.NET Core

Question 1

What is the ASP.NET Core?

Answer 1

ASP.NET Core is not an upgraded version of ASP.NET. ASP.NET Core is completely rewriting that work with .net Core framework. It is much faster, configurable, modular, scalable, extensible and cross-platform support. It can work with both .NET Core and .net framework via the .NET standard framework. It is best suitable for developing cloud-based such as web application, mobile application, IoT application.

Question 2

What are the features provided by ASP.NET Core?

Answer 2

• Built-in supports for Dependency Injection
• Built-in supports for the logging framework and it can be extensible
  I* Introduced new, fast and cross-platform web server - Kestrel. So, a web application can run without IIS, Apache, and Nginx.
• Multiple hosting ways are supported
• It supports modularity, so the developer needs to include the module required by the application.
• Command-line supports to create, build and run the application
• There is no web.config file. We can store the custom configuration into an appsettings.json file
• There is no Global.asax file. We can now register and use the services into startup class
• It has good support for asynchronous programming
• Support WebSocket and SignalR
• Provide protection against CSRF (Cross-Site Request Forgery)

Question 3

What are the advantages of ASP.NET Core over ASP.NET?

Answer 3

• It is cross-platform, so it can be run on Windows, Linux, and Mac.
• There is no dependency on framework installation because all the required dependencies are ship with our application
• ASP.NET Core can handle more request than the ASP.NET
• Multiple deployment options available with ASP.NET Core

Question 4

What are Metapackages?

Answer 4

The framework .NET Core 2.0 introduced Metapackage that includes all the supported package by ASP.NET code with their dependencies into one package. It helps us to do fast development as we don’t require to include the individual ASP.NET Core packages. The assembly Microsoft.AspNetCore. All is a meta package provide by ASP.NET core.

Question 5

What is the purpose of the startup class in ASP.NET core?

Answer 5

Startup class is the entry point of the ASP.NET Core application. Every .NET Core application must have this class. This class contains the application configuration related items.

Question 6

What is the purpose of the ConfigureServices method of startup class?

Answer 6

This is an optional method of startup class. It can be used to configure the services that are used by the application. This method calls first when the application is requested for the first time. Using this method, we can add the services to the DI container, so services are available as a dependency in controller constructor.

ConfigureServices is most used for configuring custom Dependency Injection by adding custom interfaces into the services IServiceCollection (IoC Container).

This is also where swagger and Newtonsoft settings are applied

Question 7

What is the purpose of the Configure method of the startup class?

Answer 7

It sets up the Http request pipeline. It defines how the application will respond to each HTTP request. We can configure the request pipeline by configuring the middleware. It accepts IApplicationBuilder as a parameter and also it has two optional parameters: IHostingEnvironment and ILoggerFactory. Using this method, we can configure built-in middleware such as routing, authentication, session, etc. as well as third-party middleware.

This is where CORS (Cross Origin Request System) policy is typically configured, which specifies which hosts are permitted to access this api

Question 8

What is middleware?

Answer 8

It is software which is injected into the application pipeline to handle request and responses. They are just like chained to each other and form as a pipeline. The incoming requests are passes through this pipeline where all middleware is configured, and middleware can perform some action on the request before passes it to the next middleware. Same as for the responses, they are also passing through the middleware but in reverse order.

Question 9

What is the difference between IApplicationBuilder.Use() and IApplicationBuilder.Run()?

Answer 9

The IApplicationBuilder interface’s Use() method will execute the middleware and then continue to the next middleware component. The IApplicationBuilder interface’s Run() method will stop the middleware pipeline once the current middleware is added. Any services added below this line will not get added.

Question 10

What is the use of “Map” extension while adding middleware to ASP.NET Core pipeline?

Answer 10

It is used for branching the pipeline. It branches the ASP.NET Core pipeline based on request path matching. If request path starts with the given path, middleware on to that branch will execute.

Question 11

What is routing in ASP.NET Core?

Answer 11

Routing is functionality that map incoming request to the route handler. The route can have values (extract them from URL) that used to process the request. Using the route, routing can find route handler based on URL. All the routes are registered when the application is started. There are two types of routing supported by ASP.NET Core

• Conventional routing
• Attribute routing

The Routing uses routes for map incoming request with route handler and Generate URL that used in response. Mostly, the application having a single collection of routes and this collection are used for the process the request. The RouteAsync method is used to map incoming request (that match the URL) with available in route collection.

Question 12

How to enable Session in ASP.NET Core?

Answer 12

The middleware for the session is provided by the package Microsoft.AspNetCore.Session. To use the session in ASP.NET Core application, we need to add this package to csproj file and add the Session middleware to ASP.NET Core request pipeline.

Question 13

What are the various JSON files available in ASP.NET Core?

Answer 13

There are following JSON files in ASP.NET Core :

• global.json
• launchsettings.json
• appsettings.json
• bundleconfig.json
• browser.json
• package.json

Question 14

What are Razor Pages in ASP.NET Core?

Answer 14

This is a new feature introduced in ASP.NET Core 2.0. It follows a page-centric development model just like ASP.NET web forms. It supports all the feature of ASP.NET Core

Question 15

How can we do automatic model binding in Razor pages?

Answer 15

The Razor pages provide the option to bind property automatically when posted the data using BindProperty attribute. By default, it only binds the properties only with non-GET verbs. we need to set SupportsGet property to true to bind a property on getting request.

Question 16

How do you inject a service dependency into a controller?

Answer 16

Step 1: Create the service (interface and at least one concrete implementation)

Step 2: Add this service to Service container (in Startup.ConfigureServices). The service can either added by singleton, transient or scoped

Step 3: Use this service as a dependency in the controller (adding interface to constructor parameters definition)

Question 17

What are the available scopes for service dependencies?

Answer 17

Singleton

ASP.NET Core will create and share a single instance of the service through the application life. The service can be added as a singleton using AddSingleton method of IServiceCollection. ASP.NET Core creates service instance at the time of registration and subsequent request use this service instance. Here, we do not require to implement Singleton design pattern and single instance maintained by the ASP.NET Core itself.

Transient

ASP.NET Core will create and share an instance of the service every time to the application when we ask for it. The service can be added as Transient using AddTransient method of IServiceCollection. This lifetime can be used in stateless service. It is a way to add lightweight service.

Scoped

ASP.NET Core will create and share an instance of the service per request to the application. It means that a single instance of service available per request. It will create a new instance in the new request. The service can be added as scoped using an AddScoped method of IServiceCollection. We need to take care while, service registered via Scoped in middleware and inject the service in the Invoke or InvokeAsync methods. If we inject dependency via the constructor, it behaves like singleton object.