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# Copyright (C) 2008 Google Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.
"""Provides HTTP functions for gdata.service to use on Google App Engine
AppEngineHttpClient: Provides an HTTP request method which uses App Engine's
urlfetch API. Set the http_client member of a GDataService object to an
instance of an AppEngineHttpClient to allow the gdata library to run on
Google App Engine.
run_on_appengine: Function which will modify an existing GDataService object
to allow it to run on App Engine. It works by creating a new instance of
the AppEngineHttpClient and replacing the GDataService object's
__author__ = 'api.jscudder (Jeff Scudder)'
import StringIO
import pickle
import atom.http_interface
import atom.token_store
from google.appengine.api import urlfetch
from google.appengine.ext import db
from google.appengine.api import users
from google.appengine.api import memcache
def run_on_appengine(gdata_service, store_tokens=True,
single_user_mode=False, deadline=None):
"""Modifies a GDataService object to allow it to run on App Engine.
gdata_service: An instance of AtomService, GDataService, or any
of their subclasses which has an http_client member and a
token_store member.
store_tokens: Boolean, defaults to True. If True, the gdata_service
will attempt to add each token to it's token_store when
SetClientLoginToken or SetAuthSubToken is called. If False
the tokens will not automatically be added to the
single_user_mode: Boolean, defaults to False. If True, the current_token
member of gdata_service will be set when
SetClientLoginToken or SetAuthTubToken is called. If set
to True, the current_token is set in the gdata_service
and anyone who accesses the object will use the same
Note: If store_tokens is set to False and
single_user_mode is set to False, all tokens will be
ignored, since the library assumes: the tokens should not
be stored in the datastore and they should not be stored
in the gdata_service object. This will make it
impossible to make requests which require authorization.
deadline: int (optional) The number of seconds to wait for a response
before timing out on the HTTP request. If no deadline is
specified, the deafault deadline for HTTP requests from App
Engine is used. The maximum is currently 10 (for 10 seconds).
The default deadline for App Engine is 5 seconds.
gdata_service.http_client = AppEngineHttpClient(deadline=deadline)
gdata_service.token_store = AppEngineTokenStore()
gdata_service.auto_store_tokens = store_tokens
gdata_service.auto_set_current_token = single_user_mode
return gdata_service
class AppEngineHttpClient(atom.http_interface.GenericHttpClient):
def __init__(self, headers=None, deadline=None):
self.debug = False
self.headers = headers or {}
self.deadline = deadline
def request(self, operation, url, data=None, headers=None):
"""Performs an HTTP call to the server, supports GET, POST, PUT, and
Usage example, perform and HTTP GET on
import atom.http
client = atom.http.HttpClient()
http_response = client.request('GET', '')
operation: str The HTTP operation to be performed. This is usually one
of 'GET', 'POST', 'PUT', or 'DELETE'
data: filestream, list of parts, or other object which can be converted
to a string. Should be set to None when performing a GET or DELETE.
If data is a file-like object which can be read, this method will
read a chunk of 100K bytes at a time and send them.
If the data is a list of parts to be sent, each part will be
evaluated and sent.
url: The full URL to which the request should be sent. Can be a string
or atom.url.Url.
headers: dict of strings. HTTP headers which should be sent
in the request.
all_headers = self.headers.copy()
if headers:
# Construct the full payload.
# Assume that data is None or a string.
data_str = data
if data:
if isinstance(data, list):
# If data is a list of different objects, convert them all to strings
# and join them together.
converted_parts = [_convert_data_part(x) for x in data]
data_str = ''.join(converted_parts)
data_str = _convert_data_part(data)
# If the list of headers does not include a Content-Length, attempt to
# calculate it based on the data object.
if data and 'Content-Length' not in all_headers:
all_headers['Content-Length'] = str(len(data_str))
# Set the content type to the default value if none was set.
if 'Content-Type' not in all_headers:
all_headers['Content-Type'] = 'application/atom+xml'
# Lookup the urlfetch operation which corresponds to the desired HTTP verb.
if operation == 'GET':
method = urlfetch.GET
elif operation == 'POST':
method = urlfetch.POST
elif operation == 'PUT':
method = urlfetch.PUT
elif operation == 'DELETE':
method = urlfetch.DELETE
method = None
if self.deadline is None:
return HttpResponse(urlfetch.Fetch(url=str(url), payload=data_str,
method=method, headers=all_headers, follow_redirects=False))
return HttpResponse(urlfetch.Fetch(url=str(url), payload=data_str,
method=method, headers=all_headers, follow_redirects=False,
def _convert_data_part(data):
if not data or isinstance(data, str):
return data
elif hasattr(data, 'read'):
# data is a file like object, so read it completely.
# The data object was not a file.
# Try to convert to a string and send the data.
return str(data)
class HttpResponse(object):
"""Translates a urlfetch resoinse to look like an hhtplib resoinse.
