diff --git a/actionpack/lib/action_controller/caching/fragments.rb b/actionpack/lib/action_controller/caching/fragments.rb
index 806e6a1750811fc3beceb25bbfaf98ff07bd014b..00a7f034d3b6c28c5b305cd61c76a7d33db0988c 100644
--- a/actionpack/lib/action_controller/caching/fragments.rb
+++ b/actionpack/lib/action_controller/caching/fragments.rb
@@ -36,8 +36,8 @@ def fragment_cache_key(key)
 
       def fragment_for(buffer, name = {}, options = nil, &block) #:nodoc:
         if perform_caching
-          if fragment_exist?(name,options)
-            buffer.concat(read_fragment(name, options).html_safe!)
+          if fragment_exist?(name, options)
+            buffer.safe_concat(read_fragment(name, options))
           else
             pos = buffer.length
             block.call
diff --git a/actionpack/lib/action_controller/railtie.rb b/actionpack/lib/action_controller/railtie.rb
index 6b94c32b2a888e4183b935204e5bbe0dfc4f65db..42257f9400d0f00f1062b59410f21a0f6bbc1fc2 100644
--- a/actionpack/lib/action_controller/railtie.rb
+++ b/actionpack/lib/action_controller/railtie.rb
@@ -37,11 +37,33 @@ class Railtie < Rails::Railtie
       ActionController::Base.view_paths = view_path if ActionController::Base.view_paths.blank?
     end
 
+    class MetalMiddlewareBuilder
+      def initialize(metals)
+        @metals = metals
+      end
+
+      def new(app)
+        ActionDispatch::Cascade.new(@metals, app)
+      end
+
+      def name
+        ActionDispatch::Cascade.name
+      end
+      alias_method :to_s, :name
+    end
+
     initializer "action_controller.initialize_metal" do |app|
-      Rails::Rack::Metal.requested_metals = app.config.metals
+      metal_root = "#{Rails.root}/app/metal"
+      load_list = app.config.metals || Dir["#{metal_root}/**/*.rb"]
+
+      metals = load_list.map { |metal|
+        metal = File.basename(metal.gsub("#{metal_root}/", ''), '.rb')
+        require_dependency metal
+        metal.camelize.constantize
+      }.compact
 
-      app.config.middleware.insert_before(:"ActionDispatch::ParamsParser",
-        Rails::Rack::Metal, :if => Rails::Rack::Metal.metals.any?)
+      middleware = MetalMiddlewareBuilder.new(metals)
+      app.config.middleware.insert_before(:"ActionDispatch::ParamsParser", middleware)
     end
 
     # # Prepare dispatcher callbacks and run 'prepare' callbacks
diff --git a/actionpack/test/template/javascript_helper_test.rb b/actionpack/test/template/javascript_helper_test.rb
index f0f686f6e2434686074ba39d1cb00686a8b965a1..03caad3d465161aa367198a93034ccee2e9e0797 100644
--- a/actionpack/test/template/javascript_helper_test.rb
+++ b/actionpack/test/template/javascript_helper_test.rb
@@ -13,8 +13,13 @@ def reset_formats(format)
 
   def setup
     super
+    ActiveSupport.escape_html_entities_in_json  = true
     @template = self
   end
+  
+  def teardown
+    ActiveSupport.escape_html_entities_in_json  = false
+  end
 
   def _evaluate_assigns_and_ivars() end
 
diff --git a/actionpack/test/template/prototype_helper_test.rb b/actionpack/test/template/prototype_helper_test.rb
index 313a769088ee7d7bfec4e5b3b333432bb6fe5cb6..9225153798db223a65b3f6cce22f8c7780b09c83 100644
--- a/actionpack/test/template/prototype_helper_test.rb
+++ b/actionpack/test/template/prototype_helper_test.rb
@@ -317,6 +317,11 @@ class JavaScriptGeneratorTest < PrototypeHelperBaseTest
   def setup
     super
     @generator = create_generator
+    ActiveSupport.escape_html_entities_in_json  = true
+  end
+
+  def teardown
+    ActiveSupport.escape_html_entities_in_json  = false
   end
 
