How to get SignalR Hub Context in a ASP.NET Core?

I'm trying to get the context for a hub using the following:

var hubContext = GlobalHost.ConnectionManager.GetHubContext<SomeHub>();

The problem is that GlobalHost is not defined. I see it is part of the SignalR.Core dll. At the moment, I have the following in my project .json file, under dependencies:

"Microsoft.AspNet.SignalR.Server": "3.0.0-*"

If I add the latest available version of Core:

"Microsoft.AspNet.SignalR.Server": "3.0.0-*",
"Microsoft.AspNet.SignalR.Core" :  "2.1.2"

I get a whole bunch of errors because server and core are conflicting. If I change them to both use version "3.0.0-*", all the conflicts go away, but GlobalHost cannot be found. If I remove Server, and just user Core version 2.1.2 then GlobalHost works, but all the other things needing Server, obviously do not.

Any ideas?

IConnectionManager does not exist any more in SignalR for ASP.Net Core.
I've been using HubContext for getting access to a hub.

public class HomeController : Controller
{
    private readonly IHubContext<LiveHub> _hubContext;

    public HomeController(IHubContext<LiveHub> hubContext)
    {
        _hubContext = hubContext;
    }

    public void SendToAll(string message)
    {
        _hubContext.Clients.All.InvokeAsync("Send", message);
    }
}

I'm using .net core 2.0.0 and SignalR 1.0.0-alpha1-final

Microsoft.AspNet.SignalR.Infrastructure.IConnectionManager is a DI injected service through which you can get the hub context...For example:

using Microsoft.AspNet.SignalR;
using Microsoft.AspNet.SignalR.Infrastructure;
using Microsoft.AspNet.Mvc;

public class TestController : Controller
{
     private IHubContext testHub;

     public TestController(IConnectionManager connectionManager)
     {
         testHub = connectionManager.GetHubContext<TestHub>();
     }
 .....

To use the hub in a backgroud service, in addition to controllers, you must use the IHostedService interface and get the hub by DI.

public class MyBackgroundService : IHostedService, IDisposable
{
    public static IHubContext<NotifierHub> HubContext;

    public MyBackgroundService(IHubContext<NotifierHub> hubContext)
    {
        HubContext = hubContext;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        //TODO: your start logic, some timers, singletons, etc
        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        //TODO: your stop logic
        return Task.CompletedTask;
    }

    public void Dispose()
    {
    }
}

Then you can call your hub from anywhere in your code from HubContext static field:

MyBackgroundService.HubContext.Clients.All.SendAsync("UpdateData", myData).Wait();

Learn more about IHostedService: https://docs.microsoft.com/en-us/aspnet/core/fundamentals/host/hosted-services?view=aspnetcore-2.1

You can create and start a timer in MyBackgroundService and call the hub in ElapsedEvent.

I added some code to my Startup.cs to grab reference to the ConnectionManager which you can then use to do a GetHubContext at anytime from anywhere in your code. Similar to Nimo's answer but a little different, maybe simpler.

services.AddSignalR(options =>
{
    options.Hubs.EnableDetailedErrors = true;
});

var provider = services.BuildServiceProvider();

//Hold on to the reference to the connectionManager
var connManager = provider.GetService(typeof(IConnectionManager)) as IConnectionManager;

//Use it somewhere else
var hub = connManager.GetHubContext<SignalHub>();

I needed to be able to access the Hub Context from outside the app request thread - because I was subscribing to NServicebus messages, and needed to be able to trigger a client function when I received a message.

Here's how I got it sorted:

public static IServiceProvider __serviceProvider;

then during startup configuration

app.UseServices(services =>
        {
            __serviceProvider = new ServiceCollection()
            .BuildServiceProvider(CallContextServiceLocator.Locator.ServiceProvider);
        });

Then anywhere else in the vNext asp.net application (any other thread)

 var manager = Startup.__serviceProvider.GetRequiredService<IConnectionManager>();
            var hub = manager.GetHubContext<ChatHub>();

Hope this helps!