diff --git a/.gitignore b/.gitignore
index 20535e3..6311c3e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,7 @@
 .project
 .pydevproject
 .settings
+*.swp
 build/
 dist/
 MANIFEST
diff --git a/docs/source/conf.py b/docs/source/conf.py
index bce5d90..43be1a0 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -49,9 +49,9 @@
 # built documents.
 #
 # The short X.Y version.
-version = '0.6'
+version = '0.7'
 # The full version, including alpha/beta/rc tags.
-release = '0.6.3'
+release = '0.7.0'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/docs/source/predictionio.rst b/docs/source/predictionio.rst
index 4890e5c..4249a99 100644
--- a/docs/source/predictionio.rst
+++ b/docs/source/predictionio.rst
@@ -79,6 +79,18 @@
 
     >>> result = client.get_itemsim_topn("engine-2", "i200", 5)
 
+  To get top 5 similar items given a list of items i200,i300,i400 from the item similarity engine "engine-2"
+
+    >>> result = client.get_itemsim_topn("engine-2", "i200,i300,i400", 5)
+
+**Item Rank Engine**
+
+  To rank a list of items i100, i101, i102, i103 for user "u100" from the item rank engine "engine-3"
+
+    >>> client.identify("u100")
+    >>> result = client.get_itemrank_ranked("engine-3", ["i100","i101","i102", "i103"])
+
+
 Please refer to the documentation of the :class:`predictionio.Client` class for more details of all available methods.
 
 
@@ -193,7 +205,7 @@
   .. automethod:: pending_requests
 
     .. versionadded:: 0.6.1
-    
+
   |
 
   .. _sync-methods-label:
@@ -224,13 +236,17 @@
 
     .. versionadded:: 0.6.0
 
+  .. automethod:: get_itemrank_ranked
+
+    .. versionadded:: 0.7.0
+
   .. automethod:: get_itemrec
-  
+
     .. deprecated:: 0.5.0
       Use :func:`get_itemrec_topn` instead.
 
   .. automethod:: user_conversion_item
-      
+
     .. deprecated:: 0.5.0
       Use :func:`record_action_on_item` instead.
 
@@ -283,6 +299,10 @@
 
     .. versionadded:: 0.6.0
 
+  .. automethod:: aget_itemrank_ranked
+
+    .. versionadded:: 0.7.0
+
   .. automethod:: aget_itemrec
 
     .. deprecated:: 0.5.0
@@ -314,5 +334,3 @@
       Use :func:`arecord_action_on_item` instead.
 
   .. automethod:: aresp
-
-
diff --git a/examples/__init__.py b/examples/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/examples/__init__.py
diff --git a/examples/itemrec/__init__.py b/examples/itemrec/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/examples/itemrec/__init__.py
diff --git a/examples/itemrec/movies/README.md b/examples/itemrec/movies/README.md
new file mode 100644
index 0000000..9ef357a
--- /dev/null
+++ b/examples/itemrec/movies/README.md
@@ -0,0 +1,15 @@
+PredictionIO Python SDK Example
+===============================
+
+Please execute all commands from repository root.
+
+Step 1. Get sample data and unzip it.
+
+    > wget http://www.grouplens.org/system/files/ml-100k.zip
+    > unzip ml-100k.zip
+
+Step 2. Configurate examples/itemrec/movies/appdata.py
+
+Step 3. Run this app:
+
+    > python -m examples.itemrec.movies.movie_rec_app
diff --git a/examples/itemrec/movies/__init__.py b/examples/itemrec/movies/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/examples/itemrec/movies/__init__.py
diff --git a/examples/itemrec/movies/app_config.py b/examples/itemrec/movies/app_config.py
index 24636ab..5efa7a0 100644
--- a/examples/itemrec/movies/app_config.py
+++ b/examples/itemrec/movies/app_config.py
@@ -1,4 +1,2 @@
-
-APP_KEY = 'wWKeyokhpwEgis9BHCHkwqB7Hcop0OEF6KzkZWXfz2uMJYjl2QDwNlFVGl5hhHfy'
+APP_KEY = 'uJKTKyUAFNZYQQO5yxkdrSo3XIlaf9LXejI63CWE0mtZVEYF89hyVtOwpMKfXXXX'
 API_URL = 'http://localhost:8000'
-
diff --git a/examples/itemrec/movies/appdata.py b/examples/itemrec/movies/appdata.py
index f7dad34..fb3c7fd 100644
--- a/examples/itemrec/movies/appdata.py
+++ b/examples/itemrec/movies/appdata.py
@@ -15,134 +15,134 @@
 
 
 class User:
-	def __init__(self, uid):
-		self.uid = uid
-		self.rec = [] # recommendations, list of iid
+  def __init__(self, uid):
+    self.uid = uid
+    self.rec = [] # recommendations, list of iid
 
-	def __str__(self):
-		return "User[uid=%s,rec=%s]" % (self.uid, self.rec)
+  def __str__(self):
+    return "User[uid=%s,rec=%s]" % (self.uid, self.rec)
 
 class Item:
-	def __init__(self, iid, name):
-		self.iid = iid
-		self.name = name
+  def __init__(self, iid, name):
+    self.iid = iid
+    self.name = name
 
-	def __str__(self):
-		return "Item[iid=%s,name=%s]" % (self.iid, self.name)
+  def __str__(self):
+    return "Item[iid=%s,name=%s]" % (self.iid, self.name)
 
 class RateAction:
-	def __init__(self, uid, iid, rating, t):
-		self.uid = uid
-		self.iid = iid
-		self.rating = rating
-		self.t = t
+  def __init__(self, uid, iid, rating, t):
+    self.uid = uid
+    self.iid = iid
+    self.rating = rating
+    self.t = t
 
-	def __str__(self):
-		return "RateAction[uid=%s,iid=%s,rating=%s,t=%s]" % (self.uid, self.iid, self.rating, self.t)
+  def __str__(self):
+    return "RateAction[uid=%s,iid=%s,rating=%s,t=%s]" % (self.uid, self.iid, self.rating, self.t)
 
 
 class AppData:
 
-	def __init__(self):
-		self._users = {} # dict of User obj
-		self._items = {} # dict of Item obj
-		self._rate_actions = [] # list of RateAction obj
+  def __init__(self):
+    self._users = {} # dict of User obj
+    self._items = {} # dict of Item obj
+    self._rate_actions = [] # list of RateAction obj
 
-		self._users_file = "%s/%s" % (APPDATA_DIRNAME, USERS_FILENAME)
-		self._items_file = "%s/%s" % (APPDATA_DIRNAME, ITEMS_FILENAME)
-		self._rate_actions_file = "%s/%s" % (APPDATA_DIRNAME, RATE_ACTIONS_FILENAME)
-		self.__init_users()
-		self.__init_items()
-		self.__init_rate_actions()
+    self._users_file = "%s/%s" % (APPDATA_DIRNAME, USERS_FILENAME)
+    self._items_file = "%s/%s" % (APPDATA_DIRNAME, ITEMS_FILENAME)
+    self._rate_actions_file = "%s/%s" % (APPDATA_DIRNAME, RATE_ACTIONS_FILENAME)
+    self.__init_users()
+    self.__init_items()
+    self.__init_rate_actions()
 
-	def __init_users(self):
-		"""
-		uid|
-		"""
-		print "[Info] Initializing users..."
-		f = open(self._users_file, 'r')
-		for line in f:
-			data = line.rstrip('\r\n').split(USERS_FILE_DELIMITER)
-			self.add_user(User(data[0]))
-		f.close()
-		print "[Info] %s users were initialized." % len(self._users)
+  def __init_users(self):
+    """
+    uid|
+    """
+    print "[Info] Initializing users..."
+    f = open(self._users_file, 'r')
+    for line in f:
+      data = line.rstrip('\r\n').split(USERS_FILE_DELIMITER)
+      self.add_user(User(data[0]))
+    f.close()
+    print "[Info] %s users were initialized." % len(self._users)
 
-	def __init_items(self):
-		"""
-		iid|name
-		"""
-		print "[Info] Initializing items..."
-		f = open(self._items_file, 'r')
-		for line in f:
-			data = line.rstrip('\r\n').split(ITEMS_FILE_DELIMITER)
-			self.add_item(Item(data[0], data[1]))
-		f.close()
-		print "[Info] %s items were initialized." % len(self._items)
+  def __init_items(self):
+    """
+    iid|name
+    """
+    print "[Info] Initializing items..."
+    f = open(self._items_file, 'r')
+    for line in f:
+      data = line.rstrip('\r\n').split(ITEMS_FILE_DELIMITER)
+      self.add_item(Item(data[0], data[1]))
+    f.close()
+    print "[Info] %s items were initialized." % len(self._items)
 
-	def __init_rate_actions(self):
-		"""
-		uid|iid|rating|timestamp
-		"""
-		print "[Info] Initializing rate actions..."
-		f = open(self._rate_actions_file, 'r')
-		for line in f:
-			data = line.rstrip('\r\n').split(RATE_ACTIONS_DELIMITER)
-			t = datetime.datetime.utcfromtimestamp(int(data[3])).isoformat()
-			self.add_rate_action(RateAction(data[0], data[1], data[2], t))
-		f.close()
-		print "[Info] %s rate actions were initialized." % len(self._rate_actions)
+  def __init_rate_actions(self):
+    """
+    uid|iid|rating|timestamp
+    """
+    print "[Info] Initializing rate actions..."
+    f = open(self._rate_actions_file, 'r')
+    for line in f:
+      data = line.rstrip('\r\n').split(RATE_ACTIONS_DELIMITER)
+      t = datetime.datetime.utcfromtimestamp(int(data[3])).isoformat()
+      self.add_rate_action(RateAction(data[0], data[1], data[2], t))
+    f.close()
+    print "[Info] %s rate actions were initialized." % len(self._rate_actions)
 
-	def add_user(self, user):
-		self._users[user.uid] = user
+  def add_user(self, user):
+    self._users[user.uid] = user
 
-	def add_item(self, item):
-		self._items[item.iid] = item
+  def add_item(self, item):
+    self._items[item.iid] = item
 
-	def add_rate_action(self, action):
-		self._rate_actions.append(action)
+  def add_rate_action(self, action):
+    self._rate_actions.append(action)
 
-	def get_users(self):
-		return self._users
+  def get_users(self):
+    return self._users
 
-	def get_items(self):
-		return self._items
+  def get_items(self):
+    return self._items
 
-	def get_rate_actions(self):
-		return self._rate_actions
+  def get_rate_actions(self):
+    return self._rate_actions
 
-	def get_user(self, uid):
-		"""return single user
-		"""
-		if uid in self._users:
-			return self._users[uid]
-		else:
-			return None
+  def get_user(self, uid):
+    """return single user
+    """
+    if uid in self._users:
+      return self._users[uid]
+    else:
+      return None
 
-	def get_item(self, iid):
-		"""return single item
-		"""
-		if iid in self._items:
-			return self._items[iid]
-		else:
-			return None
+  def get_item(self, iid):
+    """return single item
+    """
+    if iid in self._items:
+      return self._items[iid]
+    else:
+      return None
 
-	def get_top_rated_items(self, uid, n):
-		"""get top n rated iids by this uid
-		"""
-		if uid in self._users:
-			actions = filter(lambda u: u.uid==uid, self._rate_actions)
-			top = sorted(actions, key=attrgetter('rating'), reverse=True)
-			topn_iids = map(lambda a: a.iid, top[:n])
-			return topn_iids
-		else:
-			return None
+  def get_top_rated_items(self, uid, n):
+    """get top n rated iids by this uid
+    """
+    if uid in self._users:
+      actions = filter(lambda u: u.uid==uid, self._rate_actions)
+      top = sorted(actions, key=attrgetter('rating'), reverse=True)
+      topn_iids = map(lambda a: a.iid, top[:n])
+      return topn_iids
+    else:
+      return None
 
-	def get_top_rate_actions(self, uid, n):
-		"""get top n rated actions by this uid
-		"""
-		if uid in self._users:
-			actions = filter(lambda u: u.uid==uid, self._rate_actions)
-			top = sorted(actions, key=attrgetter('rating'), reverse=True)
-			return top[:n]
-		else:
-			return None
+  def get_top_rate_actions(self, uid, n):
+    """get top n rated actions by this uid
+    """
+    if uid in self._users:
+      actions = filter(lambda u: u.uid==uid, self._rate_actions)
+      top = sorted(actions, key=attrgetter('rating'), reverse=True)
+      return top[:n]
+    else:
+      return None
diff --git a/examples/itemrec/movies/batch_import.py b/examples/itemrec/movies/batch_import.py
index 1cb797a..b2e0e63 100644
--- a/examples/itemrec/movies/batch_import.py
+++ b/examples/itemrec/movies/batch_import.py
@@ -1,4 +1,3 @@
-
 from appdata import AppData
 import predictionio
 import sys
@@ -7,60 +6,60 @@
 
 def batch_import_task(app_data, client, all_info=False):
 
