Does Microsoft.AspNetCore.SignalR.Client support AOT?

[JusterZhu]

Expected behavior
Can Microsoft.AspNetCore.SignalR.Client be used for AOT publishing in a console application or WPF

Actual behavior
When I publish the console application with AOT, it cannot receive server push messages. However, if I cancel the AOT publishing, it can send and receive messages normally. This issue occurs in .NET 9 and the latest version of Microsoft.AspNetCore.SignalR.Client 9.0.0.

Steps to reproduce
The code to reproduce the issue is very simple. It's just a standard example of a SignalR server and client. Once the client is compiled with AOT, it can no longer receive messages.

[martincostello]

Looks like not all parts of SignalR support native AoT yet: #41704

[dotnet-policy-service]

Thank you for filing this issue. In order for us to investigate this issue, please provide a minimal repro project that illustrates the problem without unnecessary code. Please share with us in a public GitHub repo because we cannot open ZIP attachments, and don't include any confidential content.

[eerhardt]

@JusterZhu - native AOT is supported on both the client and server of SignalR. However, you need to use the JSON protocol. And you need to hook up the System.Text.Json source generator on both the client and server. See https://learn.microsoft.com/aspnet/core/release-notes/aspnetcore-9.0?view=aspnetcore-9.0#signalr-supports-trimming-and-native-aot

For the Client, this means configuring the JsonHubProtocolOptions object and adding a JsonSerializerContext to the PayloadSerializerOptions. For example:

[JsonSerializable(typeof(string))]
[JsonSerializable(typeof(int))]
// add all the types you need to serialize
internal partial class AppJsonSerializerContext : JsonSerializerContext
{
}

...

var hubConnectionBuilder = new HubConnectionBuilder()
    .WithUrl(server.Url + "/hub");

hubConnectionBuilder.Services.Configure<JsonHubProtocolOptions>(o =>
{
    o.PayloadSerializerOptions.TypeInfoResolverChain.Insert(0, AppJsonSerializerContext.Default);
});

var connection = hubConnectionBuilder.Build();

Closing as answsered. If this doesn't work for you, please reopen with a repro application that exhibits the problem.

[JusterZhu]

It can now be used normally under AOT compilation according to your description. Thank you very much.