diff --git a/lib/ross/client.rb b/lib/ross/client.rb
index d8f402d..b45a9c6 100644
--- a/lib/ross/client.rb
+++ b/lib/ross/client.rb
@@ -1,5 +1,6 @@
 # coding: utf-8
 require 'rest-client'
+require 'base64'
 
 module ROSS
   class Client
@@ -9,43 +10,108 @@ def initialize(options)
       @bucket_name = options[:bucket_name]
       @appid = options[:appid]
       @appkey = options[:appkey]
-      @aliyun_host = "oss.aliyuncs.com"
+      @aliyun_host = options[:bucket_host] || "oss.aliyuncs.com"
       if options[:aliyun_internal] == true
         @aliyun_host = "oss-internal.aliyuncs.com"
       end
     end
     
-    def put(path, file, options={})
-      content_md5 = Digest::MD5.hexdigest(file)
-      content_type = options[:content_type] || "image/jpg"
+    def put(path, content, options={}, xoss = {})
+      # content_md5 = Digest::MD5.hexdigest(content)
+      content_type = options.has_key?(:content_type) ? options[:content_type] : "application/octet-stream"
       date = Time.now.gmtime.strftime("%a, %d %b %Y %H:%M:%S GMT")
-      path = "#{@bucket_name}/#{path}"
-      url = "http://#{@aliyun_host}/#{path}"
-      auth_sign = sign("PUT", path, content_md5, content_type, date)
       headers = {
-                  "Authorization" => auth_sign, 
-                  "Content-Type" => content_type,
-                  "Content-Length" => file.length,
-                  "Date" => date,
-                  "Host" => @aliyun_host,
-                }
-                
-      response = RestClient.put(url, file, headers)
+        "Authorization" => auth_sign("PUT", path, date, content_type, nil, xoss),
+        "Content-Type" => content_type,
+        "Date" => date,
+        "Host" => @aliyun_host
+      }
+      headers["Content-Length"] = content.length unless content.nil? # content can be nil
+      xoss.each_pair{|k,v| headers["x-oss-#{k}"] = v }
+      response = RestClient.put(request_url(path), content, headers)
+    end
+
+    def delete(path)
+      date = Time.now.gmtime.strftime("%a, %d %b %Y %H:%M:%S GMT")
+      headers = {
+        "Authorization" => auth_sign("DELETE", path, date),
+        "Content-Type" => nil,
+        "Date" => date,
+        "Host" => @aliyun_host
+      }
+      response = RestClient.delete(request_url(path), headers)
+    end
+
+    def head(path)
+      date = Time.now.gmtime.strftime("%a, %d %b %Y %H:%M:%S GMT")
+      headers = {
+        "Authorization" => auth_sign("HEAD", path, date),
+        "Content-Type" => nil,
+        "Date" => date,
+        "Host" => @aliyun_host
+      }
+      response = RestClient.head(request_url(path), headers)
+    end
+
+    def exists?(path)
+      begin
+        head(path)
+      rescue RestClient::ResourceNotFound
+        false
+      else
+        true
+      end
+    end
+
+    def copy(sour_path, dest_path)
+      put(dest_path, nil, {content_type: nil}, {'copy-source' => bucket_path(sour_path)})
+    end
+
+    def rename(sour_path, dest_path)
+      copy(sour_path, dest_path)
+      delete(sour_path)
+    end
+
+    def put_file(path, file, options = {})
+      put(path, File.read(file), options)
     end
     
-    def get(path)
-      return "http://#{@bucket_name}.#{@aliyun_host}/#{path}"
+    def public_url(path)
+      "http://#{@bucket_name}.#{@aliyun_host}/#{path}"
+    end
+
+    alias :get :public_url
+
+    def private_url(path, expires_in = 3600)
+      expires_at = (8*3600 + Time.now.gmtime.to_i) + expires_in
+      params = {
+        'Expires' => expires_at,
+        'OSSAccessKeyId' => @appid,
+        'Signature' => sign('GET', path, expires_at)
+      }
+      public_url(path) + '?' + URI.encode_www_form(params)
     end
     
     private
-    def sign(verb, path, content_md5, content_type, date)
-      canonicalized_oss_headers = ''
-      canonicalized_resource = "/#{path}"
+    def sign(verb, path, date, content_type = nil, content_md5 = nil, xoss = {})
+      canonicalized_oss_headers = xoss.sort.map{|k,v| "x-oss-#{k}:".downcase + v + "\n"}.join
+      canonicalized_resource = bucket_path(path)
       string_to_sign = "#{verb}\n\n#{content_type}\n#{date}\n#{canonicalized_oss_headers}#{canonicalized_resource}"
-      digest = OpenSSL::Digest::Digest.new('sha1')
+      digest = OpenSSL::Digest.new('sha1')
       h = OpenSSL::HMAC.digest(digest, @appkey, string_to_sign)
-      h = Base64.encode64(h)
-      "OSS #{@appid}:#{h}"
+      Base64.encode64(h).strip
+    end
+
+    def auth_sign(verb, path, date, content_type = nil, content_md5 = nil, xoss = {})
+      "OSS #{@appid}:#{sign(verb, path, date, content_type, content_md5, xoss)}"
+    end
+
+    def bucket_path(path)
+      "/#{@bucket_name}/#{path.gsub(/^\//, '')}"
+    end
+
+    def request_url(path)
+      "http://#{@aliyun_host}/#{@bucket_name}/#{URI.encode(path)}"
     end
   end
 end
\ No newline at end of file
diff --git a/ross.gemspec b/ross.gemspec
index 8326f2b..a873522 100644
--- a/ross.gemspec
+++ b/ross.gemspec
@@ -1,7 +1,7 @@
 # coding: utf-8
 Gem::Specification.new do |s|
   s.name = 'ross'
-  s.version = '0.0.1'
+  s.version = '0.0.2'
   s.platform = Gem::Platform::RUBY
   s.summary = "ROSS is a ruby client for aliyun oss"
   s.authors = ["Fizz Wu"]