-	print "[Info] Importing users to PredictionIO..."
-	count = 0 
-	for k, v in app_data.get_users().iteritems():
-		count += 1
-		if all_info:
-			print "[Info] Importing %s..." % v
-		else:
-			if (count % 32 == 0):
-				sys.stdout.write('\r[Info] %s' % count)
-				sys.stdout.flush()
+  print "[Info] Importing users to PredictionIO..."
+  count = 0 
+  for k, v in app_data.get_users().iteritems():
+    count += 1
+    if all_info:
+      print "[Info] Importing %s..." % v
+    else:
+      if (count % 32 == 0):
+        sys.stdout.write('\r[Info] %s' % count)
+        sys.stdout.flush()
 
-		client.create_user(v.uid)
-	
-	sys.stdout.write('\r[Info] %s users were imported.\n' % count)
-	sys.stdout.flush()
+    client.create_user(v.uid)
+  
+  sys.stdout.write('\r[Info] %s users were imported.\n' % count)
+  sys.stdout.flush()
 
-	print "[Info] Importing items to PredictionIO..."
-	count = 0
-	for k, v in app_data.get_items().iteritems():
-		count += 1
-		if all_info:
-			print "[Info] Importing %s..." % v
-		else:
-			if (count % 32 == 0):
-				sys.stdout.write('\r[Info] %s' % count)
-				sys.stdout.flush()
+  print "[Info] Importing items to PredictionIO..."
+  count = 0
+  for k, v in app_data.get_items().iteritems():
+    count += 1
+    if all_info:
+      print "[Info] Importing %s..." % v
+    else:
+      if (count % 32 == 0):
+        sys.stdout.write('\r[Info] %s' % count)
+        sys.stdout.flush()
 
-		client.create_item(v.iid, ("movie",))
-	
-	sys.stdout.write('\r[Info] %s items were imported.\n' % count)
-	sys.stdout.flush()
+    client.create_item(v.iid, ("movie",))
+  
+  sys.stdout.write('\r[Info] %s items were imported.\n' % count)
+  sys.stdout.flush()
 
-	print "[Info] Importing rate actions to PredictionIO..."
-	count = 0
-	for v in app_data.get_rate_actions():
-		count += 1
-		if all_info:
-			print "[Info] Importing %s..." % v
-		else:
-			if (count % 32 == 0):
-				sys.stdout.write('\r[Info] %s' % count)
-				sys.stdout.flush()
+  print "[Info] Importing rate actions to PredictionIO..."
+  count = 0
+  for v in app_data.get_rate_actions():
+    count += 1
+    if all_info:
+      print "[Info] Importing %s..." % v
+    else:
+      if (count % 32 == 0):
+        sys.stdout.write('\r[Info] %s' % count)
+        sys.stdout.flush()
 
-		client.identify(v.uid)
-		client.record_action_on_item("rate", v.iid, { "pio_rate": v.rating, "pio_t": v.t })
+    client.identify(v.uid)
+    client.record_action_on_item("rate", v.iid, { "pio_rate": v.rating, "pio_t": v.t })
 
-	sys.stdout.write('\r[Info] %s rate actions were imported.\n' % count)
-	sys.stdout.flush()
+  sys.stdout.write('\r[Info] %s rate actions were imported.\n' % count)
+  sys.stdout.flush()
 
 
 if __name__ == '__main__':
 
-	app_data = AppData()
-	client = predictionio.Client(APP_KEY, 1, API_URL)
-	batch_import_task(app_data, client)
-	client.close()
+  app_data = AppData()
+  client = predictionio.Client(APP_KEY, 1, API_URL)
+  batch_import_task(app_data, client)
+  client.close()
 
diff --git a/examples/itemrec/movies/movie_rec_app.py b/examples/itemrec/movies/movie_rec_app.py
index 21bc51e..436af38 100644
--- a/examples/itemrec/movies/movie_rec_app.py
+++ b/examples/itemrec/movies/movie_rec_app.py
@@ -1,3 +1,15 @@
+# To run this example app
+#
+# Please execute all commands from repository root.
+#
+# Step 1. Get sample data and unzip it.
+# > wget http://www.grouplens.org/system/files/ml-100k.zip
+# > unzip ml-100k.zip
+#
+# Step 2. Configurate examples/itemrec/movies/appdata.py
+#
+# Step 3. Run this app:
+# python -m examples.itemrec.movies.movie_rec_app
 
 from appdata import AppData
 import predictionio
@@ -9,132 +21,132 @@
 
 class App:
 
-	def __init__(self):
-		self._app_data = AppData()
-		self._client = predictionio.Client(APP_KEY, 1, API_URL)
+  def __init__(self):
+    self._app_data = AppData()
+    self._client = predictionio.Client(APP_KEY, 1, API_URL)
 
-	def run(self):
-		state = "[Main Menu]"
+  def run(self):
+    state = "[Main Menu]"
 
-		prompt = "\n"\
-			"%s\n"\
-			"%s\n"\
-			"Please input selection:\n"\
-			" 0: Quit application.\n"\
-			" 1: Get Recommendations from PredictionIO.\n"\
-			" 2: Display user's data." % (state, '-'*len(state))
+    prompt = "\n"\
+      "%s\n"\
+      "%s\n"\
+      "Please input selection:\n"\
+      " 0: Quit application.\n"\
+      " 1: Get Recommendations from PredictionIO.\n"\
+      " 2: Display user's data." % (state, '-'*len(state))
 
-		while True:
-			print prompt
-			choice = raw_input().lower()
-			if choice == '0':
-				print "\nGood Bye!\n"
-				break
-			elif choice == '1':
-				self.recommend_task(state)
-			elif choice == '2':
-				self.display_user_task(state)
-			else:
-				print '[Error] \'%s\' is not a valid selection.' % choice
+    while True:
+      print prompt
+      choice = raw_input().lower()
+      if choice == '0':
+        print "\nGood Bye!\n"
+        break
+      elif choice == '1':
+        self.recommend_task(state)
+      elif choice == '2':
+        self.display_user_task(state)
+      else:
+        print '[Error] \'%s\' is not a valid selection.' % choice
 
-		self._client.close()
+    self._client.close()
 
-	def recommend_task(self, prev_state):
-		state = prev_state + " / [Get Recommendations]"
-		prompt = "\n"\
-			"%s\n"\
-			"%s\n"\
-			"Please enter user id:" % (state, '-'*len(state))
+  def recommend_task(self, prev_state):
+    state = prev_state + " / [Get Recommendations]"
+    prompt = "\n"\
+      "%s\n"\
+      "%s\n"\
+      "Please enter user id:" % (state, '-'*len(state))
 
-		while True:
-			print prompt
-			choice = raw_input().lower()
-			u = self._app_data.get_user(choice)
-			if u:
-				n = 10
-				print "[Info] Getting top %s item recommendations for user %s..." % (n, u.uid)
-				try:
-					self._client.identify(u.uid)
-					rec = self._client.get_itemrec_topn(ENGINE_NAME, n)
-					u.rec = rec['pio_iids']
-					self.display_items(u.rec)
-				except predictionio.ItemRecNotFoundError:
-					print "[Info] Recommendation not found"
+    while True:
+      print prompt
+      choice = raw_input().lower()
+      u = self._app_data.get_user(choice)
+      if u:
+        n = 10
+        print "[Info] Getting top %s item recommendations for user %s..." % (n, u.uid)
+        try:
+          self._client.identify(u.uid)
+          rec = self._client.get_itemrec_topn(ENGINE_NAME, n)
+          u.rec = rec['pio_iids']
+          self.display_items(u.rec)
+        except predictionio.ItemRecNotFoundError:
+          print "[Info] Recommendation not found"
 
-				print "[Info] Go back to previous menu..."
-				break
-			else:
-				print "[Error] invalid user id %s. Go back to previous menu..." % choice
-				break
+        print "[Info] Go back to previous menu..."
+        break
+      else:
+        print "[Error] invalid user id %s. Go back to previous menu..." % choice
+        break
 
-	def display_user_task(self, prev_state):
-		state = prev_state + " / [Display User]"
-		prompt = "\n"\
-			"%s\n"\
-			"%s\n"\
-			"Please enter user id:" % (state, '-'*len(state))
+  def display_user_task(self, prev_state):
+    state = prev_state + " / [Display User]"
+    prompt = "\n"\
+      "%s\n"\
+      "%s\n"\
+      "Please enter user id:" % (state, '-'*len(state))
 
-		while True:
-			print prompt
-			choice = raw_input().lower()
-			u = self._app_data.get_user(choice)
-			if u:
-				print "[Info] User %s:" % u.uid
-				n = 10
-				topn_rate_actions = self._app_data.get_top_rate_actions(u.uid, n)
-				print "\n[Info] Top %s movies rated by this user:" % n
-				self.display_rate_actions(topn_rate_actions)
+    while True:
+      print prompt
+      choice = raw_input().lower()
+      u = self._app_data.get_user(choice)
+      if u:
+        print "[Info] User %s:" % u.uid
+        n = 10
+        topn_rate_actions = self._app_data.get_top_rate_actions(u.uid, n)
+        print "\n[Info] Top %s movies rated by this user:" % n
+        self.display_rate_actions(topn_rate_actions)
 
-				print "\n[Info] Movies recommended to this user:"
-				self.display_items(u.rec)
+        print "\n[Info] Movies recommended to this user:"
+        self.display_items(u.rec)
 
-				self.wait_for_ack()
-				print "\n[Info] Go back to previous menu..."
-				break
-			else:
-				print "[Error] invalid user id %s. Go back to previous menu..." % choice
-				break
-	
-	def display_items(self, iids, all_info=False):
-		"""print item info for each iid in the list
-		"""
-		if iids:
-			for iid in iids:
-				item = self._app_data.get_item(iid)
-				if item:
-					if all_info:
-						print "[Info] %s" % item
-					else:
-						print "[Info] %s" % item.name
-				else:
-					print "[Error] Invalid item id %s" % iid
-		else:
-			print "[Info] Empty."
+        self.wait_for_ack()
+        print "\n[Info] Go back to previous menu..."
+        break
+      else:
+        print "[Error] invalid user id %s. Go back to previous menu..." % choice
+        break
+  
+  def display_items(self, iids, all_info=False):
+    """print item info for each iid in the list
+    """
+    if iids:
+      for iid in iids:
+        item = self._app_data.get_item(iid)
+        if item:
+          if all_info:
+            print "[Info] %s" % item
+          else:
+            print "[Info] %s" % item.name
+        else:
+          print "[Error] Invalid item id %s" % iid
+    else:
+      print "[Info] Empty."
 
-	def display_rate_actions(self, actions):
-		"""print iid and rating
-		"""
-		if actions:
-			for a in actions:
-				item = self._app_data.get_item(a.iid)
-				if item:
-					print "[Info] %s, rating = %s" % (item.name, a.rating)
-				else:
-					print "[Error] Invalid item id %s" % a.iid
-		else:
-			print "[Info] Empty."
+  def display_rate_actions(self, actions):
+    """print iid and rating
+    """
+    if actions:
+      for a in actions:
+        item = self._app_data.get_item(a.iid)
+        if item:
+          print "[Info] %s, rating = %s" % (item.name, a.rating)
+        else:
+          print "[Error] Invalid item id %s" % a.iid
+    else:
+      print "[Info] Empty."
 