Used to allow the resoinse from HttpRequest to be usable by gdata.service
def __init__(self, urlfetch_response):
self.body = StringIO.StringIO(urlfetch_response.content)
self.headers = urlfetch_response.headers
self.status = urlfetch_response.status_code
self.reason = ''
def read(self, length=None):
if not length:
def getheader(self, name):
if not self.headers.has_key(name):
return self.headers[name.lower()]
return self.headers[name]
class TokenCollection(db.Model):
"""Datastore Model which associates auth tokens with the current user."""
user = db.UserProperty()
pickled_tokens = db.BlobProperty()
class AppEngineTokenStore(atom.token_store.TokenStore):
"""Stores the user's auth tokens in the App Engine datastore.
Tokens are only written to the datastore if a user is signed in (if
users.get_current_user() returns a user object).
def __init__(self):
self.user = None
def add_token(self, token):
"""Associates the token with the current user and stores it.
If there is no current user, the token will not be stored.
False if the token was not stored.
tokens = load_auth_tokens(self.user)
if not hasattr(token, 'scopes') or not token.scopes:
return False
for scope in token.scopes:
tokens[str(scope)] = token
key = save_auth_tokens(tokens, self.user)
if key:
return True
return False
def find_token(self, url):
"""Searches the current user's collection of token for a token which can
be used for a request to the url.
The stored token which belongs to the current user and is valid for the
desired URL. If there is no current user, or there is no valid user
token in the datastore, a atom.http_interface.GenericToken is returned.
if url is None:
return None
if isinstance(url, (str, unicode)):
url = atom.url.parse_url(url)
tokens = load_auth_tokens(self.user)
if url in tokens:
token = tokens[url]
if token.valid_for_scope(url):
return token
del tokens[url]
save_auth_tokens(tokens, self.user)
for scope, token in tokens.iteritems():
if token.valid_for_scope(url):
return token
return atom.http_interface.GenericToken()
def remove_token(self, token):
"""Removes the token from the current user's collection in the datastore.
False if the token was not removed, this could be because the token was
not in the datastore, or because there is no current user.
token_found = False
scopes_to_delete = []
tokens = load_auth_tokens(self.user)
for scope, stored_token in tokens.iteritems():
if stored_token == token:
token_found = True
for scope in scopes_to_delete:
del tokens[scope]
if token_found:
save_auth_tokens(tokens, self.user)
return token_found
def remove_all_tokens(self):
"""Removes all of the current user's tokens from the datastore."""
save_auth_tokens({}, self.user)
def save_auth_tokens(token_dict, user=None):
"""Associates the tokens with the current user and writes to the datastore.
If there us no current user, the tokens are not written and this function
returns None.
The key of the datastore entity containing the user's tokens, or None if
there was no current user.
if user is None:
user = users.get_current_user()
if user is None:
return None
memcache.set('gdata_pickled_tokens:%s' % user, pickle.dumps(token_dict))
user_tokens = TokenCollection.all().filter('user =', user).get()
if user_tokens:
user_tokens.pickled_tokens = pickle.dumps(token_dict)
return user_tokens.put()
user_tokens = TokenCollection(
return user_tokens.put()
def load_auth_tokens(user=None):
"""Reads a dictionary of the current user's tokens from the datastore.
If there is no current user (a user is not signed in to the app) or the user
does not have any tokens, an empty dictionary is returned.
if user is None:
user = users.get_current_user()
if user is None:
return {}
pickled_tokens = memcache.get('gdata_pickled_tokens:%s' % user)
if pickled_tokens:
return pickle.loads(pickled_tokens)
user_tokens = TokenCollection.all().filter('user =', user).get()
if user_tokens:
memcache.set('gdata_pickled_tokens:%s' % user, user_tokens.pickled_tokens)
return pickle.loads(user_tokens.pickled_tokens)
return {}