The Request Life Cycle in the Yii2 framework explains in the following stages :
1. Pre-initialize the application with CApplication::preinit();
2. Set up the error handling;
3. Register core application components;
4. Load application configuration;
5. Initialize the application with CApplication::init()
* Register application behaviors;
* Load static application components;
6. Raise an onBeginRequest event;
7. Process the user request.
* Collect information about the request;
* Create a controller;
* Run the controller;
8. Raise an onEndRequest event;
