diff --git a/config/config.exs b/config/config.exs
index 93b9ad9..4113ff7 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -3,11 +3,12 @@
 use Mix.Config
 
 config :tres,
-  callback_module: Tres.ExampleHandler,
+  protocol:        :tcp,
+  port:            6633,
   max_connections: 10,
-  num_acceptors: 10,
-  protocol: :tcp,
-  port: 6653
+  num_acceptors:   10,
+  callback_module: Tres.ExampleHandler,
+  callback_args:   []
 
 config :logger,
   level: :info,
diff --git a/lib/openflow.ex b/lib/openflow.ex
index a5ca2bc..a0e5f0d 100644
--- a/lib/openflow.ex
+++ b/lib/openflow.ex
@@ -26,6 +26,10 @@ defmodule Openflow do
     end
   end
 
+  def to_binary(messages) when is_list(messages) do
+    binaries = for message <- messages, do: to_binary(message)
+    Enum.join(binaries, "")
+  end
   def to_binary(%{__struct__: encoder, version: version, xid: xid} = msg) do
     case encoder.to_binary(msg) do
       body_bin when is_binary(body_bin) ->
@@ -36,6 +40,16 @@ defmodule Openflow do
     end
   end
 
+  def append_body(nil, message), do: message
+  def append_body(message, continue) do
+    mod = message.__struct__
+    if function_exported?(mod, :append_body, 2) do
+      mod.append_body(message, continue)
+    else
+      message
+    end
+  end
+
   # private functions
 
   defp do_read({:error, reason}, _) do
diff --git a/lib/openflow/.#nx_packet_in2.ex b/lib/openflow/.#nx_packet_in2.ex
deleted file mode 120000
index b4344b8..0000000
--- a/lib/openflow/.#nx_packet_in2.ex
+++ /dev/null
@@ -1 +0,0 @@
-shun159@shun159.5674:1510580208
\ No newline at end of file
diff --git a/lib/openflow/actions/nx_bundle.ex b/lib/openflow/actions/nx_bundle.ex
index 6a65bc4..8fcd5f0 100644
--- a/lib/openflow/actions/nx_bundle.ex
+++ b/lib/openflow/actions/nx_bundle.ex
@@ -14,15 +14,12 @@ defmodule Openflow.Action.NxBundle do
   alias __MODULE__
 
   def new(options) do
-    hash_field = Keyword.get(options, :hash_field, :eth_src)
-    basis = Keyword.get(options, :basis, 0)
-    alg = Keyword.get(options, :algorithm, :active_backup)
-    slaves = Keyword.get(options, :slaves, [])
-    %NxBundle{algorithm: alg,
-              hash_field: hash_field,
-              basis: basis,
-              n_slaves: length(slaves),
-              slaves: slaves}
+    slaves = options[:slaves] || []
+    %NxBundle{algorithm:  options[:algorithm]  || :active_backup,
+              hash_field: options[:hash_field] || :eth_src,
+              basis:      options[:basis]      || 0,
+              n_slaves:   length(slaves),
+              slaves:     slaves}
   end
 
   def to_binary(%NxBundle{algorithm: alg,
diff --git a/lib/openflow/actions/nx_bundle_load.ex b/lib/openflow/actions/nx_bundle_load.ex
index a76d9f4..b9c4ef1 100644
--- a/lib/openflow/actions/nx_bundle_load.ex
+++ b/lib/openflow/actions/nx_bundle_load.ex
@@ -19,22 +19,17 @@ defmodule Openflow.Action.NxBundleLoad do
   alias __MODULE__
 
   def new(options) do
-    hash_field = Keyword.get(options, :hash_field, :eth_src)
-    basis = Keyword.get(options, :basis, 0)
-    alg = Keyword.get(options, :algorithm, :active_backup)
-    slaves = Keyword.get(options, :slaves, [])
-    dst_field = Keyword.get(options, :dst_field)
+    dst_field = options[:dst_field]
     default_n_bits = Openflow.Match.Field.n_bits_of(dst_field)
-    n_bits = Keyword.get(options, :n_bits, default_n_bits)
-    ofs = Keyword.get(options, :offset, 0)
-    %NxBundleLoad{algorithm: alg,
-                  hash_field: hash_field,
-                  basis: basis,
-                  n_slaves: length(slaves),
-                  slaves: slaves,
-                  offset: ofs,
-                  n_bits: n_bits,
-                  dst_field: dst_field}
+    slaves = options[:slaves] || []
+    %NxBundleLoad{algorithm:  options[:algorithm]  || :active_backup,
+                  hash_field: options[:hash_field] || :eth_src,
+                  basis:      options[:basis]      || 0,
+                  n_slaves:   length(slaves),
+                  slaves:     slaves,
+                  offset:     options[:offset] || 0,
+                  n_bits:     options[:n_bits] || default_n_bits,
+                  dst_field:  options[:dst_field]}
   end
 
   def to_binary(%NxBundleLoad{algorithm: alg,
diff --git a/lib/openflow/actions/nx_conjunction.ex b/lib/openflow/actions/nx_conjunction.ex
index 3b90b4d..b9818d6 100644
--- a/lib/openflow/actions/nx_conjunction.ex
+++ b/lib/openflow/actions/nx_conjunction.ex
@@ -11,10 +11,9 @@ defmodule Openflow.Action.NxConjunction do
   alias __MODULE__
 
   def new(options) do
-    clause = Keyword.get(options, :clause, 0)
-    n_clauses = Keyword.get(options, :n_clauses, 0)
-    id = Keyword.get(options, :id, 0)
-    %NxConjunction{clause: clause, n_clauses: n_clauses, id: id}
+    %NxConjunction{clause:    options[:clause] || 0,
+                   n_clauses: options[:n_clauses] || 0,
+                   id:        options[:id] || 0}
   end
 
   def to_binary(%NxConjunction{clause: clause, n_clauses: n_clauses, id: id}) do
diff --git a/lib/openflow/actions/nx_conntrack.ex b/lib/openflow/actions/nx_conntrack.ex
index 76b033f..4c4dafc 100644
--- a/lib/openflow/actions/nx_conntrack.ex
+++ b/lib/openflow/actions/nx_conntrack.ex
@@ -18,24 +18,14 @@ defmodule Openflow.Action.NxConntrack do
   alias __MODULE__
 
   def new(options \\ []) do
-    flags = Keyword.get(options, :flags, [])
-    zone_src = Keyword.get(options, :zone_src)
-    zone_ofs = Keyword.get(options, :zone_offset)
-    zone_n_bits = Keyword.get(options, :zone_n_bits)
-    zone_imm = Keyword.get(options, :zone_imm, 0)
-    recirc_table = Keyword.get(options, :recirc_table, 255)
-    alg = Keyword.get(options, :alg, 0)
-    exec = Keyword.get(options, :exec, [])
-    %NxConntrack{
-      flags:        flags,
-      zone_src:     zone_src,
-      zone_imm:     zone_imm,
-      zone_offset:  zone_ofs,
-      zone_n_bits:  zone_n_bits,
-      recirc_table: recirc_table,
-      alg:          alg,
-      exec:         exec
-    }
+    %NxConntrack{flags:        options[:flags] || [],
+                 zone_src:     options[:zone_src],
+                 zone_imm:     options[:zone_imm] || 0,
+                 zone_offset:  options[:zone_offset],
+                 zone_n_bits:  options[:zone_n_bits],
+                 recirc_table: options[:recirc_table] || 255,
+                 alg:          options[:alg]  || 0,
+                 exec:         options[:exec] || []}
   end
 
   def to_binary(%NxConntrack{
diff --git a/lib/openflow/actions/nx_controller.ex b/lib/openflow/actions/nx_controller.ex
index 8128f40..4faf769 100644
--- a/lib/openflow/actions/nx_controller.ex
+++ b/lib/openflow/actions/nx_controller.ex
@@ -11,10 +11,9 @@ defmodule Openflow.Action.NxController do
   alias __MODULE__
 
   def new(options) do
-    max_len = Keyword.get(options, :max_len, :no_buffer)
-    controller_id = Keyword.get(options, :id, 0)
-    reason = Keyword.get(options, :reason, :action)
-    %NxController{max_len: max_len, id: controller_id, reason: reason}
+    %NxController{max_len: options[:max_len] || :no_buffer,
+                  id:      options[:id]      || 0,
+                  reason:  options[:reason]  || :action}
   end
 
   def to_binary(%NxController{max_len: max_len, id: controller_id, reason: reason}) do
diff --git a/lib/openflow/actions/nx_controller2.ex b/lib/openflow/actions/nx_controller2.ex
index 6e1637c..5b932e7 100644
--- a/lib/openflow/actions/nx_controller2.ex
+++ b/lib/openflow/actions/nx_controller2.ex
@@ -21,16 +21,11 @@ defmodule Openflow.Action.NxController2 do
   alias __MODULE__
 
   def new(options) do
-    max_len = Keyword.get(options, :max_len, :no_buffer)
-    controller_id = Keyword.get(options, :id, 0)
-    reason = Keyword.get(options, :reason, :action)
-    userdata = Keyword.get(options, :userdata)
-    pause = Keyword.get(options, :pause, false)
-    %NxController2{max_len: max_len,
-                   id: controller_id,
-                   reason: reason,
-                   userdata: userdata,
-                   pause: pause}
+    %NxController2{max_len:  options[:max_len]  || :no_buffer,
+                   id:       options[:id]       || 0,
+                   reason:   options[:reason]   || :action,
+                   userdata: options[:userdata],
+                   pause:    options[:pause]    || false}
   end
 
