Add System.Net.ServerSentEvents to runtime shared framework

[captainsafia]

This enables us to support SSE in minimal APIs for dotnet/aspnetcore#56172.

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

[stephentoub]

@ericstj, how should we think about whether System.Net.ServerSentEvents should be in netcoreapp vs aspnetcoreapp?

[ericstj]

If the library is generally useful to all .NET customers and it should be available to libraries that target .NET then it should be in the base netcoreapp shared framework.

If it's only needed for folks building aspnet core applications or libraries that are only used in aspnetcore then it can go in the ASP.NET shared framework.

My understanding of this library is that it has nothing to do with ASP.NET and can be used by anyone making Http requests - that leads me to believe it should be in the base shared framework, so that would be my suggestion.

[captainsafia]

I think I've done the needful to move the library to the runtime shared framework. Let me know if i missed something.

[ViktorHofer]

Now that you switched the library to be part of the Microsoft.NETCore.App shared framework, you need to define its inbox dependencies in the ref and source project.

[captainsafia]

Pushed a change with the applicable dependencies here.

[ericstj]

@captainsafia @eiriktsarpalis - should we add a note to dotnet/core#9824 about SSE being part of the framework and no longer requiring a package?

[ViktorHofer]

The library is missing from the PackageOverrides.txt file which is the input to NuGet package pruning and conflict resolution. It should get added.

I filed an issue recently to add automation for generating that file here in runtime.

[stephentoub]

@captainsafia @eiriktsarpalis - should we add a note to dotnet/core#9824 about SSE being part of the framework and no longer requiring a package?

For the most part this doesn't really affect people, other than their app might be a bit smaller.