A new push implementation. This updates us to the latest revision of the push
API which has a much simpler interface. Look in the module doc string for how
this API would be used.
Reviewed in https://codereview.appspot.com/9885043/.
diff --git a/apiclient/channel.py b/apiclient/channel.py
new file mode 100644
index 0000000..61a7ec4
--- /dev/null
+++ b/apiclient/channel.py
@@ -0,0 +1,285 @@
+"""Channel notifications support.
+
+Classes and functions to support channel subscriptions and notifications
+on those channels.
+
+Notes:
+ - This code is based on experimental APIs and is subject to change.
+ - Notification does not do deduplication of notification ids, that's up to
+ the receiver.
+ - Storing the Channel between calls is up to the caller.
+
+
+Example setting up a channel:
+
+ # Create a new channel that gets notifications via webhook.
+ channel = new_webhook_channel("https://example.com/my_web_hook")
+
+ # Store the channel, keyed by 'channel.id'. Store it before calling the
+ # watch method because notifications may start arriving before the watch
+ # method returns.
+ ...
+
+ resp = service.objects().watchAll(
+ bucket="some_bucket_id", body=channel.body()).execute()
+ channel.update(resp)
+
+ # Store the channel, keyed by 'channel.id'. Store it after being updated
+ # since the resource_id value will now be correct, and that's needed to
+ # stop a subscription.
+ ...
+
+
+An example Webhook implementation using webapp2. Note that webapp2 puts
+headers in a case insensitive dictionary, as headers aren't guaranteed to
+always be upper case.
+
+ id = self.request.headers[X_GOOG_CHANNEL_ID]
+
+ # Retrieve the channel by id.
+ channel = ...
+
+ # Parse notification from the headers, including validating the id.
+ n = notification_from_headers(channel, self.request.headers)
+
+ # Do app specific stuff with the notification here.
+ if n.resource_state == 'sync':
+ # Code to handle sync state.
+ elif n.resource_state == 'exists':
+ # Code to handle the exists state.
+ elif n.resource_state == 'not_exists':
+ # Code to handle the not exists state.
+
+
+Example of unsubscribing.
+
+ service.channels().stop(channel.body())
+"""
+
+import datetime
+import uuid
+
+from apiclient import errors
+from oauth2client import util
+
+
+# The unix time epoch starts at midnight 1970.
+EPOCH = datetime.datetime.utcfromtimestamp(0)
+
+# Map the names of the parameters in the JSON channel description to
+# the parameter names we use in the Channel class.
+CHANNEL_PARAMS = {
+ 'address': 'address',
+ 'id': 'id',
+ 'expiration': 'expiration',
+ 'params': 'params',
+ 'resourceId': 'resource_id',
+ 'resourceUri': 'resource_uri',
+ 'type': 'type',
+ 'token': 'token',
+ }
+
+X_GOOG_CHANNEL_ID = 'X-GOOG-CHANNEL-ID'
+X_GOOG_MESSAGE_NUMBER = 'X-GOOG-MESSAGE-NUMBER'
+X_GOOG_RESOURCE_STATE = 'X-GOOG-RESOURCE-STATE'
+X_GOOG_RESOURCE_URI = 'X-GOOG-RESOURCE-URI'
+X_GOOG_RESOURCE_ID = 'X-GOOG-RESOURCE-ID'
+
+
+def _upper_header_keys(headers):
+ new_headers = {}
+ for k, v in headers.iteritems():
+ new_headers[k.upper()] = v
+ return new_headers
+
+
+class Notification(object):
+ """A Notification from a Channel.
+
+ Notifications are not usually constructed directly, but are returned
+ from functions like notification_from_headers().
+
+ Attributes:
+ message_number: int, The unique id number of this notification.
+ state: str, The state of the resource being monitored.
+ uri: str, The address of the resource being monitored.
+ resource_id: str, The unique identifier of the version of the resource at
+ this event.
+ """
+ @util.positional(5)
+ def __init__(self, message_number, state, resource_uri, resource_id):
+ """Notification constructor.
+
+ Args:
+ message_number: int, The unique id number of this notification.
+ state: str, The state of the resource being monitored. Can be one
+ of "exists", "not_exists", or "sync".
+ resource_uri: str, The address of the resource being monitored.
+ resource_id: str, The identifier of the watched resource.
+ """
+ self.message_number = message_number
+ self.state = state
+ self.resource_uri = resource_uri
+ self.resource_id = resource_id
+
+
+class Channel(object):
+ """A Channel for notifications.
+
+ Usually not constructed directly, instead it is returned from helper
+ functions like new_webhook_channel().
+
+ Attributes:
+ type: str, The type of delivery mechanism used by this channel. For
+ example, 'web_hook'.
+ id: str, A UUID for the channel.
+ token: str, An arbitrary string associated with the channel that
+ is delivered to the target address with each event delivered
+ over this channel.
+ address: str, The address of the receiving entity where events are
+ delivered. Specific to the channel type.
