I've been keeping my head down working on various projects and apparently Microsoft has been busy making some big changes and it's confusing the hell out of me. ASP.NET Core first came onto my radar when I installed Visual Studio 2017 last year and went to create a new project and suddenly had choices of .NET Framework, .NET Standard, and .NET Core. So I looked into them a little and saw that the latter two are, in some way, abbreviated versions of the full framework. I read this post by Scott Hanselman ASP.NET 5 is dead – Introducing ASP.NET Core 1.0 and .NET Core 1.0 I also found this, which steered me away from ASP.NET Core: Choose between ASP.NET and ASP.NET Core. My takeaway was "Core is new, you're fine to keep using the full framework." So I created a new ASP.NET MVC site using .NET Framework 4.6.2 and Microsoft.AspNet.Mvc 5.2.3.
Since creating that project, I found what seemed like some bugs in both MVC and Entity Framework only to find that the only mention of them on the web seems to be in Core and that's the only place they're being considered being fixed.
Now, today, I'm trying to look up the documentation on System.Web.Mvc.Controller and System.Web.Mvc.JsonResult and it's gone except under Core documentation. I did finally dig it up here where it says it's no longer being maintained?
I understood this much about Core and said, "ok, why should I care? I'm going to keep doing what I'm doing and check back on that when it's done." But now it seems that 4.6.2 is not even supported anymore. Can someone explain what's going on? Is my NET 4.6.2/MVC 5.2.3 project now obsolete before I'm even finished writing it? If not, why has the documentation been retired and hidden away? I'm worried some of my dependencies might not even be available for or compatible with Core.
Best Answer
(This answer is regularly updated whenever a new .NET announcement is made, and it has been updated with details of ASP.NET Core 3.0, .NET 3, and .NET 5)
Microsoft needs a good slapping for the amount of confusion over the past
3 years5 years over .NET Core / DNX, ASP.NET Core, .NET Standard, .NET 5 and the rest.(and I'm saying that as a former FTE SE in DevDiv... ("hi from building 16!"))
System.Web.Http
) that didn't share much with ASP.NET MVC (System.Web.Mvc
). Attempting to combine an ASP.NET Web API service with an ASP.NET MVC web-application in the same project is an exercise in pain.System.Web.Mvc
andMicrosoft.Web.Mvc
namespaces - which is confusing. Fortunately this was short-lived and irrelevant today.System.Web.dll
or any (now-legacy) IIS dependencies (e.g. the old request pipeline,IHttpHandler
andIHttpModule
no longer exist).Microsoft.AspNet
and notSystem.Web
. This was a source of confusion for me. This means that upgrading projects from ASP.NET MVC and ASP.NET WebAPI to ASP.NET Core are non-trivial, despite their fundamental architecture of Controllers and Middleware being the same.I note that "Core" is Microsoft's hot branding for the current generation of .NET platforms which work with .NET Core (i.e. they have no Windows dependencies and so are portable). (Just like how Microsoft stuck "Active" onto things in the 1990s if they used COM or ActiveX, e.g. Active Desktop, Active Channels, ActiMates, Active Directory, ActiveSync, etc).
Because there are many .NET runtimes and BCLs currently available (.NET Framework, .NET Core, UWP, Xamarin (which uses Mono), Unity and others) Microsoft introduced .NET Standard which is basically a reboot of the Portable Class Library concept: where Visual Studio projects target a known subset of common functionality instead of a specific implementation. (I just wish they'd start the version numbering from 4 to match .NET Framework instead of starting at
1.0
because that got me thinking about 2001 all over again.) - but the important part is that ASP.NET Core 1 and ASP.NET Core 2 target .NET Standard instead of .NET Core - which means that ASP.NET Core runs on top of the .NET Framework on Windows in addition to running on top of .NET Core as well.I note that all previous .NET cross-platform compatibility techniques are now obsolete (including targeting Compact Framework subsets, Portable Class Libraries, and even "Shared Projects" in Visual Studio), as they were meant for other editions of .NET which no-longer exist, such as .NET Compact Framework, XNA, Silverlight, and Windows Phone 7's subset.
In May 2019, Microsoft announced ".NET 5". In short, the .NET Framework is being replaced with .NET Core, and the next version of .NET Core after .NET Core 3.0 will be named .NET 5). This announcement does not concern ASP.NET Core at all, other than the fact that .NET 5 will fully support ASP.NET Core 3.0 applications running on it.
Throughout the Covid-themed summer of 2020 Microsoft finalized .NET 5 and ASP.NET Core. As of October 2020, ASP.NET Core's NuGet package versions have jumped from 3.1.x to 5.0.0 - so it looks as though the next major release of ASP.NET Core will be versioned
5.x.x
which suggests its release may be named "ASP.NET Core 5" though recent Microsoft blog articles suggest the name will be "ASP.NET Core for .NET 5" - though given that this whole thread was created out of the confusion over "ASP.NET MVC 5" vs "ASP.NET 5" I'm sure that naming it either "ASP.NET Core 5" or "ASP.NET Core for .NET 5" will absolutely not be confusing at all, no sir-ee-bob!In summary:
System.Web.dll
). Note that the entire ASP.NET MVC library is now obsolete.All of them (in chronological order):
System.Web.dll
.System.Web.dll
.System.Web.Mvc.dll
.System.Web.dll
.System.Web.Mvc.dll
.System.Web.Http.dll
.System.Web.dll
under OWIN.5.0.0
. Microsoft has not yet formally/officially referred to this new release of ASP.NET Core as "ASP.NET Core 5", but I see it as a foregone conclusion.Timeline and block diagram
(I got carried away making this...)