diff --git a/features/examples/topology.change-history.feature b/features/examples/topology.change-history.feature
deleted file mode 100644
index 9f1f33225..000000000
--- a/features/examples/topology.change-history.feature
+++ /dev/null
@@ -1,38 +0,0 @@
-Feature: Topology Ruby API example
-  
-  The change-history.rb example ([trema]/src/examples/topology/change-history.rb)
-  is a sample controller which uses Topology Ruby API.
-
-  @slow_process
-  Scenario: Run the Ruby example
-    Given a file named "change-history.conf" with:
-      """
-      1.upto( 3 ).each do | sw |
-        vswitch { dpid sw }
-        1.upto( sw - 1 ).each do | peer |
-          link "%#x" % sw, "%#x" % peer
-        end
-      end
-      
-      run {
-        path "../../objects/topology/topology"
-      }
-      
-      run {
-        path "../../objects/examples/dumper/dumper"
-      }
-      
-      event :port_status => "topology", :packet_in => "filter", :state_notify => "topology"
-      filter :lldp => "topology", :packet_in => "dumper"
-      """
-    When I run `../../trema run ../../src/examples/topology/change-history.rb -c change-history.conf -d`
-    Then wait until "topology" is up
-    Then *** sleep 32 ***
-
-    Then the file "change-history.dot" should match /.*graph \[label="Gen \d+\\n\(0x3 -> 0x1\) up"\];.*/
-    Then the file "change-history.dot" should match /.*graph \[label="Gen \d+\\n\(0x3 -> 0x2\) up"\];.*/
-    Then the file "change-history.dot" should match /.*graph \[label="Gen \d+\\n\(0x2 -> 0x1\) up"\];.*/
-    Then the file "change-history.dot" should match /.*graph \[label="Gen \d+\\n\(0x2 -> 0x3\) up"\];.*/
-    Then the file "change-history.dot" should match /.*graph \[label="Gen \d+\\n\(0x1 -> 0x2\) up"\];.*/
-    Then the file "change-history.dot" should match /.*graph \[label="Gen \d+\\n\(0x1 -> 0x3\) up"\];.*/
-    
\ No newline at end of file
diff --git a/features/topology/topology.map.feature b/features/topology/topology.map.feature
deleted file mode 100644
index 6110a1b81..000000000
--- a/features/topology/topology.map.feature
+++ /dev/null
@@ -1,167 +0,0 @@
-Feature: topology map Ruby API
-  
-  As a developer using Trema
-  I want to develop topology aware application.
-
-  Scenario: map_ready handler
-    Given a file named "topology.conf" with:
-      """
-      vswitch("topology1") { datapath_id "0x1" }
-      
-      run {
-        path "../../objects/topology/topology"
-        options "--always_run_discovery"
-      }
-      
-      event :port_status => "topology", :packet_in => "filter", :state_notify => "topology"
-      filter :lldp => "topology", :packet_in => "MapReadyTestTopology"
-      """
-    And a file named "MapReadyTestTopology.rb" with:
-      """
-      require "trema/topology/map_api"
-      
-      class MapReadyTestTopology < Controller
-        include TopologyMap
-      
-        oneshot_timer_event :test_start, 0
-        
-        def test_start
-          send_rebuild_map_request
-        end
-        
-        def map_ready c
-          info "map_ready"
-        end
-      end
-      """
-    When I run `trema run MapReadyTestTopology.rb -c topology.conf -d`
-    And wait until "topology" is up
-    And *** sleep 1 ***
-    Then the file "../../tmp/log/MapReadyTestTopology.log" should contain "map_ready"
-
-  Scenario: map_ready handler (block)
-    Given a file named "topology.conf" with:
-      """
-      vswitch("topology1") { datapath_id "0x1" }
-      
-      run {
-        path "../../objects/topology/topology"
-        options "--always_run_discovery"
-      }
-      
-      event :port_status => "topology", :packet_in => "filter", :state_notify => "topology"
-      filter :lldp => "topology", :packet_in => "MapReadyTestTopologyB"
-      """
-    And a file named "MapReadyTestTopologyB.rb" with:
-      """
-      require "trema/topology/map_api"
-      
-      class MapReadyTestTopologyB < Controller
-        include TopologyMap
-      
-        oneshot_timer_event :test_start, 0
-        
-        def test_start
-          send_rebuild_map_request { |map|
-            info "map_ready_block"
-          }
-        end
-        
-        def map_ready c
-          info "map_ready_should_not_be_called"
-        end
-      end
-      """
-    When I run `trema run MapReadyTestTopologyB.rb -c topology.conf -d`
-    And wait until "topology" is up
-    And *** sleep 1 ***
-    Then the file "../../tmp/log/MapReadyTestTopologyB.log" should contain "map_ready_block"
-    And the file "../../tmp/log/MapReadyTestTopologyB.log" should not contain "map_ready_should_not_be_called"
-
-  Scenario: get map without rebuilding
-    Given a file named "topology.conf" with:
-      """
-      vswitch("topology1") { datapath_id "0x1" }
-      vswitch("topology2") { datapath_id "0x2" }
-      
-      link "topology1", "topology2"
-      
-      run {
-        path "../../objects/topology/topology"
-        options "--always_run_discovery"
-      }
-      
-      event :port_status => "topology", :packet_in => "filter", :state_notify => "topology"
-      filter :lldp => "topology", :packet_in => "RebuildTestController"
-      """
-    And a file named "RebuildTestController.rb" with:
-      """
-      require "trema/topology/map_api"
-      
-      class RebuildTestController < Controller
-        include TopologyMap
-      
-        oneshot_timer_event :delayed_event, 4
-        
-        def delayed_event
-          send_rebuild_map_request false
-        end
-        
-        def map_ready c
-          info c.to_s
-        end
-      end
-      """
-    When I run `trema run RebuildTestController.rb -c topology.conf -d`
-    And wait until "topology" is up
-    And *** sleep 4 ***
-    Then the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Map:
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Switch: 0x1 - {up:true}
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should match / Port: 0x1:1 - \{external:false, mac:"[0-9a-f:]+", name:".*", up:true\}/
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-       Links_in
-        <= 0x2:1
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-       Links_out
-        => 0x2:1
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Switch: 0x2 - {up:true}
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should match / Port: 0x2:1 - \{external:false, mac:"[0-9a-f:]+", name:".*", up:true\}/
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-       Links_in
-        <= 0x1:1
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-       Links_out
-        => 0x1:1
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Port: 0x1:1 - {
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Port: 0x2:1 - {
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Link: (0x1:1)->(0x2:1) - {unstable:false, up:true}
-      """
-    And the file "../../tmp/log/RebuildTestController.log" should contain:
-      """
-      Link: (0x2:1)->(0x1:1) - {unstable:false, up:true}
-      """
diff --git a/ruby/trema/topology.c b/ruby/trema/topology.c
index 5d10b35c7..8f195e920 100644
--- a/ruby/trema/topology.c
+++ b/ruby/trema/topology.c
@@ -91,7 +91,6 @@ static VALUE
 switch_status_to_hash( const topology_switch_status* sw_status ) {
   VALUE sw = rb_hash_new();
   rb_hash_aset( sw, ID2SYM( rb_intern( "dpid" ) ), ULL2NUM( sw_status->dpid ) );
-//  rb_hash_aset( sw, ID2SYM( rb_intern( "status" ) ), INT2FIX( (int)sw_status->status ) );
 
   if ( sw_status->status == TD_SWITCH_UP ) {
     rb_hash_aset( sw, ID2SYM( rb_intern( "up" ) ), Qtrue );
@@ -124,8 +123,6 @@ port_status_to_hash( const topology_port_status* port_status ) {
   const uint8_t* mac = port_status->mac;
   snprintf( macaddr, sizeof(macaddr), "%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5] );
   rb_hash_aset( port, ID2SYM( rb_intern( "mac" ) ), rb_str_new2( macaddr ) );
-//  rb_hash_aset( port, ID2SYM( rb_intern( "external" ) ), INT2FIX( (int)port_status->external ) );
-//  rb_hash_aset( port, ID2SYM( rb_intern( "status" ) ), INT2FIX( (int)port_status->status ) );
 
