diff --git a/app/assets/javascripts/discourse/initializers/1_init_message_bus.js b/app/assets/javascripts/discourse/initializers/1_init_message_bus.js
index 04bce514c..8d644b103 100644
--- a/app/assets/javascripts/discourse/initializers/1_init_message_bus.js
+++ b/app/assets/javascripts/discourse/initializers/1_init_message_bus.js
@@ -8,8 +8,9 @@ Discourse.addInitializer(function() {
 
   Discourse.MessageBus.alwaysLongPoll = Discourse.Environment === "development";
   Discourse.MessageBus.start();
+
   Discourse.MessageBus.subscribe("/global/asset-version", function(version){
-    Discourse.set("assetVersion",version);
+    Discourse.set("assetVersion", version);
 
     if(Discourse.get("requiresRefresh")) {
       // since we can do this transparently for people browsing the forum
@@ -24,5 +25,15 @@ Discourse.addInitializer(function() {
     }
 
   });
+
+  Discourse.set("isReadOnly", Discourse.Site.currentProp("is_readonly"));
+
+  Discourse.MessageBus.subscribe("/global/read-only", function (enabled) {
+    Discourse.set("isReadOnly", enabled);
+    if (enabled) {
+      bootbox.alert(I18n.t("read_only_mode_enabled"));
+    }
+  });
+
   Discourse.KeyValueStore.init("discourse_", Discourse.MessageBus);
 }, true);
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 234b0a7c5..3170aff42 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -29,7 +29,7 @@ class ApplicationController < ActionController::Base
   before_filter :set_mobile_view
   before_filter :inject_preview_style
   before_filter :disable_customization
-  before_filter :block_if_maintenance_mode
+  before_filter :block_if_readonly_mode
   before_filter :authorize_mini_profiler
   before_filter :store_incoming_links
   before_filter :preload_json
@@ -50,7 +50,6 @@ class ApplicationController < ActionController::Base
     raise
   end
 
-
   # Some exceptions
   class RenderEmpty < Exception; end
 
@@ -87,6 +86,11 @@ class ApplicationController < ActionController::Base
     rescue_discourse_actions("[error: 'invalid access']", 403) # TODO: this breaks json responses
   end
 
+  rescue_from Discourse::ReadOnly do
+    # can this happen on a not .json format?
+    render json: failed_json.merge(message: I18n.t("read_only_mode_enabled"))
+  end
+
   def rescue_discourse_actions(message, error)
     if request.format && request.format.json?
       # TODO: this doesn't make sense. Stuffing an html page into a json response will cause
@@ -249,16 +253,6 @@ class ApplicationController < ActionController::Base
       end
     end
 
-    def block_if_maintenance_mode
-      if Discourse.maintenance_mode?
-        if request.format.json?
-          render status: 503, json: failed_json.merge(message: I18n.t('site_under_maintenance'))
-        else
-          render status: 503, file: File.join( Rails.root, 'public', '503.html' ), layout: false
-        end
-      end
-    end
-
     def mini_profiler_enabled?
       defined?(Rack::MiniProfiler) && current_user.try(:admin?)
     end
@@ -288,6 +282,11 @@ class ApplicationController < ActionController::Base
       redirect_to :login if SiteSetting.login_required?
     end
 
+    def block_if_readonly_mode
+      return if request.put? && request.fullpath == "/admin/backups/readonly"
+      raise Discourse::ReadOnly.new unless request.get? || !Discourse.readonly_mode?
+    end
+
     def build_not_found_page(status=404, layout=false)
       @top_viewed = Topic.top_viewed(10)
       @recent = Topic.recent(10)
diff --git a/app/serializers/site_serializer.rb b/app/serializers/site_serializer.rb
index c3953a8da..0f2f1b699 100644
--- a/app/serializers/site_serializer.rb
+++ b/app/serializers/site_serializer.rb
@@ -8,7 +8,8 @@ class SiteSerializer < ApplicationSerializer
              :periods,
              :top_menu_items,
              :anonymous_top_menu_items,
-             :uncategorized_category_id # this is hidden so putting it here
+             :uncategorized_category_id, # this is hidden so putting it here
+             :is_readonly
 
   has_many :categories, serializer: BasicCategorySerializer, embed: :objects
   has_many :post_action_types, embed: :objects
@@ -45,4 +46,8 @@ class SiteSerializer < ApplicationSerializer
     SiteSetting.uncategorized_category_id
   end
 
