Im trying to connect to wireless network from my uwp application (windows iot core os)
I can scan and list all wireless networks around me without any problem.
When i try to connect without credential connection fails as expected and program continues.
My problem is when i try to connect to a network with credentials my app closes and i cannot catch it even with using try catch.App goes from screen ( rasberry pi 3 ) and debug session is lost.Instead it should return me connection failed invalid credentials.
I'm also testing Microsoft samples for connecting wireless and i observed this behave happens in Microsoft sample when you try to connect to a network that you already connected it crashes without any exception
https://github.com/ms-iot/samples/tree/develop/WiFiConnector/CS
To Summurize; With following code if call firstAdapter.ConnectAsync() without credentials its normal but if call it with credentials program goes off from screen even without exception.
Note: i call await WiFiAdapter.RequestAccessAsync(); before i start.
my code as following
var adapterResult = await WiFiAdapter.FindAllAdaptersAsync();
if (adapterResult.Count >= 1)
{
WiFiAdapter firstAdapter = adapterResult[0];
await firstAdapter.ScanAsync();
var network = firstAdapter.NetworkReport.AvailableNetworks.FirstOrDefault();
PasswordCredential credential = new PasswordCredential();
credential.Password = "zp1PDQPdYFpCU";
try
{
WiFiConnectionResult result;
if (network.SecuritySettings.NetworkAuthenticationType == Windows.Networking.Connectivity.NetworkAuthenticationType.Open80211 &&
network.SecuritySettings.NetworkEncryptionType == NetworkEncryptionType.None)
{
result = await firstAdapter.ConnectAsync(network, WiFiReconnectionKind.Automatic);
}
else
{
result = await firstAdapter.ConnectAsync(network, WiFiReconnectionKind.Automatic, credential);
}
}
catch (Exception)
{
throw;
}
Related
We have 2 UWP apps. One app shares data to the other app through StreamSocket. The server app will send data to client app. There will be 30-40 or more devices running the client app and connecting to the server's socket to receive data.
When we test with one client app, all the data sharing happens without any issue. But when we started testing with about 10 devices using the client app, sometimes some apps don't receive data. And there seems to be an error saying A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
In general it get shared to most of the devices, but few fails sometimes randomly. What could be the reason for this? Is there a connection limit to connect to a socket with given IP and port using Stream Socket?
Here is some parts of our code. Please let me know what we have to correct here to avoid getting that error.
Server side
public async Task StartServer(string serverIp, string serverPort)
{
try
{
HostName serverAddress = new HostName(serverIp);
//Create a StreamSocketListener to start listening for TCP connections.
StreamSocketListener socketListener = new StreamSocketListener();
//Hook up an event handler to call when connections are received.
socketListener.ConnectionReceived += SocketListener_ConnectionReceived;
//Start listening for incoming TCP connections on the specified port.
await socketListener.BindEndpointAsync(serverAddress, serverPort);
}
catch (Exception e)
{
}
}
private async void SocketListener_ConnectionReceived(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
{
try
{
await Task.Run(() => ShareFile(args.Socket));
}
catch (Exception e)
{
}
}
Client side
public async Task ServerConnect(string serverIP, string serverPort)
{
try
{
HostName serverAddress = new HostName(serverIP);
StreamSocket socket = new StreamSocket();
socket.Control.KeepAlive = false;
// Connect to the server.
await socket.ConnectAsync(serverAddress, serverPort, SocketProtectionLevel.PlainSocket);
}
catch (Exception e)
{
}
}
Also would like to get these clarified
-What is the difference between BindServiceNameAsync and BindEndpointAsync? Most examples seems to use the first one. When should we use the second one?
-If we call sender.Dispose(); in SocketListener_ConnectionReceived, will that affect the other clients trying to join the same socket?
-In the ShareFile() function, if we close args.Socket() after sending data, can it close the socket before the client actually read the data from that side?
I use SignalR in an Angular app. When I destroy component in Angular I also want to stop connection to the hub. I use the command:
this.hubConnection.stop();
But I get an error in Chrome console:
Websocket closed with status code: 1006
In Edge: ERROR Error: Uncaught (in promise): Error: Invocation canceled due to connection being closed. Error: Invocation canceled due to connection being closed.