   def to_binary(%NxController2{} = ctl) do
diff --git a/lib/openflow/actions/nx_fin_timeout.ex b/lib/openflow/actions/nx_fin_timeout.ex
index 00a14d4..a94a4dd 100644
--- a/lib/openflow/actions/nx_fin_timeout.ex
+++ b/lib/openflow/actions/nx_fin_timeout.ex
@@ -10,9 +10,8 @@ defmodule Openflow.Action.NxFinTimeout do
   alias __MODULE__
 
   def new(options) do
-    fin_idle = Keyword.get(options, :idle_timeout, 0)
-    fin_hard = Keyword.get(options, :hard_timeout, 0)
-    %NxFinTimeout{idle_timeout: fin_idle, hard_timeout: fin_hard}
+    %NxFinTimeout{idle_timeout: options[:idle_timeout] || 0,
+                  hard_timeout: options[:hard_timeout] || 0}
   end
 
   def to_binary(%NxFinTimeout{idle_timeout: fin_idle, hard_timeout: fin_hard}) do
diff --git a/lib/openflow/actions/nx_flow_spec_load.ex b/lib/openflow/actions/nx_flow_spec_load.ex
index 120a90d..5b35f20 100644
--- a/lib/openflow/actions/nx_flow_spec_load.ex
+++ b/lib/openflow/actions/nx_flow_spec_load.ex
@@ -14,17 +14,13 @@ defmodule Openflow.Action.NxFlowSpecLoad do
   alias __MODULE__
 
   def new(options) do
-    src = Keyword.get(options, :src)
-    dst = Keyword.get(options, :dst)
-    src_ofs = Keyword.get(options, :src_offset, 0)
-    dst_ofs = Keyword.get(options, :dst_offset, 0)
-    default_n_bits = Openflow.Match.Field.n_bits_of(dst)
-    n_bits = Keyword.get(options, :n_bits, default_n_bits)
-    %NxFlowSpecLoad{src: src,
-                    dst: dst,
-                    n_bits: n_bits,
-                    src_offset: src_ofs,
-                    dst_offset: dst_ofs}
+    dst = options[:dst]
+    n_bits = options[:n_bits] || Openflow.Match.Field.n_bits_of(dst)
+    %NxFlowSpecLoad{src:        options[:src],
+                    dst:        dst,
+                    n_bits:     n_bits,
+                    src_offset: options[:src_offset] || 0,
+                    dst_offset: options[:dst_offset] || 0}
   end
 
   def to_binary(%NxFlowSpecLoad{} = fsm) do
diff --git a/lib/openflow/actions/nx_flow_spec_match.ex b/lib/openflow/actions/nx_flow_spec_match.ex
index 8312fb4..c8e2e1c 100644
--- a/lib/openflow/actions/nx_flow_spec_match.ex
+++ b/lib/openflow/actions/nx_flow_spec_match.ex
@@ -14,17 +14,13 @@ defmodule Openflow.Action.NxFlowSpecMatch do
   alias __MODULE__
 
   def new(options) do
-    src = Keyword.get(options, :src)
-    dst = Keyword.get(options, :dst)
-    default_n_bits = Openflow.Match.Field.n_bits_of(dst)
-    n_bits = Keyword.get(options, :n_bits, default_n_bits)
-    src_ofs = Keyword.get(options, :src_offset, 0)
-    dst_ofs = Keyword.get(options, :dst_offset, 0)
-    %NxFlowSpecMatch{src: src,
-                     dst: dst,
-                     n_bits: n_bits,
-                     src_offset: src_ofs,
-                     dst_offset: dst_ofs}
+    dst = options[:dst]
+    n_bits = options[:n_bits] || Openflow.Match.Field.n_bits_of(dst)
+    %NxFlowSpecMatch{src:        options[:src],
+                     dst:        dst,
+                     n_bits:     n_bits,
+                     src_offset: options[:src_offset] || 0,
+                     dst_offset: options[:dst_offset] || 0}
   end
 
   def to_binary(%NxFlowSpecMatch{} = fsm) do
diff --git a/lib/openflow/actions/nx_flow_spec_output.ex b/lib/openflow/actions/nx_flow_spec_output.ex
index ae0b18f..75ad422 100644
--- a/lib/openflow/actions/nx_flow_spec_output.ex
+++ b/lib/openflow/actions/nx_flow_spec_output.ex
@@ -11,13 +11,11 @@ defmodule Openflow.Action.NxFlowSpecOutput do
   alias __MODULE__
 
   def new(options) do
-    src = Keyword.get(options, :src)
-    src_ofs = Keyword.get(options, :src_offset, 0)
-    default_n_bits = Openflow.Match.Field.n_bits_of(src)
-    n_bits = Keyword.get(options, :n_bits, default_n_bits)
-    %NxFlowSpecOutput{n_bits: n_bits,
-                      src: src,
-                      src_offset: src_ofs}
+    src = options[:src]
+    n_bits = options[:n_bits] || Openflow.Match.Field.n_bits_of(src)
+    %NxFlowSpecOutput{n_bits:     n_bits,
+                      src:        src,
+                      src_offset: options[:src_offset] || 0}
   end
 
   def to_binary(%NxFlowSpecOutput{n_bits: n_bits,
diff --git a/lib/openflow/actions/nx_learn.ex b/lib/openflow/actions/nx_learn.ex
index df6932f..b57f380 100644
--- a/lib/openflow/actions/nx_learn.ex
+++ b/lib/openflow/actions/nx_learn.ex
@@ -17,24 +17,15 @@ defmodule Openflow.Action.NxLearn do
   alias __MODULE__
 
   def new(options) do
-    idle = Keyword.get(options, :idle_timeout, 0)
-    hard = Keyword.get(options, :hard_timeout, 0)
-    prio = Keyword.get(options, :priority, 0)
-    cookie = Keyword.get(options, :cookie, 0)
-    flags = Keyword.get(options, :flags, [])
-    table_id = Keyword.get(options, :table_id, 0)
-    fin_idle = Keyword.get(options, :fin_idle_timeout, 0)
-    fin_hard = Keyword.get(options, :fin_hard_timeout, 0)
-    flow_specs = Keyword.get(options, :flow_specs, [])
-    %NxLearn{idle_timeout: idle,
-             hard_timeout: hard,
-             priority: prio,
-             cookie: cookie,
-             flags: flags,
-             table_id: table_id,
-             fin_idle_timeout: fin_idle,
-             fin_hard_timeout: fin_hard,
-             flow_specs: flow_specs}
+    %NxLearn{idle_timeout:     options[:idle_timeout]     || 0,
+             hard_timeout:     options[:hard_timeout]     || 0,
+             priority:         options[:priority]         || 0,
+             cookie:           options[:cookie]           || 0,
+             flags:            options[:flags]            || [],
+             table_id:         options[:table_id]         || 0xff,
+             fin_idle_timeout: options[:fin_idle_timeout] || 0,
+             fin_hard_timeout: options[:fin_hard_timeout] || 0,
+             flow_specs:       options[:flow_specs]       || []}
   end
 
   def to_binary(%NxLearn{idle_timeout: idle,
@@ -52,7 +43,7 @@ defmodule Openflow.Action.NxLearn do
       prio::16, cookie::64, flags_int::16, table_id::8,
       0::size(1)-unit(8), fin_idle::16, fin_hard::16,
       flow_specs_bin::bitstring>>
-  exp_body_size =  byte_size(exp_body)
+    exp_body_size =  byte_size(exp_body)
     padding_length = Openflow.Utils.padding(4 + exp_body_size, 8)
     length = 4 + exp_body_size + padding_length
     <<0xffff::16, length::16, exp_body::bytes, 0::size(padding_length)-unit(8)>>
diff --git a/lib/openflow/actions/nx_learn2.ex b/lib/openflow/actions/nx_learn2.ex
index 4a47ef5..fac6e77 100644
--- a/lib/openflow/actions/nx_learn2.ex
+++ b/lib/openflow/actions/nx_learn2.ex
@@ -20,30 +20,18 @@ defmodule Openflow.Action.NxLearn2 do
   alias __MODULE__
 
   def new(options) do
-    idle = Keyword.get(options, :idle_timeout, 0)
-    hard = Keyword.get(options, :hard_timeout, 0)
-    prio = Keyword.get(options, :priority, 0)
-    cookie = Keyword.get(options, :cookie, 0)
-    flags = Keyword.get(options, :flags, [])
-    table_id = Keyword.get(options, :table_id, 0)
-    fin_idle = Keyword.get(options, :fin_idle_timeout, 0)
-    fin_hard = Keyword.get(options, :fin_hard_timeout, 0)
-    flow_specs = Keyword.get(options, :flow_specs, [])
-    limit = Keyword.get(options, :limit, 0)
-    result_dst_offset = Keyword.get(options, :result_dst_offset, 0)
-    result_dst = Keyword.get(options, :result_dst)
-    %NxLearn2{idle_timeout: idle,
-              hard_timeout: hard,
-              priority: prio,
-              cookie: cookie,
-              flags: flags,
-              table_id: table_id,
-              fin_idle_timeout: fin_idle,
-              fin_hard_timeout: fin_hard,
-              limit: limit,
-              result_dst_offset: result_dst_offset,
-              result_dst: result_dst,
-              flow_specs: flow_specs}
+    %NxLearn2{idle_timeout:      options[:idle_timeout]      || 0,
+              hard_timeout:      options[:hard_timeout]      || 0,
+              priority:          options[:priority]          || 0,
+              cookie:            options[:cookie]            || 0,
+              flags:             options[:flags]             || [],
+              table_id:          options[:table_id]          || 0xff,
+              fin_idle_timeout:  options[:fin_idle_timeout]  || 0,
+              fin_hard_timeout:  options[:fin_hard_timeout]  || 0,
+              limit:             options[:limit]             || 0,
+              result_dst_offset: options[:result_dst_offset] || 0,
+              result_dst:        options[:result_dst],
+              flow_specs:        options[:flow_specs]        || []}
   end
 