   if ( port_status->external == TD_PORT_EXTERNAL ) {
     rb_hash_aset( port, ID2SYM( rb_intern( "external" ) ), Qtrue );
@@ -160,7 +157,6 @@ link_status_to_hash( const topology_link_status* link_status ) {
   rb_hash_aset( link, ID2SYM( rb_intern( "from_portno" ) ), INT2FIX( (int)link_status->from_portno ) );
   rb_hash_aset( link, ID2SYM( rb_intern( "to_dpid" ) ), ULL2NUM( link_status->to_dpid ) );
   rb_hash_aset( link, ID2SYM( rb_intern( "to_portno" ) ), INT2FIX( (int)link_status->to_portno ) );
-//  rb_hash_aset( link, ID2SYM( rb_intern( "status" ) ), INT2FIX( (int)link_status->status ) );
 
   if ( link_status->status != TD_LINK_DOWN ) {
     rb_hash_aset( link, ID2SYM( rb_intern( "up" ) ), Qtrue );
@@ -504,33 +500,6 @@ topology_send_all_switch_status( VALUE self ) {
 void Init_topology( void ) {
   mTopology = rb_define_module_under( mTrema, "Topology" );
 
-  /* @!group enum topology_switch_status_type */
-  /* Same as C API enum topology_switch_status_type */
-  rb_define_const( mTopology, "TD_SWITCH_DOWN", INT2NUM( TD_SWITCH_DOWN ) );
-  /* Same as C API enum topology_switch_status_type */
-  rb_define_const( mTopology, "TD_SWITCH_UP", INT2NUM( TD_SWITCH_UP ) );
-
-  /* @!group enum topology_port_status_type */
-  /* Same as C API enum topology_port_status_type */
-  rb_define_const( mTopology, "TD_PORT_DOWN", INT2NUM( TD_PORT_DOWN ) );
-  /* Same as C API enum topology_port_status_type */
-  rb_define_const( mTopology, "TD_PORT_UP", INT2NUM( TD_PORT_UP ) );
-
-  /* @!group enum topology_port_external_type */
-  /* Same as C API enum topology_port_external_type */
-  rb_define_const( mTopology, "TD_PORT_INACTIVE", INT2NUM( TD_PORT_INACTIVE ) );
-  /* Same as C API enum topology_port_external_type */
-  rb_define_const( mTopology, "TD_PORT_EXTERNAL", INT2NUM( TD_PORT_EXTERNAL ) );
-
-  /* @!group enum topology_link_status_type */
-  /* Same as C API enum topology_link_status_type */
-  rb_define_const( mTopology, "TD_LINK_DOWN", INT2NUM( TD_LINK_DOWN ) );
-  /* Same as C API enum topology_link_status_type */
-  rb_define_const( mTopology, "TD_LINK_UP", INT2NUM( TD_LINK_UP ) );
-  /* Same as C API enum topology_link_status_type */
-  rb_define_const( mTopology, "TD_LINK_UNSTABLE", INT2NUM( TD_LINK_UNSTABLE ) );
-  /* @!endgroup */
-
   rb_define_protected_method( mTopology, "init_libtopology", topology_init_libtopology, 1 );
   rb_define_protected_method( mTopology, "finalize_libtopology", topology_finalize_libtopology, 0 );
 
diff --git a/ruby/trema/topology.rb b/ruby/trema/topology.rb
index 7304ac34b..9edfc59a3 100644
--- a/ruby/trema/topology.rb
+++ b/ruby/trema/topology.rb
@@ -220,7 +220,7 @@ def subscribed?
     #    def start
     #      init_libtopology "topology"
     #      send_subscribe_topology if topology_handler_implemented?
-    #
+    #      send_enable_topology_discovery if respond_to?( :link_status_updated )
     #      # your application's pre-start_trema() call initialization here.
     #    end
     #  end
diff --git a/ruby/trema/topology/guarded-property-accessor.rb b/ruby/trema/topology/guarded-property-accessor.rb
deleted file mode 100644
index 68229bcb2..000000000
--- a/ruby/trema/topology/guarded-property-accessor.rb
+++ /dev/null
@@ -1,61 +0,0 @@
-#
-# Copyright (C) 2008-2013 NEC Corporation
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2, as
-# published by the Free Software Foundation.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-#
-
-
-module Trema
-  module Topology
-    module GuardedPropertyAccesor
-      
-      # Accessor for the property value of this node
-      def []( key )
-        return @property[key]
-      end
-
-
-      # Overwrite a property value of this node
-      # @raise [ArgumentError] if key was a mandatory key of a node
-      def []=( key, value )
-        raise ArgumentError, "Overwriting #{key} is not allowed" if self.class.is_mandatory_key?(key)
-        return @property[key] = value
-      end
-
-
-      # Delete a property of this node.
-      # mandatory key will be treated as if it didn't exist.
-      def delete( key )
-        if block_given? then
-          yield key if not @property.has_key?(key) or self.class.is_mandatory_key?(key)
-        end
-        return nil if self.class.is_mandatory_key?(key)
-        return deleted = @property.delete(key)
-      end
-
-
-      # Update properties of this node using specified Hash or node
-      # mandatory keys will be ignored
-      def update( other )
-        other = other.properties if other.is_a?(self.class)
-        other = other.to_hash if not other.is_a?(Hash)
-
-        other.each_pair do |key,value|
-          @property[key] = value if not self.class.is_mandatory_key?(key)
-        end
-      end
-      alias :merge! :update
-    end
-  end
-end
\ No newline at end of file
diff --git a/ruby/trema/topology/link.rb b/ruby/trema/topology/link.rb
index d228e3dd5..b3e11b6ab 100644
--- a/ruby/trema/topology/link.rb
+++ b/ruby/trema/topology/link.rb
@@ -70,7 +70,7 @@ def unstable?
       end
 
 
-      # @return [Array(Integer,Integer,Integer,Integer)] Link key 4-tuple for this Link instance
+      # @return [[Integer,Integer,Integer,Integer]] Link key 4-tuple for this Link instance
       def key
         return [ from_dpid, from_portno, to_dpid, to_portno ]
       end
@@ -82,7 +82,6 @@ def key
       # @option link [Integer] :from_portno port number of switch which this link departs from
       # @option link [Integer] :to_dpid Switch dpid which this link peer to
       # @option link [Integer] :to_portno port number of switch which this link peer to
-      # @return [Link]
       # @example
       #   link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
       def initialize( link )
@@ -125,10 +124,11 @@ def to_s
 
