Discussion: ASP.NET Core 3.0 will only run on .NET Core

[natemcmaster]

This is a discussion item for aspnet/Announcements#324.

[poke]

I think this makes a lot of sense in the overall picture now. Both .NET Core and ASP.NET Core have been around for long enough by now that people already had or still have the chance to switch to it, without causing huge issues (compared to when the support was first dropped in the past with 2.0).

However, I am sad about the implications though for certain components of ASP.NET Core that can currently exist as separate dependencies. Because this will probably mean that the individual components will drop netstandard support, requiring netcoreapp3.0 instead; and especially with #3756 those components would be unusable outside of an ASP.NET Core context.

For example, projects like RazorLight will then effectively be forced to drop .NET Framework and more importantly .NET Standard support in general.

[mythz]

This is going to leave a lot of people who've sold moving to the new ASP.NET Core programming model in their organization to stay on a supported and actively developed platform out in the cold on an unsupported platform in less than 3 years (.NET Core 2.1 LTS).

I'm not sure what analytics you've used to justify this move but for Running ServiceStack ASP.NET Core Apps on the .NET Framework we're seeing that the most popular web-corefx template for running ASP.NET Core project on the .NET Framework is over 1/3 (33.8%) share then the same empty web template which is our most popular project template for running on .NET Core.

IMO 3 years is not enough time to abandon Customers that have started to or have made move to the new ASP.NET programming model (to escape the stagnated ASP.NET Framework platform) only to find out now that the platform that they've sold to their organization to move to has been abandoned.

For whatever reason there are Customers who cannot move to .NET Core due to relying on .NET Framework only dependencies, if MS doesn't want to maintain support for .NET Framework in ASP.NET Core 3.0 in future IMO you should extend the support for ASP.NET Core 2.1 on .NET Framework to an extended period like 7 years. Migrations of existing production systems can take years, since starting .NET Core it's clear the ASP.NET Framework has been left to stagnate with the official stance being that ASP.NET Core is the future programming model for .NET, now the same Customers will soon start finding out that the new programming model that they've move/moving to will be unsupported in a few years. The best way to accommodate these existing .NET Customers is to support .NET 2.1 for an additional LTS period, for security patches at least (ideally for resolving bugs as well).

[kevinchalet]

"killing .NET Framework", episode 2: same story, same characters 🤣

Sadly, this just highlights one thing: you completely failed to make .NET Standard the front car of the .NET ecosystem. It doesn't move as fast as it should and is nothing more than a lowest common denominator that is always updated at the very last moment, when all platforms include (or are about to include) the new APIs.

Perhaps that's just me, but I've never understood why it didn't move as fast as netcoreapp (which is the first to get the new APIs, by definition).

You're a NuGet package author and want them to use the latest stuff? Target the most recent netstandard version: sure, initially, only netcoreapp-based applications will be able to use them, but eventually other platforms - like Xamarin, Mono or .NET Framework - will catch up and folks will be able to use your packages without requiring you to change anything. That's how things should work.

Of course, it may take a while for non-.NET Core platforms like .NET Framework to catch up as the releases are rarer and the stability bar much higher, but even if it takes 6, 12 or even 18 months, I don't think it's a problem, because that's what people want when using .NET Framework: a stable framework, not a fast moving target.

IMHO, it would be a much better approach to make ASP.NET Core 3.0 target a new netstandard TFM exposing all the .NET Core APIs you need. Once you're sure the new APIs are stable enough, backport them to the .NET Framework so that it is compatible with the latest standard.

I'm sure people would prefer having to wait a few months before being able to move their .NET Framework app to the latest ASP.NET Core version rather than being blocked forever on an old version with a super short 3-year support.

Do what you promised: make .NET Framework a stable framework that evolves slower instead of a dead end for the ones who trusted you when migrating to ASP.NET Core.

[John0King]

I don't like this. At the beginning of .net core , Microsoft wasn't chooce mono or .net framework as a cross platform, and u said there are multiple .net runtime there so u design the .netstandard , now there'r still many nuget package that do not support .net core (mean reason) .Many developer will leave behide in the old asp.net core programming model if asp.net core only run on .net core. then .net standard will exist in name only (at least for asp.net core, people start build netcoreapp only packages ) .
Maybe oneday, .net core can replace .net framework on window, but what about mono , and other platform rely on mono (xamarin,unity3d) .
and another reason for sometime I prefer .net framework is that .net core share framework is really huge, how big is your C:/program file/dotnet folder if you upgrade your app from .net core 2.0 to latest .net core 2.1 ? There GBs file in my folder , and it grows when I update .net core runtime. but .net framework will just replace the old version.

[mythz]

Do what you promised: make .NET Framework a stable framework that evolves slower instead of a dead end for the ones who trusted you when migrating to ASP.NET Core.

