), map(), term()) -> true.
+insert(Tid, Xid, Orig, From) ->
+    ets:insert(Tid, #?ENTRY{xid = Xid, orig = Orig, from = From}).
+
 -spec update(reference(), integer(), map()) -> integer().
 update(Tid, Xid, #{'__struct__' := 'Elixir.Openflow.ErrorMsg'} = Error) ->
     ets:select_replace(Tid, ms_for_handle_error(Tid, Xid, Error));