Learning Rails (Ruby on Rails) Web Application Framework

What is Rails?

Rails is a web application development framework written in the Ruby language. It is designed to make programming web applications easier by making assumptions about what every developer needs to get started. It allows you to write less code while accomplishing more than many other languages and frameworks. Experienced Rails developers also report that it makes web application development more fun.

Rails is opinionated software. It makes the assumption that there is a “best” way to do things, and it’s designed to encourage that way – and in some cases to discourage alternatives. If you learn “The Rails Way” you’ll probably discover a tremendous increase in productivity. If you persist in bringing old habits from other languages to your Rails development, and trying to use patterns you learned elsewhere, you may have a less happy experience.

The Rails philosophy includes several guiding principles:

• DRY – “Don’t Repeat Yourself” – suggests that writing the same code over and over again is a bad thing.
• Convention Over Configuration – means that Rails makes assumptions about what you want to do and how you’re going to do it, rather than requiring you to specify every little thing through endless configuration files.
• REST is the best pattern for web applications – organizing your application around resources and standard HTTP verbs is the fastest way to go.

The MVC Architecture

At the core of Rails is the Model, View, Controller architecture, usually just called MVC. MVC benefits include:

• Isolation of business logic from the user interface
• Ease of keeping code DRY
• Making it clear where different types of code belong for easier maintenance

1. Models

A model represents the information (data) of the application and the rules to manipulate that data. In the case of Rails, models are primarily used for managing the rules of interaction with a corresponding database table. In most cases, each table in your database will correspond to one model in your application. The bulk of your application’s business logic will be concentrated in the models.

2. Views

Views represent the user interface of your application. In Rails, views are often HTML files with embedded Ruby code that perform tasks related solely to the presentation of the data. Views handle the job of providing data to the web browser or other tool that is used to make requests from your application.

3. Controllers

Controllers provide the “glue” between models and views. In Rails, controllers are responsible for processing the incoming requests from the web browser, interrogating the models for data, and passing that data on to the views for presentation.

The Components of Rails

Rails ships as many individual components. Each of these components are briefly explained below. If you are new to Rails, as you read this section, don’t get hung up on the details of each component, as they will be explained in further detail later. For instance, we will bring up Rack applications, but you don’t need to know anything about them to continue with this guide.

• Action Pack
  • Action Controller
  • Action Dispatch
  • Action View
• Action Mailer
• Active Model
• Active Record
• Active Resource
• Active Support
• Railties

1. Action Pack

Action Pack is a single gem that contains Action Controller, Action View and Action Dispatch. The “VC” part of “MVC”.

1.1. Action Controller

Action Controller is the component that manages the controllers in a Rails application. The Action Controller framework processes incoming requests to a Rails application, extracts parameters, and dispatches them to the intended action. Services provided by Action Controller include session management, template rendering, and redirect management.

1.2. Action View

Action View manages the views of your Rails application. It can create both HTML and XML output by default. Action View manages rendering templates, including nested and partial templates, and includes built-in AJAX support. View templates are covered in more detail in another guide called Layouts and Rendering.

1.3. Action Dispatch

Action Dispatch handles routing of web requests and dispatches them as you want, either to your application or any other Rack application. Rack applications are a more advanced topic and are covered in a separate guide called Rails on Rack.

2. Action Mailer

Action Mailer is a framework for building e-mail services. You can use Action Mailer to receive and process incoming email and send simple plain text or complex multipart emails based on flexible

3. Active Model

Active Model provides a defined interface between the Action Pack gem services and Object Relationship Mapping gems such as Active Record. Active Model allows Rails to utilize other ORM frameworks in place of Active Record if your application needs this.

4. Active Record

Active Record is the base for the models in a Rails application. It provides database independence, basic CRUD functionality, advanced finding capabilities, and the ability to relate models to one another, among other services.

5. Active Resource

Active Resource provides a framework for managing the connection between business objects and RESTful web services. It implements a way to map web-based resources to local objects with CRUD semantics.

6. Active Support

Active Support is an extensive collection of utility classes and standard Ruby library extensions that are used in Rails, both by the core code and by your applications.

7. Railties

Railties is the core Rails code that builds new Rails applications and glues the various frameworks and plugins together in any Rails application.

source : guides.rubyonrails.org