plugins within their own custom framework; version 3.2 deprecates these in favor of standard Ruby "gems". Deployment Ruby on Rails is often installed using RubyGems, a package manager which is included with current versions of Ruby. Many free Unix-like systems also support installation of Ruby on Rails and its dependencies through their native package management system. Ruby on Rails is typically deployed with a database server such as MySQL or PostgreSQL, and a web server such as Apache running the Phusion Passenger module. Philosophy and design Ruby on Rails is intended to emphasize Convention over Configuration (CoC), and the Don't Repeat Yourself (DRY) principle. The Rails Doctrine is an enduring enabler that guides the philosophy, design, and implementation of the Ruby on Rails framework. "Convention over Configuration" means a developer only needs to specify unconventional aspects of the application. For example, if there is a class Sale in the model, the corresponding table in the database is called sales by default. It is only if one deviates from this convention, such as calling the table "products sold", that the developer needs to write code regarding these names. Generally, Ruby on Rails conventions lead to less code and less repetition. "Don't repeat yourself" means that information is located in a single, unambiguous place. For example, using the ActiveRecord module of Rails, the developer does not need to specify database column names in class definitions. Instead, Ruby on Rails can retrieve this information from the database based on the class name. "Fat models, skinny controllers" means that most of the application logic should be placed within the model while leaving the controller as light as possible. HTML Over The Wire (Hotwire), Conceptual compression, and robust security mark Rails 7.0's approach to the One person framework. Trademarks In March 2007, David Heinemeier Hansson applied to register three Ruby on Rails-related trademarks with the USPTO. These applications concern the phrase "RUBY ON RAILS", the word "RAILS", and the official Rails logo. In the summer of 2007, Hansson denied the publisher Apress permission to use the Ruby on Rails logo on the cover of a new Ruby on Rails book written by some authoritative community members. The episode gave rise to a polite protest in the Ruby on Rails community. In response to this criticism, Hansson replied: I only grant promotional use [of the Rails logo] for products I'm directly involved with. Such as books