   def to_binary(%NxLearn2{idle_timeout: idle,
diff --git a/lib/openflow/actions/set_field.ex b/lib/openflow/actions/set_field.ex
index ed962ab..a1b0c1d 100644
--- a/lib/openflow/actions/set_field.ex
+++ b/lib/openflow/actions/set_field.ex
@@ -25,7 +25,7 @@ defmodule Openflow.Action.SetField do
   end
 
   def read(<<25::16, _length::16, match_field_bin::bytes>>) do
-    <<_class::16, _field::7, _hm::1, flen::8, _rest::bytes>>= match_field_bin
+    <<_class::16, _field::7, _hm::1, flen::8, _rest::bytes>> = match_field_bin
     match_len = 4 + 4 + flen
     match_bin = <<1::16, match_len::16, match_field_bin::bytes>>
     {[field|_], _rest} = Openflow.Match.read(match_bin)
diff --git a/lib/openflow/enums.ex b/lib/openflow/enums.ex
index 32f36d4..ab41448 100644
--- a/lib/openflow/enums.ex
+++ b/lib/openflow/enums.ex
@@ -316,8 +316,9 @@ defmodule Openflow.Enums do
     ],
 
     experimenter_oxm_vendors: [
-      nicira_ext_match:    0x00002320,
-      onf_ext_match:       0x4f4e4600
+      nicira_ext_match: 0x00002320,
+      hp_ext_match:     0x00002428,
+      onf_ext_match:    0x4f4e4600
     ],
 
     match_type: [
@@ -618,6 +619,24 @@ defmodule Openflow.Enums do
       nsh_c4:     9
     ],
 
+    hp_ext_match: [
+      hp_udp_src_port_range: 0,
+      hp_udp_dst_port_range: 1,
+      hp_tcp_src_port_range: 2,
+      hp_tcp_dst_port_range: 3,
+      hp_tcp_flags:          4,
+      hp_custom_1:           5,
+      hp_custom_2:           6,
+      hp_custom_3:           7,
+      hp_custom_4:           8
+    ],
+
+    hp_custom_match_type: [
+      l2_start: 1,
+      l3_start: 2,
+      l4_start: 3
+    ],
+
     onf_ext_match: [
       onf_tcp_flags:     42,
       onf_actset_output: 43,
diff --git a/lib/openflow/match.ex b/lib/openflow/match.ex
index baac231..bd40634 100644
--- a/lib/openflow/match.ex
+++ b/lib/openflow/match.ex
@@ -18,7 +18,7 @@ defmodule Openflow.Match do
 
   def read(binary) do
     <<1::16, no_pad_len::16, binary1::binary>> = binary
-    padding_length = @match_size - rem(no_pad_len, 8)
+    padding_length = Openflow.Utils.pad_length(no_pad_len, 8)
     match_field_len = no_pad_len - @header_size
     <<match_fields::size(match_field_len)-binary, _::size(padding_length)-unit(8), rest::bitstring>> = binary1
     {decode_fields(match_fields, []), rest}
@@ -58,7 +58,7 @@ defmodule Openflow.Match do
 
   def header_size(<<_oxm_class_int::16, _oxm_field_int::7, _oxm_has_mask::1, _oxm_length::8, _::bytes>>),
     do: 4
-    def header_size(<<0xffff::16, _oxm_field_int::7, _oxm_has_mask::1, _oxm_length::8, _exp_int::32, _::bytes>>),
+  def header_size(<<0xffff::16, _oxm_field_int::7, _oxm_has_mask::1, _oxm_length::8, _exp_int::32, _::bytes>>),
     do: 8
 
   # private functions
diff --git a/lib/openflow/match/field.ex b/lib/openflow/match/field.ex
index 4c45221..8a6e411 100644
--- a/lib/openflow/match/field.ex
+++ b/lib/openflow/match/field.ex
@@ -275,6 +275,17 @@ defmodule Openflow.Match.Field do
   def vendor_of(:nsh_c3),     do: :nicira_ext_match
   def vendor_of(:nsh_c4),     do: :nicira_ext_match
 
+  # HP Ext Match
+  def vendor_of(:hp_udp_src_port_range), do: :hp_ext_match
+  def vendor_of(:hp_udp_dst_port_range), do: :hp_ext_match
+  def vendor_of(:hp_tcp_src_port_range), do: :hp_ext_match
+  def vendor_of(:hp_tcp_dst_port_range), do: :hp_ext_match
+  def vendor_of(:hp_tcp_flags), do: :hp_ext_match
+  def vendor_of(:hp_custom_1),  do: :hp_ext_match
+  def vendor_of(:hp_custom_2),  do: :hp_ext_match
+  def vendor_of(:hp_custom_3),  do: :hp_ext_match
+  def vendor_of(:hp_custom_4),  do: :hp_ext_match
+
   # ONF Ext Match
   def vendor_of(:onf_tcp_flags),     do: :onf_ext_match
   def vendor_of(:onf_actset_output), do: :onf_ext_match
@@ -518,6 +529,17 @@ defmodule Openflow.Match.Field do
   def format_of(:nsh_c3),     do: {:be32, :decimal}
   def format_of(:nsh_c4),     do: {:be32, :decimal}
 
+  # HP Ext Match
+  def format_of(:hp_udp_src_port_range), do: {:be32, :decimal}
+  def format_of(:hp_udp_dst_port_range), do: {:be32, :decimal}
+  def format_of(:hp_tcp_src_port_range), do: {:be32, :decimal}
+  def format_of(:hp_tcp_dst_port_range), do: {:be32, :decimal}
+  def format_of(:hp_tcp_flags),          do: {:be16, :tcp_flags}
+  def format_of(:hp_custom_1),           do: {:dynamic, :bytes}
+  def format_of(:hp_custom_2),           do: {:dynamic, :bytes}
+  def format_of(:hp_custom_3),           do: {:dynamic, :bytes}
+  def format_of(:hp_custom_4),           do: {:dynamic, :bytes}
+
   # ONF Ext Match
   def format_of(:onf_tcp_flags),     do: {:be16, :tcp_flags}
   def format_of(:onf_actset_output), do: {:be32, :openflow13_port}
diff --git a/lib/openflow/multipart/aggregate/reply.ex b/lib/openflow/multipart/aggregate/reply.ex
index bcc208f..7bb7beb 100644
--- a/lib/openflow/multipart/aggregate/reply.ex
+++ b/lib/openflow/multipart/aggregate/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Aggregate.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     packet_count: 0,
     byte_count:   0,
diff --git a/lib/openflow/multipart/desc/reply.ex b/lib/openflow/multipart/desc/reply.ex
index db3c818..7794428 100644
--- a/lib/openflow/multipart/desc/reply.ex
+++ b/lib/openflow/multipart/desc/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Desc.Reply do
     version:        4,
     xid:            0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     mfr_desc:     "",
     hw_desc:      "",
diff --git a/lib/openflow/multipart/flow/reply.ex b/lib/openflow/multipart/flow/reply.ex
index 5d41dbc..41941f0 100644
--- a/lib/openflow/multipart/flow/reply.ex
+++ b/lib/openflow/multipart/flow/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Flow.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     flows:        []
   )
@@ -19,6 +20,16 @@ defmodule Openflow.Multipart.Flow.Reply do
     flows = Openflow.Multipart.FlowStats.read(flows_bin)
     %Reply{flows: flows}
   end
+
+  def append_body(%Reply{flows: flows} = message, %Reply{flags: [:more], flows: continue}) do
+    %{message|flows: [continue|flows]}
+  end
+  def append_body(%Reply{flows: flows} = message, %Reply{flags: [], flows: continue}) do
+    new_flows = [continue|flows]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|flows: new_flows}
+  end
 end
 
 defmodule Openflow.Multipart.FlowStats do
diff --git a/lib/openflow/multipart/flow/request.ex b/lib/openflow/multipart/flow/request.ex
index 9485c63..53e8146 100644
--- a/lib/openflow/multipart/flow/request.ex
+++ b/lib/openflow/multipart/flow/request.ex
@@ -16,13 +16,13 @@ defmodule Openflow.Multipart.Flow.Request do
 
   def ofp_type, do: 18
 
-  def new(options) do
+  def new(options \\ []) do
     table_id = Keyword.get(options, :table_id, :all)
     out_port = Keyword.get(options, :out_port, :any)
     out_group = Keyword.get(options, :out_group, :any)
     cookie = Keyword.get(options, :cookie, 0)
     cookie_mask = Keyword.get(options, :cookie, 0)
-    match = Keyword.get(options, :match, [])
+    match = Keyword.get(options, :match, Openflow.Match.new)
     %Request{table_id: table_id,
              out_port: out_port,
              out_group: out_group,
diff --git a/lib/openflow/multipart/group/reply.ex b/lib/openflow/multipart/group/reply.ex
index 8d96406..fc434a0 100644
--- a/lib/openflow/multipart/group/reply.ex
+++ b/lib/openflow/multipart/group/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Group.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     groups:       []
   )
@@ -19,6 +20,16 @@ defmodule Openflow.Multipart.Group.Reply do
     groups = Openflow.Multipart.Group.read(groups_bin)
     %Reply{groups: groups}
   end
+
+  def append_body(%Reply{groups: groups} = message, %Reply{flags: [:more], groups: continue}) do
+    %{message|groups: [continue|groups]}
+  end
+  def append_body(%Reply{groups: groups} = message, %Reply{flags: [], groups: continue}) do
+    new_groups = [continue|groups]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|groups: new_groups}
+  end
 end
 