 
       def property_to_s
-        kvp_ary = @property.select { |key,_| not Link.is_mandatory_key?( key ) }
-        kvp_ary = kvp_ary.sort_by { |key,_| key.to_s }
-        s = kvp_ary.map { |key, val| "#{key.to_s}:#{val.inspect}" }.join(", ")
-        return s
+        kvp_ary = @property.select { |key,_| not Link.is_mandatory_key?( key ) }. 
+          map { |key, val| [key.to_s, val] }. 
+          sort { |lhs,rhs| lhs.first <=> rhs.first }. 
+          map { |key, val| "#{key}:#{val.inspect}"} 
+        return kvp_ary.join(", ")
       end
     end
   end
diff --git a/ruby/trema/topology/map.rb b/ruby/trema/topology/map.rb
deleted file mode 100644
index ea731d659..000000000
--- a/ruby/trema/topology/map.rb
+++ /dev/null
@@ -1,219 +0,0 @@
-#
-# Copyright (C) 2008-2013 NEC Corporation
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2, as
-# published by the Free Software Foundation.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-#
-
-
-module Trema
-  module Topology
-    # Topology Map structure
-    class Map
-      # @return [{Integer=>Switch}]  Hash of Switches: dpid => Switch
-      # @note Do not directly add/remove elements in this Hash.
-      attr_reader :switches
-      # @return [{[Integer,Integer,Integer,Integer]=>Link}] Hash of Links: [from.dpid, from.port_no, to.dpid, to.port_no] => Links
-      # @note Do not directly add/remove elements in this Hash.
-      attr_reader :links
-      # Create empty Map
-      def initialize
-        @switches = Hash.new
-        @links = Hash.new
-      end
-
-      # @!group Switch manipulation methods
-
-
-      # Add a switch to topology map.
-      # @return [Switch] Switch instance added.
-      def add_switch sw
-        raise TypeError, "Trema::Topology::Switch expected" if not sw.is_a?(Switch)
-        @switches[ sw.dpid ] = sw
-      end
-
-
-      # Delete a switch from Topology map.
-      # @note Links from/to the switch will also be removed
-      # @param [Switch,Hash] sw Switch instance or a Hash with Switch info
-      def del_switch sw
-        del_switch_by_dpid sw[:dpid]
-      end
-
-
-      # Delete a switch from Topology map using dpid
-      # @see #del_switch
-      def del_switch_by_dpid dpid
-        remove_links = @links.select { |key,_| (key[FROM_DPID] == dpid || key[TO_DPID] == dpid) }
-        remove_links.each { |kv_pair| self.del_link( kv_pair.first ) }
-        @switches.delete dpid
-      end
-
-
-      # Get a switch from Topology map using dpid.
-      # Switch instance will be created if not found.
-      # @param [Integer] dpid dpid of the switch to look for.
-      # @return [Switch] Switch instance for specified dpid
-      def get_switch_for_dpid dpid
-        sw = lookup_switch_by_dpid dpid
-        sw ||= add_switch Switch.new( { :dpid => dpid } )
-        return sw
-      end
-
-      # @!group Link manipulation methods
-
-
-      # Add a link to Topology map.
-      # @note Corresponding Switch object's links_out, links_in will also be updated.
-      def add_link link
-        raise TypeError, "Trema::Topology::Link expected" if not link.is_a?(Link)
-
-        key = link.key
-        key.each { |each| each.freeze }
-        key.freeze
-
-        sw_from = get_switch_for_dpid link.from_dpid
-        sw_to = get_switch_for_dpid  link.to_dpid
-
-        sw_from.add_link link
-        sw_to.add_link link
-        @links[ key ] = link
-      end
-
-
-      # Delete a link from Topology map.
-      # @note Corresponding Switch object's links_out, links_in will also be updated.
-      # @param [Link,Hash] link Link instance or a Hash with link info.
-      def del_link link
-        del_link_by_key [ link[:from_dpid], link[:from_portno], link[:to_dpid], link[:to_portno] ]
-      end
-
-
-      # Delete a link from Topology map.
-      # @param [Array(Integer,Integer,Integer,Integer)] key
-      #   4 element array. [from.dpid, from.port_no, to.dpid, to.port_no]
-      def del_link_by_key key
-        sw_from = @switches[ key[FROM_DPID] ];
-        sw_to = @switches[ key[TO_DPID] ];
-
-        sw_from.delete_link( key ) if sw_from
-        sw_to.delete_link( key ) if sw_to
-        @links.delete( key )
-      end
-
-      #
-      # @!group Lookup map contents
-      #
-
-      # Lookup a switch from Topology map using dpid
-      # @param [Integer] dpid dpid of the switch to look for.
-      # @return [Switch] Switch instance found, or nil if not found.
-      def lookup_switch_by_dpid dpid
-        @switches[dpid]
-      end
-
-
-      # Lookup a link from Topology map.
-      # @param [Hash] link look up a link instance using key elements listed in Options
-      # @option (see Link#initialize)
-      # @return [Link] Link instance found, or nil if not found.
-      def lookup_link_by_hash link
-        key = [ link[:from_dpid], link[:from_portno], link[:to_dpid], link[:to_portno] ];
-        return @links[ key ]
-      end
-
-
-      #
-      # @!group Update by Hash methods
-      #
-
-      # Update Switch instance. Switch instance will be created if it does not exist.
-      # Switch instance will be removed if the state is not up
-      # @param [Switch,Hash] sw Switch instance or a Hash with switch info
-      # @option (see Switch#initialize)
-      def update_switch sw
-        sw = sw.property if sw.is_a?(Switch)
-        raise ArgumentError, "Mandatory key element for Switch missing in Hash" if not Switch.has_mandatory_keys?( sw )
-
-        dpid = sw[:dpid]
-        if sw[:up] then
-          s = lookup_switch_by_dpid( dpid )
-          if s != nil then
-            s.update( sw )
-          else
-            add_switch Switch.new( sw )
-          end
-        else
-          del_switch_by_dpid dpid
-        end
-      end
-
-
-      # Update Link instance. Link instance will be created if it does not exist.
-      # Link instance will be removed if the state is not up
-      # @param [Link,Hash] link Link instance or a Hash with link info
-      # @option (see Link#initialize)
-      def update_link link
-        link = link.property if link.is_a?(Link)
-        raise ArgumentError, "Mandatory key element for Link missing in Hash" if not Link.has_mandatory_keys?( link )
-
-        if link[:up] then
-          l = lookup_link_by_hash( link )
-          if l != nil then
-            l.update( link )
-          else
-            add_link Link.new( link )
-          end
-        else
-          del_link link
-        end
-      end
-
-
-      # Update Port instance. Port instance will be created if it does not exist.
-      # Port instance will be removed if the state is not up
-      # @param [Port,Hash] port Port instance or a Hash with port info
-      # @option (see Port#initialize)
-      def update_port port
-        port = port.property if port.is_a?(Port)
-        raise ArgumentError, "Mandatory key element for Port missing in Hash" if not Port.has_mandatory_keys?( port )
-        
-        dpid = port[:dpid]
-        s = lookup_switch_by_dpid( dpid )
-        if port[:up] then
-          s ||= add_switch Switch.new( { :dpid => dpid } )
-        end
-        s.update_port( port ) if s != nil
-      end
-      
-      #
-      # @!endgroup
-      #
-      
-      # Dump map info as a String
-      # @return [String] content of this map.
-      def to_s
-        s = "Map:\n"
-        s << "(Empty)\n" if @switches.empty? and @links.empty?
-        @switches.each_pair do |_, sw|
-          s << sw.to_s
-        end
-        @links.each_pair do |_, link|
-          s << "#{ link.to_s }\n"
-        end
-        return s
-      end
-      
-    end
-  end
-end
diff --git a/ruby/trema/topology/map_api.rb b/ruby/trema/topology/map_api.rb
deleted file mode 100644
index 66f7efae9..000000000
--- a/ruby/trema/topology/map_api.rb
+++ /dev/null
@@ -1,339 +0,0 @@
-#
-# Copyright (C) 2008-2013 NEC Corporation
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2, as
-# published by the Free Software Foundation.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-#
-
-require 'trema/topology'
-require 'trema/topology/map'
-require 'trema/topology/guarded-property-accessor'
-
-
-module Trema
-  
-  module Topology
-    class Switch
-      include Topology::GuardedPropertyAccesor
-
-      # @!group Additional methods for Map maintenance
-
-      # @return [Hash] Raw access to properties of a Switch. User must not modify mandatory key elements in Hash.
-      attr_reader :property
-
-
-      # @return [String] Switch key as a String
-      def key_str
-        return "S#{ dpid.to_s(16) }"
-      end
-
-
-      # @!attribute [w] up
-      #   @param [Boolean] new_state_up
-      #   @return [Boolean] returns new state
-      def up= new_state_up
-        if new_state_up then
-          @property[:up] = true
-        else
-          @property[:up] = false
-        end
-      end
-
-
-      # Update port on this switch
-      # @overload update_port port
-      #   @param [Port] port Port instance to update
-      # @overload update_port port_hash
-      #   @param [Hash] port_hash a Hash with port info about instance to update
-      #   @option (see Port#initialize)
-      def update_port port
-        port = port.property if port.is_a?(Port)