FWIW this would be the optimal strategy, my suggestion of extending the LTS is the minimum bar to give more time to existing Customers that have been aggressively marketed to migrate to ASP.NET Core who have now been left abandoned on a future unsupported platform with this announcement.

[iJzFan]

So .net standard is a joke? Hope mono team will fork aspnetcore repos and rename to aspnetmono,otherwise I may leave .net stack.😔

[Sebazzz]

I guess that this means that at my work we will never use ASP.NET Core. We will stay at ASP.NET forever never mind porting an app to Core because that would now involve even more changes.

[gulbanana]

Sure, if your goal is to have no changes then you can keep doing the same thing forever. Where I work, we began using ASP.NET Core a couple of years ago, initially running on .NET Framework. Over time, as the .NET Core platform matured and gained features, we switched our projects to netcoreapp. One or two older projects are still using ASP.NET, and we have no plans to rewrite those - it’s working code. But for the newer stuff we’re looking forward to features like Span.

Change can be put off but it isn’t something you can or should avoid forever - technology is change and a developer’s job will always require learning new things. If you’re using ASP.NET Core on .NET Framework today, it’s unlikely to take three years of work to move it to .NET Core.

[benaadams]

Come to .NET Core, the water's warm...

For whatever reason there are Customers who cannot move to .NET Core due to relying on .NET Framework only dependencies...

More seriously, you can use .NET 4.x libraries on .NET Core 2.0 since .NET Standard 2.0; though there is the possibility they may use some features that .NET Core doesn't have; although there is the Windows Compatibility Pack for .NET Core that plugs a lot of these holes and many more features are being supported in .NET Core 3.0 including COM interop and other app models like WinForms and WPF etc.

Any blockers preventing an ASP.NET Core application moving to .NET Core from .NET Framework should probably be raised in dotnet/corefx.

For Xamarin; I could be wrong, but I assume its unlikely that you'd use it to run a webserver on iOS or Android.

For Mono client apps the webserver could run out of process and run on .NET Core while the UI runs in Mono. Kestrel has never been able to run on a Big Endian platform which cuts out some of Mono's other platforms though BSD flavours are currently a .NET Core gap.

For Unity; games do all sorts of strange stuff, so maybe that's a scenario not covered; if the game was using the webserver in the client; rather than on a server or out of proc; when .NET Core could run that part.

Outside the ASP.NET Core app model; e.g. for libraries .NET Standard is more important as ASP.NET Core has all sorts of useful features, Razor being a particular example.

Not all the libraries are moving to .NET Core only (e.g. Microsoft.Extensions.* are staying as .NET Standard) and it would likely be helpful to provide specific scenarios that would be impacted as @daveaglick has done in #3757 (comment) so they can be taken into consideration; as to which specific libraries and/or features can be kept available on .NET Standard rather than just a nebulous "everything".

ASP.NET Core is driving a lot of changes and new apis in .NET Core and I can understand the desire to then use those features (since that's was one of their use-cases); otherwise its a bit self-defeating.

On the other hand it would be nice if they were also in a .NET Standard version so other runtimes could then support ASP.NET Core 3.0 when they get around to implementing it. Realistically that wouldn't be soon (as .NET Standard 2.1 is not finalised yet and it would need to be a version beyond that).

Perhaps the ASP.NET Core app model will return to .NET Standard at a later date when things have caught up? Though it may always be moving too fast for the .NET Standard process as it currently works?

[John0King]

@gulbanana what if your asp.net core on .net framework using com ? or there's a nuget package that only support .net framework ?

[dasMulli]

I believe it was never a question of if the move should be done or not, but only when.
Last time this caused a discussion shitstorm, the ecosystem wasn't ready to allow porting existing apps.
Now there are the windows compatibility packages and WinForms and WPF are coming to .NET Core.

I think that the 2.1 packages being around for .NET Framework provide a good migration path: Migrate to 2.1 on netfx and then on to .NET Core.

This is similar to AngularJS vs Angular: Migrate existing code to components (hard) in the latest 1.*, then move to the latests Angular version. It's super hard but doable.

With exciting new features being added to both CoreCLR and mono (e.g. default interface methods or just fast Spans) which would never make it to .NET Framework, it seems reasonable to leave .NET Framework behind at some point.
That doesn't necessarily mean "not supporting" .NET Framework, but rather just leaving it as is.

There are still some sites around that use classic ASP (not ASP.NET, but the really old stuff). It still works and ships in Windows, you just wouldn't create new apps with it.
I believe that in <10 years, this may be the situation with .NET Framework.

I do agree with the requested extended support for 2.1, but I'd like the team to monitor 2.1 package downloads to make a decision in 2-3 years if they'd need to support (= fix important security issues) it for a little bit longer.

