Asynchronous Publish-Subscribe With Python

KEY FEATURES

• Implemented an asynchronous publish-subscribe application using asyncio package with pure python.
• Publisher and Subscribers are decoupled thus publisher does not maintain track of subscribers.
• This demonstrates how broadcasting of notifications to multiple subscribed users works asynchronously with leveraging asyncio in python.

Asyncio enables concurrent programming in python, it makes world of multiple subscribers reading the same notification simultaneously. Performance of this asynchronous publish-subscriptions model is overall always much higher than sequential model.

Here, publisher and subscribers are decoupled with introducing a middle layer 'hub' which does task of maintaining subscribers and publishing to them. This way publisher need not take extra job to maintain subscribers, keeping publisher's main job to publish.

Requirements

python >= 3.7

How To Run

python main.py

OUTPUT

Publisher has 0 subscribers
Subscriber0 is ready now to read
Subscriber2 is ready now to read
Publisher has 5 subscribers
Subscriber0 got message: THIS IS EVENT-1
Subscriber2 got message: THIS IS EVENT-1
Subscriber3 is ready now to read
Subscriber3 got message: THIS IS EVENT-1
Subscriber1 is ready now to read
Subscriber1 got message: THIS IS EVENT-1
Publisher has 5 subscribers
Subscriber3 got message: THIS IS EVENT-2
Subscriber0 got message: THIS IS EVENT-2
Subscriber1 got message: THIS IS EVENT-2
Subscriber2 got message: THIS IS EVENT-2
Subscriber4 is ready now to read
Subscriber4 got message: THIS IS EVENT-1
Subscriber4 got message: THIS IS EVENT-2
Publisher has 5 subscribers
Subscriber3 got message: THIS IS EVENT-3
Subscriber0 got message: THIS IS EVENT-3
Subscriber1 got message: THIS IS EVENT-3
Subscriber1 has enough reading!
Subscriber1 is terminating!
Subscriber4 got message: THIS IS EVENT-3
Subscriber2 got message: THIS IS EVENT-3
Publisher has 4 subscribers
Subscriber3 got message: THIS IS EVENT-4
Subscriber0 got message: THIS IS EVENT-4
Subscriber4 got message: THIS IS EVENT-4
Subscriber2 got message: THIS IS EVENT-4
Publisher has 4 subscribers
Subscriber3 got message: THIS IS EVENT-5
Subscriber0 got message: THIS IS EVENT-5
Subscriber4 got message: THIS IS EVENT-5
Subscriber2 got message: THIS IS EVENT-5
Publisher has 4 subscribers
Subscriber3 got message: THIS IS EVENT-6
Subscriber0 got message: THIS IS EVENT-6
Subscriber4 got message: THIS IS EVENT-6
Subscriber2 got message: THIS IS EVENT-6
Publisher has 4 subscribers
Subscriber3 got message: THIS IS EVENT-7
Subscriber3 has enough reading!
Subscriber3 is terminating!
Subscriber0 got message: THIS IS EVENT-7
Subscriber4 got message: THIS IS EVENT-7
Subscriber2 got message: THIS IS EVENT-7
Publisher has 3 subscribers
Subscriber0 got message: THIS IS EVENT-8
Subscriber0 has enough reading!
Subscriber0 is terminating!
Subscriber4 got message: THIS IS EVENT-8
Subscriber2 got message: THIS IS EVENT-8
Publisher has 2 subscribers
Subscriber4 got message: THIS IS EVENT-9
Subscriber2 got message: THIS IS EVENT-9
Subscriber4 got message: TERMINATE
Subscriber4 is terminating!
Subscriber2 got message: TERMINATE
Subscriber2 has enough reading!
Subscriber2 is terminating!