Ruby on Rails hands on: What's so hot about Rails?

August 31, 2006 (Computerworld) --

This article is excerpted from the book Ruby on Rails: Up and Running, published by O'Reilly Media Inc., copyright 2006. Reprinted with permission, all rights reserved.

Rails may just be the most important open-source project to be introduced in the past 10 years. It's promoted as one of the most productive Web development frameworks of all time and is based on the increasingly important Ruby programming language. What has happened so far?

• By December 2006, you're likely to see more published books on Rails than any of Java's single flagship frameworks, including JSF, Spring, or Hibernate.
• The Rails framework has been downloaded at least 500,000 times in only its second year, as of May 2006. These statistics compare favorably with the most popular open source frameworks in any language.
• The Rails community mailing lists get hundreds of notes a day, compared to dozens on the most popular Web development frameworks in other languages.
• The Rails framework has caused an explosion in the use of the Ruby programming language, which has been relatively obscure until recently.
• The Rails buzz generates increasingly hot debates on portals that focus on other programming languages. The Java community in particular has fiercely debated the Rails platform.

You don't have to go far to find great overviews of Rails. You can watch several educational videos that show Rails in action, narrated by the founder David Heinemeier Hansson. You can watch him build simple working applications, complete with a backing database and validation, in less than 10 minutes. But unlike the many quick-and-dirty environments you've seen, Rails lets you keep the quick and leave the dirty behind. It lets you build clean applications based on the model-view-controller philosophy. Rails is a special framework.

Sure, Rails has its limitations. Ruby has poor support for object-relational mapping (ORM) for legacy schemas; the Rails approach is less powerful than Java's approach, for example. Ruby does not yet have flagship integrated development environments. Every framework has limitations, and Rails is no different. But for a wide range of applications, the strengths of Rails far outpace its weaknesses.

Rails Strengths

Rails can thrive without all of the extensive libraries required by other languages. Ruby's flexibility lets you extend your applications in ways that might have been previously unavailable to you. You'll be able to use a Rails feature called scaffolding to put database-backed user interfaces in front of your customers quickly. Then, as you improve your code, the scaffolding melts away. You'll be able to build database-backed model objects with just a couple of lines of code, and Rails will fill in the tedious details.

The most common programming problem in today's typical development project involves building a Web-based user interface to manage a relational database. For that class of problems, Rails is much more productive than any other Web development framework either of us has ever used. The strengths aren't limited to any single groundbreaking invention; rather, Rails is packed with features that make you more productive, with many of the following features building on one other:

Metaprogramming

Metaprogramming techniques use programs to write programs. Other frameworks use extensive code generation, which gives users a one-time productivity boost but little else, and customization scripts let the user add customization code in only a small number of carefully selected points. Metaprogramming replaces these two primitive techniques and eliminates their disadvantages. Ruby is one of the best languages for metaprogramming, and Rails uses this capability well.

Active Record

Rails introduces the Active Record framework, which saves objects to the database. Based on a design pattern cataloged by Martin Fowler, the Rails version of Active Record discovers the columns in a database schema and automatically attaches them to your domain objects using metaprogramming. This approach to wrapping database tables is simple, elegant, and powerful.

Convention over configuration

Most Web development frameworks for .NET or Java force you to write pages of configuration code. If you follow suggested naming conventions, Rails doesn't need much configuration. In fact, you can often cut your total configuration code by a factor of five or more over similar Java frameworks just by following common conventions.

Scaffolding

You often create temporary code in the early stages of development to help get an application up quickly and see how major components work together. Rails automatically creates much of the scaffolding you'll need.

Built-in testing

Rails creates simple automated tests you can then extend. Rails also provides supporting code called harnesses and fixtures that make test cases easier to write and run. Ruby can then execute all your automated tests with the rake utility.

Three environments: development, testing, and production

Rails gives you three default environments: development, testing, and production. Each behaves slightly differently, making your entire software development cycle easier. For example, Rails creates a fresh copy of the Test database for each test run.

There's much more, too, including Ajax for rich user interfaces, partial views and helpers for reusing view code, built-in caching, a mailing framework, and Web services. We can't get to all of Rails' features; however, we will let you know where to get more information. But the best way to appreciate Rails is to see it in action