-        raise ArgumentError, "Mandatory key element for Port missing in Hash" if not Port.has_mandatory_keys?( port )
-
-        portno = port[:portno]
-        if port[:up] then
-          if @ports.include?( portno ) then
-            @ports[ portno ].update port
-          else
-            add_port Port.new( port )
-          end
-        else
-          @ports.delete( portno )
-        end
-      end
-    end
-    
-    class Port
-      include Topology::GuardedPropertyAccesor
-
-      # @!group Additional methods for Map maintenance
-
-      # @return [Hash] Raw access to properties of a Port. User must not modify mandatory key elements in Hash.
-      attr_reader :property
-
-
-      # @return [String] Port key as a String
-      def key_str
-        return "P#{ dpid.to_s(16) }-#{ portno.to_s }"
-      end
-    end
-    
-    class Link
-      include Topology::GuardedPropertyAccesor
-
-      # @!group Additional methods for Map maintenance
-
-      # @return [Hash] Raw access to properties of a Link. User must not modify mandatory key elements in Hash.
-      attr_reader :property
-
-
-      # @return [String] Link key as a String
-      def key_str
-        return "L#{ from_dpid.to_s(16) }-#{ from_portno.to_s }-#{ to_dpid.to_s(16) }-#{ to_portno.to_s }"
-      end
-    end
-  end
-  
-  # Module to add Topology Map feature
-  module TopologyMap
-    include Topology
-    
-    #
-    # @private Just a placeholder for YARD.
-    #
-    def self.handler name
-      # Do nothing.
-    end
-
-    # @!group Basic Map events and methods
-    #
-    # @example
-    #  class TestController < Controller
-    #    include Topology
-    #
-    #    oneshot_timer_event :on_start, 0
-    #    def on_start
-    #      send_enable_topology_discovery
-    #      send_rebuild_map_request
-    #    end
-    #
-    #    def map_ready map
-    #      info "Topology Map ready!"
-    #      p map
-    #
-    #      # You can do whatever with map after this point.
-    #      # Topology::Map instance can also be obtained later using #get_map method.
-    #
-    #      # example:
-    #      # build spanning trees for each vertices
-    #    end
-    #
-    #    def link_status_updated link
-    #      # Directly read Hash containing link info.
-    #      p link[:from_dpid]
-    #      # Or, create Topology::Link instance.
-    #      linkObj = Link.new( links )
-    #      p linkObj.from_dpid
-    #
-    #      # Do what ever before Topology Map update
-    #      # Note: Link instance will be removed after map update, 
-    #      #       if the notified link state was not up.
-    #
-    #      # example:
-    #      if not linkObj.up? then
-    #        # Link down event:
-    #        # 1. drop flow path, which contains this link.
-    #        # 2. resolve alternate path with updated topology.
-    #        # 3. set newly calculated flow path.
-    #      else
-    #        # Link up event:
-    #        # 1. PathResolver rebuild spanning trees.
-    #        # 2. replace existing path  by newly calculated path using using FlowManager::libPath?
-    #      end
-    #
-    #      # (Optional) Manually update Map
-    #      # Note: Map will be automatically updated after exit from this handler
-    #      #       even if this manual update
-    #      update_map_by_link_hash link
-    #
-    #      if map_ready?
-    #        # Check to see if we're at a point after map_ready event.
-    #
-    #        # Do whatever with updated map.
-    #        puts get_map
-    #      end
-    #    end
-    #  end
-    #
-    # Start rebuilding topology map.
-    # `map_ready` or specified block will be called, when map rebuild is complete.
-    # @param [Boolean] clear_map Clear map before update.
-    # @yieldparam map [Map]  Current map
-    # @return [Boolean] true if request sent successfully
-    def send_rebuild_map_request clear_map=true, &block
-      @need_map_ready_notify = true
-      @map_up_to_date = false
-      @map = Map.new if clear_map
-      @all_link_received = false
-      @all_switch_received = false
-      @all_port_received = false
-
-      succ = true
-      succ &= get_all_switch_status do |switches|
-        switches.each { |sw| update_map_by_switch_hash(sw) }
-        @all_switch_received = true
-        notify_map_ready( &block ) if @need_map_ready_notify and map_ready?
-      end
-
-      succ &= get_all_port_status do |ports|
-        ports.each { |port| update_map_by_port_hash(port) }
-        @all_port_received = true
-        notify_map_ready( &block ) if @need_map_ready_notify and map_ready?
-      end
-
-      succ &= get_all_link_status do |links|
-        links.each { |link| update_map_by_link_hash(link) }
-        @all_link_received = true
-        notify_map_ready( &block ) if @need_map_ready_notify and map_ready?
-      end
-      return succ
-    end
-
-
-    #
-    # @!method map_ready( map )
-    # Event handler for map_ready event.
-    # @abstract map_ready event handler. Override this to implement a custom handler.
-    # @param [Map] map
-    # @return [void]
-    #   Reference to current topology map.
-    # @see #send_rebuild_map_request See #send_rebuild_map_request for usage example.
-    handler :map_ready
-
-    
-    #
-    # Returns a reference to latest map available.
-    # @note Returned instance may be outdated, when invoked inside Topology update event handlers
-    # before manually update of the map.
-    # @return [Map] Returns a reference to available map.
-    #
-    # @see #get_map
-    #
-    def get_last_map
-      return @map
-    end
-    
-    #
-    # Returns a reference to current map when available.
-    # @note This method will return nil when a updated map is not ready.
-    # @return [Map] Returns a reference to latest map or nil, when current map is not available.
-    #
-    # @example
-    #  def link_status_updated lnk
-    #    get_last_map  # returns a outdated network map.
-    #    get_map       # returns nil
-    #    update_map_by_link_hash lnk
-    #    get_last_map  # returns the current map
-    #    get_map       # returns the current map
-    #  end
-    #
-    def get_map
-      return @map if map_up_to_date?
-      return nil
-    end
-
-
-    # Check if map is ready to use.
-    def map_ready?
-      @all_link_received and @all_switch_received and @all_port_received
-    end
-
-
-    # Check if current map is in latest state.
-    def map_up_to_date?
-      map_ready? and @map_up_to_date
-    end
-
-
-    # Call inside switch_status_updated handler to manually update map to latest state
-    # @note Map will be automatically updated even if this method call was omitted.
-    # @param [Hash] sw Specify switch hash given to switch_status_updated. Additional properties may be added to reflect internal map.
-    # @return [void]
-    # @see #send_rebuild_map_request See #send_rebuild_map_request for usage example.
-    def update_map_by_switch_hash sw
-      @map ||= Topology::Map.new
-      @map.update_switch( sw )
-      @map_up_to_date = true
-    end
-
-
-    # Call inside link_status_updated handler to manually update map to latest state
-    # @note Map will be automatically updated even if this method call was omitted.
-    # @param [Hash] link Specify link hash given to link_status_updated. Additional properties may be added to reflect internal map.
-    # @return [void]
-    # @see #send_rebuild_map_request See #send_rebuild_map_request for usage example.
-    def update_map_by_link_hash link
-      @map ||= Topology::Map.new
-      @map.update_link( link )
-      @map_up_to_date = true
-    end
-
-
-    # Call inside port_status_updated handler to manually update map to latest state
-    # @note Map will be automatically updated even if this method call was omitted.
-    # @param [Hash] port Specify link hash given to port_status_updated. Additional properties may be added to reflect internal map.
-    # @return [void]
-    # @see #send_rebuild_map_request See #send_rebuild_map_request for usage example.
-    def update_map_by_port_hash port
-      @map ||= Topology::Map.new
-      @map.update_port( port )
-      @map_up_to_date = true
-    end
-
-    ######################
-    protected
-    ######################
-
-
-    alias_method :super_switch_status_updated, :_switch_status_updated
-    def _switch_status_updated sw
-      super_switch_status_updated( sw )
-      update_map_by_switch_hash( sw )
-    end
-
-
-    alias_method :super_port_status_updated, :_port_status_updated
-    def _port_status_updated port
-      super_port_status_updated( port )
-      update_map_by_port_hash( port )
-    end
-
-
-    alias_method :super_link_status_updated, :_link_status_updated
-    def _link_status_updated link
-      super_link_status_updated( link )
-      update_map_by_link_hash( link )
-    end
-
-
-    def notify_map_ready &block
-      if block then
-        block.call( @map )
-      elsif self.respond_to? :map_ready then
-        map_ready @map
-      end
-      @need_map_ready_notify = false
-    end
-  end
-end
-
diff --git a/ruby/trema/topology/port.rb b/ruby/trema/topology/port.rb
index 997365907..77b6022f6 100644
--- a/ruby/trema/topology/port.rb
+++ b/ruby/trema/topology/port.rb
@@ -62,7 +62,7 @@ def mac
       end
 
