PubNub Python-Tornado SDK 5.1.4
Python version support
Python SDK versions 5.0.0 and higher no longer support Python v2.7 and the Twisted and Tornado frameworks. If you require support for any of these, use SDK version 4.8.1.
Note that PubNub will stop supporting versions of Python lower than 3.7 by the end of 2021.
Get Code: pip
The simplest way to get started is to install PubNub Python SDK via pip:
pip install 'pubnub>=5.1.4'
Get Code: git
git clone https://github.com/pubnub/python
Get Code: Source
https://github.com/pubnub/python
Hello World
Add PubNub to your project using one of the procedures defined under How to Get It.
from pubnub.callbacks import SubscribeCallback
from pubnub.enums import PNStatusCategory
from pubnub.pnconfiguration import PNConfiguration
from pubnub.pubnub_tornado import PubNubTornado
from tornado.ioloop import IOLoop
from tornado import gen
@gen.coroutine
def main():
def my_publish_callback(future):
# Check whether request successfully completed or not
exception = future.exception()
if exception is None:
envelope = future.result()
pass # Message successfully published to specified channel.
else:
pass # Handle message publish error. Check 'category' property to find out possible issue
# because of which request did fail.
# Request can be resent using: [status retry];
class MySubscribeCallback(SubscribeCallback):
def presence(self, pubnub, presence):
pass # handle incoming presence data
def status(self, pubnub, status):
if status.category == PNStatusCategory.PNUnexpectedDisconnectCategory:
pass # This event happens when radio / connectivity is lost
elif status.category == PNStatusCategory.PNConnectedCategory:
# Connect event. You can do stuff like publish, and know you'll get it.
# Or just use the connected event to confirm you are subscribed for
# UI / internal notifications, etc
pubnub.ioloop.add_future(
pubnub.publish().channel("awesomeChannel").message("hello!!").future(),
my_publish_callback
)
elif status.category == PNStatusCategory.PNReconnectedCategory:
pass
# Happens as part of our regular operation. This event happens when
# radio / connectivity is lost, then regained.
elif status.category == PNStatusCategory.PNDecryptionErrorCategory:
pass
# Handle message decryption error. Probably client configured to
# encrypt messages and on live data feed it received plain text.
def message(self, pubnub, message):
# Handle new message stored in message.message
pass
pubnub.add_listener(MySubscribeCallback())
pubnub.subscribe().channels('awesomeChannel').execute()
yield gen.sleep(10)
if __name__ == '__main__':
IOLoop.current().run_sync(main)
Builders
There are two ways to invoke callbacks in PubNub Python SDK for Tornado:
Using
result(). The builder returns a future that yields an only result, no state available on success call. Exceptions in this builder are raised explicitly.statusfield of an error is populated with an associated status object.try: result = yield pubnub.publish().message('hey').channel('blah').result() print(result) except PubNubException as e: print("PubNubException: %s" % e) print("category id: #%d" % e.status.category) print("operation id: #%d" % e.status.operation) _handle_error(e) except Exception as e: print("Error: %s" % e) _handle_error(e)Using
future(). The builder returns a future that yields a message envelope that wraps both a result (the same as inresult()call) and a state objects. Exception, if any, will not be raised explicitly and you should check for it usinge.is_error()helper. To access original exception value usee.value()method.e = yield pubnub.publish().message('hey').channel('blah').future() if e.is_error(): print("Error: %s" % e) print("category id: #%d" % e.status.category) print("operation id: #%d" % e.status.operation) _handle_error(e) else: print(e.result)
Copy and paste examples
In addition to the Hello World sample code, we also provide some copy and paste snippets of common API functions:
Init
Instantiate a new Pubnub instance. Only the subscribe_key is mandatory. Also include publish_key if you intend to publish from this instance, and the secret_key if you wish to perform PAM administrative operations from this Python-Tornado instance.
Important
For security reasons you should only include the secret-key on a highly secured server. The secret-key is only required for granting rights using our Access Manager.
When you init with secret_key, you get root permissions for the Access Manager. With this feature you don't have to grant access to your servers to access channel data. The servers get all access on all channels.
Note
Always set the UUID to uniquely identify the user or device that connects to PubNub. This UUID should be persisted, and should remain unchanged for the lifetime of the user or the device. Not setting the UUID can significantly impact your billing if your account uses the Monthly Active Users (MAUs) based pricing model, and can also lead to unexpected behavior if you have Presence enabled.
from pubnub.pnconfiguration import PNConfiguration
from pubnub.pubnub_tornado import PubNubTornado
pnconfig = PNConfiguration()
pnconfig.subscribe_key = 'my_subscribe_key'
pnconfig.publish_key = 'my_publish_key'
pnconfig.secret_key = 'my_secret_key'
pnconfig.uuid = "my_custom_uuid"
pnconfig.ssl = False
pubnub = PubNubTornado(pnconfig)
Listeners
Adding Listeners
from pubnub.callbacks import SubscribeCallback
from pubnub.enums import PNOperationType, PNStatusCategory
class MySubscribeCallback(SubscribeCallback):
def status(self, pubnub, status):
# The status object returned is always related to subscribe but could contain
# information about subscribe, heartbeat, or errors
# use the operationType to switch on different options
if status.operation == PNOperationType.PNSubscribeOperation \
or status.operation == PNOperationType.PNUnsubscribeOperation:
if status.category == PNStatusCategory.PNConnectedCategory:
pass
# This is expected for a subscribe, this means there is no error or issue whatsoever
elif status.category == PNStatusCategory.PNReconnectedCategory:
pass
# This usually occurs if subscribe temporarily fails but reconnects. This means
# there was an error but there is no longer any issue
elif status.category == PNStatusCategory.PNDisconnectedCategory:
pass
# This is the expected category for an unsubscribe. This means there
# was no error in unsubscribing from everything
elif status.category == PNStatusCategory.PNUnexpectedDisconnectCategory:
pass
# This is usually an issue with the internet connection, this is an error, handle
# appropriately retry will be called automatically
elif status.category == PNStatusCategory.PNAccessDeniedCategory:
pass
# This means that PAM does not allow this client to subscribe to this
# channel and channel group configuration. This is another explicit error
else:
pass
# This is usually an issue with the internet connection, this is an error, handle appropriately
# retry will be called automatically
elif status.operation == PNOperationType.PNSubscribeOperation:
