I have a StreamSocket in UWP and I send my messages like this using a DataWriter object using the StoreAsync() method:
public static async Task<bool> SendNetworkMessage(NetworkMember member, NetworkMessage message)
{
DataWriter writer = member.DataWriter;
//Check that writer is not null
if (writer != null)
{
try
{
//Serialize Message
string stringToSend = SerializeObject<NetworkMessage>(message);
//Send Message Length
writer.WriteUInt32(writer.MeasureString(stringToSend));
//Send Message
writer.WriteString(stringToSend);
await writer.StoreAsync();
return true;
}
catch (Exception e)
{
Debug.WriteLine("DataWriter failed because of " + e.Message);
Debug.WriteLine("");
Disconnect(member);
OnMemberDisconnectedEvent(member);
return false;
}
}
else { return false; }
}
All is well, the only problem is that I don't know if a connection went down.
Now I want to check my connection using a DispatcherTimer like this:
private static async void NetworkTimer_Tick(object sender, object e)
{
foreach (NetworkMember member in networkMemberCollection)
{
if (member.Connected == true && member.Disconnecting == false)
{
await SendNetworkMessage(member, new PingMessage());
}
}}
However, this is causing timing issues which is causing ObjectDisposedExceptions on the DataWriter. It seems that the DispatcherTimer thread cannot use the StreamSocket when I send a message from a different thread. My question is: How can I make sure the Ping is sent each time but that SendNetworkMessage operations are done in order instead of overlapping?
Thanks
It seems that the DispatcherTimer thread cannot use the StreamSocket when I send a message from a different thread.
How can I make sure the Ping is sent each time but that SendNetworkMessage operations are done in order instead of overlapping?
It's possible, and I think your code using foreach and await operation can ensure the work of sending message in order.
the only problem is that I don't know if a connection went down.
If you want to know if the connection went down, you can refer to Handling WinRT StreamSocket disconnects (both server and client side).
Related
I'm developing a cloud service (worker role) for collecting data from a number of instruments. These instruments reports data randomly every minute or so. The service itself is not performance critical and doesn't need to be asynchronous. The instruments are able to resend their data up to an hour on failed connection attempt.
I have tried several implementations for my cloud service including this one:
http://msdn.microsoft.com/en-us/library/system.net.sockets.tcplistener.stop(v=vs.110).aspx
But all of them hang my cloud server sooner or later (sometimes within an hour).
I suspect something is wrong with my code. I have a lot of logging in my code but I get no errors. The service just stops to receive incoming connections.
In Azure portal it seems like the service is running fine. No error logs and no suspicious cpu usage etc.
If I restart the service it will run fine again until it hangs next time.
Would be most grateful if someone could help me with this.
public class WorkerRole : RoleEntryPoint
{
private LoggingService _loggingService;
public override void Run()
{
_loggingService = new LoggingService();
StartListeningForIncommingTCPConnections();
}
private void StartListeningForIncommingTCPConnections()
{
TcpListener listener = null;
try
{
listener = new TcpListener(RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["WatchMeEndpoint"].IPEndpoint);
listener.Start();
while (true)
{
_loggingService.Log(SeverityLevel.Info, "Waiting for connection...");
var client = listener.AcceptTcpClient();
var remoteEndPoint = client.Client != null ? client.Client.RemoteEndPoint.ToString() : "Unknown";
_loggingService.Log(SeverityLevel.Info, String.Format("Connected to {0}", remoteEndPoint));
var netStream = client.GetStream();
var data = String.Empty;
using (var reader = new StreamReader(netStream, Encoding.ASCII))
{
data = reader.ReadToEnd();
}
_loggingService.Log(SeverityLevel.Info, "Received data: " + data);
ProcessData(data); //data is processed and stored in database (all resources are released when done)
client.Close();
_loggingService.Log(SeverityLevel.Info, String.Format("Connection closed for {0}", remoteEndPoint));
}
}
catch (Exception exception)
{
_loggingService.Log(SeverityLevel.Error, exception.Message);
}
finally
{
if (listener != null)
listener.Stop();
}
}
private void ProcessData(String data)
{
try
{
var processor = new Processor();
var lines = data.Split('\n');
foreach (var line in lines)
processor.ProcessLine(line);
processor.ProcessMessage();
}
catch (Exception ex)
{
_loggingService.Log(SeverityLevel.Error, ex.Message);
throw new Exception(ex.InnerException.Message);
}
}
}
One strange observation i just did:
I checked the log recently and no instrument has connected for the last 30 minutes (which indicates that the service is down).