+ expiration: int, The time, in milliseconds from the epoch, when this
+ channel will expire.
+ params: dict, A dictionary of string to string, with additional parameters
+ controlling delivery channel behavior.
+ resource_id: str, An opaque id that identifies the resource that is
+ being watched. Stable across different API versions.
+ resource_uri: str, The canonicalized ID of the watched resource.
+ """
+
+ @util.positional(5)
+ def __init__(self, type, id, token, address, expiration=None,
+ params=None, resource_id="", resource_uri=""):
+ """Create a new Channel.
+
+ In user code, this Channel constructor will not typically be called
+ manually since there are functions for creating channels for each specific
+ type with a more customized set of arguments to pass.
+
+ Args:
+ type: str, The type of delivery mechanism used by this channel. For
+ example, 'web_hook'.
+ id: str, A UUID for the channel.
+ token: str, An arbitrary string associated with the channel that
+ is delivered to the target address with each event delivered
+ over this channel.
+ address: str, The address of the receiving entity where events are
+ delivered. Specific to the channel type.
+ expiration: int, The time, in milliseconds from the epoch, when this
+ channel will expire.
+ params: dict, A dictionary of string to string, with additional parameters
+ controlling delivery channel behavior.
+ resource_id: str, An opaque id that identifies the resource that is
+ being watched. Stable across different API versions.
+ resource_uri: str, The canonicalized ID of the watched resource.
+ """
+ self.type = type
+ self.id = id
+ self.token = token
+ self.address = address
+ self.expiration = expiration
+ self.params = params
+ self.resource_id = resource_id
+ self.resource_uri = resource_uri
+
+ def body(self):
+ """Build a body from the Channel.
+
+ Constructs a dictionary that's appropriate for passing into watch()
+ methods as the value of body argument.
+
+ Returns:
+ A dictionary representation of the channel.
+ """
+ result = {
+ 'id': self.id,
+ 'token': self.token,
+ 'type': self.type,
+ 'address': self.address
+ }
+ if self.params:
+ result['params'] = self.params
+ if self.resource_id:
+ result['resourceId'] = self.resource_id
+ if self.resource_uri:
+ result['resourceUri'] = self.resource_uri
+ if self.expiration:
+ result['expiration'] = self.expiration
+
+ return result
+
+ def update(self, resp):
+ """Update a channel with information from the response of watch().
+
+ When a request is sent to watch() a resource, the response returned
+ from the watch() request is a dictionary with updated channel information,
+ such as the resource_id, which is needed when stopping a subscription.
+
+ Args:
+ resp: dict, The response from a watch() method.
+ """
+ for json_name, param_name in CHANNEL_PARAMS.iteritems():
+ value = resp.get(json_name)
+ if value is not None:
+ setattr(self, param_name, value)
+
+
+def notification_from_headers(channel, headers):
+ """Parse a notification from the webhook request headers, validate
+ the notification, and return a Notification object.
+
+ Args:
+ channel: Channel, The channel that the notification is associated with.
+ headers: dict, A dictionary like object that contains the request headers
+ from the webhook HTTP request.
+
+ Returns:
+ A Notification object.
+
+ Raises:
+ errors.InvalidNotificationError if the notification is invalid.
+ ValueError if the X-GOOG-MESSAGE-NUMBER can't be converted to an int.
+ """
+ headers = _upper_header_keys(headers)
+ channel_id = headers[X_GOOG_CHANNEL_ID]
+ if channel.id != channel_id:
+ raise errors.InvalidNotificationError(
+ 'Channel id mismatch: %s != %s' % (channel.id, channel_id))
+ else:
+ message_number = int(headers[X_GOOG_MESSAGE_NUMBER])
+ state = headers[X_GOOG_RESOURCE_STATE]
+ resource_uri = headers[X_GOOG_RESOURCE_URI]
+ resource_id = headers[X_GOOG_RESOURCE_ID]
+ return Notification(message_number, state, resource_uri, resource_id)
+
+
+@util.positional(2)
+def new_webhook_channel(url, token=None, expiration=None, params=None):
+ """Create a new webhook Channel.
+
+ Args:
+ url: str, URL to post notifications to.
+ token: str, An arbitrary string associated with the channel that
+ is delivered to the target address with each notification delivered
+ over this channel.
+ expiration: datetime.datetime, A time in the future when the channel
+ should expire. Can also be None if the subscription should use the
+ default expiration. Note that different services may have different
+ limits on how long a subscription lasts. Check the response from the
+ watch() method to see the value the service has set for an expiration
+ time.
+ params: dict, Extra parameters to pass on channel creation. Currently
+ not used for webhook channels.
+ """
+ expiration_ms = 0
+ if expiration:
+ delta = expiration - EPOCH
+ expiration_ms = delta.microseconds/1000 + (
+ delta.seconds + delta.days*24*3600)*1000
+ if expiration_ms < 0:
+ expiration_ms = 0
+
+ return Channel('web_hook', str(uuid.uuid4()),
+ token, url, expiration=expiration_ms,
+ params=params)
+