 
-      # @return [Array(Integer,Integer)] Port key 2-tuple for this Port instance
+      # @return [[Integer,Integer]] Port key 2-tuple for this Port instance
       def key
         return [dpid, portno]
       end
@@ -72,7 +72,6 @@ def key
       # @param [Hash] port Hash containing Port properties. Must at least contain keys listed in Options.
       # @option port [Integer] :dpid Switch dpid which this port belongs
       # @option port [Integer] :portno port number
-      # @return [Port]
       # @example
       #   port = Port.new( {:dpid => 1234, :portno => 42} )
       def initialize( port )
@@ -115,10 +114,11 @@ def to_s
 
 
       def property_to_s
-        kvp_ary = @property.select { |key,_| not Port.is_mandatory_key?( key ) }
-        kvp_ary = kvp_ary.sort_by { |key,_| key.to_s }
-        s = kvp_ary.map { |key, val| "#{key.to_s}:#{val.inspect}" }.join(", ")
-        return s
+        kvp_ary = @property.select { |key,_| not Port.is_mandatory_key?( key ) }. 
+          map { |key, val| [key.to_s, val] }. 
+          sort { |lhs,rhs| lhs.first <=> rhs.first }. 
+          map { |key, val| "#{key}:#{val.inspect}"} 
+        return kvp_ary.join(", ")
       end
     end
   end
diff --git a/ruby/trema/topology/switch.rb b/ruby/trema/topology/switch.rb
index c6eb82288..fd6b7c3fe 100644
--- a/ruby/trema/topology/switch.rb
+++ b/ruby/trema/topology/switch.rb
@@ -57,10 +57,12 @@ def key
 
       # Add a port on this Switch.
       # @param [Port] port Port instance to add to switch
+      # @return self
       def add_port port
         raise TypeError, "Trema::Topology::Port expected" if not port.is_a?(Port)
         raise ArgumentError, "dpid mismatch. 0x#{ self.dpid.to_s(16) } expected but received: 0x#{ port.dpid.to_s(16) }" if ( self.dpid != port.dpid )
         @ports[ port.portno ] = port
+          return self
       end
 
 
@@ -68,10 +70,13 @@ def add_port port
       # It will be silently ignored if the port did not belong to this switch
       # @overload delete_port port
       #   @param [Port] port Port instance to delete
+      #   @return self
       # @overload delete_port port_hash
       #   @param [Hash] port_hash a Hash with port info about instance to delete
+      #   @return self
       # @overload delete_port portno
       #   @param [Integer] portno portno of instance to delete
+      #   @return self
       def delete_port port
         if port.is_a?(Port)
           @ports.delete( port.portno )
@@ -82,15 +87,18 @@ def delete_port port
         else
           raise TypeError, "Either Port, Port info(Hash), portno(Integer) expected"
         end
+        return self
       end
 
 
       # Add a link to this Switch.
       # It will be silently ignored if the link was not bound to this switch
       # @param [Link] link link to add.
+      # @return self
       def add_link link
         @links_in[ link.key ] = link if link.to_dpid == self.dpid
         @links_out[ link.key ] = link if link.from_dpid == self.dpid
+        return self
       end
 
 
@@ -98,10 +106,13 @@ def add_link link
       # It will be silently ignored if the link was not bound to this switch
       # @overload delete_link link
       #   @param [Port] port Link instance to delete
+      #   @return self
       # @overload delete_link link_hash
       #   @param [Hash] port_hash a Hash with link info about instance to delete
+      #   @return self
       # @overload delete_link key
       #   @param [[Integer, Integer, Integer, Integer]] key Link key 4-tuple of the link to delete
+      #   @return self
       def delete_link link
         if link.is_a?(Link)
           key = link.key
@@ -118,6 +129,7 @@ def delete_link link
         else
           raise TypeError, "Either Link, Link info(Hash), Link key tuple([Integer,Integer,Integer,Integer]) expected"
         end
+        return self
       end
 
 
@@ -126,8 +138,7 @@ def delete_link link
       #   @param [Hash] sw_hash a Hash containing Switch properties. Must at least contain keys listed in Options.
       #   @option sw_hash [Integer] :dpid Switch dpid
       # @overload initialize dpid
-      #     @param [Integer] dpid datapath_id  
-      # @return Switch
+      #   @param [Integer] dpid datapath_id  
       # @example
       #  sw = Switch.new( {:dpid => 0x1234} )
       #  sw = Switch.new( 0x1234 )
@@ -184,10 +195,11 @@ def to_s
 
