siemakuba/res

RubyEventStore research

Using RailsEventStore outside of Rails

The RailsEventStore gem can be easily used outside of Rails. To accomplish this you need to use the RubyEventStore gem, wchich is a part of RailsEventStore. It comes without any additional dependencies.

RubyEventStore uses InMemoryRepository as a storage backend - this means that published events are not persisted.

event_store = RubyEventStore::Client.new(
  repository: RubyEventStore::InMemoryRepository.new
)

Using RubyEventStore with Amazon DynamoDB as a backend

It's fairly easy to create a simple backend repository for storing published events. The simplest use case requires creating an object responding to create method, accepting two arguments: event object and stream_name value.

class DynamodbRepository
  def create(event, stream_name)
    # DynamoDB persistance logic
  end
end

Example use case

1. Install and run local instance of Amazon DynamoDB

Follow the instructions at http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBLocal.html to install the databse locally.

Start the database server: (adjust the path accordingly)

$ java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb

2. Clone this repo and install dependencies

$ git clone [email protected]:siemakuba/res.git
gem install bundler
bundle install

2. Prepare a table for storing events

Execute the code in dynamodb_create_table.rb:

$ ruby dynamodb_create_table.rb

You should see the following output:

Created table. Status: ACTIVE

3. Publish some events

Execute the code in events.rb:

$ ruby events.rb

You should see the following output, indicating that event has been published and consumed:

* Publishing FooEvent
   - FooEventHandler received FooEvent with data: {:sample=>"Foo Event Data"}
   - GeneralEventHandler received FooEvent with data: {:sample=>"Foo Event Data"}

* Publishing BarEvent
   - BarEventHandler received BarEvent with data: {:sample=>"Bar Event Data"}
   - GeneralEventHandler received BarEvent with data: {:sample=>"Bar Event Data"}

* Publishing OtherEvent
   - GeneralEventHandler received OtherEvent with data: {:sample=>"Other Event Data"}

4. Verify that the events has been stored inside Dynamo DB

Execute the code in dynamodb_read_table.rb:

$ ruby dynamodb_read_table.rb

You should see the following output, showing the stored events:

All items in table: 3

Stored items:
{"id"=>"e32926cf-1bc7-4a56-b3ba-1bf52597a957", "timestamp"=>"2017-11-07T09:54:54.334293+01:00", "info"=>{"metadata"=>{"timestamp"=>"2017-11-07T09:54:54+01:00"}, "event_type"=>"BarEvent", "stream_name"=>"all", "data"=>{"sample"=>"Bar Event Data"}}}
{"id"=>"dabd1724-a3bc-4279-9aee-f8eb73da5c90", "timestamp"=>"2017-11-07T09:54:54.322915+01:00", "info"=>{"metadata"=>{"timestamp"=>"2017-11-07T09:54:54+01:00"}, "event_type"=>"FooEvent", "stream_name"=>"all", "data"=>{"sample"=>"Foo Event Data"}}}
{"id"=>"463a3b6d-cf76-4634-80ed-5a7986158d52", "timestamp"=>"2017-11-07T09:54:54.342175+01:00", "info"=>{"metadata"=>{"timestamp"=>"2017-11-07T09:54:54+01:00"}, "event_type"=>"OtherEvent", "stream_name"=>"all", "data"=>{"sample"=>"Other Event Data"}}}