Is it safe to have a .NET6 application which references a .NET Core 3.1 NuGet library?
I tested this case using a simple console application. Everything looks good and there are no errors/warning. However, I haven't found any specific information so prefer to make sure.
This is important, as one of my providers offers only a .NET Core 3.1 NuGet package. Knowing the company it'll take them a year or so to prepare a .NET6 / .NETStandard version.
There is a good chance that your .NET Core 3.1 library will run without any compatibility problems as part of your .NET 6 application.
Quoting the .NET fundamentals article Changes that affect compatibility (emphasis mine):
Throughout its history, .NET has attempted to maintain a high level of
compatibility from version to version and across implementations of
.NET. …
Along with compatibility across .NET implementations, developers
expect a high level of compatibility across versions of a given
implementation of .NET. In particular, code written for an earlier
version of .NET Core should run seamlessly on .NET 5 or a later
version. In fact, many developers expect that the new APIs found in
newly released versions of .NET should also be compatible with the
pre-release versions in which those APIs were introduced.
However, compatibility is not guaranteed. The article goes on to say:
This article outlines changes that affect compatibility and the
way in which the .NET team evaluates each type of change.
Understanding how the .NET team approaches possible breaking
changes is particularly helpful for developers who open pull
requests that modify the behavior of existing .NET APIs.
Furthermore, in an answer to the question Clarification on backwards compatibility of .NET Core, a member of the .NET runtime team says:
We do not guarantee 100% compatibility between major versions. This is true for both ASP.NET Core and the runtime itself. We
intentionally make breaking changes where we believe that they are
necessary to move the platform forward and the cost of the .NET
ecosystem adjusting to them is low enough.
Breaking changes that could potentially affect the compatibility of your .NET Core 3.1 library are those that are documented for .NET 5 and .NET 6.
But, if you are not experiencing any problems with your .NET Core 3.1 library, it would appear that none of the documented compatibility problems apply.
Ultimately, of course, you'll have a higher degree of confidence in the library when your vendor provides one that has been updated for .NET 6.
Finally, with the introduction of .NET 5, there became a lesser need for .NET Standard:
.NET Standard is a formal specification of .NET APIs that are
available on multiple .NET implementations. The motivation behind .NET
Standard was to establish greater uniformity in the .NET ecosystem.
.NET 5 and later versions adopt a different approach to establishing uniformity that eliminates the need for .NET Standard in most
scenarios. However, if you want to share code between .NET Framework
and any other .NET implementation, such as .NET Core, your library
should target .NET Standard 2.0. No new versions of .NET Standard will
be released, but .NET 5, .NET 6, and all future versions will continue
to support .NET Standard 2.1 and earlier.
Related
We're trying to select a minimum .NET Framework version for a new business software product. We're trying to balance compatibility with modern NuGet libraries against compatibility with business infrastructure. The product will run on .NET Core and .NET Framework.
For .NET Core targeting 3.1 is an easy decision, but for .NET Framework the choice is much less clear. We want to minimize the chances of users having to upgrade their .NET Framework version, as this is often difficult in a corporate environment, but if we choose to implement compatibility with really old version, such as .NET Framework 4.0, then we can't use a lot of modern NuGet packages.
One thing that could help us make this decision is statistics on which .NET Frameworks businesses have installed. Does anyone know where we can find such statistics?
I done created an application in .net framework 4.6.1 which works perfectly in localhost. But in the server(Windows server 2012), we have .net framework 4.5.
Should we upgrade it to framework 4.7 or will it work in the current framework?
It depends on whether you use any new features introduced in .NET 4.5.1 or later or not.
To ensure compatibility, you should either
upgrade your target system to (at least) 4.6.1 or
reduce the "Target Framework" setting of your project to (at most) 4.5:
Option 1 would ensure that all features that you use in development are available on the target system.
Option 2 would ensure that you get a compile-time error if you use features which are unavailable in .NET 4.5.
The .NET Framework 4.5 and later versions are backward-compatible with apps that were built with earlier versions of the .NET Framework. In other words, apps and components built with previous versions will work without modification on the .NET Framework 4.5 and later versions. However, by default, apps run on the version of the common language runtime for which they were developed, so you may have to provide a configuration file to enable your app to run on the .NET Framework 4.5 or later versions.
In practice, this compatibility can be broken by seemingly inconsequential changes in the .NET Framework and changes in programming techniques. For example, performance improvements in the .NET Framework 4.5 can expose a race condition that did not occur on earlier versions. Similarly, using a hard-coded path to .NET Framework assemblies, performing an equality comparison with a particular version of the .NET Framework, and getting the value of a private field by using reflection are not backward-compatible practices.
In addition, each version of the .NET Framework includes bug fixes and security-related changes that can affect the compatibility of some apps and components.
So i would suggest you to upgrade it to framework 4.7.
For more details please check:
https://learn.microsoft.com/en-us/dotnet/framework/migration-guide/version-compatibility
.NET Standard prescribes an API that all .NET Platforms must implement. What are its versioning rules? Is it breaking.adding, in which 1.4 adds to and remains backward compatible with 1.3 whereas 2.x is not backward compatible with 1.x?