I connected to the service myself via a TCP client i've written myself and uploaded some test data.
This worked fine.
When I checked the log again my test data had been stored.
The strange thing is, that 4 other instruments had connected about the same time and send their data successfully.
Why couldn't they connect by themself before I connected with my test client?
Also, what does this setting in .csdef do for an InputEndpoint, idleTimeoutInMinutes?
===============================================
Edit:
Since a cuple of days back my cloud service has been running successfully.
Unfortunately this morning last log entry was from this line:
_loggingService.Log(SeverityLevel.Info, String.Format("Connected to {0}", remoteEndPoint));
No other connections could be made after this. Not even from my own test TCP client (didn't get any error though, but no data was stored and no new logs).
This makes me think that following code causes the service to hang:
var netStream = client.GetStream();
var data = String.Empty;
using (var reader = new StreamReader(netStream, Encoding.ASCII))
{
data = reader.ReadToEnd();
}
I've read somewhere that StremReader's ReadToEnd() could hang. Is this possible?
I have now changed this piece of code to this:
int i;
var bytes = new Byte[256];
var data = new StringBuilder();
const int dataLimit = 10;
var dataCount = 0;
while ((i = netStream.Read(bytes, 0, bytes.Length)) != 0)
{
data.Append(Encoding.ASCII.GetString(bytes, 0, i));
if (dataCount >= dataLimit)
{
_loggingService.Log(SeverityLevel.Error, "Reached data limit");
break;
}
dataCount++;
}
Another explanation could be something hanging in the database. I use the SqlConnection and SqlCommand classes to read and write to my database. I always close my connection afterwards (finally block).
SqlConnection and SqlCommand should have default timeouts, right?
===============================================
Edit:
After some more debugging I found out that when the service wasn't responding it "hanged" on this line of code:
while ((i = netStream.Read(bytes, 0, bytes.Length)) != 0)
After some digging I found out that the NetStream class and its read methods could actually hang. Even though MS declares otherwise.
NetworkStream read hangs
I've now changed my code into this:
Thread thread = null;
var task = Task.Factory.StartNew(() =>
{
thread = Thread.CurrentThread;
while ((i = netStream.Read(bytes, 0, bytes.Length)) != 0)
{
// Translate data bytes to a ASCII string.
data.Append(Encoding.ASCII.GetString(bytes, 0, i));
}
streamReadSucceeded = true;
});
task.Wait(5000);
if (streamReadSucceeded)
{
//Process data
}
else
{
thread.Abort();
}
Hopefully this will stop the hanging.
I'd say that part of your problem is you are processing your data on the thread that listens for connections from clients. This would prevent new clients from connecting if another client has started a long running operation of some type. I'd suggest you defer your processing to worker threads thus freeing the "listener" thread to accept new connections.
Another problem you could be experiencing, if your service throws an error, then the service will stop accepting connections as well.
private static void ListenForClients()
{
tcpListener.Start();
while (true)
{
TcpClient client = tcpListener.AcceptTcpClient();
Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));
clientThread.Start(client);
}
}
private static void HandleClientComm(object obj)
{
try
{
using(TcpClient tcpClient = (TcpClient)obj)
{
Console.WriteLine("Got Client...");
using (NetworkStream clientStream = tcpClient.GetStream())
using (StreamWriter writer = new StreamWriter(clientStream))
using(StreamReader reader = new StreamReader(clientStream))
{
//do stuff
}
}
}
catch(Exception ex)
{
}
}
Writing to remote MSMQ seems to be working on/off. I am not sure what is wrong and what else to do to confirm sending.
I am reluctant to setup some kind of ack. It seems to be an overkill.
using (var queue = new MessageQueue(queueName, QueueAccessMode.Send))
{
var messageQueueTransaction = new MessageQueueTransaction();
messageQueueTransaction.Begin();
try
{
queue.Formatter = new XmlMessageFormatter(new Type[] { typeof(EmailMessage) });
var msg = new Message();
msg.Label = emailMessage.Subject;
msg.Body = emailMessage;
queue.Send(msg, messageQueueTransaction);
messageQueueTransaction.Commit();
}
catch (Exception e)
{
LoggerLib.Logger.ErrorException(e, "Error Sending Email using MSMQ", emailMessage);
messageQueueTransaction.Abort();
}
finally
{
queue.Close();
}
}
The Connection string for MSMQ is in the format of:"FormatName:DIRECT=OS:FULLMACHINENAME\private$\emailmessagequeue"
Also, I used "FormatName:DIRECT:TCP:IPAddress\private$\emailmessagequeue".
