sample3.rb

require 'webrick'
require 'json'
binding = TOPLEVEL_BINDING.dup
srv = WEBrick::HTTPServer.new({:BindAddress => '127.0.0.1',
                               :Port => 8080})
srv.mount_proc('/') {|req, res|
  body = JSON.parse req.body
  expr = body['expression']
  result = binding.eval(expr)
  puts result
  res.body = JSON.generate({result: result})
}

srv.mount_proc('/files') {|req, res|
  body = JSON.parse req.body
  text = body['text']
  file = Tempfile.create(%w[debug- .rb])
  file.write(text)
  file.close
  res.body = JSON.generate({path: file.path})
}

srv.mount_proc('/debug') {|req, res|
  body = JSON.parse req.body
  Thread.new do
  end
  pid = Process.fork {
    b = binding.eval("load '#{body['path']}'")
  }
  res.body = JSON.generate({})
}
Signal.trap(:INT){ srv.shutdown }
srv.start