Welcome to my new book on ASP.NET Core 3!
.NET and ASP.NET Core are relatively new in the technological landscape, as they were onlyofficially released in August 2017. Given that .NET is in the name, you would think that these would probably only be new versions of the highly popular .NET Framework, but that is not the case: we are talking about something that is truly new!
It's not just multiplatform support (howdy, Linux!), but it's so much more. It's the new modularity in everything: the transparent way by which we can now change things—the source code in front of our eyes teasing us to contribute to it, to make it better—is indeed a lot different from previous versions of .NET Core!
In this first chapter, we are going to talk a bit about what changed in ASP.NET and .NET in the core versions, and also about the new underlying concepts, such as OWIN, runtime environments, and dependency injection (DI).
In this chapter, we will cover the following topics:
- History of ASP.NET Core
- Introduction to .NET Core
- Inversion of control and DI
- OWIN
- The MVC pattern
- Hosting
- Environments
- How the bootstrap process works for ASP.NET Core apps
- The generic host
- What's new since ASP.NET Core 2
- The NuGet and dotnet tools
Technical requirements
This chapter does not require any particular software component, as it deals more with concepts.
You can find the GitHub link at https://github.com/PacktPublishing/Modern-Web-Development-with-ASP.NET-Core-3-Second-Edition.
Getting started
Microsoft ASP.NET was released 15 years ago, in 2002, as part of the then shiny new .NET Framework. It inherited the name ASP (short for Active Server Pages) from its predecessor, with which it barely shared anything else, other than being a technology for developing dynamic server-side content for the internet, which ran on Windows platforms only.
ASP.NET gained tremendous popularity, it has to be said, and competed hand to hand with other popular web frameworks, such as Java Enterprise Edition (JEE) and PHP. In fact, it still does, with sites such as BuiltWith giving it a share of 21% (ASP.NET and ASP.NET MVC combined), way ahead of Java (https://trends.builtwith.com/framework). ASP.NET was not just for writing dynamic web pages. It could also be used for XML (SOAP) web services, which, in early 2000, were quite popular. It benefited from the .NET Framework and its big library of classes and reusable components, which made enterprise development almost seem easy!
Its first version, ASP.NET 1, introduced web forms, an attempt to bring to the web the event and component model of desktop-style applications, shielding users from some of the less friendly aspects of HTML, HTTP, and state maintenance. To a degree, it was highly successful; using Visual Studio,you could easily create a data-driven dynamic site in just a few minutes! A great deal of stuff could be accomplished merely through markup, with no code changes (read or compile) needed.
Version 2 came along a few years afterward, and among all the other goodies, it brought with it extensibility in the form of a provider model. A lot of its functionality could be adapted by the means of custom providers. Later on, it received the addition of the AJAX Extensions, which made AJAX-style effects astonishingly easy. It set the standard for years to come, leaving only room for more components.
To be honest, the following versions, 3.5, 4, and 4.5, only offered more of the same, with new specialized controls for displaying data and charts for retrieving and manipulating data and a few security improvements. A big change was that some of the framework libraries were released as open source.
Between versions 3.5 and 4, Microsoft released a totally new framework, based on the model-view-controller (MVC) pattern, and it was mostly open source. Although it sits on top of the infrastructure laid out by ASP.NET, it offered a whole new development paradigm, which this time fully embraced HTTP and HTML. It seemed to be the current trend for web development across technologies, and the likes of PHP, Ruby, and Java, and .NET developers were generally pleased with it. ASP.NET developers nowhad two choices—Web Forms and MVC, both sharing the ASP.NET pipeline and .NET libraries, but offering two radically different approaches to getting content to the browser.
In the meantime, the now venerable .NET Framework had grown up in an ever-changing world. In the modern enterprise, the needs have changed, and sentences such as runs on Windows only or we need to wait XX years for the next version became barely acceptable. Acknowledging this, Microsoft started working on something new, something different that would set the agenda for years to come. Enter .NET Core!
In late 2014, Microsoft announced .NET Core. It was meant to be a platform-independent, language-agnostic, free, and open source full rewrite of the .NET Framework. Its main characteristics were as follows:
- The base class libraries of .NET were to be rewritten from scratch while keeping the same (simplified) public APIs, which meant that not all of them would be initially available.
- It was also able to run on non-Windows operating systems, specifically several Linux and macOS flavors, and in mobile devices, so all Windows-specific code (and APIs) would be discarded.
- All of its components were to be delivered as NuGet packages, meaning that only a small bootstrap binary would need to be installed in the host machine.
- There was no longer a dependency (or, let's say, a very close relationship) with IIS, so it was able to be autohosted or run inside a hosting process, like, well, IIS.
- It would be open source and developers would be able to influence it, either by creating issues or by submitting pull requests.
This eventually took place in July 2016, when version 1.0 of .NET Core was released. The .NET developers could now write once and deploy (almost) everywhere and they finally had a say on the direction the framework was taking!
Rewriting the whole .NET Framework from scratch is a task of epic proportions, so Microsoft had to make decisions and define priorities. One of them was to ditch ASP.NET Web Forms and to only include MVC. So gone were the days when ASP.NET and Web Forms were synonyms, and the same happened with ASP.NET Core and MVC: it's now just ASP.NET Core! And it's not just that the ASP.NET Web API, which used to be a different project type, was now merged with ASP.NET Core as well (a wise decision from Microsoft, as basically the two technologies, MVC and Web API, had a lot of overlap and even had classes with the same name for pretty much the same purpose).
So, what does this mean for developers? Here are my personal thoughts about how the tech has fared:
- C#, Visual Basic, and F#; F# has gained a lot of momentum among the developer communities, and they have built templates for Visual Studio as...