 defmodule Openflow.Multipart.Group do
diff --git a/lib/openflow/multipart/group_desc/reply.ex b/lib/openflow/multipart/group_desc/reply.ex
index 49bd412..fea5684 100644
--- a/lib/openflow/multipart/group_desc/reply.ex
+++ b/lib/openflow/multipart/group_desc/reply.ex
@@ -19,6 +19,16 @@ defmodule Openflow.Multipart.GroupDesc.Reply do
     groups = Openflow.Multipart.GroupDescStats.read(groups_bin)
     %Reply{groups: groups}
   end
+
+  def append_body(%Reply{groups: groups} = message, %Reply{flags: [:more], groups: continue}) do
+    %{message|groups: [continue|groups]}
+  end
+  def append_body(%Reply{groups: groups} = message, %Reply{flags: [], groups: continue}) do
+    new_groups = [continue|groups]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|groups: new_groups}
+  end
 end
 
 defmodule Openflow.Multipart.GroupDescStats do
diff --git a/lib/openflow/multipart/group_features/reply.ex b/lib/openflow/multipart/group_features/reply.ex
index 498d9ea..495ad83 100644
--- a/lib/openflow/multipart/group_features/reply.ex
+++ b/lib/openflow/multipart/group_features/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.GroupFeatures.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     types:        0,
     capabilities: [],
diff --git a/lib/openflow/multipart/meter/reply.ex b/lib/openflow/multipart/meter/reply.ex
index bafd74f..2aede6e 100644
--- a/lib/openflow/multipart/meter/reply.ex
+++ b/lib/openflow/multipart/meter/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Meter.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     meters:       []
   )
@@ -15,6 +16,16 @@ defmodule Openflow.Multipart.Meter.Reply do
     meters = Openflow.Multipart.Meter.read(meters_bin)
     %Reply{meters: meters}
   end
+
+  def append_body(%Reply{meters: meters} = message, %Reply{flags: [:more], meters: continue}) do
+    %{message|meters: [continue|meters]}
+  end
+  def append_body(%Reply{meters: meters} = message, %Reply{flags: [], meters: continue}) do
+    new_meters = [continue|meters]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|meters: new_meters}
+  end
 end
 
 defmodule Openflow.Multipart.Meter do
diff --git a/lib/openflow/multipart/port_desc/reply.ex b/lib/openflow/multipart/port_desc/reply.ex
new file mode 100644
index 0000000..73e0573
--- /dev/null
+++ b/lib/openflow/multipart/port_desc/reply.ex
@@ -0,0 +1,33 @@
+defmodule Openflow.Multipart.PortDesc.Reply do
+  defstruct(
+    version:      4,
+    xid:          0,
+    datapath_id:  nil, # virtual field
+    aux_id:       nil,
+    flags:        [],
+    ports:        []
+  )
+
+  alias __MODULE__
+
+  def ofp_type, do: 18
+
+  def new(ports \\ []) do
+    %Reply{ports: ports}
+  end
+
+  def read(<<ports_bin::bytes>>) do
+    ports = for (<<port_bin::64-bytes <- ports_bin>>), do: Openflow.Port.read(port_bin)
+    %Reply{ports: Enum.reverse(ports)}
+  end
+
+  def append_body(%Reply{ports: ports} = message, %Reply{flags: [:more], ports: continue}) do
+    %{message|ports: [continue|ports]}
+  end
+  def append_body(%Reply{ports: ports} = message, %Reply{flags: [], ports: continue}) do
+    new_ports = [continue|ports]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|ports: new_ports}
+  end
+end
diff --git a/lib/openflow/multipart/port_desc/request.ex b/lib/openflow/multipart/port_desc/request.ex
new file mode 100644
index 0000000..be0abde
--- /dev/null
+++ b/lib/openflow/multipart/port_desc/request.ex
@@ -0,0 +1,24 @@
+defmodule Openflow.Multipart.PortDesc.Request do
+  defstruct(
+    version:      4,
+    xid:          0,
+    datapath_id:  nil, # virtual field
+    flags: []
+  )
+
+  alias __MODULE__
+
+  def ofp_type, do: 18
+
+  def new do
+    %Request{}
+  end
+
+  def read("") do
+    %Request{}
+  end
+
+  def to_binary(%Request{} = msg) do
+    Openflow.Multipart.Request.header(msg)
+  end
+end
diff --git a/lib/openflow/multipart/port_stats/reply.ex b/lib/openflow/multipart/port_stats/reply.ex
index e51d0a3..e57ed32 100644
--- a/lib/openflow/multipart/port_stats/reply.ex
+++ b/lib/openflow/multipart/port_stats/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.PortStats.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     ports:        []
   )
@@ -19,6 +20,16 @@ defmodule Openflow.Multipart.PortStats.Reply do
     ports = Openflow.Multipart.PortStats.read(ports_bin)
     %Reply{ports: ports}
   end
+
+  def append_body(%Reply{ports: ports} = message, %Reply{flags: [:more], ports: continue}) do
+    %{message|ports: [continue|ports]}
+  end
+  def append_body(%Reply{ports: ports} = message, %Reply{flags: [], ports: continue}) do
+    new_ports = [continue|ports]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|ports: new_ports}
+  end
 end
 
 defmodule Openflow.Multipart.PortStats do
diff --git a/lib/openflow/multipart/queue/reply.ex b/lib/openflow/multipart/queue/reply.ex
index 53d3284..38afbbc 100644
--- a/lib/openflow/multipart/queue/reply.ex
+++ b/lib/openflow/multipart/queue/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Queue.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     queues:       []
   )
@@ -19,6 +20,16 @@ defmodule Openflow.Multipart.Queue.Reply do
     queues = Openflow.Multipart.Queue.read(queues_bin)
     %Reply{queues: queues}
   end
+
+  def append_body(%Reply{queues: queues} = message, %Reply{flags: [:more], queues: continue}) do
+    %{message|queues: [continue|queues]}
+  end
+  def append_body(%Reply{queues: queues} = message, %Reply{flags: [], queues: continue}) do
+    new_queues = [continue|queues]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|queues: new_queues}
+  end
 end
 
 defmodule Openflow.Multipart.Queue do
diff --git a/lib/openflow/multipart/table/reply.ex b/lib/openflow/multipart/table/reply.ex
index 496450b..457de7c 100644
--- a/lib/openflow/multipart/table/reply.ex
+++ b/lib/openflow/multipart/table/reply.ex
@@ -3,6 +3,7 @@ defmodule Openflow.Multipart.Table.Reply do
     version:      4,
     xid:          0,
     datapath_id:  nil, # virtual field
+    aux_id:       nil,
     flags:        [],
     tables:       []
   )
@@ -15,6 +16,16 @@ defmodule Openflow.Multipart.Table.Reply do
     tables = Openflow.Multipart.TableStats.read(tables_bin)
     %Reply{tables: tables}
   end
+
+  def append_body(%Reply{tables: tables} = message, %Reply{flags: [:more], tables: continue}) do
+    %{message|tables: [continue|tables]}
+  end
+  def append_body(%Reply{tables: tables} = message, %Reply{flags: [], tables: continue}) do
+    new_tables = [continue|tables]
+    |> Enum.reverse
+    |> List.flatten
+    %{message|tables: new_tables}
+  end
 end
 
 defmodule Openflow.Multipart.TableStats do
diff --git a/lib/openflow/nx_packet_in2.ex b/lib/openflow/nx_packet_in2.ex
index 1ba67e0..dfa8b34 100644
--- a/lib/openflow/nx_packet_in2.ex
+++ b/lib/openflow/nx_packet_in2.ex
@@ -13,14 +13,13 @@ defmodule Openflow.NxPacketIn2 do
     reason:       nil,
     metadata:     nil,
     userdata:     nil,
-    continuation: nil,
     # continuation properties:
-    continuation_bridge:      nil,
-    continuation_stack:       nil,
-    continuation_conntracked: nil,
+    continuation_bridge:      "",
+    continuation_stack:       [],
+    continuation_conntracked: false,
     continuation_table_id:    nil,
     continuation_cookie:      nil,
-    continuation_actions:     nil,
+    continuation_actions:     [],
     continuation_action_set:  nil
   )
 
@@ -29,6 +28,138 @@ defmodule Openflow.NxPacketIn2 do
   @experimenter 0x00002320
   @nx_type 30
 
+  @packet       0
+  @full_len     1
+  @buffer_id    2
+  @table_id     3
+  @cookie       4
+  @reason       5
+  @metadata     6
+  @userdata     7
+  @continuation 8
+
+  @nxcpt_bridge      0x8000
+  @nxcpt_stack       0x8001
+  @nxcpt_mirrors     0x8002
+  @nxcpt_conntracked 0x8003
+  @nxcpt_table_id    0x8004
+  @nxcpt_cookie      0x8005
+  @nxcpt_actions     0x8006
+  @nxcpt_action_set  0x8007
+
+  @prop_header_length 4
+
   def ofp_type, do: 4
 