+  def is_readonly
+    Discourse.readonly_mode?
+  end
+
 end
diff --git a/config/site_settings.yml b/config/site_settings.yml
index a88b1234d..dd8e54f7a 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -409,7 +409,9 @@ uncategorized:
   summary_likes_required: 1
   summary_percent_filter: 20
   send_welcome_message: true
-  allow_import: false
+  allow_import:
+    client: true
+    default: false
   educate_until_posts:
     client: true
     default: 2
diff --git a/lib/discourse.rb b/lib/discourse.rb
index f6e02c7e2..1f67d21f9 100644
--- a/lib/discourse.rb
+++ b/lib/discourse.rb
@@ -27,6 +27,9 @@ module Discourse
 
   class InvalidPost < Exception; end
 
+  # When read-only mode is enabled
+  class ReadOnly < Exception; end
+
   # Cross site request forgery
   class CSRF < Exception; end
 
@@ -138,18 +141,20 @@ module Discourse
     return base_url_no_prefix + base_uri
   end
 
-  def self.enable_maintenance_mode
-    $redis.set maintenance_mode_key, 1
+  def self.enable_readonly_mode
+    $redis.set readonly_mode_key, 1
+    MessageBus.publish(readonly_channel, true)
     true
   end
 
-  def self.disable_maintenance_mode
-    $redis.del maintenance_mode_key
+  def self.disable_readonly_mode
+    $redis.del readonly_mode_key
+    MessageBus.publish(readonly_channel, false)
     true
   end
 
-  def self.maintenance_mode?
-    !!$redis.get( maintenance_mode_key )
+  def self.readonly_mode?
+    !!$redis.get(readonly_mode_key)
   end
 
   def self.git_version
@@ -198,9 +203,12 @@ module Discourse
     Rails.configuration.action_controller.asset_host
   end
 
-private
-
-  def self.maintenance_mode_key
-    'maintenance_mode'
+  def self.readonly_mode_key
+    "readonly_mode"
   end
+
+  def self.readonly_channel
+    "/global/read-only"
+  end
+
 end
diff --git a/spec/components/discourse_spec.rb b/spec/components/discourse_spec.rb
index 66a128ead..402f4535c 100644
--- a/spec/components/discourse_spec.rb
+++ b/spec/components/discourse_spec.rb
@@ -82,5 +82,39 @@ describe Discourse do
 
   end
 
+  context "#enable_readonly_mode" do
+
+    it "adds a key in redis and publish a message through the message bus" do
+      $redis.expects(:set).with(Discourse.readonly_mode_key, 1)
+      MessageBus.expects(:publish).with(Discourse.readonly_channel, true)
+      Discourse.enable_readonly_mode
+    end
+
+  end
+
+  context "#disable_readonly_mode" do
+
+    it "removes a key from redis and publish a message through the message bus" do
+      $redis.expects(:del).with(Discourse.readonly_mode_key)
+      MessageBus.expects(:publish).with(Discourse.readonly_channel, false)
+      Discourse.disable_readonly_mode
+    end
+
+  end
+
+  context "#readonly_mode?" do
+
+    it "returns true when the key is present in redis" do
+      $redis.expects(:get).with(Discourse.readonly_mode_key).returns("1")
+      Discourse.readonly_mode?.should == true
+    end
+
+    it "returns false when the key is not present in redis" do
+      $redis.expects(:get).with(Discourse.readonly_mode_key).returns(nil)
+      Discourse.readonly_mode?.should == false
+    end
+
+  end
+
 end