websubsub 0.9.3

Django websub subscriber

Django websub subscriber.

Installation

pip install websubsub

Add websubsub.apps.WebsubsubConfig to the list of INSTALLED_APPS in your settings.py:

INSTALLED_APPS = [
    ...,
    'websubsub.apps.WebsubsubConfig'
]

Set the WEBSUBSUB_OWN_ROOTURL setting in your settings.py to the full url of your project site, e.g. https://example.com/. It will be used to build full callback urls.

Set DUMBLOCK_REDIS_URL settings in your settings.py. Redis locks are used to ensure subscription/unsubscription tasks are consistent with hub and local database.

WEBSUBSUB_OWN_ROOTURL = 'http://example.com/'
DUMBLOCK_REDIS_URL= 'redis://redishost:6379'

Add websubsub.tasks.refresh_subscriptions and websubsub.tasks.retry_failed to celerybeat schedule. If you define it in settings.py:

CELERY_BEAT_SCHEDULE = {
    'websub_refresh': {
        'task': 'websubsub.tasks.refresh_subscriptions',
        'schedule': 3600  # Hourly
    },
    'websub_retry': {
        'task': 'websubsub.tasks.retry_failed',
        'schedule': 600  # Every 10 minutes
    },
}

Usage

Create Websub callback

Create celery task handler, usually in tasks.py:

from celery import shared_task

@shared_task
def news_task(data):
    print('got news!')

Callback url should end with uuid. Register url for handler in urls.py:

from websubsub.views import WssView
from .tasks import news_task, reports_task

urlpatterns = [
    path('/websubcallback/news/<uuid:id>', WssView.as_view(news_task), name='webnews')
    path('/websubcallback/reports/<uuid:id>', WssView.as_view(reports_task), name='webreports')
]

Subscribe

You can create subscription on the go, or use static subscriptions.

To create subscription in the code:

from websubsub.models import Subscription
Subscription.create(topic='mytopic', urlname='webnews', hub='http://example.com')

This will create Subscription object in the database and schedule celery task to subscribe with hub.

Static subscriptions

Static subscriptions can be defined in your settings.py, they are then materialized with management command ./manage.py websub_static_subscribe.

Add static subscriptions in your settings.py:

WEBSUBSUB_HUBS = {
    'http://example.com': {
        'subscriptions': [
            {'topic': 'mytopic', 'callback_urlname': 'webnews'},
            ...
        ]
    }
}

Execute ./manage.py websub_static_subscribe

Unsubscribe

To unsubscribe existing subscription, call Subscription.unsubscribe() method:

from websubsub.models import Subscription
Subscription.objects.get(pk=4).unsubscribe()

Settings

WEBSUBSUB_OWN_ROOTURL - ex.: https://example.com/. Required. Will be used to build full callback urls.

DUMBLOCK_REDIS_URL - ex.: redis://redishost:6379. Required. Will be used to lock atomic tasks.

WEBSUBSUB_AUTOFIX_URLS - If True, then websubsub.tasks.subscribe() task will be allowed to ovewrite subscription.callback_url, resolving its callback_urlname. If False, it will print an error and exit. Default: True

WEBSUBSUB_DEFAULT_HUB_URL

WEBSUBSUB_MAX_CONNECT_RETRIES

WEBSUBSUB_MAX_HUB_ERROR_RETRIES

WEBSUBSUB_MAX_VERIFY_RETRIES

WEBSUBSUB_VERIFY_WAIT_TIME - How many seconds should pass before unverified subscription is considered failed. After that time, websubsub.tasks.retry_failed() task will be able to retry subscription process again.

Management commands

./manage.py websub_static_subscribe - Materialize static subscriptions from settings. Optional arguments:

• --purge-orphans - delete old static subscriptions from database

• -y, --yes - answer yes to all

• --reset-counters - reset retry counters

• --force - send new subscription request to hub even if already subscribed or explicitly unsubscribed

./manage.py websub_purge_unresolvable - Delete all subscriptions with unresolvable urlname from database.

./manage.py websub_purge_all - Delete all subscriptions from database.

./manage.py websub_reset_counters - Reset retry counters for all subscriptions in database.

./manage.py websub_handle_url_changes - Guess changed urlnames for subscriptions from current callback_url. Also detect changed url patterns and schedule resubscribe with new url.

./manage.py dumpdata websubsub --indent 2 - Show all subscriptions.

Testing

pip install -r tests/requirements.txt
py.test