+  def read(<<@experimenter::32, @nx_type::32, props_bin::bytes>>) do
+    %NxPacketIn2{}
+    |> decode_props(props_bin)
+  end
+
+  ## private functions
+
+  defp decode_props(pktin, ""), do: pktin
+  defp decode_props(pktin, <<@packet::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    packet_length = length - @prop_header_length
+    <<packet::size(packet_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_props(%{pktin|packet: packet}, rest)
+  end
+  defp decode_props(pktin, <<@full_len::16, _length::16, full_len::32, rest::bytes>>) do
+    decode_props(%{pktin|full_len: full_len}, rest)
+  end
+  defp decode_props(pktin, <<@buffer_id::16, _length::16, buffer_id::32, rest::bytes>>) do
+    decode_props(%{pktin|buffer_id: buffer_id}, rest)
+  end
+  defp decode_props(pktin, <<@table_id::16, _length::16, table_id::8, _::24, rest::bytes>>) do
+     decode_props(%{pktin|table_id: table_id}, rest)
+  end
+  defp decode_props(pktin, <<@cookie::16, _length::16, _::32, cookie::64, rest::bytes>>) do
+    decode_props(%{pktin|cookie: cookie}, rest)
+  end
+  defp decode_props(pktin, <<@reason::16, _length::16, reason_int::8, _::24, rest::bytes>>) do
+    reason = Openflow.Enums.to_atom(reason_int, :packet_in_reason)
+    decode_props(%{pktin|reason: reason}, rest)
+  end
+  defp decode_props(pktin, <<@metadata::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    match_field_length = length - @prop_header_length
+    <<match_fields_bin::size(match_field_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    match_len = 4 + byte_size(match_fields_bin)
+    padding = Openflow.Utils.pad_length(match_len, 8)
+    match_bin = (<<1::16, match_len::16, match_fields_bin::bytes, 0::size(padding)-unit(8)>>)
+    {fields, _rest} = Openflow.Match.read(match_bin)
+    decode_props(%{pktin|metadata: fields}, rest)
+  end
+  defp decode_props(pktin, <<@userdata::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    userdata_length = length - @prop_header_length
+    <<userdata::size(userdata_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_props(%{pktin|userdata: userdata}, rest)
+  end
+  defp decode_props(pktin, <<@continuation::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length - 4
+    <<_pad::32, data::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    pktin
+    |> decode_continuations(data)
+    |> decode_props(rest)
+  end
+  defp decode_props(pktin, <<_::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length
+    <<_data::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_props(pktin, rest)
+  end
+
+  defp decode_continuations(pktin, ""), do: pktin
+  defp decode_continuations(pktin, <<@nxcpt_bridge::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length
+    <<bridge::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_bridge: bridge}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_stack::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = (length - @prop_header_length) * 8
+    <<stack::size(data_length), _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_stack: pktin.continuation_stack ++ [stack]}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_mirrors::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length
+    <<mirrors::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_mirrors: mirrors}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_conntracked::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length
+    <<_::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_conntracked: true}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_table_id::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    <<table_id::8, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_table_id: table_id}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_cookie::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    <<cookie::64, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_cookie: cookie}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_actions::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length - 4
+    <<_pad::32, actions::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_actions: Openflow.Action.read(actions)}, rest)
+  end
+  defp decode_continuations(pktin, <<@nxcpt_action_set::16, length::16, tail::bytes>>) do
+    pad_length = Openflow.Utils.pad_length(length, 8)
+    data_length = length - @prop_header_length
+    <<action_set::size(data_length)-bytes, _::size(pad_length)-unit(8), rest::bytes>> = tail
+    decode_continuations(%{pktin|continuation_action_set: action_set}, rest)
+  end
+  defp decode_continuations(pktin, _) do
+    decode_continuations(pktin, "")
+  end
 end
diff --git a/lib/tres/application.ex b/lib/tres/application.ex
index 5dc3b16..3186d9d 100644
--- a/lib/tres/application.ex
+++ b/lib/tres/application.ex
@@ -8,8 +8,9 @@ defmodule Tres.Application do
   def start(_type, _args) do
     import Supervisor.Spec
 
+    {cb_mod, _cb_args} = Tres.Utils.get_callback_module
     children = [worker(Registry, [[keys: :unique, name: SwitchRegistry]], id: SwitchRegistry),
-                supervisor(Tres.MessageHandlerSup, [], id: MessageHandlerSup)]
+                supervisor(Tres.MessageHandlerSup, [cb_mod], id: MessageHandlerSup)]
     opts = [strategy: :one_for_one, name: Tres.Supervisor]
     {:ok, _connection_pid} = Tres.Utils.start_openflow_listener
     Supervisor.start_link(children, opts)
diff --git a/lib/tres/controller.ex b/lib/tres/controller.ex
new file mode 100644
index 0000000..c9e0a38
--- /dev/null
+++ b/lib/tres/controller.ex
@@ -0,0 +1,14 @@
+defmodule Tres.Controller do
+  def controller_helpers do
+    quote do
+      import Tres.SwitchRegistry, only: [send_message: 2]
+
+      use Tres.Messages
+      use Tres.MessageHelper
+    end
+  end
+
+  defmacro __using__(_) do
+    controller_helpers()
+  end
+end
diff --git a/lib/tres/example_handler.ex b/lib/tres/example_handler.ex
new file mode 100644
index 0000000..deaf722
--- /dev/null
+++ b/lib/tres/example_handler.ex
@@ -0,0 +1,108 @@
+defmodule Tres.ExampleHandler do
+  use GenServer
+  use Tres.Controller
+
+  import Logger
+
+  defmodule State do
+    defstruct [
+      datapath_id: nil,
+      aux_id:      nil,
+      conn_ref:    nil
+    ]
+  end
+
+  def start_link(datapath, args) do
+    GenServer.start_link(__MODULE__, [datapath, args])
+  end
+
+  def init([{datapath_id, aux_id}, _args]) do
+    info("[#{__MODULE__}] Switch Ready: "
+      <> "datapath_id: #{datapath_id} "
+      <> "aux_id: #{aux_id} "
+      <> "in #{inspect(self())}")
+    _ = send_flows_for_test(datapath_id)
+    _ = send_flow_stats_request(datapath_id)
+    _ = send_desc_stats_request(datapath_id)
+    _ = send_port_desc_stats_request(datapath_id)
+    conn_ref = SwitchRegistry.monitor(datapath_id)
+    state = %State{datapath_id: datapath_id, aux_id: aux_id, conn_ref: conn_ref}
+    {:ok, state}
+  end
+
+  def handle_info(%Flow.Reply{datapath_id: datapath_id} = desc, state) do
+    handle_flow_stats_reply(desc, datapath_id)
+    {:noreply, state}
+  end
+  def handle_info(%PortDesc.Reply{datapath_id: datapath_id} = desc, state) do
+    handle_port_desc_stats_reply(desc, datapath_id)
+    {:noreply, state}
+  end
+  def handle_info(%Desc.Reply{datapath_id: datapath_id} = desc, state) do
+    handle_desc_stats_reply(desc, datapath_id)
+    {:noreply, state}
+  end
+
+  # To prevent process leakage, following section is required.
+  def handle_info({:'DOWN', ref, :process, _pid, _reason}, %State{conn_ref: ref} = state) do
+    :ok = warn("[#{__MODULE__}] Switch Disconnected: datapath_id: #{state.datapath_id}")
+    {:stop, :normal, state}
+  end
+
+  # `Catch all` function is required.
+  def handle_info(info, state) do
+    :ok = warn("[#{__MODULE__}] unhandled message #{inspect(info)}: #{state.datapath_id}")
+    {:noreply, state}
+  end
+
+  # private functions
+
+  defp send_flows_for_test(datapath_id) do
+    for count <- Range.new(1, 1024) do
+      send_flow_mod_add(datapath_id, match: Match.new(metadata: count))
+    end
+  end
+
+  defp send_flow_stats_request(datapath_id) do
+    Flow.Request.new
+    |> send_message(datapath_id)
+  end
+
+  defp send_desc_stats_request(datapath_id) do
+    Desc.Request.new
+    |> send_message(datapath_id)
+  end
+
+  defp send_port_desc_stats_request(datapath_id) do
+    PortDesc.Request.new
+    |> send_message(datapath_id)
+  end
+
+  defp handle_flow_stats_reply(desc, datapath_id) do
+    info("[#{__MODULE__}] Switch #{length(desc.flows)} installed on #{datapath_id}")
+  end
+
+  defp handle_desc_stats_reply(desc, datapath_id) do
+    info(
+      "[#{__MODULE__}] Switch Desc: "
+      <> "mfr = #{desc.mfr_desc} "
+      <> "hw = #{desc.hw_desc} "
+      <> "sw = #{desc.sw_desc} "
+      <> "for #{datapath_id}"
+    )
+  end
+
+  defp handle_port_desc_stats_reply(port_desc, datapath_id) do
+    for port <- port_desc.ports do
+      info(
+        "[#{__MODULE__}] Switch has port: "
+        <> "number = #{port.number} "
+        <> "hw_addr = #{port.hw_addr} "
+        <> "name = #{port.name} "
+        <> "config = #{inspect(port.config)} "
+        <> "current_speed = #{port.current_speed} "
+        <> "on #{datapath_id}"
+      )
+    end
+  end
+end
diff --git a/lib/tres/message_handler.ex b/lib/tres/message_handler.ex
deleted file mode 100644
index 7f01ed8..0000000
--- a/lib/tres/message_handler.ex
+++ /dev/null
@@ -1,52 +0,0 @@
-defmodule Tres.MessageHandler do
-  use GenServer
-
-  defmodule State do
-    defstruct [
-      ip_addr:     nil,
-      port:        nil,
-      datapath_id: nil,
-      conn_pid:    nil,
-      conn_ref:    nil,
-      handler_pid: nil,
-      handler_ref: nil
-    ]
-  end
-
-  alias Tres.MessageHandler.State
-
-  @process_flags [trap_exit: true]
-
-  def start_link({ip_addr, port}, conn_pid) do
-    GenServer.start_link(__MODULE__, [{ip_addr, port}, conn_pid])
-  end
-
-  def init([{ip_addr, port}, conn_pid]) do
-    init_process()
-    conn_ref = Process.monitor(conn_pid)
-    state = %State{
-      conn_pid: conn_pid,
-      conn_ref: conn_ref,
-      ip_addr:  ip_addr,
-      port:     port
-    }
-    {:ok, state}
-  end
-
-  def handle_info({:'EXIT', _pid, _reason}, state) do
-    {:stop, :normal, state}
-  end
-  def handle_info({:'DOWN', conn_ref, :process, _conn_pid, _reason}, %State{conn_ref: conn_ref} = state) do
-    {:stop, :normal, state}
-  end
-
-  def terminate(_reason, state) do
-    {:shutdown, state}
-  end
-
-  ## private functions
-
-  defp init_process do
-    for {flag, value} <- @process_flags, do: Process.flag(flag, value)
-  end
-end
diff --git a/lib/tres/message_handler_sup.ex b/lib/tres/message_handler_sup.ex
index ca6d393..9c250f6 100644
--- a/lib/tres/message_handler_sup.ex
+++ b/lib/tres/message_handler_sup.ex
@@ -1,16 +1,17 @@
 defmodule Tres.MessageHandlerSup do
   use Supervisor
 
