Introduction to ASP.NET

Introduction to .NET

• .NET is a free and open-source developer platform for building websites and applications.
• It is built on a high-performance runtime used by several high-scale apps such as Microsoft Teams, UPS mobile app, Forza Horizon, and Allegiance Consulting.
• .NET apps and libraries are built from a project file and a source code or using the .NET CLI (command-line interface) or an Integrated Development Environment (IDE) like Visual Studio.

.NET CLI

• The .NET CLI is a tool for building and running .NET apps.
• The app can be built and run using the .NET CLI command dotnet run.

.NET Runtimes

• .NET Runtimes are binary distributions of .NET that include a set of tools, libraries, and runtimes for app development, building, and testing.
• The Common Language Runtime (CLR) is considered the foundation of all .NET apps.
• .NET is often called a “managed code” runtime as it uses a garbage collector for memory allocation and release and because it enforces type and memory safety.

Supported Programming Languages

• .NET supports several programming languages, including:
  • C# - a general-purpose object- and component-oriented programming language.
  • F# - a programming language for writing compact, strong, and performant code.
  • Visual Basic - an event-driven programming language that provides a graphical user interface (GUI) by dragging and dropping objects and modifying their codes.

.NET Framework, Mono, and .NET Core

• There are three versions of .NET that support different types of apps:
  • .NET Framework - a software development framework for building and running applications on Windows.
  • Mono - provides complete SDK features to develop .NET applications on various platforms.
  • .NET Core - a cross-platform and open-source implementation of .NET for the cloud age, compatible with the .NET Framework.

ASP.NET

• ASP.NET is a framework developed and marketed by Microsoft to allow programmers to build dynamic web pages that run on Windows, Linux, macOS, and Docker.
• ASP.NET extends the .NET platform with more tools and libraries for building web apps.
• ASP.NET adds features such as Blazor, Razor Pages, and authentication systems to the .NET platform.

ASP.NET Frameworks

• ASP.NET offers three frameworks for creating web applications, each targeting a different development style:
  • Web Forms - building dynamic websites using a drag-and-drop, event-driven model.
  • ASP.NET MVC - a design pattern separating user interfaces with business logic.
  • ASP.NET Web Pages - a fast, approachable, and lightweight way to combine server code with HTML for dynamic web content.

Advantages of ASP.NET

• ASP.NET provides several advantages, including:
  • Web APIs - a framework for building HTTP services that can be accessed using browsers and mobile devices.
  • Real-time technologies - ASP.NET SignalR is a new library that makes developing real-time web functionality easier.
  • Single-page applications (SPA) - ASP.NET SPA helps build applications with major client-side interactions.
  • Mobile apps and sites - ASP.NET can power native mobile apps with a Web API back end and mobile websites using responsive design frameworks.

ASP.NET Core Essentials

• ASP.NET Core is a cross-platform, high-performance, open-source framework that runs on .NET Core to build modern, cloud-enabled, and Internet-connected web apps, services, and mobile backends.
• It can be developed and run on Windows, macOS, and Linux.
• ASP.NET Core is considered the new and enhanced version of ASP.NET with better functionality and libraries and a comfortable interface.

Content Root

• The content root defaults to the project’s root directory during development.
• It includes the executable hosting the application (.exe), compiled assemblies of the app (.dll), and content files used by the app.

Program.cs

• ASP.NET Core apps created with web templates have the application startup code in the Program.cs, where services required by the app are configured.
• A sample app startup code using C# is provided.

Host

• An ASP.NET Core app on startup builds a host that encapsulates all of the app’s resources, such as logging, configuration, middleware, and dependency injection services.
• There are three different hosts capable of running an ASP.NET Core app: ASP.NET Core WebApplication, .NET Generic Host, and ASP.NET Core WebHost.

Benefits of ASP.NET Core

• ASP.NET Core provides several benefits, including:
  • Cloud-ready
  • Community-focused
  • Crafted for testability
  • Tooling that simplifies modern web development

Handling Errors

• ASP.NET Core has built-in features for handling errors, including:
  • Developer Exception Page - provides complete information about unhandled request exceptions.
  • Custom Error Page - UseExceptionHandler is called to configure a custom error handling page.
  • Status Code Page - UseStatusCodePages is used to provide a status code page for HTTP error status codes.
  • Startup Exception Handling - only the hosting layer can handle exceptions during app startup to capture startup and detailed errors.