 
       def property_to_s
-        kvp_ary = @property.select { |key,_| not Switch.is_mandatory_key?( key ) }
-        kvp_ary = kvp_ary.sort_by { |key,_| key.to_s }
-        s = kvp_ary.map { |key, val| "#{key.to_s}:#{val.inspect}" }.join(", ")
-        return s
+        kvp_ary = @property.select { |key,_| not Switch.is_mandatory_key?( key ) }. 
+          map { |key, val| [key.to_s, val] }. 
+          sort { |lhs,rhs| lhs.first <=> rhs.first }. 
+          map { |key, val| "#{key}:#{val.inspect}"} 
+        return kvp_ary.join(", ")
       end
     end
   end
diff --git a/spec/trema/topology-map_spec.rb b/spec/trema/topology-map_spec.rb
deleted file mode 100644
index 9119f8386..000000000
--- a/spec/trema/topology-map_spec.rb
+++ /dev/null
@@ -1,459 +0,0 @@
-#
-# Copyright (C) 2008-2013 NEC Corporation
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2, as
-# published by the Free Software Foundation.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-#
-
-
-require File.join( File.dirname( __FILE__ ), "..", "spec_helper" )
-require "trema"
-require "trema/topology/map_api"
-
-
-include Trema::TopologyMap
-
-describe Trema::TopologyMap, :nosudo => true do
-
-  describe "Monkey patched Switch" do
-    it "should have method key_str" do
-      s = Switch.new( { :dpid => 0x1234, :magic => 42 } )
-      expect( s.key_str ).to match("1234")
-    end
-
-    it "up state should be overwritable" do
-      s = Switch.new( { :dpid => 0x1234, :up => true } )
-      s.up = false
-      expect( s.up? ).to be_false
-
-      s = Switch.new( { :dpid => 0x1234, :up => false } )
-      s.up = true
-      expect( s.up? ).to be_true
-    end
-
-    describe "[],[]=" do
-      before do
-        @s = Switch.new( {:dpid => 0x1234, :extra => true } )
-      end
-      
-      it "should have access to it's property" do
-        expect( @s[:extra] ).to be_true
-      end
-
-      it "should be writable to non mandatory key" do
-        @s[:extra] = false
-        expect( @s[:extra] ).to be_false
-      end
-
-      it "should raise exception if attempt to write to non mandatory key" do
-        expect {
-          @s[:dpid] = 0x5678
-        }.to raise_error(ArgumentError)
-      end
-    end
-
-    describe "delete" do
-      before do
-        @s = Switch.new( {:dpid => 0x1234, :extra => true } )
-      end
-      
-      it "should remove property value" do
-        @s.delete(:extra)
-        expect( @s.property.has_key?(:extra) ).to be_false
-      end
-
-      it "should ignore mandatory key" do
-        @s.delete(:dpid)
-        expect( @s[:dpid] ).to eq(0x1234)
-      end
-    end
-
-    describe "update" do
-      before do
-        @s = Switch.new( {:dpid => 0x1234, :extra => true } )
-      end
-      it "should update property by given hash" do
-        @s.update( {:extra => false, :new => 42})
-        expect( @s[:extra] ).to be_false
-        expect( @s[:new] ).to eq(42)
-      end
-
-      it "should ignore update to mandatory key" do
-        @s.update( {:extra => false, :dpid => 42})
-        expect( @s[:extra] ).to be_false
-        expect( @s[:dpid] ).to eq(0x1234)
-      end
-    end
-  end
-  
-  describe "Monkey Patched Port" do
-    it "should have method key_str" do
-      port = Port.new( {:dpid => 0x1234, :portno => 42 } )
-      expect( port.key_str ).to match("1234-42")
-    end
-  end
-
-  describe "Monkey Patched Link" do
-    it "should have method key_str" do
-      link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-      expect( link.key_str ).to match("1234-42-5678-72")
-    end
-
-    describe "[],[]=" do
-      it "should have access to it's property" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :extra => true  } )
-        expect( link[:extra] ).to be_true
-      end
-
-      it "should be writable to non mandatory key" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :extra => true  } )
-        link[:extra] = false
-        expect( link[:extra] ).to be_false
-      end
-
-      it "should raise exception if attempt to write to non mandatory key" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        expect {
-          link[:from_portno] = 55
-        }.to raise_error(ArgumentError)
-      end
-    end
-
-    describe "delete" do
-      it "should remove property value" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :extra => true  } )
-        link.delete(:extra)
-        expect( link.property.has_key?(:extra) ).to be_false
-      end
-
-      it "should ignore mandatory key" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :extra => true  } )
-        link.delete(:from_dpid)
-        expect( link[:from_dpid] ).to eq(0x1234)
-      end
-    end
-
-    describe "update" do
-      it "should update property by given hash" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :extra => true  } )
-        link.update( {:extra => false, :new => 42})
-        expect( link[:extra] ).to be_false
-        expect( link[:new] ).to eq(42)
-      end
-
-      it "should ignore update to mandatory key" do
-        link = Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :extra => true  } )
-        link.update( {:extra => false, :from_dpid => 42})
-        expect( link[:extra] ).to be_false
-        expect( link[:from_dpid] ).to eq(0x1234)
-      end
-    end
-  end
-  
-  describe Map do
-    it "should initialize it's members to empty" do
-      c = Map.new
-      expect( c.switches.empty? ).to be_true
-      expect( c.links.empty? ).to be_true
-    end
-
-    it "should have switch manipulation methods" do
-      c = Map.new
-      c.add_switch Switch.new( {:dpid => 0x1234 } )
-      expect( c.switches.empty? ).to be_false
-
-      expect( c.lookup_switch_by_dpid( 0x1234 ) ).not_to be_nil
-
-      c.add_switch Switch.new( {:dpid => 0x5678 } )
-      expect( c.switches[ 0x5678 ] ).not_to be_nil
-
-      c.del_switch Switch.new( {:dpid => 0x5678 } )
-      c.del_switch_by_dpid 0x1234
-      expect( c.switches.empty? ).to be_true
-    end
-
-    describe "link manipulation methods" do
-      before do
-        @c = Map.new
-        @c.add_switch Switch.new( {:dpid => 0x1234 } )
-        @c.add_switch Switch.new( {:dpid => 0x5678 } )
-      end
-
-      it "should have add_link" do
-        @c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        expect( @c.links.empty? ).to be_false
-      end
-
-      it "should have lookup_link_by_hash" do
-        @c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        expect( @c.lookup_link_by_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } ) ).not_to be_nil
-      end
-
-      it "should have del_link(Link)" do
-        @c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        @c.del_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        expect( @c.lookup_link_by_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } ) ).to be_nil
-      end
-
-      it "should have del_link(Hash)" do
-        @c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        @c.del_link( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        expect( @c.lookup_link_by_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } ) ).to be_nil
-      end
-
-      it "should have del_link_by_key" do
-        @c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        @c.del_link_by_key [0x1234, 42, 0x5678, 72]
-        expect( @c.lookup_link_by_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } ) ).to be_nil
-      end
-    end
-
-    describe "Switch events" do
-      it "should add Switch on switch up event" do
-        c = Map.new
-        c.update_switch( {:dpid => 0x1234, :up => true } )
-        expect( c.switches ).to include(0x1234)
-
-        expect( c.switches[ 0x1234 ].up? ).to be_true
-        expect( c.switches[ 0x1234 ][:up] ).to be_true
-      end
-
-      it "should delete Switch on switch up event" do
-        c = Map.new
-        c.add_switch Switch.new( {:dpid => 0x1234, :up => true } )
-        c.add_switch Switch.new( {:dpid => 0x5678, :up => true } )
-
-        c.update_switch( {:dpid => 0x1234, :up => false } )
-        expect( c.switches ).not_to include(0x1234)
-        expect( c.switches ).to include(0x5678)
-      end
-
-      it "should update Switch on existing switch's up event" do
-        c = Map.new
-        c.add_switch Switch.new( {:dpid => 0x1234, :up => true, :extra => "Old Value", :no_change => true } )
-        c.update_switch( {:dpid => 0x1234, :up => true, :extra => "New Value" } )
-        expect( c.switches ).to include(0x1234)
-        expect( c.switches[ 0x1234 ].up? ).to be_true
-        expect( c.switches[ 0x1234 ][:up] ).to be_true
-        expect( c.switches[ 0x1234 ][:extra] ).to match("New Value")
-        expect( c.switches[ 0x1234 ][:no_change] ).to be_true
-      end
-    end
-
-    describe "Link event" do
-      before do
-        @c = Map.new
-        @c.add_switch Switch.new( {:dpid => 0x1234, :up => true } )
