Welcome to Rails
Rails is a web-application framework that includes everything needed to create
database-backed web applications according to the Model-View-Controller (MVC) pattern.
Understanding the MVC pattern is key to understanding Rails. MVC divides your application into three layers, each with a specific responsibility.
The View layer is composed of “templates” that are responsible for providing appropriate representations of your application's resources. Templates can come in a variety of formats, but most view templates are HTML with embedded Ruby code (.erb files).
The Model layer represents your domain model (such as Account, Product, Person, Post) and encapsulates the business logic that is specific to your application. In Rails, database-backed model classes are derived from ActiveRecord::Base. ActiveRecord allows you to present the data from database rows as objects and embellish these data objects with business logic methods. Although most Rails models are backed by a database, models can also be ordinary Ruby classes, or Ruby classes that implement a set of interfaces as provided by the ActiveModel module. You can read more about Active Record in its README.
The controller and view are handled by the Action Pack, which handles both layers by its two parts: Action View and Action Controller. These two layers are bundled in a single package due to their heavy interdependence. This is unlike the relationship between the Active Record and Action Pack that is much more separate. Each of these packages can be used independently outside of Rails. You can read more about Action Pack in its README.
Install Rails at the command prompt if you haven't yet:
gem install rails
At the command prompt, create a new Rails application:
rails new myapp
where “myapp” is the application name.
Change directory to myapp and start the web server:
cd myapp; rails server
Run with --help for options.
Go to localhost:3000/ and you'll see:
"Welcome aboard: You're riding Ruby on Rails!"
Follow the guidelines to start developing your application. You may find the following resources handy:
The README file created within your application.
The Ruby on Rails Guides.
The API Documentation.
Ruby on Rails is released under the MIT license.