It works without a glitch when I ran it locally. So, I allowed Everyone to have Full access and It still doesn't work.
Any ideas?
The port number 1801 was blocked. That resolved it. –
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
I am newbie for WP7 and Socket programming. I have gone through msdn sample code http://msdn.microsoft.com/en-us/library/hh202864(v=VS.92).aspx#Y4537 and tested for use. Send works fine but it couldn't receive, this is the code I have used for receiving udp packet data.
In this my Breakpoint always fails # if (e.SocketError == SocketError.Success)
public string Receive(int portNumber)
{
string response = "Operation Timeout";
// We are receiving over an established socket connection
if (_socket != null)
{
// Create SocketAsyncEventArgs context object
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
socketEventArg.RemoteEndPoint = new IPEndPoint(IPAddress.Any, portNumber);
// Setup the buffer to receive the data
socketEventArg.SetBuffer(new Byte[MAX_BUFFER_SIZE], 0, MAX_BUFFER_SIZE);
// Inline event handler for the Completed event.
// Note: This even handler was implemented inline in order to make this method self-contained.
socketEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(delegate(object s, SocketAsyncEventArgs e)
{
try
{
if (e.SocketError == SocketError.Success)
{
// Retrieve the data from the buffer
response = Encoding.UTF8.GetString(e.Buffer, e.Offset,e.BytesTransferred);
response = response.Trim('\0');
}
else
{
response = e.SocketError.ToString();
}
_clientDone.Set();
}
catch (Exception ex)
{
ex.ToString();
}
});
// Sets the state of the event to nonsignaled, causing threads to block
_clientDone.Reset();
// Make an asynchronous Receive request over the socket
_socket.ReceiveFromAsync(socketEventArg);
// Block the UI thread for a maximum of TIMEOUT_MILLISECONDS milliseconds.
// If no response comes back within this time then proceed
_clientDone.WaitOne(TIMEOUT_MILLISECONDS);
}
else
{
response = "Socket is not initialized";
}
return response;
}
Have you tried using the specific UDP support in WP7/Silverlight? Either using UdpSingleSourceMulticastClient or UdpAnySourceMulticastClient depending on your scenario and requirements. Here's an intro article on UDP in Silverlight # Working with Multicast
I'm having an issue using sockets in flash builder 4. The code below sends a set of bytes to a receiving c# sockerServer. If I dismiss the error I get in flash builder manually, the bytes are sent fine and all comes across as it should on 127.0.0.1:10. Now if I could just get the same results without an error being displayed in Flex.
So, I have two questions:
1) Why does it return an error when I try to close the socket? See closeConnection() below for context. I tried flushing it just before which didn't help.
2) Why is nothing sent when I use socket.flush()?
package
{
import flash.events.IOErrorEvent;
import flash.net.Socket;
import flash.utils.ByteArray;
public class socketClient
{
private var socket:Socket;
public function openConnection(address:String, port:int):void
{
if (socket != null && socket.connected)
socket.close();
socket = new Socket();
try {
socket.connect( address, port );
}
catch( e:Error ) { }
}
public function sendProtocol(p:socketProtocol):void {
//p.serialize() gets me a bunch of bytes in a ByteArray
var buffer:ByteArray = p.serialize();
socket.writeBytes(buffer, 0, buffer.length);
//Nothing happens when I flush
socket.flush();
}
public function closeConnection():void {
//As soon as I get to socket.close(), I get this
//"Unhandled IOErrorEvent:. text=Error #2031: Socket Error."
socket.close();
}
}
}
I use the class like this:
var socket:socketClient = new socketClient();
//works fine, I see the connection on the server
socket.openConnection("127.0.0.1", 10);
//no errors, but nothing sent
socket.sendProtocol(protocol);
//returns the error. (if manually dismissed, data is sent)
socket.closeConnection();
I finally solved it after hammering this one since I posted the question.
I had to add a
socket.addEventListener(flash.events.Event.CLOSE, closeHandler)
and do the socket.close() from there.