Yii 2.0 Application Structure

The most important directories and files in your application are (assuming the application's root directory is basic):

basic/                  application base path
    composer.json       used by Composer, describes package information
    config/             contains application and other configurations
        console.php     the console application configuration
        web.php         the Web application configuration
    commands/           contains console command classes
    controllers/        contains controller classes
    models/             contains model classes
    runtime/            contains files generated by Yii during runtime, such as logs and cache files
    vendor/             contains the installed Composer packages, including the Yii framework itself
    views/              contains view files
    web/                application Web root, contains Web accessible files
        assets/         contains published asset files (javascript and css) by Yii
        index.php       the entry (or bootstrap) script for the application
    yii                 the Yii console command execution script

In general, the files in the application can be divided into two types: those under basic/web and those under other directories. The former can be directly accessed via HTTP (i.e., in a browser), while the latter can not and should not be.

Yii implements the model-view-controller (MVC) design pattern, which is reflected in the above directory organization. The models directory contains all model classes, the views directory contains all view scripts, and the controllers directory contains all controller classes.

The following diagram shows the static structure of an application.

Each application has an entry script web/index.php which is the only Web accessible PHP script in the application. The entry script takes an incoming request and creates an application instance to handle it. The application resolves the request with the help of its components, and dispatches the request to the MVC elements. Widgets are used in the views to help build complex and dynamic user interface elements.