diff --git a/README.md b/README.md
index e52ef13..7e11551 100644
--- a/README.md
+++ b/README.md
@@ -30,14 +30,47 @@ $ bundle
 ### Config
 
 ```ruby
+# required
 WxPay.appid = 'YOUR_APPID'
 WxPay.key = 'YOUR_KEY'
 WxPay.mch_id = 'YOUR_MCH_ID'
+
+# optional
+WxPay.extra_rest_client_options = {timeout: 2, open_timeout: 3}
 ```
 
 ### APIs
 
-**PLACEHOLDER**
+**Check official document for detailed request params and return fields**
+
+#### unifiedorder
+ 
+```ruby
+# required fields 
+params = {
+body: '测试商品',
+out_trade_no: 'test003',
+total_fee: 1,
+spbill_create_ip: '127.0.0.1',
+notify_url: 'http://making.dev',
+trade_type: 'JSAPI'
+}
+
+# Return a WxPay::Result instance(subclass of Hash) contains parsed result
+r = WxPay::Service.invoke_unifiedorder params
+# => {"return_code"=>"SUCCESS",
+#     "return_msg"=>"OK",
+#     "appid"=>"YOUR APPID",
+#     "mch_id"=>"YOUR MCH_ID",
+#     "nonce_str"=>"8RN7YfTZ3OUgWX5e",
+#     "sign"=>"623AE90C9679729DDD7407DC7A1151B2",
+#     "result_code"=>"SUCCESS",
+#     "prepay_id"=>"wx2014111104255143b7605afb0314593866",
+#     "trade_type"=>"JSAPI"}
+
+# Return true if both return_code and result_code equal SUCCESS
+r.success? # => true
+```
 
 ## Contributing
 
diff --git a/lib/wx_pay.rb b/lib/wx_pay.rb
index 9cdb48d..72ef3a9 100644
--- a/lib/wx_pay.rb
+++ b/lib/wx_pay.rb
@@ -1,7 +1,6 @@
-require 'wx_pay/utils'
+require 'wx_pay/result'
 require 'wx_pay/sign'
 require 'wx_pay/service'
-require 'wx_pay/notify'
 
 module WxPay
   class<< self
diff --git a/lib/wx_pay/notify.rb b/lib/wx_pay/notify.rb
deleted file mode 100644
index 01c3b59..0000000
--- a/lib/wx_pay/notify.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-module WxPay
-  module Notify
-    GATEWAY = 'https://gw.tenpay.com/gateway/simpleverifynotifyid.xml'
-    SUCCESS_STR = '<retcode>0</retcode>'
-
-    def self.verify?(params)
-      return false unless Sign.verify?(params)
-
-      params = {
-          'input_charset' => 'UTF-8',
-          'partner' => WxPay.appid,
-          'notify_id' => CGI.escape(params[:notify_id].to_s)
-      }
-
-      open("#{GATEWAY}?#{Utils.make_query_string(params)}").read.include?(SUCCESS_STR)
-    end
-  end
-end
diff --git a/lib/wx_pay/result.rb b/lib/wx_pay/result.rb
new file mode 100644
index 0000000..92622fe
--- /dev/null
+++ b/lib/wx_pay/result.rb
@@ -0,0 +1,19 @@
+module WxPay
+  class Result < ::Hash
+    SUCCESS_FLAG = 'SUCCESS'.freeze
+
+    def initialize(result)
+      super
+
+      if result['xml'].class == Hash
+        result['xml'].each_pair do |k, v|
+          self[k] = v
+        end
+      end
+    end
+
+    def success?
+      self['return_code'] == SUCCESS_FLAG && self['result_code'] == SUCCESS_FLAG
+    end
+  end
+end
diff --git a/lib/wx_pay/service.rb b/lib/wx_pay/service.rb
index 6808805..f47eb94 100644
--- a/lib/wx_pay/service.rb
+++ b/lib/wx_pay/service.rb
@@ -8,14 +8,18 @@ module WxPay
     INVOKE_UNIFIEDORDER_REQUIRED_FIELDS = %i(body out_trade_no total_fee spbill_create_ip notify_url trade_type)
     def self.invoke_unifiedorder(params)
       params = {
-        app_id: WxPay.appid,
+        appid: WxPay.appid,
         mch_id: WxPay.mch_id,
         nonce_str: SecureRandom.uuid.tr('-', ''),
       }.merge(params)
 
       check_required_options(params, INVOKE_UNIFIEDORDER_REQUIRED_FIELDS)
 