-	def wait_for_ack(self):
+  def wait_for_ack(self):
 
-		prompt = "\nPress enter to continue..."
-		print prompt
-		choice = raw_input().lower()
+    prompt = "\nPress enter to continue..."
+    print prompt
+    choice = raw_input().lower()
 
 
 if __name__ == '__main__':
 
-	print "\nWelcome To PredictionIO Python-SDK Demo App!"
-	print "============================================\n"
-	
-	my_app = App()
-	my_app.run()
+  print "\nWelcome To PredictionIO Python-SDK Demo App!"
+  print "============================================\n"
+  
+  my_app = App()
+  my_app.run()
diff --git a/predictionio/__init__.py b/predictionio/__init__.py
index 648c0cd..30e39e6 100644
--- a/predictionio/__init__.py
+++ b/predictionio/__init__.py
@@ -6,18 +6,20 @@
 
 __author__ = "The PredictionIO Team"
 __email__ = "help@tappingstone.com"
-__copyright__ = "Copyright 2013, TappingStone, Inc."
+__copyright__ = "Copyright 2014, TappingStone, Inc."
 __license__ = "Apache License, Version 2.0"
 
-__version__ = "0.6.3"
+__version__ = "0.7.0"
 
 
 # import packages
 import re
 try:
-    import httplib
+  import httplib
 except ImportError:
-    from http import client as httplib
+  # pylint: disable=F0401
+  # http is a Python3 module, replacing httplib
+  from http import client as httplib
 import json
 import urllib
 
@@ -33,68 +35,72 @@
 
 class ServerStatusError(PredictionIOAPIError):
 
-    "Error happened when tried to get status of the API server"
-    pass
+  "Error happened when tried to get status of the API server"
+  pass
 
 
 class UserNotCreatedError(PredictionIOAPIError):
 
-    "Error happened when tried to create user"
-    pass
+  "Error happened when tried to create user"
+  pass
 
 
 class UserNotFoundError(PredictionIOAPIError):
 
-    "Error happened when tried to get user"
-    pass
+  "Error happened when tried to get user"
+  pass
 
 
 class UserNotDeletedError(PredictionIOAPIError):
 
-    "Error happened when tried to delete user"
-    pass
+  "Error happened when tried to delete user"
+  pass
 
 
 class ItemNotCreatedError(PredictionIOAPIError):
 
-    "Error happened when tried to create item"
-    pass
+  "Error happened when tried to create item"
+  pass
 
 
 class ItemNotFoundError(PredictionIOAPIError):
 
-    "Error happened when tried to get item"
-    pass
+  "Error happened when tried to get item"
+  pass
 
 
 class ItemNotDeletedError(PredictionIOAPIError):
 
-    "Error happened when tried to delete item"
-    pass
+  "Error happened when tried to delete item"
+  pass
 
 
 class U2IActionNotCreatedError(PredictionIOAPIError):
 
-    "Error happened when tried to create user-to-item action"
-    pass
+  "Error happened when tried to create user-to-item action"
+  pass
 
 
 class ItemRecNotFoundError(PredictionIOAPIError):
 
-    "Error happened when tried to get item recommendation"
-    pass
+  "Error happened when tried to get item recommendation"
+  pass
 
 
 class ItemSimNotFoundError(PredictionIOAPIError):
 
-    "Error happened when tried to get similar items"
-    pass
+  "Error happened when tried to get similar items"
+  pass
 
+class ItemRankNotFoundError(PredictionIOAPIError):
+
+  "Error happened when treid to rank item"
+  pass
 
 class InvalidArgumentError(PredictionIOAPIError):
 
-    "Arguments are not valid"
-    pass
+  "Arguments are not valid"
+  pass
 
 # map to API
 LIKE_API = "like"
@@ -106,1012 +112,1103 @@
 
 class Client(object):
 
-    """PredictionIO client object.
+  """PredictionIO client object.
 
-    This is an object representing a PredictionIO's client. This object
-    provides methods for making PredictionIO API requests.
+  This is an object representing a PredictionIO's client. This object
+  provides methods for making PredictionIO API requests.
 
-    :param appkey: the App Key provided by PredictionIO.
-    :param threads: number of threads to handle PredictionIO API requests.
-                    Must be >= 1.
-    :param apiurl: the PredictionIO API URL path.
-    :param apiversion: the PredictionIO API version. (optional)
-           (eg. "", or "/v1")
-    :param qsize: the max size of the request queue (optional).
-            The asynchronous request becomes blocking once this size has been
-            reached, until the queued requests are handled.
-            Default value is 0, which means infinite queue size.
-    :param timeout: timeout for HTTP connection attempts and requests in
-        seconds (optional).
-        Default value is 5.
+  :param appkey: the App Key provided by PredictionIO.
+  :param threads: number of threads to handle PredictionIO API requests.
+          Must be >= 1.
+  :param apiurl: the PredictionIO API URL path.
+  :param apiversion: the PredictionIO API version. (optional)
+       (eg. "", or "/v1")
+  :param qsize: the max size of the request queue (optional).
+      The asynchronous request becomes blocking once this size has been
+      reached, until the queued requests are handled.
+      Default value is 0, which means infinite queue size.
+  :param timeout: timeout for HTTP connection attempts and requests in
+    seconds (optional).
+    Default value is 5.
+
+  """
+
+  def __init__(self, appkey, threads=1, apiurl="http://localhost:8000",
+         apiversion="", qsize=0, timeout=5):
+    """Constructor of Client object.
+
+    """
+    self.appkey = appkey
+    self.threads = threads
+    self.apiurl = apiurl
+    self.apiversion = apiversion
+    self.qsize = qsize
+    self.timeout = timeout
+
+    # check connection type
+    https_pattern = r'^https://(.*)'
+    http_pattern = r'^http://(.*)'
+    m = re.match(https_pattern, apiurl)
+    self.https = True
+    if m is None:  # not matching https
+      m = re.match(http_pattern, apiurl)
+      self.https = False
+      if m is None:  # not matching http either
+        raise InvalidArgumentError("apiurl is not valid: %s" % apiurl)
+    self.host = m.group(1)
+
+    self._uid = None  # identified uid
+    self._connection = Connection(host=self.host, threads=self.threads,
+                    qsize=self.qsize, https=self.https,
+                    timeout=self.timeout)
+
+  def close(self):
+    """Close this client and the connection.
+
+    Call this method when you want to completely terminate the connection
+    with PredictionIO.
+    It will wait for all pending requests to finish.
+    """
+    self._connection.close()
+
+  def pending_requests(self):
+    """Return the number of pending requests.
+
+    :returns:
+      The number of pending requests of this client.
+    """
+    return self._connection.pending_requests()
+
+  def identify(self, uid):
+    """Identify the uid
+
+    :param uid: user id. type str.
+    """
+    self._uid = uid
+
+  def get_status(self):
+    """Get the status of the PredictionIO API Server
+
+    :returns:
+      status message.
+
+    :raises:
+      ServerStatusError.
+    """
+    path = "/"
+    request = AsyncRequest("GET", path)
+    request.set_rfunc(self._aget_status_resp)
+    self._connection.make_request(request)
+    result = self.aresp(request)
+    return result
+
+  def _aget_status_resp(self, response):
+    """Handle the AsyncResponse of get status request"""
+    if response.error is not None:
+      raise ServerStatusError("Exception happened: %s for request %s" %
+                  (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise ServerStatusError("request: %s status: %s body: %s" %
+                  (response.request, response.status,
+                   response.body))
+
+    # data = json.loads(response.body) # convert json string to dict
+    return response.body
+
+  def acreate_user(self, uid, params={}):
+    """Asynchronously create a user.
+
+    :param uid: user id. type str.
+    :param params: optional attributes. type dictionary.
+        For example,
+        { 'custom': 'value', 'pio_inactive' : True,
+        'pio_latlng': [4.5,67.8] }
+
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
 
     """
 
-    def __init__(self, appkey, threads=1, apiurl="http://localhost:8000",
-                 apiversion="", qsize=0, timeout=5):
-        """Constructor of Client object.
+    if "pio_latlng" in params:
+      params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
+    if "pio_inactive" in params:
+      params["pio_inactive"] = str(params["pio_inactive"]).lower()
 
-        """
-        self.appkey = appkey
-        self.threads = threads
-        self.apiurl = apiurl
-        self.apiversion = apiversion
-        self.qsize = qsize
-        self.timeout = timeout
+    path = "%s/users.json" % self.apiversion
+    request = AsyncRequest(
+      "POST", path, pio_appkey=self.appkey, pio_uid=uid, **params)
+    request.set_rfunc(self._acreate_user_resp)
+    self._connection.make_request(request)
 
-        # check connection type
-        https_pattern = r'^https://(.*)'
-        http_pattern = r'^http://(.*)'
-        m = re.match(https_pattern, apiurl)
-        self.https = True
-        if m is None:  # not matching https
-            m = re.match(http_pattern, apiurl)
-            self.https = False
-            if m is None:  # not matching http either
-                raise InvalidArgumentError("apiurl is not valid: %s" % apiurl)
-        self.host = m.group(1)
+    return request
 
-        self._uid = None  # identified uid
-        self._connection = Connection(host=self.host, threads=self.threads,
-                                      qsize=self.qsize, https=self.https,
-                                      timeout=self.timeout)
+  def _acreate_user_resp(self, response):
+    """Private function to handle the AsyncResponse of the acreate_user
+    request.
 
-    def close(self):
-        """Close this client and the connection.
+    :param response: AsyncResponse object.
 
-        Call this method when you want to completely terminate the connection
-        with PredictionIO.
-        It will wait for all pending requests to finish.
-        """
-        self._connection.close()
+    :returns:
+      None.
 
-    def pending_requests(self):
-        """Return the number of pending requests.
+    :raises:
+      UserNotCreatedError.
 
-        :returns:
-            The number of pending requests of this client.
-        """
-        return self._connection.pending_requests()
+    """
+    if response.error is not None:
+      raise UserNotCreatedError("Exception happened: %s for request %s" %
+                    (response.error, response.request))
+    elif response.status != httplib.CREATED:
+      raise UserNotCreatedError("request: %s status: %s body: %s" %
+                    (response.request, response.status,
+                     response.body))
 
-    def identify(self, uid):
-        """Identify the uid
+    return None
 
-        :param uid: user id. type str.
-        """
-        self._uid = uid
+  def aget_user(self, uid):
+    """Asynchronously get user.
 
-    def get_status(self):
-        """Get the status of the PredictionIO API Server
+    :param uid: user id. type str.
 
-        :returns:
-            status message.
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-        :raises:
-            ServerStatusError.
-        """
-        path = "/"
-        request = AsyncRequest("GET", path)
-        request.set_rfunc(self._aget_status_resp)
-        self._connection.make_request(request)
-        result = self.aresp(request)
-        return result
+    enc_uid = urllib.quote(uid, "")  # replace special char with %xx
+    path = "%s/users/%s.json" % (self.apiversion, enc_uid)
+    request = AsyncRequest("GET", path, pio_appkey=self.appkey)
+    request.set_rfunc(self._aget_user_resp)
+    self._connection.make_request(request)
 
-    def _aget_status_resp(self, response):
-        """Handle the AsyncResponse of get status request"""
-        if response.error is not None:
-            raise ServerStatusError("Exception happened: %s for request %s" %
-                                    (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise ServerStatusError("request: %s status: %s body: %s" %
-                                    (response.request, response.status,
-                                     response.body))
+    return request
 
-        # data = json.loads(response.body) # convert json string to dict
-        return response.body
+  def _aget_user_resp(self, response):
+    """Private function to handle the AsyncResponse of the aget_user
+    request .
 
-    def acreate_user(self, uid, params={}):
-        """Asynchronously create a user.
+    :param response: AsyncResponse object.
 
-        :param uid: user id. type str.
-        :param params: optional attributes. type dictionary.
-                For example, 
-                { 'custom': 'value', 'pio_inactive' : True,
-                'pio_latlng': [4.5,67.8] }
+    :returns:
+      User data in Dictionary format.
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
+    :rasies:
+      UserNotFoundError.
 
-        """
+    """
+    if response.error is not None:
+      raise UserNotFoundError("Exception happened: %s for request %s" %
+                  (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise UserNotFoundError("request: %s status: %s body: %s" %
+                  (response.request, response.status,
+                   response.body))
 
-        if "pio_latlng" in params:
-            params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
-        if "pio_inactive" in params:
-            params["pio_inactive"] = str(params["pio_inactive"]).lower()
+    data = json.loads(response.body)  # convert json string to dict
+    return data
 
-        path = "%s/users.json" % self.apiversion
-        request = AsyncRequest(
-            "POST", path, pio_appkey=self.appkey, pio_uid=uid, **params)
-        request.set_rfunc(self._acreate_user_resp)
-        self._connection.make_request(request)
+  def adelete_user(self, uid):
+    """Asynchronously delete user.
 
-        return request
+    :param uid: user id. type str.
 
-    def _acreate_user_resp(self, response):
-        """Private function to handle the AsyncResponse of the acreate_user
-        request.
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-        :param response: AsyncResponse object.
+    enc_uid = urllib.quote(uid, "")  # replace special char with %xx
+    path = "%s/users/%s.json" % (self.apiversion, enc_uid)
+    request = AsyncRequest("DELETE", path, pio_appkey=self.appkey)
+    request.set_rfunc(self._adelete_user_resp)
+    self._connection.make_request(request)
 
-        :returns:
-            None.
+    return request
 
-        :raises:
-            UserNotCreatedError.
+  def _adelete_user_resp(self, response):
+    """Private function to handle the AsyncResponse of the adelete_user
+    request.
 