-        @c.add_switch Switch.new( {:dpid => 0x5678, :up => true } )
-      end
-
-      it "should add Link on link up event" do
-        @c.update_link( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => true, :unstable => false } )
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ].up? ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ].unstable? ).to be_false
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ][:up] ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ][:unstable] ).to be_false
-
-        expect( @c.switches[0x1234].links_out[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-        expect( @c.switches[0x5678].links_in[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-      end
-
-      it "should remove Link on link down event" do
-        @c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } )
-        expect( @c.links.empty? ).to be_false
-
-        @c.update_link( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => false, :unstable => false } )
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ] ).to be_nil
-      end
-
-      it "should update Link on existing link event" do
-        @c.update_link( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => true, :unstable => false } )
-
-        @c.update_link( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => true, :unstable => true } )
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ].up? ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ].unstable? ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ][:up] ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ][:unstable] ).to be_true
-
-        expect( @c.switches[0x1234].links_out[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-        expect( @c.switches[0x5678].links_in[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-      end
-    end
-
-    describe "Link event recoverable error" do
-      before do
-        @c = Map.new
-      end
-      it "should add Switch and Link on link up event, when switch did not exist" do
-        @c.update_link( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => true, :unstable => false } )
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ].up? ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ].unstable? ).to be_false
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ][:up] ).to be_true
-        expect( @c.links[ [0x1234, 42, 0x5678, 72] ][:unstable] ).to be_false
-
-        expect( @c.switches[0x1234].links_out[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-        expect( @c.switches[0x5678].links_in[ [0x1234, 42, 0x5678, 72] ] ).not_to be_nil
-      end
-    end
-
-    describe "Port event" do
-      before do
-        @c = Map.new
-        @c.add_switch Switch.new( {:dpid => 0x1234, :up => true } )
-        @c.add_switch Switch.new( {:dpid => 0x5678, :up => true } )
-      end
-
-      it "should add Port on port up event" do
-        @c.update_port( { :dpid => 0x1234, :portno => 42, :name => "Port Name", :mac => "FF:FF:FF:FF:FF:FF", :external => false, :up => true } )
-        expect( @c.switches[0x1234].ports[42].up? ).to be_true
-        expect( @c.switches[0x1234].ports[42].external? ).to be_false
-        expect( @c.switches[0x1234].ports[42].name ).to eq("Port Name")
-        expect( @c.switches[0x1234].ports[42].mac ).to eq("FF:FF:FF:FF:FF:FF")
-      end
-
-      it "should delete Port on port down event" do
-        @c.update_port( { :dpid => 0x1234, :portno => 42, :name => "Port Name", :mac => "FF:FF:FF:FF:FF:FF", :external => false, :up => false } )
-        expect( @c.switches[0x1234].ports ).not_to include(42)
-      end
-
-      it "should update Port on existing port up event" do
-        @c.update_port( { :dpid => 0x1234, :portno => 42, :name => "Port Name", :mac => "FF:FF:FF:FF:FF:FF", :external => false, :up => true } )
-        @c.update_port( { :dpid => 0x1234, :portno => 42, :name => "New Port Name", :external => false, :up => true } )
-        expect( @c.switches[0x1234].ports[42].up? ).to be_true
-        expect( @c.switches[0x1234].ports[42].external? ).to be_false
-        expect( @c.switches[0x1234].ports[42].name ).to eq("New Port Name")
-        expect( @c.switches[0x1234].ports[42].mac ).to eq("FF:FF:FF:FF:FF:FF")
-      end
-    end
-
-    describe "Port event recoverable error" do
-      before do
-        @c = Map.new
-      end
-      it "should add Switch and Port on port up event, when switch did not exist" do
-        @c.update_port( { :dpid => 0x1234, :portno => 42, :name => "Port Name", :mac => "FF:FF:FF:FF:FF:FF", :external => false, :up => true } )
-        expect( @c.switches[0x1234].ports[42].up? ).to be_true
-        expect( @c.switches[0x1234].ports[42].external? ).to be_false
-        expect( @c.switches[0x1234].ports[42].name ).to eq("Port Name")
-        expect( @c.switches[0x1234].ports[42].mac ).to eq("FF:FF:FF:FF:FF:FF")
-      end
-    end
-
-    it "should be serializable to human readable form by to_s" do
-      c = Map.new
-
-      s = Switch.new( { :dpid => 0x1234, :up => true, :magic => 42 } )
-      s.add_port Port.new( { :dpid => 0x1234, :portno => 42, :up => true, :not_used => 1 } )
-      c.add_switch s
-      c.add_link Link.new( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :not_used => 1, :up => true } )
-      c.add_link Link.new( {:from_dpid => 0xABCD, :from_portno => 102, :to_dpid => 0x1234, :to_portno => 42, :not_used => 1, :up => true } )
-      expect( c.to_s ).to be == <<-EOS
-Map:
-Switch: 0x1234 - {magic:42, up:true}
- Port: 0x1234:42 - {not_used:1, up:true}
- Links_in
-  <= 0xabcd:102
- Links_out
-  => 0x5678:72
-Switch: 0xabcd - {up:true}
- Links_out
-  => 0x1234:42
-Switch: 0x5678 - {up:true}
- Links_in
-  <= 0x1234:42
-Link: (0xabcd:102)->(0x1234:42) - {not_used:1, up:true}
-Link: (0x1234:42)->(0x5678:72) - {not_used:1, up:true}
-      EOS
-    end
-  end
-
-  describe "Map management functions" do
-    before do
-      class DummyController
-        include Topology
-      end
-      @c = DummyController.new
-    end
-
-    it "should respond to get_last_map" do
-      expect( @c ).to respond_to( :get_last_map )
-    end
-
-    it "should respond to get_map" do
-      expect( @c ).to respond_to( :get_map )
-    end
-
-    it "should respond to map_ready?" do
-      expect( @c ).to respond_to( :map_ready? )
-    end
-
-    it "should respond to map_up_to_date?" do
-      expect( @c ).to respond_to( :map_up_to_date? )
-    end
-
-    it "should issue all status request on rebuild request" do
-
-      expect( @c.map_up_to_date? ).to be_false
-
-      @c.should_receive(:get_all_switch_status).and_yield( [ {:dpid => 0x1234, :up => true } ] )
-      @c.should_receive(:get_all_port_status).and_yield( [ {:dpid => 0x1234, :portno => 42, :up => true } ] )
-      @c.should_receive(:get_all_link_status).and_yield( [ {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => true } ] )
-
-      @c.should_receive(:map_ready).once
-
-      @c.send_rebuild_map_request
-
-      expect( @c.map_up_to_date? ).to be_true
-    end
-
-    it "should update Map on Switch update event" do
-      @c.update_map_by_switch_hash( {:dpid => 0x1234, :up => true } )
-      map = @c.get_last_map
-      expect( map.lookup_switch_by_dpid( 0x1234 ) ).not_to be_nil
-
-      @c.update_map_by_switch_hash( {:dpid => 0x1234, :up => false } )
-      map = @c.get_last_map
-      expect( map.lookup_switch_by_dpid( 0x1234 ) ).to be_nil
-    end
-
-    it "should update Map on Port update event" do
-      @c.update_map_by_port_hash( {:dpid => 0x1234, :portno => 42, :up => true } )
-      map = @c.get_last_map
-      expect( map.lookup_switch_by_dpid( 0x1234 ).ports[42] ).not_to be_nil
-
-      @c.update_map_by_port_hash( {:dpid => 0x1234, :portno => 42, :up => false } )
-      map = @c.get_last_map
-      expect( map.lookup_switch_by_dpid( 0x1234 ).ports[42] ).to be_nil
-    end
-
-    it "should update Map on Link update event" do
-      @c.update_map_by_link_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => true } )
-      map = @c.get_last_map
-      expect( map.lookup_link_by_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } ) ).not_to be_nil
-
-      @c.update_map_by_link_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72, :up => false } )
-      map = @c.get_last_map
-      expect( map.lookup_link_by_hash( {:from_dpid => 0x1234, :from_portno => 42, :to_dpid => 0x5678, :to_portno => 72 } ) ).to be_nil
-    end
-
-  end
-end
-
-### Local variables:
-### mode: Ruby
-### coding: utf-8-unix
-### indent-tabs-mode: nil
-### End:
diff --git a/spec/trema/topology-switch_spec.rb b/spec/trema/topology-switch_spec.rb
index 08c4e4d55..a9c75d134 100644
--- a/spec/trema/topology-switch_spec.rb
+++ b/spec/trema/topology-switch_spec.rb
@@ -78,14 +78,8 @@
       s.add_port Port.new( { :dpid => 0x1234, :portno => 1 } )
       expect( s.ports[1] ).not_to be_nil
 
