services.AddSignalR(o => o.EnableDetailedErrors =
true).AddAzureSignalR(connstring);

app.UseAzureSignalR(route =>
{
    route.MapHub<FooBarHub>("/foobarhub");
});

connection = new HubConnectionBuilder().WithUrl($"
{serviceHost}/AgentHub").Build();

await connection.StartAsync();

string myIdString = await connection.InvokeAsync<string>

public string RegisterSignalRId(string foobarId)
{
    myService.RegisterSignalRId(this.Context.ConnectionId, foobarId);
    return this.Context.ConnectionId;
}