-        """
-        if response.error is not None:
-            raise UserNotCreatedError("Exception happened: %s for request %s" %
-                                      (response.error, response.request))
-        elif response.status != httplib.CREATED:
-            raise UserNotCreatedError("request: %s status: %s body: %s" %
-                                      (response.request, response.status,
-                                       response.body))
+    :param response: AsyncResponse object.
 
-        return None
+    :returns:
+      None.
 
-    def aget_user(self, uid):
-        """Asynchronously get user.
+    :raises:
+      UserNotDeletedError.
 
-        :param uid: user id. type str.
+    """
+    if response.error is not None:
+      raise UserNotDeletedError("Exception happened: %s for request %s" %
+                    (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise UserNotDeletedError("request: %s status: %s body: %s" %
+                    (response.request, response.status,
+                     response.body))
+    return None
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
+  def acreate_item(self, iid, itypes, params={}):
+    """Asynchronously create item.
 
-        enc_uid = urllib.quote(uid, "")  # replace special char with %xx
-        path = "%s/users/%s.json" % (self.apiversion, enc_uid)
-        request = AsyncRequest("GET", path, pio_appkey=self.appkey)
-        request.set_rfunc(self._aget_user_resp)
-        self._connection.make_request(request)
+    :param iid: item id. type str.
+    :param itypes: item types. Tuple of Str.
+        For example, if this item belongs to item types "t1", "t2",
+        "t3", "t4",then itypes=("t1", "t2", "t3", "t4").
+        NOTE: if this item belongs to only one itype, use tuple of one
+        element, eg. itypes=("t1",)
+    :param params: optional attributes. type dictionary.
+        For example,
+        { 'custom': 'value', 'pio_inactive' : True,
+        'pio_latlng': [4.5,67.8] }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    itypes_str = ",".join(itypes)  # join items with ","
 
-        return request
+    if "pio_latlng" in params:
+      params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
+    if "pio_inactive" in params:
+      params["pio_inactive"] = str(params["pio_inactive"]).lower()
 
-    def _aget_user_resp(self, response):
-        """Private function to handle the AsyncResponse of the aget_user
-        request .
+    path = "%s/items.json" % self.apiversion
+    request = AsyncRequest("POST", path, pio_appkey=self.appkey,
+                 pio_iid=iid, pio_itypes=itypes_str, **params)
+    request.set_rfunc(self._acreate_item_resp)
+    self._connection.make_request(request)
+    return request
 
-        :param response: AsyncResponse object.
+  def _acreate_item_resp(self, response):
+    """Private function to handle the AsyncResponse of the acreate_item
+    request
 
-        :returns:
-            User data in Dictionary format.
+    :param response: AsyncResponse object.
 
-        :rasies:
-            UserNotFoundError.
+    :returns:
+      None
+    :raises:
+      ItemNotCreatedError
 
-        """
-        if response.error is not None:
-            raise UserNotFoundError("Exception happened: %s for request %s" %
-                                    (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise UserNotFoundError("request: %s status: %s body: %s" %
-                                    (response.request, response.status,
-                                     response.body))
+    """
+    if response.error is not None:
+      raise ItemNotCreatedError("Exception happened: %s for request %s" %
+                    (response.error, response.request))
+    elif response.status != httplib.CREATED:
+      raise ItemNotCreatedError("request: %s status: %s body: %s" %
+                    (response.request, response.status,
+                     response.body))
+    return None
 
-        data = json.loads(response.body)  # convert json string to dict
-        return data
+  def aget_item(self, iid):
+    """Asynchronously get item
 
-    def adelete_user(self, uid):
-        """Asynchronously delete user.
+    :param iid: item id. type str.
 
-        :param uid: user id. type str.
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    enc_iid = urllib.quote(iid, "")
+    path = "%s/items/%s.json" % (self.apiversion, enc_iid)
+    request = AsyncRequest("GET", path, pio_appkey=self.appkey)
+    request.set_rfunc(self._aget_item_resp)
+    self._connection.make_request(request)
+    return request
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
+  def _aget_item_resp(self, response):
+    """Private function to handle the AsyncResponse of the aget_item
+    request
 
-        enc_uid = urllib.quote(uid, "")  # replace special char with %xx
-        path = "%s/users/%s.json" % (self.apiversion, enc_uid)
-        request = AsyncRequest("DELETE", path, pio_appkey=self.appkey)
-        request.set_rfunc(self._adelete_user_resp)
-        self._connection.make_request(request)
+    :param response: AsyncResponse object.
 
-        return request
+    :returns:
+      item data in dictionary format.
 
-    def _adelete_user_resp(self, response):
-        """Private function to handle the AsyncResponse of the adelete_user
-        request.
+    :raises:
+      ItemNotFoundError.
 
-        :param response: AsyncResponse object.
+    """
+    if response.error is not None:
+      raise ItemNotFoundError("Exception happened: %s for request %s" %
+                  (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise ItemNotFoundError("request: %s status: %s body: %s" %
+                  (response.request, response.status,
+                   response.body))
 
-        :returns:
-            None.
+    data = json.loads(response.body)  # convert json string to dict
+    if "pio_itypes" in data:
+      # convert from list to tuple
+      data["pio_itypes"] = tuple(data["pio_itypes"])
 
-        :raises:
-            UserNotDeletedError.
+    return data
 
-        """
-        if response.error is not None:
-            raise UserNotDeletedError("Exception happened: %s for request %s" %
-                                      (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise UserNotDeletedError("request: %s status: %s body: %s" %
-                                      (response.request, response.status,
-                                       response.body))
-        return None
+  def adelete_item(self, iid):
+    """Asynchronously delete item
 
-    def acreate_item(self, iid, itypes, params={}):
-        """Asynchronously create item.
+    :param iid: item id. type str.
 
-        :param iid: item id. type str.
-        :param itypes: item types. Tuple of Str.
-                For example, if this item belongs to item types "t1", "t2",
-                "t3", "t4",then itypes=("t1", "t2", "t3", "t4").
-                NOTE: if this item belongs to only one itype, use tuple of one
-                element, eg. itypes=("t1",)
-        :param params: optional attributes. type dictionary.
-                For example, 
-                { 'custom': 'value', 'pio_inactive' : True, 
-                'pio_latlng': [4.5,67.8] }
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        itypes_str = ",".join(itypes)  # join items with ","
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-        if "pio_latlng" in params:
-            params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
-        if "pio_inactive" in params:
-            params["pio_inactive"] = str(params["pio_inactive"]).lower()
+    enc_iid = urllib.quote(iid, "")
+    path = "%s/items/%s.json" % (self.apiversion, enc_iid)
+    request = AsyncRequest("DELETE", path, pio_appkey=self.appkey)
+    request.set_rfunc(self._adelete_item_resp)
+    self._connection.make_request(request)
+    return request
 
-        path = "%s/items.json" % self.apiversion
-        request = AsyncRequest("POST", path, pio_appkey=self.appkey,
-                               pio_iid=iid, pio_itypes=itypes_str, **params)
-        request.set_rfunc(self._acreate_item_resp)
-        self._connection.make_request(request)
-        return request
+  def _adelete_item_resp(self, response):
+    """Private function to handle the AsyncResponse of the adelete_item
+    request
 
-    def _acreate_item_resp(self, response):
-        """Private function to handle the AsyncResponse of the acreate_item
-        request
+    :param response: AsyncResponse object
 
-        :param response: AsyncResponse object.
+    :returns:
+      None
 
-        :returns:
-            None
-        :raises:
-            ItemNotCreatedError
+    :raises:
+      ItemNotDeletedError
+    """
+    if response.error is not None:
+      raise ItemNotDeletedError("Exception happened: %s for request %s" %
+                    (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise ItemNotDeletedError("request: %s status: %s body: %s" %
+                    (response.request, response.status,
+                     response.body))
+    return None
 
-        """
-        if response.error is not None:
-            raise ItemNotCreatedError("Exception happened: %s for request %s" %
-                                      (response.error, response.request))
-        elif response.status != httplib.CREATED:
-            raise ItemNotCreatedError("request: %s status: %s body: %s" %
-                                      (response.request, response.status,
-                                       response.body))
-        return None
+  def _aget_user_itemrec_topn(self, engine, uid, n, params={}):
+    """Private function to asynchronously get recommendations for user
 
-    def aget_item(self, iid):
-        """Asynchronously get item
+    :param engine: name of the prediction engine. type str.
+    :param uid: user id. type str.
+    :param n: number of recommendation. type int.
+    :param params: optional parameters. type dictionary
+        For example, { 'pio_itypes' : ("t1","t2") }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    if "pio_itypes" in params:
+      params["pio_itypes"] = ",".join(params["pio_itypes"])
+    if "pio_latlng" in params:
+      params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
+    if "pio_attributes" in params:
+      params["pio_attributes"] = ",".join(params["pio_attributes"])
 
-        :param iid: item id. type str.
+    path = "%s/engines/itemrec/%s/topn.json" % (self.apiversion, engine)
+    request = AsyncRequest("GET", path, pio_appkey=self.appkey,
+                 pio_uid=uid, pio_n=n, **params)
+    request.set_rfunc(self._aget_user_itemrec_topn_resp)
+    self._connection.make_request(request)
+    return request
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        enc_iid = urllib.quote(iid, "")
-        path = "%s/items/%s.json" % (self.apiversion, enc_iid)
-        request = AsyncRequest("GET", path, pio_appkey=self.appkey)
-        request.set_rfunc(self._aget_item_resp)
-        self._connection.make_request(request)
-        return request
+  def _aget_user_itemrec_topn_resp(self, response):
+    """Private function to handle the AsyncResponse of the aget_itemrec
+    request
 
-    def _aget_item_resp(self, response):
-        """Private function to handle the AsyncResponse of the aget_item
-        request
+    :param response: AsyncResponse object
 
-        :param response: AsyncResponse object.
+    :returns:
+      data in dictionary format.
 
-        :returns:
-            item data in dictionary format.
+    :raises:
+      ItemRecNotFoundError.
+    """
+    if response.error is not None:
+      raise ItemRecNotFoundError(
+        "Exception happened: %s for request %s" %
+        (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise ItemRecNotFoundError("request: %s status: %s body: %s" %
+                    (response.request, response.status,
+                     response.body))
 
-        :raises:
-            ItemNotFoundError.
+    data = json.loads(response.body)  # convert json string to dict
+    return data
 
-        """
-        if response.error is not None:
-            raise ItemNotFoundError("Exception happened: %s for request %s" %
-                                    (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise ItemNotFoundError("request: %s status: %s body: %s" %
-                                    (response.request, response.status,
-                                     response.body))
+  def aget_itemrec_topn(self, engine, n, params={}):
+    """Asynchronously get recommendations for the identified user
 
-        data = json.loads(response.body)  # convert json string to dict
-        if "pio_itypes" in data:
-            # convert from list to tuple
-            data["pio_itypes"] = tuple(data["pio_itypes"])
+    :param engine: name of the prediction engine. type str.
+    :param n: number of recommendation. type int.
+    :param params: optional parameters. type dictionary
+        For example, { 'pio_itypes' : ("t1",) }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-        return data
+    if self._uid is None:
+      raise InvalidArgumentError(
+        "uid is not identified. Please call identify(uid) first.")
 
