Adding a sample CWS license server client written for Python App Engine.

chrome/common/extensions/docs/examples/apps/hello-python/main.py

Index: chrome/common/extensions/docs/examples/apps/hello-python/main.py
diff --git a/chrome/common/extensions/docs/examples/apps/hello-python/main.py b/chrome/common/extensions/docs/examples/apps/hello-python/main.py
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+#!/usr/bin/python
+# Copyright (c) 2010 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from google.appengine.ext import webapp
+from google.appengine.ext.webapp import util
+from google.appengine.api import users
+from google.appengine.api import urlfetch
+from google.appengine.ext.webapp import template
+from google.appengine.api.urlfetch import DownloadError
+import oauth2
+import urllib
+import logging
+import os
+import time
+from django.utils import simplejson
+
+# Configuration
+
+CONFIG = {
+  'oauth_consumer_key': 'anonymous',
+  'oauth_consumer_secret': 'anonymous',
+  'license_server': 'https://www.googleapis.com',
+  'license_path': '%(server)s/chromewebstore/v1/licenses/%(appid)s/%(userid)s',
+  'oauth_token': 'INSERT OAUTH TOKEN HERE',
+  'oauth_token_secret': 'INSERT OAUTH TOKEN SECRET HERE',
+  'app_id': 'INSERT APPLICATION ID HERE',
+}
+
+# Check to see if the server has been deployed.  In the dev server, this
+# env variable will start with 'Development', in production, it will start with
+# 'Google App Engine'
+IS_PRODUCTION = os.environ['SERVER_SOFTWARE'].startswith('Google App Engine')
+
+# Valid access levels that may be returned by the license server.
+VALID_ACCESS_LEVELS = ['FREE_TRIAL', 'FULL']
+
+def fetch_license_data(userid):
+  """Fetches the license for a given user by making an OAuth signed request
+  to the license server.
+
+  Args:
+    userid OpenID of the user you are checking access for.
+
+  Returns:
+    The server's response as text.
+  """
+  url = CONFIG['license_path'] % {
+    'server': CONFIG['license_server'],
+    'appid': CONFIG['app_id'],
+    'userid': urllib.quote_plus(userid),
+  }
+
+  oauth_token = oauth2.Token(**{
+    'key': CONFIG['oauth_token'],
+    'secret': CONFIG['oauth_token_secret']
+  })
+
+  oauth_consumer = oauth2.Consumer(**{
+    'key': CONFIG['oauth_consumer_key'],
+    'secret': CONFIG['oauth_consumer_secret']
+  })
+
+  logging.debug('Requesting %s' % url)
+  client = oauth2.Client(oauth_consumer, oauth_token)
+  resp, content = client.request(url, 'GET')
+  logging.debug('Got response code %s, content %s' % (resp, content))
+  return content
+
+def parse_license_data(userid):
+  """Returns the license for a given user as a structured object.
+
+  Args:
+    userid: The OpenID of the user to check.
+
+  Returns:
+    An object with the following parameters:
+      error:  True if something went wrong, False otherwise.
+      message: A descriptive message if error is True.
+      access: One of 'NO', 'FREE_TRIAL', or 'FULL' depending on the access.
+  """
+  license = {'error': False, 'message': '', 'access': 'NO'}
+  try:
+    response_text = fetch_license_data(userid)
+    try:
+      logging.debug('Attempting to JSON parse: %s' % response_text)
+      json = simplejson.loads(response_text)
+      logging.debug('Got license server response: %s' % json)
+    except ValueError:
+      logging.exception('Could not parse response as JSON: %s' % response_text)
+      license['error'] = True
+      license['message'] = 'Could not parse the license server response'
+  except DownloadError:
+    logging.exception('Could not fetch license data')
+    license['error'] = True
+    license['message'] = 'Could not fetch license data'
+
+  if json.has_key('error'):
+    license['error'] = True
+    license['message'] = json['error']['message']
+  elif json['result'] == 'YES' and json['accessLevel'] in VALID_ACCESS_LEVELS:
+    license['access'] = json['accessLevel']
+
+  return license
+
+class MainHandler(webapp.RequestHandler):
+  """Request handler class."""
+  def get(self):
+    """Handler for GET requests."""
+    user = users.get_current_user()
+    if user:
+      if IS_PRODUCTION:
+        # We should use federated_identity in production, since the license
+        # server requires an OpenID
+        userid = user.federated_identity()
+      else:
+        # On the dev server, we won't have access to federated_identity, so
+        # just use a default OpenID which will never return YES.
+        # If you want to test different response values on the development
+        # server, just change this default value (e.g. append '-yes' or
+        # '-trial').
+        userid = ('https://www.google.com/accounts/o8/id?'
+                  'id=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx')
+      license_data = parse_license_data(userid)
+      template_data = {
+        'license': license_data,
+        'user_name': user.nickname(),
+        'user_id': userid,
+        'user_logout': users.create_logout_url(self.request.uri),
+      }
+    else:
+      # Force the OpenID login endpoint to be for Google accounts only, since
+      # the license server doesn't support any other type of OpenID provider.
+      login_url = users.create_login_url(dest_url='/',
+                      federated_identity='google.com/accounts/o8/id')
+      template_data = {
+        'user_login': login_url,
+      }
+
+    # Render a simple template
+    path = os.path.join(os.path.dirname(__file__), 'templates', 'index.html')
+    self.response.out.write(template.render(path, template_data))
+
+if __name__ == '__main__':
+  application = webapp.WSGIApplication([
+    ('/', MainHandler),
+  ], debug=False)
+  util.run_wsgi_app(application)