Entry script (index.php or yii)
Folder 4
Load application config
Create application instance
Folder 5
preInit()
Register error handler
Configure application properties
init()
bootstrap()
Run application
Folder 3
EVENT_BEFORE_REQUEST
Handle request
Folder 4
Resolve request into route and parameters
Create module, controller and action
Run action
EVENT_AFTER_REQUEST
Send response to end user
Complete request processing
Configuration array
Exit status