-    def adelete_item(self, iid):
-        """Asynchronously delete item
+    request = self._aget_user_itemrec_topn(engine, self._uid, n, params)
+    return request
 
-        :param iid: item id. type str.
+  def aget_itemrec(self, uid, n, engine, **params):
+    """Deprecated. Asynchronously get recommendations
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
+    :param uid: user id. type str.
+    :param n: number of recommendation. type int.
+    :param engine: name of the prediction engine. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng="123.4, 56.7"
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    request = self._aget_user_itemrec_topn(engine, uid, n, params)
+    return request
 
-        enc_iid = urllib.quote(iid, "")
-        path = "%s/items/%s.json" % (self.apiversion, enc_iid)
-        request = AsyncRequest("DELETE", path, pio_appkey=self.appkey)
-        request.set_rfunc(self._adelete_item_resp)
-        self._connection.make_request(request)
-        return request
+  def _aget_itemsim_topn(self, engine, iid, n, params={}):
+    """Private function to asynchronously get top n similar items of the
+    item
 
-    def _adelete_item_resp(self, response):
-        """Private function to handle the AsyncResponse of the adelete_item
-        request
+    :param engine: name of the prediction engine. type str.
+    :param iid: item id. type str.
+    :param n: number of similar items. type int.
+    :param params: optional parameters. type dictionary
+        For example, { 'pio_itypes' : ("t1","t2") }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    if "pio_itypes" in params:
+      params["pio_itypes"] = ",".join(params["pio_itypes"])
+    if "pio_latlng" in params:
+      params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
+    if "pio_attributes" in params:
+      params["pio_attributes"] = ",".join(params["pio_attributes"])
 
-        :param response: AsyncResponse object
+    path = "%s/engines/itemsim/%s/topn.json" % (self.apiversion, engine)
+    request = AsyncRequest("GET", path, pio_appkey=self.appkey,
+                 pio_iid=iid, pio_n=n, **params)
+    request.set_rfunc(self._aget_itemsim_topn_resp)
+    self._connection.make_request(request)
+    return request
 
-        :returns:
-            None
+  def _aget_itemsim_topn_resp(self, response):
+    """Private function to handle the AsyncResponse of the aget_itemsim
+    request
 
-        :raises:
-            ItemNotDeletedError
-        """
-        if response.error is not None:
-            raise ItemNotDeletedError("Exception happened: %s for request %s" %
-                                      (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise ItemNotDeletedError("request: %s status: %s body: %s" %
-                                      (response.request, response.status,
-                                       response.body))
-        return None
+    :param response: AsyncResponse object
 
-    def _aget_user_itemrec_topn(self, engine, uid, n, params={}):
-        """Private function to asynchronously get recommendations for user
+    :returns:
+      data in dictionary format.
 
-        :param engine: name of the prediction engine. type str.
-        :param uid: user id. type str.
-        :param n: number of recommendation. type int.
-        :param params: optional parameters. type dictionary
-                For example, { 'pio_itypes' : ("t1","t2") }
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        if "pio_itypes" in params:
-            params["pio_itypes"] = ",".join(params["pio_itypes"])
-        if "pio_latlng" in params:
-            params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
-        if "pio_attributes" in params:
-            params["pio_attributes"] = ",".join(params["pio_attributes"])
+    :raises:
+      ItemSimNotFoundError.
+    """
+    if response.error is not None:
+      raise ItemSimNotFoundError(
+        "Exception happened: %s for request %s" %
+        (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise ItemSimNotFoundError("request: %s status: %s body: %s" %
+                    (response.request, response.status,
+                     response.body))
 
-        path = "%s/engines/itemrec/%s/topn.json" % (self.apiversion, engine)
-        request = AsyncRequest("GET", path, pio_appkey=self.appkey,
-                               pio_uid=uid, pio_n=n, **params)
-        request.set_rfunc(self._aget_user_itemrec_topn_resp)
-        self._connection.make_request(request)
-        return request
+    data = json.loads(response.body)  # convert json string to dict
+    return data
 
-    def _aget_user_itemrec_topn_resp(self, response):
-        """Private function to handle the AsyncResponse of the aget_itemrec
-        request
+  def aget_itemsim_topn(self, engine, iid, n, params={}):
+    """Asynchronously get top n similar items of the item
 
-        :param response: AsyncResponse object
+    :param engine: name of the prediction engine. type str.
+    :param iid: item id. type str.
+    :param n: number of similar items. type int.
+    :param params: optional parameters. type dictionary
+        For example, { 'pio_itypes' : ("t1",) }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-        :returns:
-            data in dictionary format.
+    request = self._aget_itemsim_topn(engine, iid, n, params)
+    return request
 
-        :raises:
-            ItemRecNotFoundError.
-        """
-        if response.error is not None:
-            raise ItemRecNotFoundError(
-                "Exception happened: %s for request %s" %
-                (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise ItemRecNotFoundError("request: %s status: %s body: %s" %
-                                      (response.request, response.status,
-                                       response.body))
+  def _aget_user_itemrank_ranked(self, engine, uid, iids, params={}):
+    """Private function to asynchronously get ranked item for user
 
-        data = json.loads(response.body)  # convert json string to dict
-        return data
+    :param engine: name of the prediction engine. type str.
+    :param uid: user id. type str.
+    :param iids: items to be ranked. type list of item ids.
+      For example, ["i0", "i1", "i2"]
+    :param params: optional parameters. type dictionary
+      For example. { 'pio_attributes' : "name" }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    if "pio_attributes" in params:
+      params["pio_attributes"] = ",".join(params["pio_attributes"])
 
-    def aget_itemrec_topn(self, engine, n, params={}):
-        """Asynchronously get recommendations for the identified user
+    pio_iids = ",".join(iids)
 
-        :param engine: name of the prediction engine. type str.
-        :param n: number of recommendation. type int.
-        :param params: optional parameters. type dictionary
-                For example, { 'pio_itypes' : ("t1",) }
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
+    path = "%s/engines/itemrank/%s/ranked.json" % \
+      (self.apiversion, engine)
+    request = AsyncRequest("GET", path, pio_appkey=self.appkey,
+                           pio_uid=uid, pio_iids=pio_iids, **params)
+    request.set_rfunc(self._aget_user_itemrank_ranked_resp)
+    self._connection.make_request(request)
+    return request
 
-        if self._uid is None:
-            raise InvalidArgumentError(
-                "uid is not identified. Please call identify(uid) first.")
+  def _aget_user_itemrank_ranked_resp(self, response):
+    """Private function to handle the AsyncResponse of the aget_itemreoder
+      request
 
-        request = self._aget_user_itemrec_topn(engine, self._uid, n, params)
-        return request
+    :param response: AsyncResponse object
 
-    def aget_itemrec(self, uid, n, engine, **params):
-        """Deprecated. Asynchronously get recommendations
+    :returns:
+      data in dictionary format.
 
-        :param uid: user id. type str.
-        :param n: number of recommendation. type int.
-        :param engine: name of the prediction engine. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng="123.4, 56.7"
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        request = self._aget_user_itemrec_topn(engine, uid, n, params)
-        return request
+    :raises:
+      ItemRankNotFoundError.
+    """
+    if response.error is not None:
+      raise ItemRankNotFoundError(
+        "Exception happened: %s for request %s" %
+        (response.error, response.request))
+    elif response.status != httplib.OK:
+      raise ItemRankNotFoundError("request: %s status: %s body: %s" %
+                                  (response.request, response.status,
+                                   response.body))
 
-    def _aget_itemsim_topn(self, engine, iid, n, params={}):
-        """Private function to asynchronously get top n similar items of the
-        item
+    data = json.loads(response.body)  # convert json string to dict
+    return data
 
-        :param engine: name of the prediction engine. type str.
-        :param iid: item id. type str.
-        :param n: number of similar items. type int.
-        :param params: optional parameters. type dictionary
-                For example, { 'pio_itypes' : ("t1","t2") }
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        if "pio_itypes" in params:
-            params["pio_itypes"] = ",".join(params["pio_itypes"])
-        if "pio_latlng" in params:
-            params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
-        if "pio_attributes" in params:
-            params["pio_attributes"] = ",".join(params["pio_attributes"])
+  def aget_itemrank_ranked(self, engine, iids, params={}):
+    """Asynchronously get ranked item for user
 
-        path = "%s/engines/itemsim/%s/topn.json" % (self.apiversion, engine)
-        request = AsyncRequest("GET", path, pio_appkey=self.appkey,
-                               pio_iid=iid, pio_n=n, **params)
-        request.set_rfunc(self._aget_itemsim_topn_resp)
-        self._connection.make_request(request)
-        return request
+    :param engine: name of the prediction engine. type str.
+    :param iids: items to be ranked. type list of item ids.
+      For example, ["i0", "i1", "i2"]
+    :param params: optional parameters. type dictionary
+      For example. { 'pio_attributes' : "name" }
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-    def _aget_itemsim_topn_resp(self, response):
-        """Private function to handle the AsyncResponse of the aget_itemsim
-        request
+    if self._uid is None:
+      raise InvalidArgumentError(
+        "uid is not identified. Please call identify(uid) first.")
 
-        :param response: AsyncResponse object
+    request = self._aget_user_itemrank_ranked(engine,
+      self._uid, iids, params)
+    return request
 
-        :returns:
-            data in dictionary format.
+  def _auser_action_on_item(self, action, uid, iid, params):
+    """Private function to asynchronously create an user action on an item
 
-        :raises:
-            ItemSimNotFoundError.
-        """
-        if response.error is not None:
-            raise ItemSimNotFoundError(
-                "Exception happened: %s for request %s" %
-                (response.error, response.request))
-        elif response.status != httplib.OK:
-            raise ItemSimNotFoundError("request: %s status: %s body: %s" %
-                                      (response.request, response.status,
-                                       response.body))
-
-        data = json.loads(response.body)  # convert json string to dict
-        return data
-
-    def aget_itemsim_topn(self, engine, iid, n, params={}):
-        """Asynchronously get top n similar items of the item
-
-        :param engine: name of the prediction engine. type str.
-        :param iid: item id. type str.
-        :param n: number of similar items. type int.
-        :param params: optional parameters. type dictionary
-                For example, { 'pio_itypes' : ("t1",) }
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
+    :param action: action type. type str. ("like", "dislike", "conversion",
+                         "rate", "view")
+    :param uid: user id. type str or int.
+    :param iid: item id. type str or int.
+    :param params: optional attributes. type dictionary.
+        For example, { 'pio_rate' : 4, 'pio_latlng' : [1.23,4.56] }
+        NOTE: For "rate" action, pio_rate attribute is required.
+            integer value of 1-5 (1 is least preferred and 5 is most
+            preferred)
 
-        request = self._aget_itemsim_topn(engine, iid, n, params)
-        return request
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    if "pio_latlng" in params:
+      params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
 
-    def _auser_action_on_item(self, action, uid, iid, params):
-        """Private function to asynchronously create an user action on an item
+    path = "%s/actions/u2i.json" % (self.apiversion)
+    request = AsyncRequest("POST", path, pio_appkey=self.appkey,
+                 pio_action=action, pio_uid=uid, pio_iid=iid,
+                 **params)
+    request.set_rfunc(self._auser_action_on_item_resp)
+    self._connection.make_request(request)
+    return request
 
-        :param action: action type. type str. ("like", "dislike", "conversion",
-                                               "rate", "view")
-        :param uid: user id. type str or int.
-        :param iid: item id. type str or int.
-        :param params: optional attributes. type dictionary.
-                For example, { 'pio_rate' : 4, 'pio_latlng' : [1.23,4.56] }
-                NOTE: For "rate" action, pio_rate attribute is required.
-                      integer value of 1-5 (1 is least preferred and 5 is most
-                      preferred)
+  def _auser_action_on_item_resp(self, response):
+    """Private function to handle the AsyncResponse of the
+    _auser_action_on_item request
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        if "pio_latlng" in params:
-            params["pio_latlng"] = ",".join(map(str, params["pio_latlng"]))
+    :param response: AsyncResponse object
 
-        path = "%s/actions/u2i.json" % (self.apiversion)
-        request = AsyncRequest("POST", path, pio_appkey=self.appkey,
-                               pio_action=action, pio_uid=uid, pio_iid=iid,
-                               **params)
-        request.set_rfunc(self._auser_action_on_item_resp)
-        self._connection.make_request(request)
-        return request
+    :returns:
+      None
 
-    def _auser_action_on_item_resp(self, response):
-        """Private function to handle the AsyncResponse of the
-        _auser_action_on_item request
+    :raises:
+      U2IActionNotCreatedError
+    """
+    if response.error is not None:
+      raise U2IActionNotCreatedError(
+        "Exception happened: %s for request %s" %
+        (response.error, response.request))
+    elif response.status != httplib.CREATED:
+      raise U2IActionNotCreatedError("request: %s status: %s body: %s" %
+                       (response.request, response.status,
+                      response.body))
+    return None
 
-        :param response: AsyncResponse object
+  def arecord_action_on_item(self, action, iid, params={}):
+    """Asynchronously create action on item
 
-        :returns:
-            None
+    :param action: action name. type String. For example, "rate", "like",
+             etc
+    :param iid: item id. type str or int.
+    :param params: optional attributes. type dictionary.
+        For example, { 'pio_rate' : 4, 'pio_latlng': [4.5,67.8] }
+        NOTE: For "rate" action, pio_rate attribute is required.
+        integer value of 1-5 (1 is least preferred and 5 is most
+        preferred)
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        if response.error is not None:
-            raise U2IActionNotCreatedError(
-                "Exception happened: %s for request %s" %
-                (response.error, response.request))
-        elif response.status != httplib.CREATED:
-            raise U2IActionNotCreatedError("request: %s status: %s body: %s" %
-                                           (response.request, response.status,
-                                            response.body))
-        return None
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
 
-    def arecord_action_on_item(self, action, iid, params={}):
-        """Asynchronously create action on item
+    :raises:
+      U2IActionNotCreatedError
+    """
 
-        :param action: action name. type String. For example, "rate", "like",
-                       etc
-        :param iid: item id. type str or int.
-        :param params: optional attributes. type dictionary.
-                For example, { 'pio_rate' : 4, 'pio_latlng': [4.5,67.8] }
-                NOTE: For "rate" action, pio_rate attribute is required.
-                integer value of 1-5 (1 is least preferred and 5 is most
-                preferred)
+    if self._uid is None:
+      raise InvalidArgumentError(
+        "uid is not identified. Please call identify(uid) first.")
 
