Use SignalR in MediatR Notifications

1    public class PortalHub : Hub<IPortalHubClient>
2    {
3         public PortalHub( ) { }
4    }

1    public interface IPortalHubClient
2    {
3        Task NewPrivateMessage(string fromUserName, string subject);
4    }

 1    public class UserPrivateMessageNewNotification : INotification
 2    {
 3        public int ToUserId { get; }
 4        public int FromUserId { get; }
 5        public string FromUserName { get; }
 6        public int MessageId { get; }
 7        public string MessageSubject { get; }
 8
 9        public UserPrivateMessageNewNotification(
10            int toUserId, 
11            int fromUserId, string fromUserName, 
12            int messageId, string messageSubject)
13        {
14            ToUserId = toUserId;
15            FromUserId = fromUserId;
16            FromUserName = fromUserName;
17            MessageId = messageId
18            MessageSubject = messageSubject;
19        }
20    }

1// this awaits all handlers
2await _mediatr.Publish(new MyNotification()); 
3
4// this does not wait, but executes the notification "in background"
5_mediatr.Publish(new MyNotification()); 
6
7// this does not wait, but executes the notification "in background"
8Task.Run(async () => await _mediatr.Publish(new MyNotification())); 

 1    public class NotifyUserOnNewPrivateMessageNotificationHandler 
 2        : INotificationHandler<UserPrivateMessageAddedNotification>
 3    {
 4        // IHubContext is used to dependency injection purposes
 5        // IPortalHubClient is used, so we dont use magic strings
 6        private readonly IHubContext<PortalHub, IPortalHubClient> _portalHubContext;
 7
 8        public NotifyUserOnNewPrivateMessageNotificationHandler(
 9            IHubContext<PortalHub, IPortalHubClient> portalHubContext)
10        {
11            _portalHubContext = portalHubContext;
12        }
13
14        public async Task Handle(
15            UserPrivateMessageNewNotification notification, 
16            CancellationToken cancellationToken)
17        {
18            // read relevant data from notification
19            string recipientUserId = notification.ToUserId;
20            string fromUsername = notification.FromUserName;
21            string subject = notification.MessageSubject;
22
23            // We use the context to avoid magic strings
24            // Our Id is also our authentication 
25            //   identifier, which is used by SignalR by default too
26            await _portalHubContext
27                        .Clients
28                        .User(recipientUserId)
29                        .NewPrivateMessage(fromUsername, subject);
30        }
31    }