Alephant::Broker

Brokers requests for rendered templates, retrieved from S3 or a HTML endpoint.

Installation

Add this line to your application's Gemfile:

gem 'alephant-broker'

And then execute:

bundle install

Or install it yourself as:

gem install alephant-broker

Usage

The Broker is capable of retrieving rendered templates from either S3 or a HTML endpoint (e.g. alephant-publisher-request). This must be decided when creating an instance of the Broker, as a load strategy is given as a parameter (see below for examples).

Barebones

S3 Load Strategy

require 'alephant/broker'

config = {
  :s3_bucket_id      => 'test_bucket',
  :s3_object_path    => 'foo',
  :lookup_table_name => 'test_lookup'
}

request = {
  'PATH_INFO'      => '/component/foo',
  'QUERY_STRING'   => 'variant=bar',
  'REQUEST_METHOD' => 'GET'
}

Alephant::Broker::Application.new(
  Alephant::Broker::LoadStrategy::S3.new,
  config
).call(request).tap do |response|
  puts "status:  #{response.status}"
  puts "content: #{response.content}"
end

HTML Load Strategy

require 'alephant/broker'

class UrlGenerator < Alephant::Broker::LoadStrategy::HTTP::URL
  def generate(id, options)
    "http://example-api.com/data?id=#{id}"
  end
end

request = {
  'PATH_INFO'      => '/component/foo',
  'QUERY_STRING'   => 'variant=bar',
  'REQUEST_METHOD' => 'GET'
}

Alephant::Broker::Application.new(
  Alephant::Broker::LoadStrategy::HTTP.new(UrlGenerator.new),
  {}
).call(request).tap do |response|
  puts "status:  #{response.status}"
  puts "content: #{response.content}"
end

Note

The HTML load strategy relies upon being given a URLGenerator, which is used to generate the URL of the HTML endpoint (see below for example). The class must:

be implemented within your own application.
extend Alephant::Broker::LoadStrategy::HTTP::URL.
include a #generate method which takes id (string) and options (hash) as parameters.

require 'alephant/broker'
require 'rack'

class UrlGenerator < Alephant::Broker::LoadStrategy::HTTP::URL
  def generate(id, options)
    "http://api.my-app.com/component/#{id}?#{to_query_string(options)}"
  end

  private

  def to_query_string(hash)
    Rack::Utils.build_query hash
  end
end

Revalidate Strategy

require 'alephant/broker'

config = {
  :s3_bucket_id                => 'test_bucket',
  :s3_object_path              => 'foo',
  :lookup_table_name           => 'test_lookup',
  :sqs_queue_name              => 'test_queue',
  :elasticache_config_endpoint => 'test_elisticache'
  :revalidate_cache_ttl        => 30
}

Alephant::Broker::Application.new(
  Alephant::Broker::LoadStrategy::Revalidate::Strategy.new,
  config
).call(request).tap do |response|
  puts "status:  #{response.status}"
  puts "content: #{response.content}"
end

The "Revalidate" strategy uses the following process flow:

And uses the following AWS resources:

S3 - for storage of rendered components
DynamoDB - for recording S3 component locations
Elasticache - for caching S3 content and recording "inflight" messages
SQS - for communication between the broker and renderer

Rack App

Create config.ru using example below, and then run:

rackup config.ru

require 'alephant/broker'
require 'alephant/broker/load_strategy/http'

class UrlGenerator < Alephant::Broker::LoadStrategy::HTTP::URL
  def generate(id, options)
    "http://example-api.com/data?id=#{id}"
  end
end

run Alephant::Broker::Application.new(
  Alephant::Broker::LoadStrategy::HTTP.new(UrlGenerator.new),
  {}
)

Cache version number

The broker looks for a configuration value elasticache_cache_version and if it exists it uses it to construct the cache key. This allows the cache to be busted if the data in the cache changes, or for any other reason that it needs to be invalidated.

This version is added as a header to the response in the following format:

X-Cache-Version: {CACHE_VERSION}

Contributing

Fork it!
Create your feature branch: git checkout -b my-new-feature
Commit your changes: git commit -am 'Add some feature'
Push to the branch: git push origin my-new-feature
Create a new Pull Request.

Feel free to create a new issue if you find a bug.

alephant-broker

Development

Runtime