The documentation is not clear on this. Some Microsoft docs indicate pure backward compatibility:
Given a .NET Standard Library version, you can use libraries that target that same or lower version. (emphasis added)
Now that 2.0 is out, the above doesn't seem correct. That being said, the release blog post said:
From a library targeting .NET Standard you’ll be able to reference [libraries targeting] .NET Standard, if their version is lower or equal to the version you’re targeting. (emphasis added)
That same blog post contradicted itself by saying:
In order to allow .NET Framework 4.6.1 to support .NET Standard 2.0, we had to remove all the APIs from .NET Standard that were introduced in .NET Standard 1.5 and 1.6.
Now that 2.0 is out, what are the versioning rules? It appears to be breaking.adding. Where has MSFT documented this?
I've explained this in a bit more detail in our On.NET episode on .NET Standard.
Generally, this is how .NET Standard works:
.NET Standard will version linearly, with the intention of not making breaking changes between versions. In other words, you can think of the API surface of .NET Standard as concentric circles, where higher versions have more APIs.
A specific version of a .NET platform will implement a specific version of .NET Standard.
When choosing a .NET Standard version to target consider this trade-off:
The higher the version number, the more APIs you can use
The lower the version number, the more .NET platforms support it
So why is there this talk about breaking changes? The short answer is because we made a mistake when defining .NET Standard 1.x and didn't take platform reach into consideration. You should ignore .NET Standard 1.5 and 1.6 and avoid taking a dependency on them. If you do that, .NET Standard 2.0 is a strict superset of .NET Standard 1.4.
For more details, read the section .NET Standard 2.0 breaking change: adding .NET Framework 4.6.1 compatibility in my blog post on .NET Standard.
Update. After a lot of community feedback we decided not to perform this breaking change. More details around this decision is listed in the .NET Standard FAQ.
I've created a new ASP.NET 5 project and I faced with something that I didn't understand well about how the new ASP.NET works.
In my references there are DNX 4.5.1 and DNX Core 5.0. When I install a new package from Nu-Get, some packages install successfully in both and some tell me they aren't supported by DNX Core 5.0.
Can I use many versions of DNX for supporting my packages or I must bound the things with DNX Core 5.0 to enjoy the advantages of ASP.NET 5, like cross-platform and others?
ASP.NET 5 projects are multi-targeted, which means you can compile for multiple platforms simultaneously. In your case .NET 4.5.1 targets ASP.NET 5 on the full .NET runtime (4.5.1) and .NET Core (5.0). When you compile your project, ASP.NET 5 actually creates output for both of these targets so - assuming you get the code to compile for both platforms - the application can run on either of them. It's possible to run additional targets to your projects.
When you actually run your application though, you have to pick a specific version of the .NET runtime you want to run under. In Visual Studio there's a drop down in the project settings where you can select that runtime that actually executes. When you use command line publish you also specify which platform to publish to with a parameter (if omitted it uses the active DNX runtime I believe).
As to the differences - .NET Core is a trimmed down version of the full .NET runtime, that is cross-platform and can run on Windows and other platforms like Linux and OSX. Because it has to run on other platforms a lot of the platform specific Windows features are not supported in this runtime, and as the platform is still evolving some APIs are simply not implemented yet in .NET Core. This is the reason you are likely to see many compile errors when you target .NET Core with existing code/libraries. In order to run on .NET core existing .NET code typically needs at least some minor adjustments to account for the smaller API footprint and potentially serious redesign to work around missing functionality.
If you need to use existing code and depend on assemblies/NuGet packages that are based on previous versions of .NET you have to stick with the full .NET version. You can still take advantage of the new ASP.NET 5 features and eco-system, as well as getting the benefit of the full .NET runtime and full API surface you are used to from previous .NET versions. The downside is that the runtime is Windows only and has a bigger resource footprint.
.NET Core is a new runtime and you should treat it as such. Migrating to this platform is likely not a trivial task. The benefits of this platform is a much leaner footprint and that it can run across multiple OS platforms.
It's likely that it'll take some time for the full potential of .NET Core to come to fruition as Microsoft expands the feature set and cross-platform compatibility but we won't really know what this will look like since it is still in Beta (well RC but it's really a beta with major changes still coming in RC2).
I Was just reading this post: http://blogs.msdn.com/b/dotnet/archive/2014/12/04/introducing-net-core.aspx
It left me a bit confused since the first picture in the article seems to imply that .NET desktop apps and ASP.NET don't share the same framework implementation. I was always under the impression that it was. Any ideas?
They use the same .NET framework.
But they don't have to. And this is the way the .NET ecosystem is evolving right now - ways to avoid using the full (ever growing) .NET framework for everything.
As a bonus, the new .NET Framework Core is open-sourced. This is not entirely posssible with the whole .NET framework, since it includes a whole lot of licenses and proprietary technologies.
Given all that, it's now possible to deploy very light-weight web applications using ASP.NET, not even having to use IIS (thanks to OWIN). You only have to include the packages you need - instead of having a single monolithic runtime and BCL, there's hundreds of NuGet packages you choose to use (or not).
You will have to better define "the same framework implementation", as they (full .NET Framework and .NET Core) are built from the same code base with different configuration, and also host your web applications in a slightly different way.
The most important getaway of that article should be "ASP.NET 5 can run on both .NET Framework 4.6 and .NET Core 5". You get different benefits from each runtimes,
.NET 4.6 gives you best compatibility against previous .NET runtimes.
.NET Core 5 gives you flexibility on running multiple customized DNX side by side, and portability to Linux and OS X.
Unfortunately Microsoft decides to limit desktop apps to .NET 4.6, but Mono guys have demonstrated possibility to run some (such as WinForms apps) on .NET Core,
https://github.com/akoeplinger/mono-winforms-netcore