Explain the MVC application life cycle

Any web application has two primary execution steps:

  1. Understanding the request
  2. Sending out an appropriate response

MVC application life cycle includes two main phases:

  1. Creating the request object
  2. Sending response to the browser

The steps included in creating a request object are:

  1. Request Routing:

    • When a user makes a request, the ASP.NET MVC application starts by using a routing engine to determine which controller and action method should handle the request. The route configuration defines how URLs map to controllers and actions.

  2. Controller Execution:

    • Once the routing engine identifies the appropriate controller and action, the corresponding controller is instantiated. The controller then executes the action method associated with the user’s request. During this phase, the controller can interact with the Model to retrieve or update data.

  3. Model Binding:

    • Model binding is the process of mapping data from the HTTP request to the parameters of the action method. The controller uses model binding to populate the action method’s parameters with values from the request, making it easy to work with form data, query strings, and route values.

  4. Action Filter Execution:

    • Action filters are used to perform pre-processing or post-processing logic before or after the execution of an action method. Examples include authentication, logging, and caching. Action filters are executed before and after the action method.

  5. Action Execution:

    • The action method is responsible for processing the request and typically involves interacting with the Model to perform business logic. After processing, the action method returns an ActionResult, which represents the data to be displayed or the next step in the user flow.

  6. Result Execution:

    • The ActionResult returned by the action method is executed to generate the response. This involves rendering the appropriate View, redirecting to another action, or returning raw data (such as JSON or XML).

  7. View Rendering:

    • If the ActionResult involves rendering a View, the ViewEngine is responsible for locating and rendering the corresponding view template. Views are responsible for presenting the data provided by the controller in a user-friendly format.

  8. Response Sent to the Browser:

    • The final HTML or content generated by the View is sent as the HTTP response to the user’s browser, completing the request-response cycle.

  9. Post-Processing and Cleanup:

    • After the response is sent, any post-processing tasks or cleanup operations can be performed. This may include logging, resource cleanup, or any other actions that need to occur after the request has been processed.
flowchart LR A(((User))) -->|Request| B{{Routing}} B --> C(Controller Initialization) C --> D(Action Execution) D --> E{Result Execution} E --> F{{View Engine}} E --> G F --> G[Result Execution] G --> |Response| A