Using Rails Event Store with Protobuf
Using RES with Protobuf or another binary serialization protocol might be a good idea if you want to share your events' data with another applications and micro-services.
Installation
Add RES and protobuf to your app's Gemfile
gem "google-protobuf"
gem "protobuf_nested_struct"
gem "rails_event_store"
Configure protobuf mapper
Rails.application.configure do
config.to_prepare do
Rails.configuration.event_store = RailsEventStore::Client.new(mapper: RubyEventStore::Mappers::Protobuf.new)
end
end
Defining events
Define your events in protobuf file format i.e.: events.proto3
syntax = "proto3";
package my_app;
message OrderPlaced {
string order_id = 1;
int32 customer_id = 2;
}
and generate the Ruby classes:
# Generated by the protocol buffer compiler. DO NOT EDIT!
# source: events.proto3
require "google/protobuf"
Google::Protobuf::DescriptorPool.generated_pool.build do
add_message "my_app.OrderPlaced" do
optional :order_id, :string, 1
optional :customer_id, :int32, 2
end
end
module MyApp
OrderPlaced = Google::Protobuf::DescriptorPool.generated_pool.lookup("my_app.OrderPlaced").msgclass
end
Publishing
event_store = Rails.configuration.event_store
event = RubyEventStore::Proto.new(data: MyApp::OrderPlaced.new(order_id: "K3THNX9", customer_id: 123))
event_store.publish(event, stream_name: "Order-K3THNX9")
Retrieving
event = client.read.stream("test").last
Subscribing
Sync handlers
event_store.subscribe(->(ev) { }, to: [MyApp::OrderPlaced.descriptor.name])
Async handlers
class SendOrderEmailHandler < ActiveJob::Base
self.queue_adapter = :inline
def perform(payload)
event = event_store.deserialize(payload)
# do something
end
private
def event_store
Rails.configuration.event_store
end
end
event_store.subscribe(SendOrderEmailHandler, to: [MyApp::OrderPlaced.descriptor.name])