IntervalResponse

is a little piece of machinery which allows your Rack/Rails application to correctly serve HTTP Range: responses. It allows you to "stitch" together multiple spans of data (such as long strings, files or remote resources) and then serve them out in response to requests with Range: headers. Features:

• Strong ETags depending on response composition
• Correct response codes/headers/offsets
• multipart/byte-range responses
• Segments comprising the body do not have to be materialized into buffers or strings prior to serving
• Responds to both GET and HEAD, to the latter without body
• Is measurometer-instrumented

Imagine you have a number of long Strings you want to serve concatenated as a single HTTP resource. Wrap them in an IntervalResponse and return it to Rack:

verses_app = ->(env) {
  all_verses = ImportantVerse.all.map(&:verse_text)
  interval_sequence = IntervalResponse::Sequence.new(*all_verses)
  response = IntervalResponse.new(interval_sequence, env)
  response.to_rack_response_triplet
}

Or imagine you want to serve out a few very large log files, concatenated together

  log_paths = Dir.glob('/tmp/logs/kafkadoop.*.log.gz').sort
  # Wrap them with "lazy file" proxies so that the files
  # do not have to stay open during the entire response output
  lazy_files = log_paths.map { |path| IntervalResponse::LazyFile.new(path) }
  interval_sequence = IntervalResponse::Sequence.new(*lazy_files)
  response = IntervalResponse.new(interval_sequence, env)
  response.to_rack_response_triplet(headers: {'X-Server' => 'teapot'})

Note that the headers IntervalResponse generates are very specific and will override your headers. The following headers will be overridden (as they must all be correct for the serving to work):

Accept-Ranges
Content-Length
Content-Type
Content-Range
ETag

Add this line to your application's Gemfile:

gem 'interval_response'

And then execute:

$ bundle

Or install it yourself as:

$ gem install interval_response

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/WeTransfer/interval_response.

The gem is available as open source under the terms of the MIT License.