[gulbanana]

@John0King COM will be supported in .NET Core 3.0.

[dasMulli]

Also: We do have legacy applications using things like .NET Remoting.
But those are legacy already.

The world basically runs on legacy code and will continue to do so. It's a business decision of whether or not to port something to a "supported" or even "new" thing, but until then, as @dylanbeattie puts it:

[gulbanana]

Yeah, it’s worth mentioning that whether something is “supported” is not all that relevant - old apps don’t actually have to be ported to a new framework just because it’s available. Web servers are a bit of a special case though due to security threats. A long period of security patch support for the LTS would help people out.

[Sebazzz]

@gulbanana It is only adding a higher bar to porting applications from System.Web to ASP.NET Core, since you need to change the web framework, the underlying application framework and then upgrade or swap out any incompatible dependencies (which may involve buying new licenses).

If you would do then a cost/benefit analysis, I'm not sure it would be in the benefit of ASP.NET Core.

This is especially applicable when you develop software on a project basis, and of course each project is tight enough on budget as it is, so while regular maintenance is of course possible, it is hard to justify swapping out the entire framework without apparent tangible benefit.

[dasMulli]

If you would do then a cost/benefit analysis, I'm not sure it would be in the benefit of ASP.NET Core.

So.. well.. leave it? If you don't need to migrate to ASP.NET Core then don't do it..
Not trying to sound sarcastic or anything, but if there is no business need to keep an application on the "latest things" then don't port it. The benefit is that .NET Framework / ASP.NET classic is still supported and your application will run as is.

[gulbanana]

Porting is frequently needless, I agree - ASP.NET to ASP.NET Core is a big change, and part of that change is that Core moves more rapidly (3.0 will have api breaking changes too, as did 2.0). This discussion issue is about the netfx to corefx change, though, and for most ASP.NET Core apps that is not a big change anymore,

[yaakov-h]

This seems to remove the "ASP.NET Core on .NET Framework" intermediate point that would make migrations a lot more gradual and easier. After this, migrating an ASP.NET MVC/WebAPI/etc. applicaton to ASP.NET Core will be a very big-bang change, changing both the web framework and underlying runtimes all at once.

For large enterprise apps I expect this to be quite painful. My team's been eyeing this closely for a year or two, but:

• EntityFrameworkCore does not do everything we require, and only now with .NET Core 3.0 is EntityFramework itself coming to .NET Core. How much of that and what platforms it will run on, I don't believe has been clearly communicated, and I'll probably need to actually test a preview build to see.

• The OData story seems to still be up in the air in terms of large-scale applications. There's a substantial amount of (re-)work required to move from OData 3 / System.Data.Services to OData 4 / WebAPI and onwards. This is something that hasn't been resolved for several years now, and I'm honestly not sure it ever will be.

Additionally, now we'd have to trim off all of the other unsupported technologies (AppDomains, Remoting, etc.) first, instead of being able to do that work in parallel or at a later stage.

[davidfowl]

Additionally, now we'd have to trim off all of the other unsupported technologies (AppDomains, Remoting, etc.) first, instead of being able to do that work in parallel or at a later stage.

Why can't you migrate to 2.1 first?

[yaakov-h]

@davidfowl We probably could use that as an intermediary, unless we come across some new feature in 3.0/3.1/etc. that we need in order to migrate. I haven't done a full analysis yet, we've mostly been blocked on EF and OData so far.

[davidfowl]

New feature in ASP.NET Core 2.1 that’s needed to migrate? I meant ASP.NET Core 2.1 on .NET Framework.

[gulbanana]

When this issue came up a couple of years ago, I remember complaining that it was too hard to port everything. Here’s a quote from an old github comment I made back then:

imagine webapps which use Active Directory, or Office COM automation, or which do thumbnailing using some System.Drawing based library, or share code with a WPF app

The cool thing is that as of .NET Core 3.0, all those scenarios are supported. A huge amount of work has been done to make it easier.

[yaakov-h]

@davidfowl so did I.

Hypothetically there might be some feature we're using in ASP.NET/MVC/WebAPI that isn't implemented in 2.1 but does arrive in a later version. In that case, 2.1 wouldn't be a workable stepping stone.

I'd have to do a more thorough analysis though, to see if there's actually anything critical we need that isn't in 2.1.

[poke]

@DamianEdwards Yeah, I understand that, thanks for your reply. I was just asking because the last comment on this was that it hasn’t been decided yet, so I just wanted to know if this extended support would carry forward iff 2.2 became LTS.

And I think it’s important enough to highlight this so that people will not upgrade their framework apps to 2.2 if they have to rely on this extended support. Otherwise they will have to downgrade again.

New features don't come to LTS as they are about stability.

