Universal Windows Platform (UWP)
A Microsoft platform for building and publishing apps for Windows desktop devices.
2,704 questions
Unable to establish socket connection between two UWP apps
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karthik kovi
0
Reputation points
I am developing a UWP application that has both client and server functionality. When I run the application on the same machine, the client and server are able to connect successfully. However, when I migrate the client and server to separate UWP applications, the client is unable to connect to the server. I am using the same code in both scenarios, and I have verified that the server is running and listening on the correct port. I am also able to see the server port in the command prompt using the netstat -ano command. I am getting the following error message from the client UWP app:
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 [::1]:1337
{count} votes
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Junjie Zhu - MSFT 10,791 Reputation points Microsoft Vendor2023-10-31T08:12:26.1733333+00:00 Hi @karthik kovi ,
Welcome to Microsoft Q&A!
Based on the current information, we cannot accurately determine what caused your error. Could you please confirm which line in the code is reporting the error?
Thank you.
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karthik kovi 0 Reputation points
2023-10-31T09:34:18.35+00:00 Below i am attaching the relavent code. Within this code, you'll find the
socketServerListeneracting as the server listener, utilizing port 1337 for TCP socket connections.The
StartClientConnectionmethod is responsible for initiating the client's connection to the server, here encounters an issue at the very start of the process, precisely at the line where it attempts to establish the initial connection, resulting in an error.await streamSocket.ConnectAsync(hostName, "1337");
ERROR : 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 [::1]:1337
As a result of the unsuccessful client connection request, the TCP connection enters the 'SYN-SENT' state, which is illustrated below
The mentioned error only arises when the client and server are launched from separate applications. When both the client and server reside within a single application, their communication functions without any issues.
For successful connection is illustrated as below:
public async void socketServerListener() { try { IPHostEntry ipHostInfo = await Dns.GetHostEntryAsync("localhost"); IPAddress ipAddress = ipHostInfo.AddressList[0]; IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, 1337); Socket listener = new Socket(ipEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp); listener.Bind(ipEndPoint); listener.Listen(100); this.serverListBox.Items.Insert(0, socketClientRequestCount + " : server is listening..."); var handler = await listener.AcceptAsync(); while (true) { socketClientRequestCount++; LogTheMessage("Welcome : " + socketClientRequestCount); Trace.WriteLine("Welcome"); // Receive message var buffer = new byte[1_024]; var received = await handler.ReceiveAsync(buffer, SocketFlags.None); var response = Encoding.UTF8.GetString(buffer, 0, received); await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => this.serverListBox.Items.Insert(0,string.Format(socketClientRequestCount + " : server received the request: \"{0}\"", response))); Trace.WriteLine("server received the request"); //send acknowledgement for message var ackMessage = "Send Acknowledgement<|ACK|>"; var echoBytes = Encoding.UTF8.GetBytes(ackMessage); await handler.SendAsync(echoBytes, 0); await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => this.serverListBox.Items.Insert(0,string.Format(socketClientRequestCount + " : server sent back the response: \"{0}\"", ackMessage))); Trace.WriteLine("server sent back the response"); } } catch (Exception ex) { Trace.WriteLine("Error : " + ex); } }private async void StartClientConnection(object sender, RoutedEventArgs e) { var hostName = new Windows.Networking.HostName("localhost"); this.clientListBox.Items.Insert(0, socketClientRequestCount + " : client is trying to connect..."); await streamSocket.ConnectAsync(hostName, "1337"); this.clientListBox.Items.Insert(0, socketClientRequestCount + " : client connected"); streamWriter = new StreamWriter(streamSocket.OutputStream.AsStreamForWrite()); streamReader = new StreamReader(streamSocket.InputStream.AsStreamForRead()); } -
Junjie Zhu - MSFT 10,791 Reputation points Microsoft Vendor
2023-11-01T07:28:27.5333333+00:00 Hi @karthik kovi ,
Have you checked that the HostName is correct? Will the connection fail if you change "localhost" to the server IP?
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karthik kovi 0 Reputation points
2023-11-02T04:26:55.9966667+00:00 In both scenarios, the host name and port number used in the client and server apps are the same. As confirmed by the output of the "netstat -ano | findstr 1337" command, the listening port matches the specified port number.
In the first scenario where the client and server are within the same application, a successful connection is established. The
netstatoutput typically displays a listening state and an established connection, indicating that the client and server are communicating successfully.However, in the second scenario where the client and server reside in separate applications, and even though the host name and port number are identical, an unsuccessful connection error occurs. The
netstatoutput reveals that the server is in a listening state, while the client is stuck in the "SYN_SENT" state. This suggests that the client is attempting to establish a connection but is not receiving a response from the server, resulting in a connection timeout or errorThis discrepancy between the two scenarios, with identical host name and port number settings, underscores the need for further investigation into the client-server code and network configuration to pinpoint the issue preventing successful communication.
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Junjie Zhu - MSFT 10,791 Reputation points Microsoft Vendor
2023-11-02T09:44:52.7833333+00:00 It may be a problem with the network settings, and I saw that you have Trace code in function
socketServerListener. In the second scenario, the server and client are separated, is there any useful output? -
karthik kovi 0 Reputation points
2023-11-02T12:20:20.5566667+00:00 No useful output. I tried to implement client ping frequently from windows service application to UWP app but resulting same error.
ERROR : 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 [::1]:1337
Kindly try it in your system and let me know if any useful output.
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Junjie Zhu - MSFT 10,791 Reputation points Microsoft Vendor
2023-11-03T08:04:39.59+00:00 I used
Windows.Networking.Socketscode sample and it worked fine.You can try to replace
System.Net.SocketswithWindows.Networking.Socketsto test and see if the problem still occurs. -
Junjie Zhu - MSFT 10,791 Reputation points Microsoft Vendor
2023-11-08T08:40:43.2433333+00:00 Any updates?
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