zacharyschmidt/eventsourcing-101

Slides and code for event sourcing 101 talk

This repo contains the code samples and slides for my "Eventsouring 101" talk.

There's a practice video of me mumbling and fumbling through it on Youtube

The master branch contains a simple shopping basket, with tests, that stores state in a mongo database. The "from_scratch" branch has the code in a state ready for the live code exercise.

You'll need Docker and Python 3.6 in a virtual environment. To install things, run make setup

To run the tests, just run make or make tests To start mongo, do make mongo and to view the slides, run make serve and then visit localhost:8000 in a browser.

Once you run make setup you can use the CLI tool to interact with shopping baskets:

bob@localhost:~/code/talks/eventsourcing-101|master 
⇒  basket create socks
Created basket with id '5ab69073421aa917e62b4734'

bob@localhost:~/code/talks/eventsourcing-101|master 
⇒  basket add 5ab69073421aa917e62b4734 rocks

bob@localhost:~/code/talks/eventsourcing-101|master 
⇒  basket add 5ab69073421aa917e62b4734 clocks

bob@localhost:~/code/talks/eventsourcing-101|master 
⇒  basket remove 5ab69073421aa917e62b4734 socks 

bob@localhost:~/code/talks/eventsourcing-101|master 
⇒  basket get 5ab69073421aa917e62b4734

rocks = 1
clocks = 1

If you fancy completing this for yourself, you should just need to checkout the from_scratch branch and make all the tests pass.

You'll also need to implement the following untested methods on the Basket class:

def save(self):
   formatted_events = []
   for e in self.new_events:
       formatted_events.append(events.to_json(e))
   db.baskets.insert(formatted_events)
   
@classmethod
def get(cls, basket_id):
    read_events = []
    data = db.baskets.find({'basket_id': basket_id})
    for json in data:
        read_events.append(events.from_json(json))
        
    return Basket(read_events)

The cli tool should then work on the from_scratch branch, too.

IF you actually want to do Eventsourcing in the real world, then I don't recommend using Mongo - why not try out Eventstore with Photon Pump?