EventStore

A Ruby implementation of an EventStore based on Active Record.

Installation

• Add following line to your application's Gemfile:

gem 'rails_event_store'

• Use provided task to generate a table to store events in you DB.

rails generate rails_event_store:migrate
rake db:migrate

Usage

To communicate with ES you have to create instance of RailsEventStore::Client class.

client = RailsEventStore::Client.new

Creating new event

Firstly you have to define own event model extending RailsEventStore::Event class.

class OrderCreated < RailsEventStore::Event
end

stream_name = "order_1"
event_data = {
               data: { data: "sample" },
               event_id: "b2d506fd-409d-4ec7-b02f-c6d2295c7edd"
             }
event = OrderCreated.new(event_data)

#publishing event for specific stream
client.publish_event(event, stream_name)

#publishing global event. In this case stream_name is 'all'.
client.publish_event(event)

Creating new event with optimistic locking:

class OrderCreated < RailsEventStore::Event
end

stream_name = "order_1"
event_data = {
               data: { data: "sample" },
               event_id: "b2d506fd-409d-4ec7-b02f-c6d2295c7edd"
             }
event = OrderCreated.new(event_data)
expected_version = "850c347f-423a-4158-a5ce-b885396c5b73" #last event_id
client.publish_event(event, stream_name, expected_version)

Reading stream's events forward in batch

stream_name = "order_1"
start = 1
count = 40
client.read_all_events(stream_name, start, count)

Reading all events from stream forward

This method allows us to load all stream's events ascending.

stream_name = "order_1"
client.read_all_events(stream_name)

Reading all events forward

This method allows us to load all stored events ascending.

client.read_all_streams

Subscribing to events

To listen on specific events synchronously you have to create subscriber reprezentation. The only requirement is that subscriber class has to implement the 'handle_event(event)' method.

class InvoiceReadModel
    def handle_event(event)
        #we deal here with event's data
    end
end

invoice = InvoiceReadModel.new
client.subscribe(invoice, ['PriceChanged', 'ProductAdded'])