   def _evaluate_assigns_and_ivars() end
diff --git a/railties/lib/rails/rack.rb b/railties/lib/rails/rack.rb
index 9705f65e52b0658aa34a72163e00bea61a3ae133..d487bd0542e5e9647a9f94fa302f5ea0f4cd0bcd 100644
--- a/railties/lib/rails/rack.rb
+++ b/railties/lib/rails/rack.rb
@@ -2,7 +2,6 @@ module Rails
   module Rack
     autoload :Debugger, "rails/rack/debugger"
     autoload :LogTailer, "rails/rack/log_tailer"
-    autoload :Metal, "rails/rack/metal"
     autoload :Static, "rails/rack/static"
   end
 end
diff --git a/railties/lib/rails/rack/metal.rb b/railties/lib/rails/rack/metal.rb
deleted file mode 100644
index 6c0732f732cf1c12a13a64f06f7ae9d568ab4d0b..0000000000000000000000000000000000000000
--- a/railties/lib/rails/rack/metal.rb
+++ /dev/null
@@ -1,59 +0,0 @@
-require 'active_support/ordered_hash'
-require 'active_support/core_ext/class/attribute_accessors'
-require 'active_support/dependencies'
-
-module Rails
-  module Rack
-    class Metal
-      NotFoundResponse = [404, {}, []].freeze
-      NotFound = lambda { NotFoundResponse }
-
-      cattr_accessor :metal_paths
-      self.metal_paths = ["#{Rails.root}/app/metal"]
-      cattr_accessor :requested_metals
-      
-      cattr_accessor :pass_through_on
-      self.pass_through_on = 404
-
-      def self.metals
-        matcher = /#{Regexp.escape('/app/metal/')}(.*)\.rb\Z/
-        metal_glob = metal_paths.map{ |base| "#{base}/**/*.rb" }
-        all_metals = {}
-
-        metal_glob.each do |glob|
-          Dir[glob].sort.map do |file|
-            file = file.match(matcher)[1]
-            all_metals[file.camelize] = file
-          end
-        end
-
-        load_list = requested_metals || all_metals.keys
-
-        load_list.map do |requested_metal|
-          if metal = all_metals[requested_metal]
-            require_dependency metal
-            requested_metal.constantize
-          end
-        end.compact
-      end
-
-      def initialize(app)
-        @app = app
-        @pass_through_on = {}
-        [*self.class.pass_through_on].each { |status| @pass_through_on[status] = true }
-        
-        @metals = ActiveSupport::OrderedHash.new
-        self.class.metals.each { |app| @metals[app] = true }
-        freeze
-      end
-
-      def call(env)
-        @metals.keys.each do |app|
-          result = app.call(env)
-          return result unless @pass_through_on.include?(result[0].to_i)
-        end
-        @app.call(env)
-      end
-    end
-  end
-end
diff --git a/railties/test/application/metal_test.rb b/railties/test/application/metal_test.rb
new file mode 100644
index 0000000000000000000000000000000000000000..225bede117e54ac0fa16226867a3484b768262a2
--- /dev/null
+++ b/railties/test/application/metal_test.rb
@@ -0,0 +1,86 @@
+require 'isolation/abstract_unit'
+
+module ApplicationTests
+  class MetalTest < Test::Unit::TestCase
+    include ActiveSupport::Testing::Isolation
+
+    def setup
+      build_app
+      boot_rails
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+    end
+
+    def app
+      @app ||= begin
+        require "#{app_path}/config/environment"
+        Rails.application
+      end
+    end
+
+    test "single metal endpoint" do
+      app_file 'app/metal/foo_metal.rb', <<-RUBY
+        class FooMetal
+          def self.call(env)
+            [200, { "Content-Type" => "text/html"}, ["FooMetal"]]
+          end
+        end
+      RUBY
+
+      get "/"
+      assert_equal 200, last_response.status
+      assert_equal "FooMetal", last_response.body
+    end
+
+    test "multiple metal endpoints" do
+      app_file 'app/metal/metal_a.rb', <<-RUBY
+        class MetalA
+          def self.call(env)
+            [404, { "Content-Type" => "text/html", "X-Cascade" => "pass" }, ["Metal A"]]
+          end
+        end
+      RUBY
+
+      app_file 'app/metal/metal_b.rb', <<-RUBY
+        class MetalB
+          def self.call(env)
+            [200, { "Content-Type" => "text/html"}, ["Metal B"]]