# Heartbeat operations can in fact have errors, so it is important to check first for an error.
# For more information on how to configure heartbeat notifications through the status
# PNObjectEventListener callback, consult http://www.pubnub.com/docs/sdks/python/tornado/api-reference/configuration#configuration
if status.is_error():
pass
# There was an error with the heartbeat operation, handle here
else:
pass
# Heartbeat operation was successful
else:
pass
# Encountered unknown status type
def presence(self, pubnub, presence):
pass # handle incoming presence data
def message(self, pubnub, message):
pass # handle incoming messages
def signal(self, pubnub, signal):
pass # handle incoming signals
pubnub.add_listener(MySubscribeCallback())
Removing Listeners
my_listener = MySubscribeCallback()
pubnub.add_listener(my_listener)
# some time later
pubnub.remove_listener(my_listener)
Handling Disconnects
from pubnub.callbacks import SubscribeCallback
from pubnub.enums import PNStatusCategory
class HandleDisconnectsCallback(SubscribeCallback):
def status(self, pubnub, status):
if status.category == PNStatusCategory.PNUnexpectedDisconnectCategory:
# internet got lost, do some magic and call reconnect when ready
pubnub.reconnect()
elif status.category == PNStatusCategory.PNTimeoutCategory:
# do some magic and call reconnect when ready
pubnub.reconnect()
else:
logger.debug(status)
def presence(self, pubnub, presence):
pass
def message(self, pubnub, message):
pass
def signal(self, pubnub, signal):
pass
disconnect_listener = HandleDisconnectsCallback()
pubnub.add_listener(disconnect_listener)
Listener status events
| Category | Description |
|---|---|
PNTimeoutCategory | Failure to establish a connection to PubNub due to a timeout. |
PNBadRequestCategory | The server responded with a bad response error because the request is malformed. |
PNNetworkIssuesCategory | A subscribe event experienced an exception when running. The SDK isn't able to reach the PubNub Data Stream Network. This may be due to many reasons, such as: the machine or device isn't connected to the internet; the internet connection has been lost; your internet service provider is having trouble; or, perhaps the SDK is behind a proxy. |
PNReconnectedCategory | The SDK was able to reconnect to PubNub. |
PNConnectedCategory | SDK subscribed with a new mix of channels. This is fired every time the channel or channel group mix changes. |
PNUnexpectedDisconnectCategory | Previously started subscribe loop did fail and at this moment client disconnected from real-time data channels. |
PNUnknownCategory | Returned when the subscriber gets a non-200 HTTP response code from the server. |
Time
Call time() to verify the client connectivity to the origin:
envelope = yield pubnub.time().future()
print('current time: %d' % envelope.result)
Subscribe
Subscribe (listen on) a channel:
pubnub.subscribe().channels("my_channel").execute()
Note
The response of the call is handled by adding a Listener. Please see the Listeners section for more details. Listeners should be added before calling the method.
Publish
Publish a message to a channel:
from tornado import gen
@gen.coroutine
def publish_snippet():
def publish_callback(task):
exception = task.exception()
if exception is None:
envelope = task.result()
# Handle PNPublishResult(envelope.result) and PNStatus (envelope.status)
pass
else:
# Handle exception
pass
pubnub.publish().channel('such_channel').message(['hello', 'there']).future().add_done_callback(publish_callback)
yield gen.sleep(10)
Here Now
Get occupancy of who's here now on the channel by UUID:
Note
Requires you to enable the Presence add-on for your key. Refer to the How do I enable add-on features for my keys? knowledge base article for details on enabling features.
envelope = yield pubnub.here_now()\
.channels(['cool_channel1', 'cool_channel2'])\
.include_uuids(True)\
.future()
if envelope.status.is_error():
# handle error
return
for channel_data in envelope.result.channels:
print("---")
print("channel: %s" % channel_data.channel_name)
print("occupancy: %s" % channel_data.occupancy)
print("occupants: %s" % channel_data.channel_name)
for occupant in channel_data.occupants:
print("uuid: %s, state: %s" % (occupant.uuid, occupant.state))
Presence
Subscribe to real-time Presence events, such as join, leave, and timeout, by UUID. Setting the presence attribute to a callback will subscribe to presents events on my_channel:
Note
Requires you to enable the Presence add-on for your key. Refer to the How do I enable add-on features for my keys? knowledge base article for details on enabling features.
pubnub.subscribe()\
.channels("my_channel")\
.with_presence()\
.execute()
Note
The response of the call is handled by adding a Listener. Please see the Listeners section for more details. Listeners should be added before calling the method.
History
Retrieve published messages from archival storage:
Note
Requires that the Storage and Playback add-on is enabled for your key. How do I enable add-on features for my keys? - see https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-
envelope = yield pubnub.history()\
.channel("history_channel")\
.count(100)\
.future()
Unsubscribe
Stop subscribing (listening) to a channel:
pubnub.unsubscribe().channels("my_channel").execute()
Note
The response of the call is handled by adding a Listener. Please see the Listeners section for more details. Listeners should be added before calling the method.