DataTables.net plus JRuby and Sinatra ... for instructions, see http://opensourcetips.blogspot.com/2014/09/datatablesnet-jruby-sinatra.html

datatables.rb

require 'sinatra'
require 'sinatra/reloader' if development?
require 'lib/jt400.jar'
require 'yaml'
require 'json'
require 'logger'

$log = Logger.new('logs/log.txt','weekly')
$log.level = Logger::DEBUG

set :public_folder, 'public'
db = YAML.load_file '/config/db.yml'
Java::JavaClass.for_name db['driver']
connection = java.sql.DriverManager.get_connection(db['dburl'], db['username'], db['password'])
 
get "/" do
  redirect 'examples/index.html' 
end
 
get '/employees' do
  rows = []
  query = %q{SELECT NAME, TITLE, OFFICE, EXTENSION, STARTDATE, SALARY from EMPLOYEE}
  statement = connection.prepare_statement(query)
  results = statement.execute_query
  meta = results.meta_data
  
  while results.next 
    row = []
    (1..meta.column_count).each do |i|
      $log.debug meta.column_type(i)
      row[i - 1] =  case meta.column_type(i) 
        when -6, -5, 5, 4
          results.get_int(i).to_s
        when 91
          results.get_date(i).to_s
        when 92
          results.get_time(i)
        when 93
          results.get_timestamp(i)
        when 2, 3, 6 
          BigDecimal.new(results.get_string(i).to_s)
        when 1, -15, -9, 12 
          results.get_string(i).to_s 
        else 
          results.get_string(i)
      end
          
    end
    rows << row
    $log.debug rows
  end
  doc = {}
  doc['data'] = rows
  $log.debug doc
  results.close
  statement.close
  
  content_type 'application/json'
    doc.to_json
end

db.yml

dburl: jdbc:as400://SEWDEV
driver: com.ibm.as400.access.AS400JDBCDriver
username: myuserid
password: mypassword

modify_the_ajax_file

In public/examples/data_sources/ajax.html, change the ready function from this: 

$(document).ready(function() {
	$('#example').dataTable( {
		"ajax": '../ajax/data/arrays.txt'
	} );
} );

to this:

$(document).ready(function() {
	$('#example').dataTable( {
		"ajax": '/employees'
	} );
} );