It actually works and connection has been stopped, but I would like to know why I get the error.
This is how I start the hub:
this.hubConnection = new HubConnectionBuilder()
.withUrl("/matchHub")
.build();
this.hubConnection.on("MatchUpdate", (match: Match) => {
// some magic
})
this.hubConnection
.start()
.then(() => {
this.hubConnection.invoke("SendUpdates");
});
EDIT
I finally find the issue. Its caused by change streams from Mongo. If I remove the code from SendUpdates() method then OnDisconnected is triggered.
public class MatchHub : Hub
{
private readonly IMatchManager matchManager;
public MatchHub(IMatchManager matchManager)
{
this.matchManager = matchManager;
}
public async Task SendUpdates() {
using (var changeStream = matchManager.GetChangeStream()) {
while (changeStream.MoveNext()) {
var changeStreamDocument = changeStream.Current.FullDocument;
if (changeStreamDocument == null) {
changeStreamDocument = BsonSerializer.Deserialize<Match>(changeStream.Current.DocumentKey);
}
await Clients.Caller.SendAsync("MatchUpdate", changeStreamDocument);
}
}
}
public override async Task OnDisconnectedAsync(Exception exception)
{
await base.OnDisconnectedAsync(exception);
}
}
Method GetChangeStream from the manager.
ChangeStreamOptions options = new ChangeStreamOptions() { FullDocument = ChangeStreamFullDocumentOption.UpdateLookup };
var watch = mongoDb.Matches.Watch(options).ToEnumerable().GetEnumerator();
return watch;
But I don't know how to fix it.
This can be for many reasons but i think it is most likely this one:
I think this is because of how the server is handling the connected / disconnected events. I can't say for sure but the connection closing needs to handled correctly on the server also with code. Try overriding the built in On Connected /Disconnected methods on the server and see. My assumption only is that you're closing it but the server isn't closing properly and therefore not relaying the proper closed response.
found as a comment at : getting the reason why websockets closed with close code 1006
Where you don't need to change the connection/disconection because evrything works fine. But as an answer this one is the most likely.
It throws error because the callback doesn't get clear properly.
And it is caused by the return data from websocket.
normally it should return like
However, for some reason it might return something like
the very last response breaking into 2 pieces
And that causes the issue.
I don't think there is a way to bypass this without changing the source code.
I reported this on github repo as well at here
It turns out that I can just utilize invocation response to notify client to stop the hub. So it doesn't trigger racing issue.
sorry,I am a beginner and my English is very bad
i have a trouble in Flutter.
i reference https://pub.dartlang.org/packages/flutter_blue
I want to use flutter to communicate with the ear thermometer device.
when i reopen bluetooth and it can work,but I reopen app and excute second it show error.
i guess bluetooth gatt cahce is causing a error.
how can i solve it?
my code
deviceConnection = flutterBlue.scan(timeout: const Duration(seconds: 5),).listen((scanResult) async {
device = scanResult.device;
deviceConnection2 = await flutterBlue.connect(device, timeout: const Duration(seconds: 10),).listen(null);//this line error is error 1
deviceStateSubscription = device.onStateChanged().listen((s) async {
await device.discoverServices().then((s) async {//this is error 2
.........
}
}
}
it show these error
error 1
Dart Error: Unhandled exception:
PlatformException(already_connected, connection with device already exists, null)
error 2
Dart Error: Unhandled exception:
PlatformException(get_services_error, no instance of BluetoothGatt, have you connected first?, null)
Error 1
Dart Error: Unhandled exception: PlatformException(already_connected, connection with device already exists, null)
Since the app detected that a bluetooth device is already connected, one workaround is check for any connected device disconnect it. You can create a function that does this like the one in this GitHub thread:
What you can do here is that you check for any connected devices and
then disconnect them. I have written a function that does just that,
here it is:
checkConnectedDevices() async{
connectedDevices = await flutterBlue.connectedDevices.whenComplete((){
print(connectedDevices);
for(int i = 0; i < connectedDevices.length; i++){
connectedDevices[i].disconnect();
}
});
}
Error 2
Dart Error: Unhandled exception: PlatformException(get_services_error, no instance of BluetoothGatt, have you connected first?, null)
Since there is an error connecting to the device, you will not be able to call the discoverServices(). Because you need to be connected to a device before you can call this function. Check the following GitHub discussions related to this error:
connected ' discoverServices ' is't get #426
discoverServices is broken #535
How do you call the Ping command with the new C# driver 2.0?
