The MVC Architecture

2.1 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

2.1.1 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, one 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.

2.1.2 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.

2.1.3 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.

2.2 The Components of Rails

Rails ships as many individual components.

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

2.2.1 Action Pack

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

2.2.2 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.

2.2.3 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.

2.2.4 Action Dispatch

Action Dispatch handles routing of web requests and dispatches them as you want, either to your application or any other Rack application.

2.2.5 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 templates.

2.2.6 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.

2.2.7 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.

2.2.8 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.

2.2.9 Active Support

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

2.2.10 Railties

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