I'm new using SignalR and I got stuck with a issue in OnDisconect event.
My project is kind of a cinema seats picker, that a user can select a seat and make a order.
When the user select the seat make it unavailable, in my front-end seat button send a post to my API that register de data of the seat and the ConnectionId of the user, and I use that connection Id when the user disconect (OnDisconectAsync in my API) without pay to make my seat available again.
The problem that I found was when a user has a Slow 3G connection, and spam checking and unchecking de reservation button, the SignalR connection get slow enought to throw this error:
"Error: Failed to start the transport 'WebSockets': Error: WebSocket failed to connect. The connection could not be found on the server, either the endpoint may not be a SignalR endpoint, the connection ID is not present on the server, or there is a proxy blocking WebSockets. If you have multiple servers check that sticky sessions are enabled."
And then "disconect" the user without calling OnDisconectAsyn() on my API and generating a new ConnectionId to my user.
So now if the user close de window the seats never comes back because the older ConnectionId got lost.
OnDisconect Method:
public override async Task OnDisconnectedAsync(Exception exception)
{
IOrderApplication order = scope.ServiceProvider.GetRequiredService<IOrderApplication>();
List<ViewOrderDto> orderList = await order.DeleteByConnectionId(Context.ConnectionId);
foreach (ViewOrderDto order in orderList)
{
await SendMessage(order);
}
await base.OnDisconnectedAsync(exception);
}
Controller Post:
[HttpPost]
public async Task<IActionResult> PostAsync([FromBody] PostOrderDto postOrderDto)
{
if (!ModelState.IsValid)
return CustomResponseFail(ModelState);
if (string.IsNullOrEmpty(postOrderDto.ConnectionId))
{
NotifyError("ConnectionId can not be null.");
return CustomResponseFail(ModelState);
}
ViewOrderDto order = await rderApplication.PostAsync(postOrderDto);
if (order is null)
{
NotifyError("Error when making a order.");
return CustomResponseFail(ModelState);
}
await messageHub.SendMessage(order);
// await pedidoBackgroundService.UpdateOrders();
return CustomResponseSuccess(order, "Succeded order!");
}
First Client Before the Error:
Second Client:
First Client after the error (after spam and get connection lost):
I don't know if there is a better way to make this, or a way to solve this problem but i'm really thankfull for all the help!
Related
I am having absolutely no luck getting push notifications to work in iOS in a Xamarin Forms project.
In AppDelegate.cs, I am calling the following in the FinishedLaunching override:
MSNotificationHub.Start("Endpoint=sb://[redacted].servicebus.windows.net/;SharedAccessKeyName=DefaultListenSharedAccessSignature;SharedAccessKey=[redacted]",
"[redacted]");
After the user logs in further in the app lifecycle, I also register the user with their user tag as follows:
public async Task UpdateTags(string token)
{
await Task.Run(() =>
{
try
{
// No point registering tags until the user has signed in and we have a device token
if (CurrentAccount == null)
{
Console.WriteLine($"UpdateTags cancelled: Account is null");
return;
}
var tag = $"user:{CurrentAccount.UserName}";
Console.WriteLine($"Registering tag: {tag}");
MSNotificationHub.AddTag(tag);
}
catch (Exception e)
{
Console.WriteLine($"Error registering tag: {e.ToString()}");
}
});
}
I have properly configured the Apple (APNS) settings in the notification hub, using the Token authentication mode (verified the four fields several times). The certificate (signing identity) is "iOS Distribution", the identifier bundle matches exactly what I have in the configuration (not using wildcard), the key has Apple Push Notifications service (APNs) enabled, and the provisioning profile has Platform: iOS and Type: App Store.
I pushed the application to TestFlight, as I don't have access to a physical Mac (we use a Cloud mac for development). When I view the device logs from my personal iPhone with the app installed, I see the following when I run it:
<Notice>: Registered for push notifications with token: [redacted]
<Notice>: Registering tag: user:[redacted]
There are no instances of "Error registering tag" or "UpdateTags cancelled" in the logs at all, which tells me that the method calls are succeeding without an exception. However, when I attempt to send a test notification to either a blank/empty tag, or the specific tag for my test user, no notifications are received and the messaging simply shows "Message was successfully sent, but there were no matching targets."
