This repository shows how to use Stream-Framework to create a simple API to manage feeds. Users follow other users, they post activities, and their respective feeds get updated. Stream-Framework uses Cassandra for storage and Celery to distribute computing. This example provides a Celery worker to give a rough idea of how this could work in production. Django and the Django REST Framework are used to handle HTTP requests.

JWT authentication is handled, although any authenticated user can add follow relationships and activities, which is obviously not safe. In a microservice architecture, these events would be received from other services. A mocked follow service is provided simply to make the example runnable. JWT are only really used to get the current user for the /feeds/aggregated end point. Also, Django user management is not used: we assume that tokens are issued by a separate authentication service.

Oh yeah, obviously, this is not production ready.

Start the containers with docker-compose:

docker-compose up

Set up Cassandra by creating the relevant keyspace and tables:

docker-compose run -e CQLENG_ALLOW_SCHEMA_MANAGEMENT=1 activity python db_setup.py

Restart the API:

docker-compose restart activity

Test that everything works by issuing simple commands:

# Token that can be generated from http://jwt.io using the private and public keys in the etc folder.
JWT="eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ1c3JfMDIifQ.XSaKEn61nL8hn9c-4rc58lsuK6upOfTAk7qstQSi2nU6liR4vM2v5IMHFGOZv6noQ9yCX9qANa3GFoE63HLpvTSimUL4B1Jxo-AmRuN_6EvPXCICjo9FobPJ_19UpADcmltf8wi1no5V48fz5g9pG0pp9NTyFwOjpcty9i1-Ah9juhlxjVPJamWClHcnebHvAxQeabrEnPFNKgLYeI-a0EqyNYPcCYyciPBU1lWHlE9Qsxf7_8wr9SL6FBTERMMDvdFAd7n5qVeMd_kXoXIgL3qZNeA9lLIfSfOoqszG4qtcczCbsEfxl_7BSNexc-Fl2_1a6lHxGnxiLcB8nNcWlA"
# Make usr_02 follow usr_01.
curl -X POST -H "Content-type: application/json" -H "authorization: JWT $JWT" -d '{ "follower": "usr_02", "following": "usr_01" }' localhost:1234/follow
# Adds a new activity for usr_01.
curl -X POST -H "Content-type: application/json" -H "authorization: JWT $JWT" -d '{ "actor": "usr_01", "object": "obj_50", "target": "usr_73" }' localhost:1234/activities
# Check that the aggregated feed (timeline) of usr_02 now contains the activity of usr_01.
curl -H "authorization: JWT $JWT" localhost:1234/feeds/aggregated

This example uses a forked version of Stream-Framework, only to allow for non-integer IDs for users and objects with the Cassandra backend.

The follow service provides a very basic logic to keep the follow graph in memory. This is not meant for production.

The /feed/aggregated endpoint does not implement pagination. This would be a nice improvement to this example.

The /follow endpoint could also notify Stream-Framework, to add past "followee" activities to the feed of the follower.

As mentioned previously, authentication only checks for a valid JWT using the public key in settings.py. This is not sufficient to protect the API. It just shows how to add JWT authorization without relying on Django user model.