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
+    request = self._auser_action_on_item(action, self._uid, iid, params)
+    return request
 
-        :raises:
-            U2IActionNotCreatedError
-        """
+  def auser_conversion_item(self, uid, iid, **params):
+    """Deprecated. Asynchronously create an user conversion action on an
+    item
 
-        if self._uid is None:
-            raise InvalidArgumentError(
-                "uid is not identified. Please call identify(uid) first.")
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    request = self._auser_action_on_item(CONVERSION_API, uid, iid, params)
+    return request
 
-        request = self._auser_action_on_item(action, self._uid, iid, params)
-        return request
+  def auser_dislike_item(self, uid, iid, **params):
+    """Deprecated. Asynchronously create an user dislike action on an item
 
-    def auser_conversion_item(self, uid, iid, **params):
-        """Deprecated. Asynchronously create an user conversion action on an
-        item
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    request = self._auser_action_on_item(DISLIKE_API, uid, iid, params)
+    return request
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        request = self._auser_action_on_item(CONVERSION_API, uid, iid, params)
-        return request
+  def auser_like_item(self, uid, iid, **params):
+    """Deprecated. Asynchronously create an user like action on an item
 
-    def auser_dislike_item(self, uid, iid, **params):
-        """Deprecated. Asynchronously create an user dislike action on an item
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    request = self._auser_action_on_item(LIKE_API, uid, iid, params)
+    return request
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        request = self._auser_action_on_item(DISLIKE_API, uid, iid, params)
-        return request
+  def auser_rate_item(self, uid, iid, rate, **params):
+    """Deprecated. Asynchronously create an user rate action on an item
 
-    def auser_like_item(self, uid, iid, **params):
-        """Deprecated. Asynchronously create an user like action on an item
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param rate: rating. integer value of 1-5 (1 is least preferred and 5
+           is most preferred)
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        request = self._auser_action_on_item(LIKE_API, uid, iid, params)
-        return request
+    params['pio_rate'] = rate
+    request = self._auser_action_on_item(RATE_API, uid, iid, params)
+    return request
 
-    def auser_rate_item(self, uid, iid, rate, **params):
-        """Deprecated. Asynchronously create an user rate action on an item
+  def auser_view_item(self, uid, iid, **params):
+    """Deprecated. Asynchronously create an user view action on an item
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param rate: rating. integer value of 1-5 (1 is least preferred and 5
-                     is most preferred)
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
+    :returns:
+      AsyncRequest object. You should call the aresp() method using this
+      AsyncRequest object as argument to get the final result or status
+      of this asynchronous request.
+    """
+    request = self._auser_action_on_item(VIEW_API, uid, iid, params)
+    return request
 
-        params['pio_rate'] = rate
-        request = self._auser_action_on_item(RATE_API, uid, iid, params)
-        return request
+  def aresp(self, request):
+    """Get the result of the asynchronous request
 
-    def auser_view_item(self, uid, iid, **params):
-        """Deprecated. Asynchronously create an user view action on an item
+    :param request: AsyncRequest object. This object must be returned by
+            the asynchronous request function
+            For example, to get the result of a aget_user()
+            request, call this aresp() with the argument of
+            AsyncRequest object returned by aget_user().
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
-        :returns:
-            AsyncRequest object. You should call the aresp() method using this
-            AsyncRequest object as argument to get the final result or status
-            of this asynchronous request.
-        """
-        request = self._auser_action_on_item(VIEW_API, uid, iid, params)
-        return request
+    :returns:
+      The result of this AsyncRequest. The return type is the same as
+      the return type of corresponding blocking request.
 
-    def aresp(self, request):
-        """Get the result of the asynchronous request
+      For example,
 
-        :param request: AsyncRequest object. This object must be returned by
-                        the asynchronous request function
-                        For example, to get the result of a aget_user()
-                        request, call this aresp() with the argument of
-                        AsyncRequest object returned by aget_user().
+      Calling aresp() with acreate_user() AsyncRequest returns the same
+      type as create_user(), which is None.
 
-        :returns:
-            The result of this AsyncRequest. The return type is the same as
-            the return type of corresponding blocking request.
+      Calling aresp() with aget_user() AsyncRequest returns the same
+      type as get_user(), which is dictionary data.
 
-            For example,
+    :raises:
+      Exception may be raised if there is error happened. The type of
+      exception is the same as exception type of the correspdoning
+      blocking request.
 
-            Calling aresp() with acreate_user() AsyncRequest returns the same
-            type as create_user(), which is None.
+      For example,
 
-            Calling aresp() with aget_user() AsyncRequest returns the same
-            type as get_user(), which is dictionary data.
+      Calling aresp() with acreate_user() AsyncRequest may raise
+      UserNotCreatedError exception.
 
-        :raises:
-            Exception may be raised if there is error happened. The type of
-            exception is the same as exception type of the correspdoning
-            blocking request.
+      Calling aresp() with aget_user() AsyncRequest may raise
+      UserNotFoundError exception.
 
-            For example,
+    """
+    response = request.get_response()
+    result = request.rfunc(response)
+    return result
 
-            Calling aresp() with acreate_user() AsyncRequest may raise
-            UserNotCreatedError exception.
+  def create_user(self, uid, params={}):
+    """Blocking request to create user
 
-            Calling aresp() with aget_user() AsyncRequest may raise
-            UserNotFoundError exception.
+    :param uid: user id. type str.
+    :param params: optional attributes. type dictionary.
+      For example, { 'custom': 'value', 'pio_inactive' : True,
+      'pio_latlng': [4.5,67.8] }
 
-        """
-        response = request.get_response()
-        result = request.rfunc(response)
-        return result
+    :returns:
+      None.
 
-    def create_user(self, uid, params={}):
-        """Blocking request to create user
+    :raises:
+      UserNotCreatedError.
 
-        :param uid: user id. type str.
-        :param params: optional attributes. type dictionary.
-            For example, { 'custom': 'value', 'pio_inactive' : True,
-            'pio_latlng': [4.5,67.8] }
+    """
+    request = self.acreate_user(uid, params)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            None.
+  def get_user(self, uid):
+    """Blocking request to get user
 
-        :raises:
-            UserNotCreatedError.
+    :param uid: user id. type str or int.
 
-        """
-        request = self.acreate_user(uid, params)
-        result = self.aresp(request)
-        return result
+    :returns:
+      User data in Dictionary format.
 
-    def get_user(self, uid):
-        """Blocking request to get user
+    :rasies:
+      UserNotFoundError.
 
-        :param uid: user id. type str or int.
+    """
+    request = self.aget_user(uid)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            User data in Dictionary format.
+  def delete_user(self, uid):
+    """Blocking request to delete the user
 
-        :rasies:
-            UserNotFoundError.
+    :param uid: user id. type str.
 
-        """
-        request = self.aget_user(uid)
-        result = self.aresp(request)
-        return result
+    :returns:
+      None.
 
-    def delete_user(self, uid):
-        """Blocking request to delete the user
+    :raises:
+      UserNotDeletedError.
 
-        :param uid: user id. type str.
+    """
+    request = self.adelete_user(uid)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            None.
+  def create_item(self, iid, itypes, params={}):
+    """Blocking request to create item
 
-        :raises:
-            UserNotDeletedError.
+    :param iid: item id. type str.
+    :param itypes: item types. Tuple of Str.
+        For example, if this item belongs to item types "t1", "t2",
+        "t3", "t4", then itypes=("t1", "t2", "t3", "t4").
+        NOTE: if this item belongs to only one itype, use tuple of one
+        element, eg. itypes=("t1",)
+    :param params: optional attributes. type dictionary.
+        For example,
+        { 'custom': 'value', 'pio_inactive' : True,
+        'pio_latlng': [4.5,67.8] }
 
-        """
-        request = self.adelete_user(uid)
-        result = self.aresp(request)
-        return result
+    :returns:
+      None
 
-    def create_item(self, iid, itypes, params={}):
-        """Blocking request to create item
+    :raises:
+      ItemNotCreatedError
 
-        :param iid: item id. type str.
-        :param itypes: item types. Tuple of Str.
-                For example, if this item belongs to item types "t1", "t2",
-                "t3", "t4", then itypes=("t1", "t2", "t3", "t4").
-                NOTE: if this item belongs to only one itype, use tuple of one
-                element, eg. itypes=("t1",)
-        :param params: optional attributes. type dictionary.
-                For example, 
-                { 'custom': 'value', 'pio_inactive' : True,
-                'pio_latlng': [4.5,67.8] }
+    """
+    request = self.acreate_item(iid, itypes, params)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            None
+  def get_item(self, iid):
+    """Blocking request to get item
 
-        :raises:
-            ItemNotCreatedError
+    :param iid: item id. type str.
 
-        """
-        request = self.acreate_item(iid, itypes, params)
-        result = self.aresp(request)
-        return result
+    :returns:
+      item data in dictionary format.
 
-    def get_item(self, iid):
-        """Blocking request to get item
+    :raises:
+      ItemNotFoundError.
 
-        :param iid: item id. type str.
+    """
+    request = self.aget_item(iid)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            item data in dictionary format.
+  def delete_item(self, iid):
+    """Blocking request to delete item
 
-        :raises:
-            ItemNotFoundError.
+    :param iid: item id. type str.
 
-        """
-        request = self.aget_item(iid)
-        result = self.aresp(request)
-        return result
+    :returns:
+      None
 
-    def delete_item(self, iid):
-        """Blocking request to delete item
+    :raises:
+      ItemNotDeletedError
 
-        :param iid: item id. type str.
+    """
+    request = self.adelete_item(iid)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            None
+  def get_itemrec_topn(self, engine, n, params={}):
+    """Blocking request to get recommendations for the identified user
 
-        :raises:
-            ItemNotDeletedError
+    :param engine: name of the prediction engine. type str.
+    :param n: number of recommendation. type int.
+    :param params: optional parameters. type dictionary
+        For example, { 'pio_itypes' : ("t1", "t2") }
+    :returns:
+      data in dictionary format.
 
-        """
-        request = self.adelete_item(iid)
-        result = self.aresp(request)
-        return result
+    :raises:
+      ItemRecNotFoundError.
+    """
+    request = self.aget_itemrec_topn(engine, n, params)
+    result = self.aresp(request)
+    return result
 
-    def get_itemrec_topn(self, engine, n, params={}):
-        """Blocking request to get recommendations for the identified user
+  def get_itemrec(self, uid, n, engine, **params):
+    """Deprecated. Blocking request to get recommendations
 
-        :param engine: name of the prediction engine. type str.
-        :param n: number of recommendation. type int.
-        :param params: optional parameters. type dictionary
-                For example, { 'pio_itypes' : ("t1", "t2") }
-        :returns:
-            data in dictionary format.
+    :param uid: user id. type str or int.
+    :param n: number of recommendation. type int.
+    :param engine: name of the prediction engine. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
 
-        :raises:
-            ItemRecNotFoundError.
-        """
-        request = self.aget_itemrec_topn(engine, n, params)
-        result = self.aresp(request)
-        return result
+    :returns:
+      data in dictionary format.
 
-    def get_itemrec(self, uid, n, engine, **params):
-        """Deprecated. Blocking request to get recommendations
+    :raises:
+      ItemRecNotFoundError.
 