That does not really match the previous LTS decisions though.

[DamianEdwards]

@poke

That does not really match the previous LTS decisions though.

This confused me. In what way? Are you referring to the fact that 1.1 was added to the 1.x LTS train? If so, that was an anomaly of our first release train that won't be repeated. Moving forward, our intent is to get more consistent with which releases become LTS vs. Current (i.e where do I get stability vs. features).

[poke]

@DamianEdwards I was mostly referring to the fact that every release so far has been a large feature release, and each LTS decision was usually made in retrospect (at least publicly).

[DamianEdwards]

@poke OK. Well, so far we've had 4 releases (1.0, 1.1, 2.0, 2.1) with the 5th coming shortly (2.2). Of those, only 1.0 and 2.0 were initially intended to be LTS, but due to a number of factors (mostly related to us being really new at doing engineering this way 😉) we ended up with 1.0, 1.1 and 2.1 being the LTS trains. 2.0 and 2.2 are (were, will) Current releases. At this stage, 3.0 will almost certainly be Current also (causing 2.2 to enter the Current "grace" period of 3 months) before 3.1 becomes the 3.x train LTS. Our hope is after that, the pattern and cadence will be more consistent (we'd love that) but so far our crystal ball has failed us.

[poke]

@DamianEdwards Thanks for the insights! 😄 (Btw. I wasn’t trying to argue about this, I was just curious ;) )

[bencyoung]

A bigger issue for us is new REST APIs hosted in-process by legacy applications that aren't likely to move off .NET Framework any time soon. At least we know not to progress beyond .NET Standard 2 supporting libraries and ASP.NET Core 2.1 now! It's good the LTS period will be extended

[lokitoth]

Hey all, a quick question: What about those of us consuming native packages in the form of C++/CLI? Is that going to be supported in .Net Core anytime soon, or are we orphaned unless we do a massive rework to use P/Invoke?

[Eilon]

@lokitoth - that would be a good question for the https://github.com/dotnet/core folks because it's more general than just ASP.NET Core.

[Suchiman]

@lokitoth yes, that will be supported, see https://github.com/dotnet/coreclr/issues/18013

[lokitoth]

o.O How did I miss that?

Okay, then I have no problems with this.

[SIkebe]

@danroth27 Could you tell us the impact of this issue for Client-Side-Blazor?

[danroth27]

@Slkebe I don't expect any impact. Client-side Blazor apps are independent of whatever runtime or platform you decide to run on the server.

[SIkebe]

@danroth27 In my understanding, Client-side Blazor can run on mono because dependent Microsoft.AspNetCore.* packages target netstandard.
Am I missing something? Blazor has to keep targeting Microsoft.AspNetCore.* 2.1.X?

[danroth27]

@Slkebe The client-side Blazor libraries only depend on components that will continue to target .NET Standard (like Microsoft.Extensions.* and friends). The server-side parts of Blazor that depend on ASP.NET Core will target .NET Core as described in this issue.

[John0King]

https://blogs.msdn.microsoft.com/dotnet/2018/11/05/announcing-net-standard-2-1/

What's the decision now? Target on .net standard 2.1 ?

[khellang]

@John0King There's no new decision.

[Graystripe17]

This is bananas! B A N A N A S

[gulbanana]

i’m sympathetic to your point of view.

[chyyran]

Apologies if this has already been brought up, but what about use cases where I just want to use Kestrel+some middleware as part of a non ASP.NET application? Will I have to pull in the entire 3.0 tree (which is not ideal, as my use case involves defining a custom SDK for consumers), or is this use case not supported on 3.x?

[FlorianGrimm]

Currently I'm developing a ASP.NET Core application running on .NET Framework, because of the the included libraries. I'm using ASP.NET Core because of it's multi-auth - capabilities. I'm feeling fooled and dead locked.

[Tratcher]

I'm using ASP.NET Core because of it's multi-auth - capabilities.

@FlorianGrimm What specifically? Microsoft.Owin provided similar auth functionality for ASP.NET 4.

[FlorianGrimm]

It's a hybrid app one source code (.exe) running on on-premises and azure, currently using windows auth, aad, basic auth and anonymous.

[danroth27]

@FlorianGrimm Which library dependencies prevent you from using .NET Core?

[FlorianGrimm]

Microsoft.Office.Project.Schema, Microsoft.SqlServer.TransactSql.ScriptDom and Microsoft.SharePointOnline.CSOM.

[FlorianGrimm]

I hope the SharePoint Team will finish
https://sharepoint.uservoice.com/forums/329220-sharepoint-dev-platform/suggestions/16585795-support-net-core-with-csom
and I find other options than ilspy.

Any way I like ASP.NET Core and I hope the other Microsoft Teams will provide more .NET Core assemblies.

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