Also, when I pull all of the registrations with var registrations = await hub.GetAllRegistrationsAsync(0);, I only see the FCM (Firebase/Android) registrations from my successful testing on the Android side of things.
I am at a complete loss and have hit a wall, as there are no exceptions being thrown, and seemingly no way to troubleshoot what is going on behind the scenes.
This is also my 2nd attempt - I was using a more complex SBNotificationHub implementation and had the same results - no exceptions and everything looked fine at face value.
Thanks to a comment pointing to another question, I have determined that all I needed to do was to ensure that my tag registration ran on the main UI thread. My updated code below is working:
public async Task UpdateTags(string token)
{
await Task.Run(() =>
{
Device.BeginInvokeOnMainThread(() =>
{
try
{
// No point registering tags until the user has signed in and we have a device token
if (CurrentAccount == null)
{
Console.WriteLine($"UpdateTags cancelled: Account: {Trico.OrbitalApp.App.CurrentAccount};");
return;
}
var tag = $"user:{CurrentAccount.UserName}";
Console.WriteLine($"Registering tag: {tag}");
MSNotificationHub.AddTag(tag);
}
catch (Exception e)
{
Console.WriteLine($"Error registering device: {e.ToString()}");
}
});
});
}
You can try implementing the MSInstallationLifecycleDelegate interface which will allow you to check and see if the installation is being saved on the back end with either success or failure.
// Set a listener for lifecycle management
MSNotificationHub.SetLifecycleDelegate(new InstallationLifecycleDelegate());
// Implementation of the lifecycle listener.
public class InstallationLifecycleDelegate : MSInstallationLifecycleDelegate
{
public InstallationLifecycleDelegate()
{
}
public override void DidFailToSaveInstallation(MSNotificationHub notificationHub, MSInstallation installation, NSError error)
{
Console.WriteLine($"Save installation failed with exception: {error.LocalizedDescription}");
}
public override void DidSaveInstallation(MSNotificationHub notificationHub, MSInstallation installation)
{
Console.WriteLine($"Installation successfully saved with Installation ID: {installation.InstallationId}");
}
}
I want to display an error screen if net is not there. I am not using connectivity package because I don't want continuous check. I just want to handle exception while calling backend api and display the screen. I am unable to catch the exception.
I found this issue and this question about socket exceptions but none seem to help me.
This is how I call my backend api -
callBackendApi() async {
try {
http.Response response = await Future.value(/*api call here*/)
.timeout(Duration(seconds: 90), onTimeout: () {
print('TIME OUT HAPPENED');
});
} catch (exception) {
Fluttertoast.showToast(msg: 'Check internet connection.');
print('Error occurred' + exception.toString());
}
}
I use dio like this:
try {
var formData = FormData.from(Map<String, dynamic>.from(data));
var response = await dio.post(
uri,
data: formData,
);
jsonResponse = json.decode(response.data);
} on DioError catch (e) {
if (DioErrorType.RECEIVE_TIMEOUT == e.type ||
DioErrorType.CONNECT_TIMEOUT == e.type) {
throw CommunicationTimeoutException(
"Server is not reachable. Please verify your internet connection and try again");
} else if (DioErrorType.RESPONSE == e.type) {
// 4xx 5xx response
// throw exception...
} else if (DioErrorType.DEFAULT == e.type) {
if (e.message.contains('SocketException')) {
throw CommunicationTimeoutException('blabla');
}
} else {
throw CommunicationException("Problem connecting to the server. Please try again.");
}
}
My solution is to import 'dart.io' in order to catch SocketException from try block:
import 'package:http/http.dart' as http;
import 'dart:io';
try{
//Handle you network call code block in here
}on SocketException catch(_){
//To handle Socket Exception in case network connection is not available during initiating your network call
}
Well i don't know if my answer will be solving your question but days ago i had a problem little bit likely yours but in my case was using firebase realtime database. I was asking to myself how can i protect my app from network fails like no internet connection available? Well i am not using connectivity package too so i solve this problem with an approach that you already has been try using a timeout for network operations. I will share two snipets with differents approaches that i had implemented to handle this kind of problem adding some comments trying explain the differences between them.
