How to restrict from getting duplicate or jumbled messages

[cmrhema]

Hi,
We have developed a socket program as below, The program works fine, except that it sometimes gives me jumbled messages or same message gets repeated twice.

The whole code is produced below.

I will let you know what exactly are we doing.

This a socket program for tracking vehicle.
The vehicle sends the signal through gprs+gsm mode, to our port.

We retrieve those messages using the above socket program.

Most of the messages come with GPRMC .

such as
$GPRMC,040302.663,A,3939.7,N,10506.6,W,0.27,358.86 ,200804,,*1A

Kindly help and let me know where am I going wrong

 
namespace SocketServer 
{
 
class Program
 
{
public AsyncCallback pfnWorkerCallBack;private Socket m_mainSocket; 
 
public string IPPort = "7030";
 
public byte[] m_byBuff = new byte[5000]; 
public int flag2 = 0;
 
public string queuePath; 
private string strDateFormat;
 
private string strLocation; 
public byte[] inValue = new byte[] { 1, 0, 0, 0, 0, 0, 5, 0, 1, 0, 0, 0 }; //1 -Minutes // 0,5 -- 6th parameter --seconds, 7th parameter--->Minutes
 
public byte[] outvalue = new byte[10];public Program() 
{
 
this.queuePath = ".\\private$\\AMI"; 
 
this.strDateFormat = null;
 
this.strLocation = null; 
StartListen();
}
 
public void StartListen() 
{
try
{
string portStr = this.IPPort; 
int port = System.Convert.ToInt32(portStr);
 
// Create the listening socket...
m_mainSocket = new Socket(AddressFamily.InterNetwork, 
SocketType.Stream,
 
ProtocolType.Tcp);IPAddress ip; 
 
string ipstr = "192.168.0.20";
 
ip=IPAddress.Parse(ipstr); 
IPEndPoint ipLocal = new IPEndPoint(ip, port);
 
//// Bind to local IP Address...
 
m_mainSocket.Bind(ipLocal);
 
//// Start listening...
 
m_mainSocket.Listen(100);
 
// Create the call back for any client connections...
 
while (true) 
{
m_mainSocket.BeginAccept(new AsyncCallback(OnClientConnect), null);Thread.Sleep(2000); 
}
}
catch (Exception e1) 
{
WriteErrorLogMessage(e1.Message);
}
}
 
public void OnClientConnect(IAsyncResult asyn) 
{
try
{
Socket msocket; 
msocket = m_mainSocket.EndAccept(asyn);
 
msocket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.KeepAlive, 1);msocket.IOControl(IOControlCode.KeepAliveValues, inValue, outvalue); 
 
WaitForData(msocket);
 
//BY COMMENTING THE BELOW LINE IT WILL NOT ACCEPT THE NEW CONNECTIONS
 
m_mainSocket.BeginAccept(new AsyncCallback(OnClientConnect), null); 
}
catch (Exception e1) 
{
WriteErrorLogMessage(e1.Message);
}
}
 
public void WaitForData(System.Net.Sockets.Socket soc) 
{
 
try
{
if (pfnWorkerCallBack == null) 
{
pfnWorkerCallBack = new AsyncCallback(OnDataReceived); 
}
 
soc.BeginReceive(m_byBuff, 0, m_byBuff.Length, SocketFlags.None, pfnWorkerCallBack, soc); 
//BY CLEARING BUFFER NO DATA EVER GETS RECEIVED, EXCEPTION WILLL BE TRHOWN IN "ONDATARECEIVED" METHOD
 
//m_byBuff = null;
}
catch (Exception e1) 
{
WriteErrorLogMessage(e1.Message);
}
}
 
public void OnDataReceived(IAsyncResult asyn) 
{
try
{
Socket sock = (Socket)asyn.AsyncState; 
 
int nBytesRec = sock.EndReceive(asyn);string sReceived = System.Text.Encoding.ASCII.GetString(m_byBuff, 0, nBytesRec); 
WriteLogMessage(sReceived);
 
//By MAKING THE BUFFER NULL OVER HERE, THE FIRST DATA GETS CAPTURED AND WHEN IT MOVES AGAIN TO SOC.BEGINRECEIVE, THE BUFFER BECOMES NULL
 
//m_byBuff = null;
 
this.ToMSMQ(sReceived);
 
Console.Write(sReceived); 
WaitForData(sock);
}
catch (SocketException e1) 
{
Socket sock = (Socket)asyn.AsyncState; 
sock.Close();
 
WriteErrorLogMessage(e1.Message);
}
catch (Exception e1) 
{
WriteErrorLogMessage(e1.Message);
}
}
 
public void ToMSMQ(string msg) 
{
//some process 
}
 
static void Main(string[] args) 
{
Program p = new Program(); 
}
}
}
 

[Plater]

The device in question makes a connection to you, sends some data then disconnects. This process is repeated.
Is that correct?
Using the AsyncConnection could allow connections to be processed out of order I think.
Why messages would be mangeled or otherwise, I don't know.

[cmrhema]

The device in question makes a connection to you, sends some data then disconnects. This process is repeated.
Is that correct?
Using the AsyncConnection could allow connections to be processed out of order I think.
Why messages would be mangeled or otherwise, I don't know.

Yes , the device sends data and then disconnects, but does not disconnect so immediately, if GPS is available it will not disconnect at all

But jumbled messages come in irrespective of its frequency of connection