2_3_Requeust and response flow

The following figure illustrates how VMS process client's request and response to client.

The client (view) sends a request in JSON format to VMS, according to HTTP method and URL which are defined in app/Http/routes.php, HTTP Routing routes the request to a corresponding method in a controller.

If any HTTP Middleware is registered on a routing, the middleware will be invoked to filter request. For example, there is a middleware \Tymon\JWTAuth\Middleware\GetUserFromToken for checking the authentication token in a request.

Next, before entering a controller, if there is a HTTP request dependency injection on a controller, the request will be created and called. Since the request may contain request validation logic and authorization control, it avoids fat controllers and duplicated code in controllers.

A request implements authorize()¹ and rules()² methods. The authorize() calls Policies via Gate and returns true or false for determining whether the request is authorized or not. The rules() returns the validation rules ³ in array type.

After that, a controller retrieves input data from requests and manipulate Models for work with database. If the model data should be sent as a response to the client, it will be passed to Transformers in order to transform from object to array as JSON response.

Reference

1. authorize(): https://laravel.com/docs/5.2/authorization#within-form-requests
2. rules(): https://laravel.com/docs/5.2/validation#form-request-validation
3. validation rules: https://laravel.com/docs/5.2/validation#available-validation-rules