Legion Extensions Home

Developing a LEX

LEXs are the only reason Legion as a framework is vaulable. They are designed to be easy to create without the overhead of managing things like workers, threads, queues, data connections, etc.

LEX folder structure

lib/legion
- name(http)
  - version.rb
  - actors(optional)
    - http.rb
  - runners(required)
    - http.rb
    - foobar.rb
  - transport(optional)
  - data(optional)
- http.rb (the bootstrap file)

Example bootstrap

require 'legion/extensions/http/version'
require 'legion/extensions'

module Legion
  module Extensions
    module Http
      extend Legion::Extensions::Core
    end
  end
end

When you create a runner, it is recommended to use the lex helper as it will give you some base functionality that will come in hand

module Legion::Extensions::Http:Runners
  module Http
    include Legion::Extensions::Helpers::Lex  
  end
end

LEX Data::Migrations

Legion automatically handles database schema migrations for a lex. All you need to do is create this folder structure legion/extensions/http/data/migrations/

Migration files should be formatted as 001_text_desc.rb

The Legion framework will handling making sure your schema is up to date. If you update a LEX gem that has new migrations, next time you start Legion with that newer version, it will be upgraded automatically.

LEX Data::Models

You can also add custom models in the case where you are adding new tables that aren’t default.

Model files should be located at legion/extensions/http/data/models and the models must extend Sequel::Model otherwise bad things will happen

Example

module Legion::Extensions::Scheduler::Data::Model
  class Schedule < Sequel::Model
    one_to_many :schedule_logs
    many_to_one :task
    many_to_one :function
  end
end

Models that are created from a LEX are not registered globally as you cannot guarantee that the lex is installed for all workers.