https://github.com/patrys/pymongo-pubsub

a publish-subscribe pattern implementation for pymongo
https://github.com/patrys/pymongo-pubsub

Last synced: 11 days ago
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a publish-subscribe pattern implementation for pymongo

• Host: GitHub
• URL: https://github.com/patrys/pymongo-pubsub
• Owner: patrys
• Archived: true
• Created: 2012-03-09T21:30:25.000Z (over 12 years ago)
• Default Branch: master
• Last Pushed: 2017-01-11T07:02:43.000Z (almost 8 years ago)
• Last Synced: 2024-08-01T22:57:04.282Z (3 months ago)
• Language: Python
• Homepage: http://room-303.com/blog/
• Size: 5.86 KB
• Stars: 29
• Watchers: 2
• Forks: 8
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
pymongo-pubsub — a publish-subscribe pattern implementation for pymongo

=======================================================================

Ever wished you could use your MongoDB to drive an event-driven environment?

Now you can.

pymongo-pubsub uses a round-robin *capped* collection to store its data on one

end and a *tailable* cursor to catch it as it is inserted on the other.

The publisher

-------------

A publisher is a piece of code responsible for pumping data into the database:

```python

import pymongo

from pymongo_pubsub import Publisher

connection = pymongo.Connection()

database = connection.pubsub_db

publisher = Publisher(database, 'test_event')

publisher.push({'message': 'hello world', 'answer': 42})

```

A `Publisher` will take care of setting up the underlying collection. You can

pass it optional `max_size` and `max_length` parameters to define storage

limits of the collection at the time it is created. The default size is

`1000000` bytes and the default length limit is `None`.

Make sure your queue is big enough to never overflow or you're going to start

losing data. You care about your data, right?

The subscriber

--------------

A subscriber is a piece of code responsible for processing data as it is pulled

from the database:

```python

import pymongo

from pymongo_pubsub import Subscriber

connection = pymongo.Connection()

database = connection.pubsub_db

def test_cb(data):

    print '{0:f}: {1:s}'.format(data['_id'], data['message'])

subscriber = Subscriber(database, 'test_event', callback=test_cb,

                        matching={'answer': 42})

subscriber.listen()

```

A `Subscriber` will never create any collections in the database and in case

the collections is missing it will cowardly raise a `KeyError` exception.

This is not a bug. This is to avoid having to synchronize collection limits

between the publisher and all of the subscribers.