-  def start_link do
-    Supervisor.start_link(__MODULE__, [], name: __MODULE__)
+  def start_link(cb_mod) do
+    Supervisor.start_link(__MODULE__, [cb_mod], name: __MODULE__)
   end
 
-  def init(_) do
-    children = [worker(Tres.MessageHandler, [], restart: :temporary)]
+  def init([cb_mod]) do
+    children = [worker(cb_mod, [], restart: :temporary, shutdown: 5000)]
     supervise(children, strategy: :simple_one_for_one)
   end
 
-  def start_child({ip_addr, port}) do
-    Supervisor.start_child(__MODULE__, [{ip_addr, port}, self()])
+  def start_child({dpid, aux_id}) do
+    {_cb_mod, cb_args} = Tres.Utils.get_callback_module
+    Supervisor.start_child(__MODULE__, [{dpid, aux_id}, cb_args])
   end
 end
diff --git a/lib/tres/message_helper.ex b/lib/tres/message_helper.ex
new file mode 100644
index 0000000..8080d5b
--- /dev/null
+++ b/lib/tres/message_helper.ex
@@ -0,0 +1,88 @@
+defmodule Tres.MessageHelper do
+  defmacro __using__(_) do
+    quote location: :keep do
+      defp send_flow_mod_add(datapath_id, options) do
+        flow_mod = %Openflow.FlowMod{
+          cookie:   options[:cookie] || 0,
+          priority: options[:priority] || 0,
+          table_id: options[:table_id] || 0,
+          command: :add,
+          idle_timeout: options[:idle_timeout] || 0,
+          hard_timeout: options[:hard_timeout] || 0,
+          buffer_id: :no_buffer,
+          out_port: :any,
+          out_group:  :any,
+          flags: options[:flags] || [],
+          match: options[:match] || Openflow.Match.new,
+          instructions: options[:instructions] || [],
+        }
+        send_message(flow_mod, datapath_id)
+      end
+
+      defp send_flow_mod_modify(datapath_id, options) do
+        command = Tres.Utils.flow_command(options, :modify)
+        flow_mod = %Openflow.FlowMod{
+          cookie:   options[:cookie] || 0,
+          table_id: options[:table_id] || 0,
+          command: command,
+          idle_timeout: options[:idle_timeout] || 0,
+          hard_timeout: options[:hard_timeout] || 0,
+          out_port: :any,
+          out_group: :any,
+          match: options[:match] || Openflow.Match.new,
+          instructions: options[:instructions] || [],
+        }
+        send_message(flow_mod, datapath_id)
+      end
+
+      defp send_flow_mod_delete(datapath_id, options) do
+        command = Tres.Utils.flow_command(options, :delete)
+        flow_mod = %Openflow.FlowMod{
+          cookie:   options[:cookie] || 0,
+          cookie_mask: options[:cookie_mask] || 0,
+          table_id: options[:table_id] || :all,
+          command: command,
+          out_port: options[:out_port] || :any,
+          out_group: options[:out_group] || :any,
+          match: options[:match] || Openflow.Match.new
+        }
+        send_message(flow_mod, datapath_id)
+      end
+
+      defp send_packet_out(datapath_id, options) do
+        packet_out = %Openflow.PacketOut{
+          buffer_id: options[:buffer_id] || :no_buffer,
+          in_port: options[:in_port] || :controller,
+          actions: options[:actions] || [],
+          data: options[:data] || ""
+        }
+        send_message(packet_out, datapath_id)
+      end
+
+      defp send_group_mod_add(datapath_id, options) do
+        group_mod = Openflow.GroupMod.new(
+          command: :add,
+          type: options[:type] || :all,
+          group_id: options[:group_id] || 0,
+          buckets: options[:buckets] || []
+        )
+        send_message(group_mod, datapath_id)
+      end
+
+      defp send_group_mod_delete(datapath_id, group_id) do
+        group_mod = Openflow.GroupMod.new(command: :delete, group_id: group_id)
+        send_message(group_mod, datapath_id)
+      end
+
+      defp send_group_mod_modify(datapath_id, options) do
+        group_mod = Openflow.GroupMod.new(
+          command: :modify,
+          type: options[:type] || :all,
+          group_id: options[:group_id] || 0,
+          buckets: options[:buckets] || []
+        )
+        send_message(group_mod, datapath_id)
+      end
+    end
+  end
+end
diff --git a/lib/tres/messages.ex b/lib/tres/messages.ex
new file mode 100644
index 0000000..04810a2
--- /dev/null
+++ b/lib/tres/messages.ex
@@ -0,0 +1,128 @@
+defmodule Tres.Messages do
+  defmacro __using__(_) do
+    quote do
+      alias Openflow.ErrorMsg
+      alias Openflow.Echo
+      alias Openflow.Features
+      alias Openflow.GetConfig
+      alias Openflow.SetConfig
+      alias Openflow.PacketIn
+      alias Openflow.FlowRemoved
+      alias Openflow.PortStatus
+      alias Openflow.PacketOut
+      alias Openflow.FlowMod
+      alias Openflow.GroupMod
+      alias Openflow.PortMod
+      alias Openflow.TableMod
+      alias Openflow.Multipart
+      alias Openflow.Barrier
+      alias Openflow.Role
+      alias Openflow.GetAsync
+      alias Openflow.SetAsync
+      alias Openflow.MeterMod
+
+      alias Openflow.Match
+      alias Openflow.Port
+
+      alias Openflow.NxSetPacketInFormat
+      alias Openflow.NxSetControllerId
+      alias Openflow.NxPacketIn2
+
+      alias Openflow.Multipart.Desc
+      alias Openflow.Multipart.Flow
+      alias Openflow.Multipart.Aggregate
+      alias Openflow.Multipart.Table
+      alias Openflow.Multipart.PortStats
+      alias Openflow.Multipart.Queue
+      alias Openflow.Multipart.Group
+      alias Openflow.Multipart.GroupDesc
+      alias Openflow.Multipart.GroupFeatures
+      alias Openflow.Multipart.Meter
+      alias Openflow.Multipart.MeterConfig
+      alias Openflow.Multipart.MeterFeatures
+      alias Openflow.Multipart.TableFeatures
+      alias Openflow.Multipart.PortDesc
+
+      alias Openflow.Instruction.GotoTable
+      alias Openflow.Instruction.WriteMetadata
+      alias Openflow.Instruction.WriteActions
+      alias Openflow.Instruction.ApplyActions
+      alias Openflow.Instruction.ClearActions
+      alias Openflow.Instruction.Meter
+
+      alias Openflow.Action.Output
+      alias Openflow.Action.CopyTtlOut
+      alias Openflow.Action.CopyTtlIn
+      alias Openflow.Action.SetMplsTtl
+      alias Openflow.Action.DecMplsTtl
+      alias Openflow.Action.PushVlan
+      alias Openflow.Action.PopVlan
+      alias Openflow.Action.PushMpls
+      alias Openflow.Action.PopMpls
+      alias Openflow.Action.SetQueue
+      alias Openflow.Action.Group
+      alias Openflow.Action.SetNwTtl
+      alias Openflow.Action.DecNwTtl
+      alias Openflow.Action.SetField
+      alias Openflow.Action.PushPbb
+      alias Openflow.Action.PopPbb
+      alias Openflow.Action.Encap
+      alias Openflow.Action.Decap
+      alias Openflow.Action.SetSequence
+      alias Openflow.Action.ValidateSequence
+
+      alias Openflow.Action.NxResubmit
+      alias Openflow.Action.NxSetTunnel
+      alias Openflow.Action.NxSetQueue
+      alias Openflow.Action.NxPopQueue
+      alias Openflow.Action.NxRegMove
+      alias Openflow.Action.NxRegLoad
+      alias Openflow.Action.NxNote
+      alias Openflow.Action.NxSetTunnel64
+      alias Openflow.Action.NxMultipath
+      alias Openflow.Action.NxBundle
+      alias Openflow.Action.NxBundleLoad
+      alias Openflow.Action.NxResubmitTable
+      alias Openflow.Action.NxOutputReg
+      alias Openflow.Action.NxLearn
+      alias Openflow.Action.NxExit
+      alias Openflow.Action.NxDecTtl
+      alias Openflow.Action.NxFinTimeout
+      alias Openflow.Action.NxController
+      alias Openflow.Action.NxDecTtlCntIds
+      alias Openflow.Action.NxWriteMetadata
+      alias Openflow.Action.NxPushMpls
+      alias Openflow.Action.NxPopMpls
+      alias Openflow.Action.NxSetMplsTtl
+      alias Openflow.Action.NxDecMplsTtl
+      alias Openflow.Action.NxStackPush
+      alias Openflow.Action.NxStackPop
+      alias Openflow.Action.NxSample
+      alias Openflow.Action.NxSetMplsLabel
+      alias Openflow.Action.NxSetMplsTc
+      alias Openflow.Action.NxOutputReg2
+      alias Openflow.Action.NxRegLoad2
+      alias Openflow.Action.NxConjunction
+      alias Openflow.Action.NxConntrack
+      alias Openflow.Action.NxNat
+      alias Openflow.Action.NxController2
+      alias Openflow.Action.NxSample2
+      alias Openflow.Action.NxOutputTrunc
+      alias Openflow.Action.NxGroup
+      alias Openflow.Action.NxSample3
+      alias Openflow.Action.NxClone
+      alias Openflow.Action.NxCtClear
+      alias Openflow.Action.NxResubmitTableCt
+      alias Openflow.Action.NxLearn2
+      alias Openflow.Action.NxEncap
+      alias Openflow.Action.NxDecap
+      alias Openflow.Action.NxDebugRecirc
+
+      alias Openflow.Action.NxFlowSpecMatch
+      alias Openflow.Action.NxFlowSpecLoad
+      alias Openflow.Action.NxFlowSpecOutput
+
+      alias Tres.SwitchRegistry
+    end
+  end
+end
diff --git a/lib/tres/secure_channel.ex b/lib/tres/secure_channel.ex
index 013e731..187b693 100644
--- a/lib/tres/secure_channel.ex
+++ b/lib/tres/secure_channel.ex
@@ -3,6 +3,7 @@ defmodule Tres.SecureChannel do
 
