python/google/appengine/tools/dev_appserver_channel.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2007 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17 """Channel support classes.
  18
  19 Classes:
  20
  21   CreateChannelDispatcher:
  22     Creates a dispatcher that is added to dispatcher chain.  Handles polls from
  23     the client to retrieve messages for a given channel.
  24 """
  25
  26
  27
  28
  29 import cgi
  30 import os
  31 import urlparse
  32
  33 from google.appengine.api.channel.channel_service_stub import InvalidTokenError
  34 from google.appengine.api.channel.channel_service_stub import TokenTimedOutError
  35
  36
  37
  38 CHANNEL_POLL_PATTERN = '/_ah/channel/dev(?:/.*)?'
  39
  40
  41 CHANNEL_JSAPI_PATTERN = '/_ah/channel/jsapi'
  42
  43
  44 def CreateChannelDispatcher(channel_service_stub):
  45   """Function to create channel dispatcher.
  46
  47   Args:
  48     channel_service_stub: The service stub responsible for creating channels and
  49       sending messages. This stub stores messages destined for channels, so we
  50       query it when the client polls the _ah/channel/ dispatcher.
  51
  52   Returns:
  53     New dispatcher capable of handling client polls for channel messages.
  54   """
  55
  56
  57
  58   from google.appengine.tools import old_dev_appserver
  59
  60   class ChannelDispatcher(old_dev_appserver.URLDispatcher):
  61     """Dispatcher that handles channel polls."""
  62
  63     def __init__(self, channel_service_stub):
  64       """Constructor.
  65
  66       Args:
  67         channel_service_stub: The channel service that receives channel messages
  68         from the application.
  69       """
  70       self._channel_service_stub = channel_service_stub
  71
  72
  73     def Dispatch(self,
  74                  request,
  75                  outfile,
  76                  base_env_dict=None):
  77       """Handle post dispatch.
  78
  79       This dispatcher handles requests under the /_ah/channel/ path. Currently
  80       it handles 3 sub-paths:
  81         connect: place-holder for parity with the java dev channel.
  82         poll:    return pending messages for the channel identified by the
  83                  channel parameter.
  84         jsapi:   return the javascript library to retrieve messages for the
  85                  channel.
  86
  87       Args:
  88         request: The HTTP request.
  89         outfile: The response file.
  90         base_env_dict: Dictionary of CGI environment parameters if available.
  91           Defaults to None.
  92       """
  93
  94       (unused_scheme, unused_netloc,
  95        path, query,
  96        unused_fragment) = urlparse.urlsplit(request.relative_url)
  97       param_dict = cgi.parse_qs(query, True)
  98
  99       page = path.rsplit('/', 1)[-1]
 100
 101       if page == 'jsapi':
 102         path = os.path.join(os.path.dirname(__file__), 'dev-channel-js.js')
 103         outfile.write('Status: 200\r\n')
 104         outfile.write('Content-type: text/javascript\r\n\r\n')
 105         outfile.write(open(path).read())
 106       elif page == 'dev':
 107         token = param_dict['channel'][0]
 108
 109         token_error = None
 110         try:
 111           self._channel_service_stub.validate_token_and_extract_client_id(token)
 112
 113
 114         except InvalidTokenError:
 115           token_error = 'Invalid+token.'
 116         except TokenTimedOutError:
 117           token_error = 'Token+timed+out.'
 118
 119         if token_error is not None:
 120           outfile.write('Status: 401 %s\r\n\r\n' % token_error)
 121           return
 122
 123         outfile.write('Status: 200\r\n')
 124         outfile.write('\r\n')
 125         command = param_dict['command'][0]
 126
 127         if command == 'connect':
 128           self._channel_service_stub.connect_channel(token)
 129           outfile.write('1')
 130         elif command == 'poll':
 131           self._channel_service_stub.connect_channel(token)
 132           if self._channel_service_stub.has_channel_messages(token):
 133             outfile.write(self._channel_service_stub.pop_first_message(token))
 134
 135   return ChannelDispatcher(channel_service_stub)