+          end
+        end
+      RUBY
+
+      get "/"
+      assert_equal 200, last_response.status
+      assert_equal "Metal B", last_response.body
+    end
+
+    test "pass through to application" do
+      app_file 'app/metal/foo_metal.rb', <<-RUBY
+        class FooMetal
+          def self.call(env)
+            [404, { "Content-Type" => "text/html", "X-Cascade" => "pass" }, ["Not Found"]]
+          end
+        end
+      RUBY
+
+      controller :foo, <<-RUBY
+        class FooController < ActionController::Base
+          def index
+            render :text => "foo"
+          end
+        end
+      RUBY
+
+      app_file 'config/routes.rb', <<-RUBY
+        AppTemplate::Application.routes.draw do |map|
+          match ':controller(/:action)'
+        end
+      RUBY
+
+      get "/foo"
+      assert_equal 200, last_response.status
+      assert_equal "foo", last_response.body
+    end
+  end
+end
diff --git a/railties/test/application/middleware_test.rb b/railties/test/application/middleware_test.rb
index 397968a4e7f3c641a83f23a144a486e269733c4d..8ba3a7bdfc29459708228729f6c63a2a966b8fd8 100644
--- a/railties/test/application/middleware_test.rb
+++ b/railties/test/application/middleware_test.rb
@@ -20,6 +20,7 @@ def setup
         "ActionDispatch::ShowExceptions",
         "ActionDispatch::Callbacks",
         "ActionDispatch::Session::CookieStore",
+        "ActionDispatch::Cascade",
         "ActionDispatch::ParamsParser",
         "Rack::MethodOverride",
         "Rack::Head",
diff --git a/railties/test/fixtures/metal/multiplemetals/app/metal/metal_a.rb b/railties/test/fixtures/metal/multiplemetals/app/metal/metal_a.rb
deleted file mode 100644
index 4ca4ddd447dd769b7e0cc9c4a27b44c6b8f7e99a..0000000000000000000000000000000000000000
--- a/railties/test/fixtures/metal/multiplemetals/app/metal/metal_a.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-class MetalA
-  def self.call(env)
-    [404, { "Content-Type" => "text/html"}, ["Metal A"]]
-  end
-end
diff --git a/railties/test/fixtures/metal/multiplemetals/app/metal/metal_b.rb b/railties/test/fixtures/metal/multiplemetals/app/metal/metal_b.rb
deleted file mode 100644
index 80e69fe0b0183926703763feb23f064a8b735645..0000000000000000000000000000000000000000
--- a/railties/test/fixtures/metal/multiplemetals/app/metal/metal_b.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-class MetalB
-  def self.call(env)
-    [200, { "Content-Type" => "text/html"}, ["Metal B"]]
-  end
-end
diff --git a/railties/test/fixtures/metal/pluralmetal/app/metal/legacy_routes.rb b/railties/test/fixtures/metal/pluralmetal/app/metal/legacy_routes.rb
deleted file mode 100644
index 0cd3737c3211f0864f38b5d57bda7091eab67cbe..0000000000000000000000000000000000000000
--- a/railties/test/fixtures/metal/pluralmetal/app/metal/legacy_routes.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-class LegacyRoutes < Rails::Rack::Metal
-  def self.call(env)
-    [301, { "Location" => "http://example.com"}, []]
-  end
-end
diff --git a/railties/test/fixtures/metal/singlemetal/app/metal/foo_metal.rb b/railties/test/fixtures/metal/singlemetal/app/metal/foo_metal.rb
deleted file mode 100644
index 5f5b0875928f1fe5d737b0a6d287d6d3f62c5b53..0000000000000000000000000000000000000000
--- a/railties/test/fixtures/metal/singlemetal/app/metal/foo_metal.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-class FooMetal < Rails::Rack::Metal
-  def self.call(env)
-    [200, { "Content-Type" => "text/html"}, ["Hi"]]
-  end
-end
diff --git a/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_a.rb b/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_a.rb
deleted file mode 100644
index 25b3bb0abc67994ecd719f63de0598e6640e5eee..0000000000000000000000000000000000000000
--- a/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_a.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-module Folder
-  class MetalA < Rails::Rack::Metal
-    def self.call(env)