   import Logger
 
+  alias :tres_xact_kv, as: XACT_KV
   alias Tres.SecureChannelState
   alias Tres.SwitchRegistry
   alias Tres.MessageHandlerSup
@@ -32,12 +33,11 @@ defmodule Tres.SecureChannel do
   end
 
   def init([ref, socket, transport, _opts]) do
-    state_data =
-      ref
-      |> init_secure_channel(socket, transport)
-      |> init_handler
-    info("[#{__MODULE__}] TCP connected to Switch on #{state_data.ip_addr}:#{state_data.port} on #{inspect(self())}")
-    :gen_statem.enter_loop(__MODULE__, [debug: []], :INIT, state_data, [])
+    state_data = init_secure_channel(ref, socket, transport)
+    debug("[#{__MODULE__}] TCP connected to Switch on"
+      <> " #{state_data.ip_addr}:#{state_data.port}"
+      <> " on #{inspect(self())}")
+    :gen_statem.enter_loop(__MODULE__, [debug: [:debug]], :INIT, state_data, [])
   end
 
   # TCP handler
@@ -73,8 +73,9 @@ defmodule Tres.SecureChannel do
     handle_WATING(type, message, state_data)
   end
 
-  def terminate(reason, state, %SecureChannelState{datapath_id: datapath_id, aux_id: aux_id}) do
+  def terminate(reason, state, %SecureChannelState{datapath_id: datapath_id, aux_id: aux_id, xact_kv_ref: kv_ref}) do
     warn("[#{__MODULE__}] termiate: #{inspect(reason)} state = #{inspect(state)}")
+    true = XACT_KV.drop(kv_ref)
     :ok = SwitchRegistry.unregister({datapath_id, aux_id})
   end
 
@@ -83,7 +84,8 @@ defmodule Tres.SecureChannel do
   defp init_secure_channel(ref, socket, transport) do
     init_process(ref)
     :ok = transport.setopts(socket, [active: :once])
-    SecureChannelState.new(ref: ref, socket: socket, transport: transport)
+    kv_ref = XACT_KV.create
+    SecureChannelState.new(ref: ref, socket: socket, transport: transport, xact_kv_ref: kv_ref)
   end
 
   defp init_process(ref) do
@@ -93,8 +95,8 @@ defmodule Tres.SecureChannel do
   end
 
   defp init_handler(state_data) do
-    %SecureChannelState{ip_addr: ip_addr, port: port} = state_data
-    {:ok, pid} = MessageHandlerSup.start_child({ip_addr, port})
+    %SecureChannelState{datapath_id: dpid, aux_id: aux_id} = state_data
+    {:ok, pid} = MessageHandlerSup.start_child({dpid, aux_id})
     ref = Process.monitor(pid)
     %{state_data|handler_pid: pid, handler_ref: ref}
   end
@@ -128,8 +130,7 @@ defmodule Tres.SecureChannel do
     close_connection(:features_handshake_timeout, state_data)
   end
   defp handle_CONNECTING(:internal, {:openflow, %Openflow.Features.Reply{} = features}, state_data) do
-    # TODO: Send to handler
-    info("[#{__MODULE__}] Switch connected datapath_id: #{features.datapath_id} auxiliary_id: #{features.aux_id}")
+    debug("[#{__MODULE__}] Switch connected datapath_id: #{features.datapath_id} auxiliary_id: #{features.aux_id}")
     _ = maybe_cancel_timer(state_data.timer_ref)
     handle_features_handshake(features, state_data)
   end
@@ -142,9 +143,10 @@ defmodule Tres.SecureChannel do
   end
 
   # CONNECTED state
-  defp handle_CONNECTED(:enter, :CONNECTING, _state_data) do
+  defp handle_CONNECTED(:enter, :CONNECTING, state_data) do
+    new_state_data = init_handler(state_data)
     start_periodic_idle_check()
-    :keep_state_and_data
+    {:keep_state, new_state_data}
   end
   defp handle_CONNECTED(:info, :idle_check, state_data) do
     start_periodic_idle_check()
@@ -162,19 +164,48 @@ defmodule Tres.SecureChannel do
     send_echo_reply(echo.xid, echo.data, state_data)
     :keep_state_and_data
   end
-  defp handle_CONNECTED(:internal, {:openflow, _message}, _state_data) do
-    # TODO: Send to handler
+  defp handle_CONNECTED(:internal, {:openflow, %Openflow.Barrier.Reply{xid: xid}}, state_data) do
+    for {:xact_entry, _xid, message, _orig} <- XACT_KV.get(state_data.xact_kv_ref, xid) do
+      unless is_nil(message) do
+        send(state_data.handler_pid, message)
+        XACT_KV.delete(state_data.xact_kv_ref, message.xid)
+      end
+    end
+    :keep_state_and_data
+  end
+  defp handle_CONNECTED(:internal, {:openflow, message}, state_data) do
+    %SecureChannelState{datapath_id: dpid, aux_id: aux_id} = state_data
+    new_message = %{message|datapath_id: dpid, aux_id: aux_id}
+    state_data.xact_kv_ref
+    |> XACT_KV.is_exists(message.xid)
+    |> handle_message(new_message, state_data)
     :keep_state_and_data
   end
   defp handle_CONNECTED(:cast, {:send_message, message}, state_data) do
-    message
-    |> send_message(state_data)
+    xid = SecureChannelState.increment_transaction_id(state_data.xid)
+    messages = [
+      %{message|xid: xid},
+      %{Openflow.Barrier.Request.new|xid: xid}
+    ]
+    XACT_KV.insert(state_data.xact_kv_ref, xid, message)
+    send_message(messages, state_data)
     :keep_state_and_data
   end
 
+  defp handle_message(_in_xact = true, message, state_data) do
+    [{:xact_entry, _xid, prev_message, _orig}|_] = XACT_KV.get(state_data.xact_kv_ref, message.xid)
+    new_message = Openflow.append_body(prev_message, message)
+    XACT_KV.update(state_data.xact_kv_ref, message.xid, new_message)
+  end
+  defp handle_message(_in_xact = false, message, %SecureChannelState{handler_pid: handler_pid}) do
+    send(handler_pid, message)
+  end
+
   # WATING state
   defp handle_WATING(:enter, :CONNECTING, state_data) do
     warn("[#{__MODULE__}] Possible HANG Detected on datapath_id: #{state_data.datapath_id} !")
+    %SecureChannelState{handler_pid: handler_pid, datapath_id: dpid, aux_id: aux_id} = state_data
+    send(handler_pid, {:switch_hang, {dpid, aux_id}})
     start_periodic_idle_check()
     :keep_state_and_data
   end
@@ -186,8 +217,9 @@ defmodule Tres.SecureChannel do
   defp handle_WATING(:info, :ping_timeout, state_data) do
     handle_ping_timeout(state_data, :WAITING)
   end
-  defp handle_WATING(:internal, {:openflow, _message}, state_data) do
-    # TODO: Send to handler
+  defp handle_WATING(:internal, {:openflow, message}, state_data) do
+    %SecureChannelState{handler_pid: handler_pid, datapath_id: dpid, aux_id: aux_id} = state_data
+    send(handler_pid, %{message|datapath_id: dpid, aux_id: aux_id})
     {:next_state, :CONNECTING, state_data}
   end
   defp handle_WATING(type, message, state_data)
@@ -249,12 +281,10 @@ defmodule Tres.SecureChannel do
     {:next_state, :CONNECTED, new_state_data}
   end
 