-        :param uid: user id. type str or int.
-        :param n: number of recommendation. type int.
-        :param engine: name of the prediction engine. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
+    """
+    request = self.aget_itemrec(uid, n, engine, **params)
+    result = self.aresp(request)
+    return result
 
-        :returns:
-            data in dictionary format.
+  def get_itemsim_topn(self, engine, iid, n, params={}):
+    """Blocking request to get top n similar items of the item
 
-        :raises:
-            ItemRecNotFoundError.
+    :param engine: name of the prediction engine. type str.
+    :param iid: item id. type str.
+    :param n: number of similar items. type int.
+    :param params: optional parameters. type dictionary
+        For example, { 'pio_itypes' : ("t1",) }
+    :returns:
+      data in dictionary format.
 
-        """
-        request = self.aget_itemrec(uid, n, engine, **params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      ItemSimNotFoundError.
+    """
 
-    def get_itemsim_topn(self, engine, iid, n, params={}):
-        """Blocking request to get top n similar items of the item
+    request = self.aget_itemsim_topn(engine, iid, n, params)
+    result = self.aresp(request)
+    return result
 
-        :param engine: name of the prediction engine. type str.
-        :param iid: item id. type str.
-        :param n: number of similar items. type int.
-        :param params: optional parameters. type dictionary
-                For example, { 'pio_itypes' : ("t1",) }
-        :returns:
-            data in dictionary format.
+  def get_itemrank_ranked(self, engine, iids, params={}):
+    """Blocking request to get ranked item for user
 
-        :raises:
-            ItemSimNotFoundError.
-        """
+    :param engine: name of the prediction engine. type str.
+    :param iids: items to be ranked. type list of item ids.
+        For example, ["i0", "i1", "i2"]
+    :param params: optional parameters. type dictionary
+        For example. { 'pio_attributes' : "name" }
+    :returns:
+      data in dictionary format.
 
-        request = self.aget_itemsim_topn(engine, iid, n, params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      ItemRankNotFoundError.
+    """
+    request = self.aget_itemrank_ranked(engine, iids, params)
+    result = self.aresp(request)
+    return result
 
-    def record_action_on_item(self, action, iid, params={}):
-        """Blocking request to create action on an item
+  def record_action_on_item(self, action, iid, params={}):
+    """Blocking request to create action on an item
 
-        :param action: action name. type String. For example, "rate", "like",
-                       etc
-        :param iid: item id. type str.
-        :param params: optional attributes. type dictionary.
-                For example, { 'pio_rate' : 4, 'pio_latlng' : [1.23,4.56] }
-                NOTE: For "rate" action, pio_rate attribute is required.
-                integer value of 1-5 (1 is least preferred and 5 is most
-                preferred)
+    :param action: action name. type String. For example, "rate", "like",
+             etc
+    :param iid: item id. type str.
+    :param params: optional attributes. type dictionary.
+        For example, { 'pio_rate' : 4, 'pio_latlng' : [1.23,4.56] }
+        NOTE: For "rate" action, pio_rate attribute is required.
+        integer value of 1-5 (1 is least preferred and 5 is most
+        preferred)
 
-        :returns:
-            None
+    :returns:
+      None
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        request = self.arecord_action_on_item(action, iid, params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      U2IActionNotCreatedError
+    """
+    request = self.arecord_action_on_item(action, iid, params)
+    result = self.aresp(request)
+    return result
 
-    def user_conversion_item(self, uid, iid, **params):
-        """Deprecated. Blocking request to create user conversion action on an
-         item
+  def user_conversion_item(self, uid, iid, **params):
+    """Deprecated. Blocking request to create user conversion action on an
+     item
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
 
-        :returns:
-            None
+    :returns:
+      None
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        request = self.auser_conversion_item(uid, iid, **params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      U2IActionNotCreatedError
+    """
+    request = self.auser_conversion_item(uid, iid, **params)
+    result = self.aresp(request)
+    return result
 
-    def user_dislike_item(self, uid, iid, **params):
-        """Deprecated. Blocking request to create user dislike action on an
-         item
+  def user_dislike_item(self, uid, iid, **params):
+    """Deprecated. Blocking request to create user dislike action on an
+     item
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
 
-        :returns:
-            None
+    :returns:
+      None
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        request = self.auser_dislike_item(uid, iid, **params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      U2IActionNotCreatedError
+    """
+    request = self.auser_dislike_item(uid, iid, **params)
+    result = self.aresp(request)
+    return result
 
-    def user_like_item(self, uid, iid, **params):
-        """Deprecated. Blocking request to create user like action on an item
+  def user_like_item(self, uid, iid, **params):
+    """Deprecated. Blocking request to create user like action on an item
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
 
-        :returns:
-            None
+    :returns:
+      None
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        request = self.auser_like_item(uid, iid, **params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      U2IActionNotCreatedError
+    """
+    request = self.auser_like_item(uid, iid, **params)
+    result = self.aresp(request)
+    return result
 
-    def user_rate_item(self, uid, iid, rate, **params):
-        """Deprecated. Blocking request to create user rate action on an item
+  def user_rate_item(self, uid, iid, rate, **params):
+    """Deprecated. Blocking request to create user rate action on an item
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param rate: rating. integer value of 1-5 (1 is least preferred and 5
-                     is most preferred)
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param rate: rating. integer value of 1-5 (1 is least preferred and 5
+           is most preferred)
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
 
-        :returns:
-            None
+    :returns:
+      None
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        request = self.auser_rate_item(uid, iid, rate, **params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      U2IActionNotCreatedError
+    """
+    request = self.auser_rate_item(uid, iid, rate, **params)
+    result = self.aresp(request)
+    return result
 
-    def user_view_item(self, uid, iid, **params):
-        """Deprecated. Blocking request to create user view action on an item
+  def user_view_item(self, uid, iid, **params):
+    """Deprecated. Blocking request to create user view action on an item
 
-        :param uid: user id. type str.
-        :param iid: item id. type str.
-        :param params: keyword arguments for optional attributes.
-                For example, pio_latlng=[123.4, 56.7]
+    :param uid: user id. type str.
+    :param iid: item id. type str.
+    :param params: keyword arguments for optional attributes.
+        For example, pio_latlng=[123.4, 56.7]
 
-        :returns:
-            None
+    :returns:
+      None
 
-        :raises:
-            U2IActionNotCreatedError
-        """
-        request = self.auser_view_item(uid, iid, **params)
-        result = self.aresp(request)
-        return result
+    :raises:
+      U2IActionNotCreatedError
+    """
+    request = self.auser_view_item(uid, iid, **params)
+    result = self.aresp(request)
+    return result
diff --git a/predictionio/connection.py b/predictionio/connection.py
index c2ee60b..e124c5b 100644
--- a/predictionio/connection.py
+++ b/predictionio/connection.py
@@ -1,29 +1,32 @@
 
 try:
-    import Queue
+  import Queue
 except ImportError:
-    import queue as Queue
+  # pylint: disable=F0401
+  # http is a Python3 module, replacing httplib. Ditto.
+  import queue as Queue
 import threading
 
 try:
-    import httplib
+  import httplib
 except ImportError:
-    from http import client as httplib
+  # pylint: disable=F0401
+  from http import client as httplib
 
 try:
-    from urllib import urlencode
+  from urllib import urlencode
 except ImportError:
-    from urllib.parse import urlencode
+  # pylint: disable=F0401,E0611
+  from urllib.parse import urlencode
 
-import urllib
 import datetime
 import logging
 
 # use generators for python2 and python3
 try:
-    xrange
+  xrange
 except NameError:
-    xrange = range
+  xrange = range
 
 # some constants
 MAX_RETRY = 1  # 0 means no retry
@@ -35,325 +38,325 @@
 
 
 def enable_log(filename=None):
-    global logger
-    global DEBUG_LOG
-    timestamp = datetime.datetime.today()
-    if not filename:
-        logfile = "./log/predictionio_%s.log" % timestamp.strftime(
-            "%Y-%m-%d_%H:%M:%S.%f")
-    else:
-        logfile = filename
-    logging.basicConfig(filename=logfile,
-                        filemode='w',
-                        level=logging.DEBUG,
-                        format='[%(levelname)s] %(name)s (%(threadName)s) %(message)s')
-    logger = logging.getLogger(__name__)
-    DEBUG_LOG = True
+  global logger
+  global DEBUG_LOG
+  timestamp = datetime.datetime.today()
+  if not filename:
+    logfile = "./log/predictionio_%s.log" % timestamp.strftime(
+      "%Y-%m-%d_%H:%M:%S.%f")
+  else:
+    logfile = filename
+  logging.basicConfig(filename=logfile,
+            filemode='w',
+            level=logging.DEBUG,
+            format='[%(levelname)s] %(name)s (%(threadName)s) %(message)s')
+  logger = logging.getLogger(__name__)
+  DEBUG_LOG = True
 
 
 class PredictionIOAPIError(Exception):
-    pass
+  pass
 
 
 class NotSupportMethodError(PredictionIOAPIError):
-    pass
+  pass
 
 
 class ProgramError(PredictionIOAPIError):
-    pass
+  pass
 
 
 class AsyncRequest(object):
 
-    """AsyncRequest object
+  """AsyncRequest object
+
+  """
+
+  def __init__(self, method, path, **params):
+    self.method = method  # "GET" "POST" etc
+    # the sub path eg. POST /v1/users.json  GET /v1/users/1.json
+    self.path = path
+    # dictionary format eg. {"appkey" : 123, "id" : 3}
+    self.params = params
+    # use queue to implement response, store AsyncResponse object
+    self.response_q = Queue.Queue(1)
+    self.qpath = "%s?%s" % (self.path, urlencode(self.params))
+    self._response = None
+    # response function to be called to handle the response
+    self.rfunc = None
+
+  def __str__(self):
+    return "%s %s %s %s" % (self.method, self.path, self.params,
+                self.qpath)
+
+  def set_rfunc(self, func):
+    self.rfunc = func
+
+  def set_response(self, response):
+    """ store the response
+
+    NOTE: Must be only called once
+    """
+    self.response_q.put(response)
+
+  def get_response(self):
+    """get the response
 
     """
+    if self._response is None:
+      self._response = self.response_q.get(True)  # NOTE: blocking
 
-    def __init__(self, method, path, **params):
-        self.method = method  # "GET" "POST" etc
-        # the sub path eg. POST /v1/users.json  GET /v1/users/1.json
-        self.path = path
-        # dictionary format eg. {"appkey" : 123, "id" : 3}
-        self.params = params
-        # use queue to implement response, store AsyncResponse object
-        self.response_q = Queue.Queue(1)
-        self.qpath = "%s?%s" % (self.path, urlencode(self.params))
-        self._response = None
-        # response function to be called to handle the response
-        self.rfunc = None
-
-    def __str__(self):
-        return "%s %s %s %s" % (self.method, self.path, self.params,
-                                self.qpath)
-
-    def set_rfunc(self, func):
-        self.rfunc = func
-
-    def set_response(self, response):
-        """ store the response
-
-        NOTE: Must be only called once
-        """
-        self.response_q.put(response)
-
-    def get_response(self):
-        """get the response
-
-        """
-        if self._response is None:
-            self._response = self.response_q.get(True)  # NOTE: blocking
-
-        return self._response
+    return self._response
 
 
 class AsyncResponse(object):
 
-    """AsyncResponse object.
+  """AsyncResponse object.
 