In the old driver it was available via Server.Ping()? Also, Is there a way to find out if the server is running/responding without running the actual query?
Using mongoClient.Cluster.Description.State doesn't help because it still gave the disconnected state even after the mongo server started responding.
You can check the cluster's status using its Description property:
var state = _client.Cluster.Description.State
If you want a specific server out of that cluster you can use the Servers property:
var state = _client.Cluster.Description.Servers.Single().State;
This worked for me on both c# driver 2 and 1
int count = 0;
var client = new MongoClient(connection);
// This while loop is to allow us to detect if we are connected to the MongoDB server
// if we are then we miss the execption but after 5 seconds and the connection has not
// been made we throw the execption.
while (client.Cluster.Description.State.ToString() == "Disconnected") {
Thread.Sleep(100);
if (count++ >= 50) {
throw new Exception("Unable to connect to the database. Please make sure that "
+ client.Settings.Server.Host + " is online");
}
}
As #i3arnon's answer I can tell it was reliable for me in this way:
var server = client.Cluster.Description.Servers.FirstOrDefault();
var serverState = ServerState.Disconnected;
if (server != null) serverState = server.State;
or in new versions of .Net
var serverState = client.Cluster.Description.Servers.FirstOrDefault()?.State
?? ServerState.Disconnected;
But if you realy want to run a ping command you can do it like this:
var command = new CommandDocument("ping", 1);
try
{
db.RunCommand<BsonDocument>(command);
}
catch (Exception ex)
{
// ping failed
}
I have simple WinRT application, that will be communicating with remote server via TCP.
In order to do that I'm creating new StreamSocket object, and connecting to remote server after clicking a proper button, like this:
private async void ConnectButtonClick(object sender, RoutedEventArgs e)
{
StreamSocket socket = new StreamSocket();
HostName host = new HostName("192.168.1.15");
await socket.ConnectAsync(host, "12121");
}
The problem is that this code is blocking the UI thread. I've created simple animation, using MonoGame (couple of moving sprites) that is running on the screen continously, in order to check if UI is blocked.
The problem is, that after clicking Connect button, animation is freezing for a second, so I assume that, connecting to the server is made in the UI thread.
Should I put my whole network code into a separate thread, or is this async/await enough?
I'd like to implement a loop, that will handle incoming data (with help od DataReader), like this:
private async void ReceiveLoop()
{
bool running = true;
while (running)
{
try
{
uint numStrBytes = await _reader.LoadAsync(BufferSize);
if (numStrBytes == 0)
{
Disconnect();
return;
}
string msg = _reader.ReadString(numStrBytes);
OnLog(string.Format("Received: {0}", msg));
OnDataReceived(msg);
}
catch (Exception exception)
{
OnLog("Receive failed with error: " + exception.Message);
Disconnect();
running = false;
}
}
}
Sending data will be done using StoreAsync from DataWriter.
So should I put these functions into separate threads?
Can't you just try doing that on a background thread to see if that helps? Something like this:
Task.Run(
async () =>
{
StreamSocket socket = new StreamSocket();
HostName host = new HostName("192.168.1.15");
await socket.ConnectAsync(host, "12121");
});
For any async calls in a normal .net library, the general rule is to use ConfigureAwait(false) which helps prevent issues like you are seeing. So for instance in WinRT stuff it would be:
await socket.ConnectAsync(host, "12121").AsTask().ConfigureAwait(false);
This has some great information:
http://blogs.msdn.com/b/windowsappdev/archive/2012/04/24/diving-deep-with-winrt-and-await.aspx