-  defp monitor_connection(datapath_id, aux_id) when aux_id > 0 do
-    datapath_id
-    |> SwitchRegistry.lookup_pid
-    |> Process.monitor
-  end
-  defp monitor_connection(_datapath_id, _aux_id), do: nil
+  defp monitor_connection(datapath_id, aux_id) when aux_id > 0,
+    do: SwitchRegistry.monitor(datapath_id)
+  defp monitor_connection(_datapath_id, _aux_id),
+    do: nil
 
   defp send_hello(state_data) do
     @supported_version
@@ -320,7 +350,7 @@ defmodule Tres.SecureChannel do
   end
 
   defp send_message(message, %SecureChannelState{socket: socket, transport: transport}) do
-    debug("[#{__MODULE__}] Sending: #{inspect(message.__struct__)}(xid: #{message.xid})")
+    #debug("[#{__MODULE__}] Sending: #{inspect(message.__struct__)}(xid: #{message.xid})")
     Tres.Utils.send_message(message, socket, transport)
   end
 
@@ -371,7 +401,7 @@ defmodule Tres.SecureChannel do
     {:stop, :normal, %{state_data|socket: nil}}
   end
   defp close_connection({:trap_detected, reason}, state_data) do
-    warn("[#{__MODULE__}] connection terminated: Handler process down by #{reason}")
+    warn("[#{__MODULE__}] connection terminated: Trapped by #{reason}")
     {:stop, :normal, %{state_data|socket: nil}}
   end
   defp close_connection(:tcp_closed, state_data) do
diff --git a/lib/tres/secure_channel_state.ex b/lib/tres/secure_channel_state.ex
index f2c163d..e3f8873 100644
--- a/lib/tres/secure_channel_state.ex
+++ b/lib/tres/secure_channel_state.ex
@@ -16,10 +16,12 @@ defmodule Tres.SecureChannelState do
     ping_xid:             0,
     ping_timer_ref:       nil,
     ping_fail_count:      0,
-    last_received:        0
+    last_received:        0,
+    xact_kv_ref:          nil
   )
 
   alias __MODULE__
+  alias :tres_xact_kv, as: XACT_KV
 
   def new(options) do
     ref = Keyword.get(options, :ref)
@@ -27,13 +29,15 @@ defmodule Tres.SecureChannelState do
     transport = Keyword.get(options, :transport)
     {:ok, {ip_addr, port}} = :inet.peername(socket)
     {:ok, xid_agent} = Agent.start_link(fn -> 0 end)
+    kv_ref = XACT_KV.create
     %SecureChannelState{
       ref:       ref,
       socket:    socket,
       transport: transport,
       ip_addr:   :inet.ntoa(ip_addr),
       port:      port,
-      xid:       xid_agent
+      xid:       xid_agent,
+      xact_kv_ref: kv_ref
     }
   end
 
diff --git a/lib/tres/switch_registry.ex b/lib/tres/switch_registry.ex
index f7b8a19..1145ee3 100644
--- a/lib/tres/switch_registry.ex
+++ b/lib/tres/switch_registry.ex
@@ -24,6 +24,12 @@ defmodule Tres.SwitchRegistry do
     send_message(message, {dpid, 0})
   end
 
+  def monitor(datapath_id) do
+    datapath_id
+    |> lookup_pid
+    |> Process.monitor
+  end
+
   # private function
 
   defp dispatch(entries, message) do
diff --git a/lib/tres/utils.ex b/lib/tres/utils.ex
index 358e44f..b99f3a1 100644
--- a/lib/tres/utils.ex
+++ b/lib/tres/utils.ex
@@ -6,10 +6,16 @@ defmodule Tres.Utils do
   @default_num_acceptors   10
   @default_openflow_port   6633
 
+  def get_callback_module do
+    cb_mod = get_config(:callback_module, Tres.ExampleHandler)
+    cb_args = get_config(:callback_args, [])
+    {cb_mod, cb_args}
+  end
+
   def start_openflow_listener do
-    max_connections = Application.get_env(:tres, :max_connections, @default_max_connections)
-    num_acceptors = Application.get_env(:tres, :num_acceptors, @default_num_acceptors)
-    port = Application.get_env(:tres, :port, @default_openflow_port)
+    max_connections = get_config(:max_connections, @default_max_connections)
+    num_acceptors = get_config(:num_acceptors, @default_num_acceptors)
+    port = get_config(:port, @default_openflow_port)
     options = [max_connections: max_connections, num_acceptors: num_acceptors, port: port]
     :ranch.start_listener(Tres, :ranch_tcp, options, @connection_manager, [])
   end
@@ -23,4 +29,31 @@ defmodule Tres.Utils do
         error("[#{__MODULE__}] Unencodable error: #{inspect(message)}")
     end
   end
+
+  def is_multipart?(message) do
+    message.__struct__
+    |> Module.split
+    |> Enum.at(1)
+    |> String.match?(~r/Multipart/)
+  end
+
+  def flow_command(:delete, options) do
+    if Keyword.get(options, :strict, false) do
+      :delete_strict
+    else
+      :delete
+    end
+  end
+  def flow_command(:modify, options) do
+    if Keyword.get(options, :strict, false) do
+      :modify_strict
+    else
+      :modify
+    end
+  end
+
+  # private functions
+  defp get_config(item, default) do
+    Application.get_env(:tres, item, default)
+  end
 end
diff --git a/mix.exs b/mix.exs
index 7a68614..8aa92e7 100644
--- a/mix.exs
+++ b/mix.exs
@@ -6,6 +6,7 @@ defmodule Tres.Mixfile do
      version: "0.1.0",
      elixir: "~> 1.5",
      start_permanent: Mix.env == :prod,
+     compilers: [:erlang] ++ Mix.compilers,
      deps: deps()]
   end
 
diff --git a/src/tres_xact_kv.erl b/src/tres_xact_kv.erl
new file mode 100644
index 0000000..6e41e90
--- /dev/null
+++ b/src/tres_xact_kv.erl
@@ -0,0 +1,61 @@
+-module(tres_xact_kv).
+
+-include_lib("stdlib/include/ms_transform.hrl").
+
+-export([create/0, drop/1]).
+-export([insert/3, update/3, get/2, delete/2, is_exists/2]).
+
+-define(TABLE, xact_kv).
+-define(ENTRY, xact_entry).
+-define(TABLE_OPTS, [set, protected, {keypos, #?ENTRY.xid}]).
+
+-record(?ENTRY, {xid = 0, pending = nil, orig = nil}).
+
+-spec create() -> reference().
+create() ->
+    ets:new(?TABLE, ?TABLE_OPTS).
+
+-spec drop(reference()) -> true.
+drop(Tid) ->
+    ets:delete(Tid).
+
+-spec insert(reference(), integer(), map()) -> true.
+insert(Tid, Xid, Orig) ->
+    ets:insert(Tid, #?ENTRY{xid = Xid, orig = Orig}).
+
+-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));
+update(Tid, Xid, Msg) ->
+    ets:select_replace(Tid, ms_for_update(Xid, Msg)).
+
+-spec get(reference(), integer()) -> [term()].
+get(Tid, Xid) ->
+    ets:select(Tid, ms_for_get(Xid)).
+
+-spec delete(reference(), integer()) -> integer().
+delete(Tid, Xid) ->
+    ets:select_delete(Tid, ms_for_exists(Xid)).
+
+-spec is_exists(reference(), integer()) -> boolean().
+is_exists(Tid, Xid) ->
+    case ets:select(Tid, ms_for_exists(Xid)) of
+        [_|_] -> true;
+        []    -> false
+    end.
+
+%% Private functions
+
+ms_for_exists(Xid) ->
+    ets:fun2ms(fun(#?ENTRY{xid = TXid}) when TXid < Xid -> true end).
+
+ms_for_get(Xid) ->
+    ets:fun2ms(fun(#?ENTRY{xid = TXid} = E) when TXid == Xid -> E end).
+
+ms_for_update(Xid, Msg) ->
+    ets:fun2ms(fun(#?ENTRY{xid = TXid} = E) when TXid == Xid -> E#?ENTRY{pending = Msg} end).
+
+ms_for_handle_error(Tid, Xid, Error) ->
+    [Orig|_] = get(Tid, Xid),
+    Error1 = maps:merge(Error, #{data => Orig}),
+    ets:fun2ms(fun(#?ENTRY{xid = TXid} = E) when TXid == Xid -> E#?ENTRY{pending = Error1} end).
diff --git a/test/flay_test.exs b/test/flay_test.exs
new file mode 100644
index 0000000..22285b8
--- /dev/null
+++ b/test/flay_test.exs
@@ -0,0 +1,5 @@
+defmodule FlayTest do
+  use ExUnit.Case
+
+  
+end
diff --git a/test/packet_data/nx_packet_in2_arp.raw b/test/packet_data/nx_packet_in2_arp.raw
new file mode 100644
index 0000000..cbf807f
Binary files /dev/null and b/test/packet_data/nx_packet_in2_arp.raw differ