Approach 1 - Setting timeout outside from network request method
Well the snipet below is a simple firebase database request where _viewsRef is a DatabaseReference and the once method do the request and returns me a Future with or without data.
// get users visualization from realtime database and returns a future
static Future<DataSnapshot> getUserVisualizations({#required String uid}) async {
return _viewsRef.child(uid).limitToLast(50).once();
}
In my BLoC component class i am calling the method below and setting a timeout to the future that is returned.
myBlocComponentMethod(){
//.. some work and finally the call
FirebaseUserViewsHelper.getUserVisualizations(uid: _currentUid)
.then(
(dataSnapshot){
if (dataSnapshot.value == null) {
// do some things to handle no data
}
else {
/// handle your data here
});
}
} // setting timeout here is an important point
).timeout( Duration(seconds: Constants.NETWORK_TIMEOUT_SECONDS),
onTimeout: (){
// method to handle a timeout exception and tell to view layer that
// network operation fails
// if we do not implement onTimeout callback the framework will throw a TimeoutException
} );
}
Well what is the point here? In this case if the timeout expires and future is not completed yet onTimeout callback is called and there i can tell to the view layer that network operation fails and show to the user some widget about it. But even with timeout expired the request to firebase database stays happening again and again, it's like the async event of request the database stays on dart event queue. I think this behavior is bad for performance aspects but if you're building your UI using a StreamBuilder with a little logic and code your requested data will be available right when you internet connection is back and with BLoC pattern the UI can respond easily to this event and we don't need provide a refresh button by example to user make the request again. I don't know if this is the right approach to implement this behavior but it works.
Approach 2 - Setting timeout inside from network request method
Below another firebase database request method
static Future<DataSnapshot> readUserNode( {#required String uid} ) async
=> USERS_REFERENCE.child(uid).once()
.timeout( Duration(seconds: Constants.NETWORK_TIMEOUT_SECONDS ) );
//note: Without timeout callback this line will throw a TimeoutException if the time expires
The usage in another BLoc component:
myBlocComponentMethod2(){
for( String uid in iterable ){
FirebaseUserHelper.readUserNode(uid: uid)
.then( (userSnapshot){
if (userSnapshot.value == null){
// do your stuffs
}
else {
// more stuffs to do
}
}).catchError( (error){
// when timeout expired we will catch the TimeoutException HERE and handling telling
// the UI what we need
} );
}
}
The big difference here that i get was in the behavior. In this second case since i put the timeout inside the request method when the timeout expires the request event do not run anymore, it's like that request event is removed from dart event queue. This can be good from performance perspective but now we need provide a refresh button in UI for user do the data again to get data from internet again.
I don't know if this workaround will solve your problem because you tell about SocketException what is not the case that i has described and i don't know what api you are using to make your requests. Anyway i hope that the concepts described in this post helps you implement a solution in your problem.
I'm working an ASP.net MVC cloud service project running two roles, a web role and a worker role. One of the pages in the web role initiate a request to build an APK file, building an APK file on the server can take anywhere from 1-5 minutes. So we came up with the following flow:
The user initiate the APK building process on the page.
The request is routed to our mvc action, creating a new message on an Azure Storage Queue.
The Worker role is always polling from the queue and starts the APK building process. Now that the APK is ready we want ideally to notify the user by:
(a) sending an email, which is working now. and (b) notifying the user on the page using SignalR.
Our problem is now in the SignalR part, how can we notify the user on the page that the APK is ready and he can download it.
EDIT - Copying contents of the first comment for the sake of completeness -
I've looked the question again and I understand that you are using a worker role to poll the queue. In this case, you can make your work role a .Net SignalR client that connects to the APK signalR hub on the web role. The signlaR hub on the web role can simple forward any message it receives from the .Net client to the javascript client (browser).
I would recommend going through the below links
Hubs API Guide - Server
Hubs API Guide - Javascript Client
before going through rest of the answer.