-      [200, { "Content-Type" => "text/html"}, ["Hi"]]
-    end
-  end
-end
diff --git a/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_b.rb b/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_b.rb
deleted file mode 100644
index 7583363f714f8dd5cade0f9cb35a2c2f595d3644..0000000000000000000000000000000000000000
--- a/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_b.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-module Folder
-  class MetalB < Rails::Rack::Metal
-    def self.call(env)
-      [200, { "Content-Type" => "text/html"}, ["Hi"]]
-    end
-  end
-end
diff --git a/railties/test/metal_test.rb b/railties/test/metal_test.rb
deleted file mode 100644
index 91f55c2b5e6af7bfbb551360aacc429373a1c9a3..0000000000000000000000000000000000000000
--- a/railties/test/metal_test.rb
+++ /dev/null
@@ -1,101 +0,0 @@
-require 'abstract_unit'
-
-class MetalTest < Test::Unit::TestCase
-  def test_metals_should_return_list_of_found_metal_apps
-    use_appdir("singlemetal") do
-      assert_equal(["FooMetal"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metals_should_respect_class_name_conventions
-    use_appdir("pluralmetal") do
-      assert_equal(["LegacyRoutes"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metals_should_return_alphabetical_list_of_found_metal_apps
-    use_appdir("multiplemetals") do
-      assert_equal(["MetalA", "MetalB"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metals_load_order_should_be_overriden_by_requested_metals
-    use_appdir("multiplemetals") do
-      Rails::Rack::Metal.requested_metals = ["MetalB", "MetalA"]
-      assert_equal(["MetalB", "MetalA"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metals_not_listed_should_not_load
-    use_appdir("multiplemetals") do
-      Rails::Rack::Metal.requested_metals = ["MetalB"]
-      assert_equal(["MetalB"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metal_finding_should_work_with_subfolders
-    use_appdir("subfolders") do
-      assert_equal(["Folder::MetalA", "Folder::MetalB"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metal_finding_with_requested_metals_should_work_with_subfolders
-    use_appdir("subfolders") do
-      Rails::Rack::Metal.requested_metals = ["Folder::MetalB"]
-      assert_equal(["Folder::MetalB"], found_metals_as_string_array)
-    end
-  end
-
-  def test_metal_finding_should_work_with_multiple_metal_paths_in_185_and_below
-    use_appdir("singlemetal") do
-      engine_metal_path = "#{File.dirname(__FILE__)}/fixtures/plugins/engines/engine/app/metal" 
-      Rails::Rack::Metal.metal_paths << engine_metal_path
-      $LOAD_PATH << engine_metal_path
-      assert_equal(["FooMetal", "EngineMetal"], found_metals_as_string_array)
-    end
-  end
-  
-  def test_metal_default_pass_through_on_404
-    use_appdir("multiplemetals") do
-      result = Rails::Rack::Metal.new(app).call({})
-      assert_equal 200, result.first
-      assert_equal ["Metal B"], result.last
-    end
-  end
-  
-  def test_metal_pass_through_on_417
-    use_appdir("multiplemetals") do
-      Rails::Rack::Metal.pass_through_on = 417
-      result = Rails::Rack::Metal.new(app).call({})
-      assert_equal 404, result.first
-      assert_equal ["Metal A"], result.last
-    end
-  end
-  
-  def test_metal_pass_through_on_404_and_200
-    use_appdir("multiplemetals") do
-      Rails::Rack::Metal.pass_through_on = [404, 200]
-      result = Rails::Rack::Metal.new(app).call({})
-      assert_equal 402, result.first
-      assert_equal ["End of the Line"], result.last
-    end
-  end
-
-  private
-  
-  def app
-    lambda{|env|[402,{},["End of the Line"]]}
-  end
-
-  def use_appdir(root)
-    dir = "#{File.dirname(__FILE__)}/fixtures/metal/#{root}"
-    Rails::Rack::Metal.metal_paths = ["#{dir}/app/metal"]
-    Rails::Rack::Metal.requested_metals = nil
-    $LOAD_PATH << "#{dir}/app/metal"
-    yield
-  end
-
-  def found_metals_as_string_array
-    Rails::Rack::Metal.metals.map { |m| m.to_s }
-  end
-end