-    Store the response of asynchronous request
+  Store the response of asynchronous request
 
-    when get the response, user should check if error is None (which means no
-    Exception happens)
-    if error is None, then should check if the status is expected
+  when get the response, user should check if error is None (which means no
+  Exception happens)
+  if error is None, then should check if the status is expected
 
-    Attributes:
-        error: exception object if any happens
-        version: int
-        status: int
-        reason: str
-        headers: dict
-        body: str (NOTE: not necessarily can be converted to JSON,
-              eg, for GET request to /v1/status)
-        request: the corresponding AsyncRequest object
-    """
+  Attributes:
+    error: exception object if any happens
+    version: int
+    status: int
+    reason: str
+    headers: dict
+    body: str (NOTE: not necessarily can be converted to JSON,
+        eg, for GET request to /v1/status)
+    request: the corresponding AsyncRequest object
+  """
 
-    def __init__(self):
-        self.error = None
-        self.version = None
-        self.status = None
-        self.reason = None
-        self.headers = None
-        self.body = None
-        self.request = None  # point back to the request object
+  def __init__(self):
+    self.error = None
+    self.version = None
+    self.status = None
+    self.reason = None
+    self.headers = None
+    self.body = None
+    self.request = None  # point back to the request object
 
-    def __str__(self):
-        return "e:%s v:%s s:%s r:%s h:%s b:%s" % (self.error, self.version,
-                                                  self.status, self.reason,
-                                                  self.headers, self.body)
+  def __str__(self):
+    return "e:%s v:%s s:%s r:%s h:%s b:%s" % (self.error, self.version,
+                          self.status, self.reason,
+                          self.headers, self.body)
 
-    def set_resp(self, version, status, reason, headers, body):
-        self.version = version
-        self.status = status
-        self.reason = reason
-        self.headers = headers
-        self.body = body
+  def set_resp(self, version, status, reason, headers, body):
+    self.version = version
+    self.status = status
+    self.reason = reason
+    self.headers = headers
+    self.body = body
 
-    def set_error(self, error):
-        self.error = error
+  def set_error(self, error):
+    self.error = error
 
-    def set_request(self, request):
-        self.request = request
+  def set_request(self, request):
+    self.request = request
 
 
 class PredictionIOHttpConnection(object):
 
-    def __init__(self, host, https=True, timeout=5):
-        if https:  # https connection
-            self._connection = httplib.HTTPSConnection(host, timeout=timeout)
-        else:
-            self._connection = httplib.HTTPConnection(host, timeout=timeout)
+  def __init__(self, host, https=True, timeout=5):
+    if https:  # https connection
+      self._connection = httplib.HTTPSConnection(host, timeout=timeout)
+    else:
+      self._connection = httplib.HTTPConnection(host, timeout=timeout)
 
-    def connect(self):
-        self._connection.connect()
+  def connect(self):
+    self._connection.connect()
 
-    def close(self):
+  def close(self):
+    self._connection.close()
+
+  def request(self, method, url, body={}, headers={}):
+    """
+    http request wrapper function, with retry capability in case of error.
+    catch error exception and store it in AsyncResponse object
+    return AsyncResponse object
+
+    Args:
+      method: http method, type str
+      url: url path, type str
+      body: http request body content, type dict
+      header: http request header , type dict
+    """
+
+    response = AsyncResponse()
+
+    try:
+      # number of retry in case of error (minimum 0 means no retry)
+      retry_limit = MAX_RETRY
+      mod_headers = dict(headers)  # copy the headers
+      mod_headers["Connection"] = "keep-alive"
+      enc_body = None
+      if body:  # if body is not empty
+        enc_body = urlencode(body)
+        mod_headers[
+          "Content-type"] = "application/x-www-form-urlencoded"
+        #mod_headers["Accept"] = "text/plain"
+    except Exception as e:
+      response.set_error(e)
+      return response
+
+    if DEBUG_LOG:
+      logger.debug("Request m:%s u:%s h:%s b:%s", method, url,
+             mod_headers, enc_body)
+    # retry loop
+    for i in xrange(retry_limit + 1):
+      try:
+        if i != 0:
+          if DEBUG_LOG:
+            logger.debug("retry request %s times" % i)
+        if self._connection.sock is None:
+          self._connection.connect()
+        self._connection.request(method, url, enc_body, mod_headers)
+      except Exception as e:
         self._connection.close()
-
-    def request(self, method, url, body={}, headers={}):
-        """
-        http request wrapper function, with retry capability in case of error.
-        catch error exception and store it in AsyncResponse object
-        return AsyncResponse object
-
-        Args:
-            method: http method, type str
-            url: url path, type str
-            body: http request body content, type dict
-            header: http request header , type dict
-        """
-
-        response = AsyncResponse()
-
+        if i == retry_limit:
+          # new copy of e created everytime??
+          response.set_error(e)
+      else:  # NOTE: this is try's else clause
+        # connect() and request() OK
         try:
-            # number of retry in case of error (minimum 0 means no retry)
-            retry_limit = MAX_RETRY
-            mod_headers = dict(headers)  # copy the headers
-            mod_headers["Connection"] = "keep-alive"
-            enc_body = None
-            if body:  # if body is not empty
-                enc_body = urlencode(body)
-                mod_headers[
-                    "Content-type"] = "application/x-www-form-urlencoded"
-                #mod_headers["Accept"] = "text/plain"
+          resp = self._connection.getresponse()
         except Exception as e:
+          self._connection.close()
+          if i == retry_limit:
             response.set_error(e)
-            return response
-
-        if DEBUG_LOG:
-            logger.debug("Request m:%s u:%s h:%s b:%s", method, url,
-                         mod_headers, enc_body)
-        # retry loop
-        for i in xrange(retry_limit + 1):
-            try:
-                if i != 0:
-                    if DEBUG_LOG:
-                        logger.debug("retry request %s times" % i)
-                if self._connection.sock is None:
-                    self._connection.connect()
-                self._connection.request(method, url, enc_body, mod_headers)
-            except Exception as e:
-                self._connection.close()
-                if i == retry_limit:
-                    # new copy of e created everytime??
-                    response.set_error(e)
-            else:  # NOTE: this is try's else clause
-                # connect() and request() OK
-                try:
-                    resp = self._connection.getresponse()
-                except Exception as e:
-                    self._connection.close()
-                    if i == retry_limit:
-                        response.set_error(e)
-                else:  # NOTE: this is try's else clause
-                    # getresponse() OK
-                    resp_version = resp.version  # int
-                    resp_status = resp.status  # int
-                    resp_reason = resp.reason  # str
-                    # resp.getheaders() returns list of tuples
-                    # converted to dict format
-                    resp_headers = dict(resp.getheaders())
-                    # NOTE: have to read the response before sending out next
-                    # http request
-                    resp_body = resp.read()  # str
-                    response.set_resp(version=resp_version, status=resp_status,
-                                      reason=resp_reason, headers=resp_headers,
-                                      body=resp_body)
-                    break  # exit retry loop
-        # end of retry loop
-        if DEBUG_LOG:
-            logger.debug("Response %s", response)
-        return response  # AsyncResponse object
+        else:  # NOTE: this is try's else clause
+          # getresponse() OK
+          resp_version = resp.version  # int
+          resp_status = resp.status  # int
+          resp_reason = resp.reason  # str
+          # resp.getheaders() returns list of tuples
+          # converted to dict format
+          resp_headers = dict(resp.getheaders())
+          # NOTE: have to read the response before sending out next
+          # http request
+          resp_body = resp.read()  # str
+          response.set_resp(version=resp_version, status=resp_status,
+                    reason=resp_reason, headers=resp_headers,
+                    body=resp_body)
+          break  # exit retry loop
+    # end of retry loop
+    if DEBUG_LOG:
+      logger.debug("Response %s", response)
+    return response  # AsyncResponse object
 
 
 def connection_worker(host, request_queue, https=True, timeout=5, loop=True):
-    """worker function which establishes connection and wait for request jobs
-    from the request_queue
+  """worker function which establishes connection and wait for request jobs
+  from the request_queue
 
-    Args:
-        request_queue: the request queue storing the AsyncRequest object
-            valid requests:
-                GET
-                POST
-                DELETE
-                KILL
-        https: HTTPS (True) or HTTP (False)
-        timeout: timeout for HTTP connection attempts and requests in seconds
-        loop: This worker function stays in a loop waiting for request
-            For testing purpose only. should always be set to True.
-    """
+  Args:
+    request_queue: the request queue storing the AsyncRequest object
+      valid requests:
+        GET
+        POST
+        DELETE
+        KILL
+    https: HTTPS (True) or HTTP (False)
+    timeout: timeout for HTTP connection attempts and requests in seconds
+    loop: This worker function stays in a loop waiting for request
+      For testing purpose only. should always be set to True.
+  """
 
-    connect = PredictionIOHttpConnection(host, https, timeout)
+  connect = PredictionIOHttpConnection(host, https, timeout)
 
-    # loop waiting for job form request queue
-    killed = not loop
+  # loop waiting for job form request queue
+  killed = not loop
 
-    while True:
-        # print "thread %s waiting for request" % thread.get_ident()
-        request = request_queue.get(True)  # NOTE: blocking get
-        # print "get request %s" % request
-        method = request.method
-        if method == "GET":
-            path = request.qpath
-            d = connect.request("GET", path)
-        elif method == "POST":
-            path = request.path
-            body = request.params
-            d = connect.request("POST", path, body)
-        elif method == "DELETE":
-            path = request.qpath
-            d = connect.request("DELETE", path)
-        elif method == "KILL":
-            # tell the thread to kill the connection
-            killed = True
-            d = AsyncResponse()
-        else:
-            d = AsyncResponse()
-            d.set_error(NotSupportMethodError(
-                "Don't Support the method %s" % method))
+  while True:
+    # print "thread %s waiting for request" % thread.get_ident()
+    request = request_queue.get(True)  # NOTE: blocking get
+    # print "get request %s" % request
+    method = request.method
+    if method == "GET":
+      path = request.qpath
+      d = connect.request("GET", path)
+    elif method == "POST":
+      path = request.path
+      body = request.params
+      d = connect.request("POST", path, body)
+    elif method == "DELETE":
+      path = request.qpath
+      d = connect.request("DELETE", path)
+    elif method == "KILL":
+      # tell the thread to kill the connection
+      killed = True
+      d = AsyncResponse()
+    else:
+      d = AsyncResponse()
+      d.set_error(NotSupportMethodError(
+        "Don't Support the method %s" % method))
 
-        d.set_request(request)
-        request.set_response(d)
-        request_queue.task_done()
-        if killed:
-            break
+    d.set_request(request)
+    request.set_response(d)
+    request_queue.task_done()
+    if killed:
+      break
 
-    # end of while loop
-    connect.close()
+  # end of while loop
+  connect.close()
 
 
 class Connection(object):
 
-    """abstract object for connection with server
+  """abstract object for connection with server
 
-    spawn multiple connection_worker threads to handle jobs in the queue q
+  spawn multiple connection_worker threads to handle jobs in the queue q
+  """
+
+  def __init__(self, host, threads=1, qsize=0, https=True, timeout=5):
+    """constructor
+
+    Args:
+      host: host of the server.
+      threads: type int, number of threads to be spawn
+      qsize: size of the queue q
+      https: indicate it is httpS (True) or http connection (False)
+      timeout: timeout for HTTP connection attempts and requests in
+        seconds
     """
+    self.host = host
+    self.https = https
+    self.q = Queue.Queue(qsize)  # if qsize=0, means infinite
+    self.threads = threads
+    self.timeout = timeout
+    # start thread based on threads number
+    self.tid = {}  # dictionary of thread object
 
-    def __init__(self, host, threads=1, qsize=0, https=True, timeout=5):
-        """constructor
+    for i in xrange(threads):
+      tname = "PredictionIOThread-%s" % i  # thread name
+      self.tid[i] = threading.Thread(
+        target=connection_worker, name=tname,
+        kwargs={'host': self.host, 'request_queue': self.q,
+            'https': self.https, 'timeout': self.timeout})
+      self.tid[i].setDaemon(True)
+      self.tid[i].start()
 
-        Args:
-            host: host of the server.
-            threads: type int, number of threads to be spawn
-            qsize: size of the queue q
-            https: indicate it is httpS (True) or http connection (False)
-            timeout: timeout for HTTP connection attempts and requests in
-                seconds
-        """
-        self.host = host
-        self.https = https
-        self.q = Queue.Queue(qsize)  # if qsize=0, means infinite
-        self.threads = threads
-        self.timeout = timeout
-        # start thread based on threads number
-        self.tid = {}  # dictionary of thread object
+  def make_request(self, request):
+    """put the request into the q
+    """
+    self.q.put(request)
 
-        for i in xrange(threads):
-            tname = "PredictionIOThread-%s" % i  # thread name
-            self.tid[i] = threading.Thread(
-                target=connection_worker, name=tname,
-                kwargs={'host':self.host, 'request_queue':self.q, 
-                        'https':self.https, 'timeout':self.timeout})
-            self.tid[i].setDaemon(True)
-            self.tid[i].start()
+  def pending_requests(self):
+    """number of pending requests in the queue
+    """
+    return self.q.qsize()
 
-    def make_request(self, request):
-        """put the request into the q
-        """
-        self.q.put(request)
+  def close(self):
+    """close this Connection. Call this when main program exits
+    """
+    # set kill message to q
+    for i in xrange(self.threads):
+      self.make_request(AsyncRequest("KILL", ""))
 
-    def pending_requests(self):
-        """number of pending requests in the queue
-        """
-        return self.q.qsize()
+    self.q.join()  # wait for q empty
 
-    def close(self):
-        """close this Connection. Call this when main program exits
-        """
-        # set kill message to q
-        for i in xrange(self.threads):
-            self.make_request(AsyncRequest("KILL", ""))
-
-        self.q.join()  # wait for q empty
-
-        for i in xrange(self.threads):  # wait for all thread finish
-            self.tid[i].join()
+    for i in xrange(self.threads):  # wait for all thread finish
+      self.tid[i].join()