As can be understood from the above two links, SignalR enables the server to 'push' data to the client. In order for this to happen, you require two things -
A signalR hub - this is the 'hub' to which clients can subscribe to in order to receive messages.
A client connected to the hub
Your signalR hub on the server can look something like this -
public class APKHub : Hub
{
public async Task JoinGroup(string groupName)
{
await Groups.Add(Context.ConnectionId, groupName);
Clients.Group(groupName).sendMessage(Context.User.Identity.Name + " joined.");
}
public Task LeaveGroup(string groupName)
{
return Groups.Remove(Context.ConnectionId, groupName);
}
public void NotifyUser(string userId)
{
this.Clients.Group(userId).notify();
}
}
On the client, your code might look something like this -
var notificationHandler = function () {
var url;
var user;
var init = function (notificationUrl, userId) {
url = notificationUrl;
user = userId;
connectToAPKHub();
}
var connectToAPKHub = function () {
$.connection.hub.url = url;
var apk= $.connection.apkHub;
apk.client.notifyUser = function (user) {
console.log(user);
}
apk.client.addMessage = function (message) {
console.log(message);
}
$.connection.hub.start().done(function () {
console.log('connected to apkhub');
apk.server.joinGroup(user);
})
}
return {
init: init
}
}();
The notificationUrl is the URL that the signalR server is listening to.
This sets up your basic hub on the server and you should now be able to connect your client to the signalR hub. When the APK is built, you can use the following code (place it anywhere - for ex - in a controller action) to actually push a message to the concerned client -
var apkHub = GlobalHost.ConnectionManager.GetHubContext<APKHub>();
apkHub.Clients.Group(groupName).notifyUser(groupName);
The groupName can be an identifier that uniquely identifies a user.
Hope this helps.
I am having a Chat app in which i have to push a message to all other users in that conversation, signalr works fine when i push message to all clients over 100 but when i loop over those 100 connections and send message individually then message receives slowly on client side and when I start to push messages faster then my server IIS worker goes to 100% CPU usage and message receiving on client end become more slower,
So help me finding the best way to send messages to specific user from signalr more than 100 users at same time
If it's a chat application, you may want to look into groups in SignalR. Simply create a new group for each "conversation" and join the users to the group.
From the documentation:
public class ContosoChatHub : Hub
{
public Task JoinRoom(string roomName)
{
return Groups.Add(Context.ConnectionId, roomName);
}
public Task LeaveRoom(string roomName)
{
return Groups.Remove(Context.ConnectionId, roomName);
}
}
Then you can simply message the group:
Clients.Group(groupName).addChatMessage(name, message);
I have setup a SignalR hub which has the following method:
public void SomeFunction(int SomeID)
{
try
{
Thread.Sleep(600000);
Clients.Caller.sendComplete("Complete");
}
catch (Exception ex)
{
// Exception Handling
}
finally
{
// Some Actions
}
m_Logger.Trace("*****Trying To Exit*****");
}
The issue I am having is that SignalR initiates and defaults to Server Sent Events and then hangs. Even though the function/method exits minutes later (10 minutes) the method is initiated again ( > 3 minutes) even when the sendComplete and hub.stop() methods are initiated/called on the client prior. Should the user stay on the page the initial "/send?" request stays open indefinitely. Any assistance is greatly appreciated.
To avoid blocking the method for so long, you could use a Taskand call the client method asynchronously.
public void SomeFunction(Int32 id)
{
var connectionId = this.Context.ConnectionId;
Task.Delay(600000).ContinueWith(t =>
{
var message = String.Format("The operation has completed. The ID was: {0}.", id);
var context = GlobalHost.ConnectionManager.GetHubContext<SomeHub>();
context.Clients.Client(connectionId).SendComplete(message);
});
}
Hubs are created when request arrives and destroyed after response is sent down the wire, so in the continuation task, you need to create a new context for yourself to be able to work with a client by their connection identifier, since the original hub instance will no longer be around to provide you with the Clients method.
Also note that you can leverage the nicer syntax that uses async and await keywords for describing asynchronous program flow. See examples at The ASP.NET Site's SignalR Hubs API Guide.