-      s.update_port( { :dpid => 0x1234, :portno => 3, :up => true } )
-      expect( s.ports[3] ).not_to be_nil
-
       s.delete_port Port.new( { :dpid => 0x1234, :portno => 2 } )
       expect( s.ports[2] ).to be_nil
-
-      s.update_port( { :dpid => 0x1234, :portno => 1, :up => false } )
-      expect( s.ports[1] ).to be_nil
     end
 
     it "should have link manipulation methods" do
diff --git a/src/examples/topology/README.md b/src/examples/topology/README.md
index 0e85a198d..14e0efc56 100644
--- a/src/examples/topology/README.md
+++ b/src/examples/topology/README.md
@@ -67,57 +67,6 @@ How to run (show_topology/show_switch_status)
         $ ./trema run src/examples/topology/show-switch_status.rb
 
 
-How to run (change-history.rb)
-------------------------------
-
-1. Change to trema directory and build trema, if you haven't done so already. 
-
-        $ cd $TREMA_HOME
-        $ ./build.rb
-
-2. Start topology daemon.
-
-        $ ./trema run -c src/examples/topology/change-history.conf &
-
-3. Run change-history.rb from trema run 
-
-        $ ./trema run src/examples/topology/change-history.rb
-
-4. Controller will output will be written to change-history.dot in current directory.
-
-        (In another terminal)
-        $ tail -F change-history.dot
-        digraph {
-          subgraph cluster0 {
-            graph [label="Gen 0\ninitial"];
-            "0x1_0" [label="0x1", color="green"];
-            "0x2_0" [label="0x2", color="green"];
-            "0x3_0" [label="0x3", color="green"];
-            "0x1_0" -> "0x2_0" [color="green"];
-            "0x1_0" -> "0x3_0" [color="green"];
-            "0x2_0" -> "0x3_0" [color="green"];
-            "0x3_0" -> "0x2_0" [color="green"];
-            "0x3_0" -> "0x1_0" [color="green"];
-            "0x2_0" -> "0x1_0" [color="green"];
-
-5. See how topology change is notified to dot file.
-   Example: stop switch with dpid 0x3
-
-        (In another terminal)
-        $ ./trema kill 0x3
-
-   Example: restart switch with dpid 0x3
-
-        $ ./trema up 0x3
-
-6. Graphically see topology change history.
-
-        $ dot -Tsvg -O change-history.dot
-        $ firefox change-history.dot.svg
-
-   You may need to install graphviz package to use dot command.
-
-        $ sudo apt-get install graphviz
 
 License & Terms
 ---------------
diff --git a/src/examples/topology/change-history.conf b/src/examples/topology/change-history.conf
deleted file mode 100644
index e838c90f1..000000000
--- a/src/examples/topology/change-history.conf
+++ /dev/null
@@ -1,20 +0,0 @@
-
-1.upto( 3 ).each do | sw |
-  vswitch { dpid sw }
-  1.upto( sw - 1 ).each do | peer |
-    link "%#x" % sw, "%#x" % peer
-  end
-end
-
-run {
-  path "./objects/topology/topology"
-#  options "-l debug"
-}
-
-run {
-  path "./objects/examples/dumper/dumper"
-}
-
-event :port_status => "topology", :packet_in => "filter", :state_notify => "topology"
-filter :lldp => "topology", :packet_in => "dumper"
-
diff --git a/src/examples/topology/change-history.rb b/src/examples/topology/change-history.rb
deleted file mode 100644
index a1eea5d98..000000000
--- a/src/examples/topology/change-history.rb
+++ /dev/null
@@ -1,187 +0,0 @@
-#
-# Copyright (C) 2008-2013 NEC Corporation
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License, version 2, as
-# published by the Free Software Foundation.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
-#
-
-require "trema/topology/map_api"
-
-
-# Controller which keeps printing Switch and Link change event as graphviz dot file.
-# It will shutdown itself if there was no Switch or Link event for 60 seconds.
-#
-class ChangeHistory < Controller
-  include TopologyMap
-
-  # TODO Add option to specify idle check interval.
-  periodic_timer_event :shutdown_on_idle, 60
-
-  oneshot_timer_event :on_start, 0
-  def on_start
-    send_enable_topology_discovery
-    send_rebuild_map_request
-
-    # TODO Add option to specify file from command line.
-    @dotfile = File.open( "change-history.dot", "w" )
-
-    # digraph {
-    puts_dotfile "digraph {"
-    at_exit do
-      # } for digraph
-      puts_dotfile "}"
-    end
-  end
-
-
-  def map_ready g
-    @generation = 0
-
-    # Initially color everything as updated (green)
-    g.switches.each do | _, sw |
-      sw[:color] = "green"
-    end
-    g.links.each do | _, lnk |
-      lnk[:color] = "green"
-    end
-
-    puts_dotfile to_dot_subgraph( g, @generation, "initial" )
-  end
-
-
-  def switch_status_up dpid
-    if not instance_variable_defined?(:@generation) then
-      return nil
-    end
-
-    @generation += 1
-    g = get_last_map
-    remove_old_colors( g, @generation )
-
-    sw = Switch.new( dpid )
-    sw[:generation] = @generation
-    sw[:color] = "green"
-    update_map_by_switch_hash sw
-    sublabel = "0x#{dpid.to_s(16)} up"
-    puts_dotfile to_dot_subgraph( g, @generation, sublabel )
-  end
-
-  
-  def switch_status_down dpid
-    if not instance_variable_defined?(:@generation) then
-      return nil
-    end
-
-    @generation += 1
-    g = get_last_map
-    remove_old_colors( g, @generation )
-
-    sw = Switch.new( dpid )
-    sw.up = false
-    sw[:generation] = @generation
-    g.switches[ dpid ][:color] = "red" if g.switches[ dpid ]
-    sublabel = "0x#{dpid.to_s(16)} down"
-    puts_dotfile to_dot_subgraph( g, @generation, sublabel )
-    # update to new state. (switch instance will be removed)
-    update_map_by_switch_hash sw
-  end
-
-
-  def link_status_updated link_attr
-    if not instance_variable_defined?(:@generation) then
-      return nil
-    end
-    link = Link.new( link_attr )
-
-    @generation += 1
-    link[:generation] = @generation
-
-    g = get_last_map
-    remove_old_colors( g, @generation )
-
-    if link.up? then
-      link[:color] = "green"
-      update_map_by_link_hash link
-      sublabel = "(0x#{link.from_dpid.to_s(16)} -> 0x#{link.to_dpid.to_s(16)}) up"
-      puts_dotfile to_dot_subgraph( g, @generation, sublabel )
-    else
-      g.links[ link.key ][:color] = "red" if g.links[ link.key ]
-      sublabel = "(0x#{link.from_dpid.to_s(16)} -> 0x#{link.to_dpid.to_s(16)}) down"
-      puts_dotfile to_dot_subgraph( g, @generation, sublabel )
-      # update to new state. (link instance will be removed)
-      update_map_by_link_hash link
-    end
-  end
-
-
-  def shutdown_on_idle
-    @last_generation ||= -1
-    if @last_generation == @generation then
-      shutdown!
-    else
-      @last_generation = @generation
-    end
-  end
-
-
-  def remove_old_colors( g, generation )
-    g.switches.each do | _, sw |
-      sw[:generation] ||= 0
-      sw.delete(:color) if sw[:generation] != generation
-    end
-    g.links.each do | _, lnk |
-      lnk[:generation] ||= 0
-      lnk.delete(:color) if lnk[:generation] != generation
-    end
-  end
-
-
-  def to_dot_subgraph( g, generation, sublabel="" )
-    s = "  subgraph cluster#{generation} {\n"
-    s << %Q(    graph [label="Gen #{generation}\\n#{sublabel}"];\n)
-    # // switches
-    g.switches.each do | _, sw |
-      dot_attrs = %Q(label="0x#{sw.dpid.to_s(16)}")
-      if sw.property.has_key?(:color) then
-        dot_attrs << ", " unless dot_attrs.empty?
-        dot_attrs << %Q(color="#{sw[:color]}")
-      end
-      s << %Q(    "0x#{sw.dpid.to_s(16)}_#{generation}" [#{dot_attrs}];\n)
-    end
-    # // links
-    g.links.each do | _, lnk |
-      dot_attrs = ""
-      if lnk.property.has_key?(:color) then
-        dot_attrs << ", " unless dot_attrs.empty?
-        dot_attrs << %Q(color="#{lnk[:color]}")
-      end
-      s << %Q(    "0x#{lnk.from_dpid.to_s(16)}_#{generation}" -> "0x#{lnk.to_dpid.to_s(16)}_#{generation}" [#{dot_attrs}];\n)
-    end
-    # } for subgraph
-    s << "  }\n"
-    return s
-  end
-
-
-  def puts_dotfile s
-    begin
-      @dotfile.puts s
-      @dotfile.flush
-    rescue
-      error "Failed to write dotfile (#{$!.inspect})\n\t#{$!.backtrace.join("\n\t") }"
-      STDERR.puts "Failed to write dotfile."
-      shutdown!
-    end
-  end
-end
-