-      WxPay::Utils.invoke_remote("#{GATEWAY_URL}/unifiedorder", WxPay::Utils.make_payload(params))
+      r = invoke_remote("#{GATEWAY_URL}/unifiedorder", make_payload(params))
+
+      yield r if block_given?
+
+      r
     end
 
     private
@@ -25,5 +29,26 @@ module WxPay
         warn("WxPay Warn: missing required option: #{name}") unless options.has_key?(name)
       end
     end
+
+    def self.make_payload(params)
+      "<xml>#{params.map { |k, v| "<#{k}>#{v}</#{k}>" }.join}<sign>#{WxPay::Sign.generate(params)}</sign></xml>"
+    end
+
+    def self.invoke_remote(url, payload)
+      r = RestClient::Request.execute(
+        {
+          method: :post,
+          url: url,
+          payload: payload,
+          headers: { content_type: 'application/xml' }
+        }.merge(WxPay.extra_rest_client_options)
+      )
+
+      if r
+        WxPay::Result.new Hash.from_xml(r)
+      else
+        nil
+      end
+    end
   end
 end
diff --git a/lib/wx_pay/sign.rb b/lib/wx_pay/sign.rb
index be44a53..9b54061 100644
--- a/lib/wx_pay/sign.rb
+++ b/lib/wx_pay/sign.rb
@@ -11,8 +11,8 @@ module WxPay
     end
 
     def self.verify?(params)
-      params = Utils.stringify_keys(params)
-      sign = params.delete('sign')
+      params = params.dup
+      sign = params.delete('sign') || params.delete(:sign)
 
       generate(params) == sign
     end
diff --git a/lib/wx_pay/utils.rb b/lib/wx_pay/utils.rb
deleted file mode 100644
index 5585866..0000000
--- a/lib/wx_pay/utils.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-module WxPay
-  module Utils
-    def self.stringify_keys(hash)
-      new_hash = {}
-      hash.each do |key, value|
-        new_hash[(key.to_s rescue key) || key] = value
-      end
-      new_hash
-    end
-
-    def self.make_payload(params)
-      "<xml>#{params.map {|k, v| "<#{k}>#{v}</#{k}>"}.join}<sign>#{WxPay::Sign.generate(params)}</sign></xml>"
-    end
-
-    def self.invoke_remote(url, payload)
-      Hash.from_xml(
-        RestClient::Request.execute(
-          {
-            method: :post,
-            url: url,
-            payload: payload,
-            headers: {content_type: 'application/xml'}
-          }.merge(WxPay.extra_rest_client_options))
-      )
-    end
-  end
-end
diff --git a/lib/wx_pay/version.rb b/lib/wx_pay/version.rb
index b867320..b74bf19 100644
--- a/lib/wx_pay/version.rb
+++ b/lib/wx_pay/version.rb
@@ -1,3 +1,3 @@
 module WxPay
-  VERSION = "0.0.1"
+  VERSION = "0.0.2"
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 6420426..5f9e6f8 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,4 @@
+require 'active_support/core_ext/hash/conversions'
 require 'minitest/autorun'
 require 'wx_pay'
 require 'fakeweb'
diff --git a/test/wx_pay/result_test.rb b/test/wx_pay/result_test.rb
new file mode 100644
index 0000000..47e2b2c
--- /dev/null
+++ b/test/wx_pay/result_test.rb
@@ -0,0 +1,29 @@
+require 'test_helper'
+
+class WxPay::ResultTest < MiniTest::Test
+  def test_success_method_with_true
+    r = WxPay::Result.new(
+      Hash.from_xml(
+        <<-XML
+        <xml>
+          <return_code>SUCCESS</return_code>
+          <result_code>SUCCESS</result_code>
+        </xml>
+        XML
+      ))
+
+    assert_equal r.success?, true
+  end
+
+  def test_success_method_with_false
+    r = WxPay::Result.new(
+      Hash.from_xml(
+        <<-XML
+        <xml>
+        </xml>
+        XML
+      ))
+
+    assert_equal r.success?, false
+  end
+end
diff --git a/test/wx_pay/sign_test.rb b/test/wx_pay/sign_test.rb
index 7a8cd4e..7b4a5e6 100644
--- a/test/wx_pay/sign_test.rb
+++ b/test/wx_pay/sign_test.rb
@@ -1,6 +1,6 @@
 require 'test_helper'
 
-class WxPay::SignTest < MiniTest::Unit::TestCase
+class WxPay::SignTest < MiniTest::Test
   def setup
     @params = {
       appid: 'wxd930ea5d5a258f4f',
diff --git a/test/wx_pay/utils_test.rb b/test/wx_pay/utils_test.rb
deleted file mode 100644
index 520e1a7..0000000
--- a/test/wx_pay/utils_test.rb
+++ /dev/null
@@ -1,8 +0,0 @@
-require 'test_helper'
-
-class WxPay::UtilsTest < MiniTest::Unit::TestCase
-  def test_stringify_keys
-    hash = { 'a' => 1, :b => 2 }
-    assert_equal({ 'a' => 1, 'b' => 2 }.sort, WxPay::Utils.stringify_keys(hash).sort)
-  end
-end
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