'***************************************************************************
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'* ClassTCPClient *
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'* *
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'* This class manages the TCP connection with an E301 module. *
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'* It tries to keep the connection alive checking continously it by *
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'* sending pings. If the connection is lost it tries to connect again. *
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'* Once connected, this class provides a function to send data to the *
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'* E301 and an event to trap the data received. *
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'* *
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'* EQUITEL C.V. February 2007 ALMDI*
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'***************************************************************************
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Imports System
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Imports System.Net
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Imports System.Net.Sockets
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Imports System.Threading
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Imports System.Text
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Imports System.IO
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Imports System.Net.NetworkInformation
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Imports System.Globalization
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Imports System.Timers
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Public Class ClassTCPClient
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#Region "Definitions"
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'Time between pings to the destination IP in miliseconds
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Private Const CheckingTime As Integer = 3000
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#End Region
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#Region "Fields"
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Private mStream As Stream
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Private mHostIP As String
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Private mHostPort As String
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Private mReceivingThread As Thread
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Private mTcpClient As TcpClient
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Private WithEvents mPingClient As New Ping()
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Private WithEvents mTimerPing As New System.Timers.Timer
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#End Region
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#Region "Events"
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Public Event ConnectionTerminated As EventHandler
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Public Event DataReceived As TCPDataReceivedEventHandler
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Public Event ConnectionSuccesful As EventHandler
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Public Event ConnectionFailed As EventHandler
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Public Event ConnectionLost As EventHandler
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Protected Overridable Sub OnConnectionTerminated()
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RaiseEvent ConnectionTerminated(Me, New EventArgs)
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End Sub
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Protected Overridable Sub OnConnectionSuccessful()
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RaiseEvent ConnectionSuccesful(Me, New EventArgs)
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End Sub
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Protected Overridable Sub OnConnectionFailed()
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RaiseEvent ConnectionFailed(Me, New EventArgs)
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End Sub
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Protected Overridable Sub OnConnectionLost()
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RaiseEvent ConnectionLost(Me, New EventArgs)
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End Sub
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Protected Overridable Sub OnDataReceived(ByVal Data() As Byte, ByVal Size As Integer)
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Dim e As New TCPDataReceivedEventArgs
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e.Data = Data
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e.Lenght = Size
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RaiseEvent DataReceived(Me, e)
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End Sub
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#End Region
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#Region "Properties"
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Public Property HostIP() As String
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Get
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HostIP = mHostIP
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End Get
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Set(ByVal Value As String)
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mHostIP = Value
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End Set
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End Property
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Public Property HostPort() As String
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Get
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HostPort = mHostPort
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End Get
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Set(ByVal Value As String)
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mHostPort = Value
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End Set
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End Property
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Public ReadOnly Property Connected() As Boolean
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Get
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Connected = mTcpClient.Connected
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End Get
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End Property
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#End Region
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#Region "Methods"
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'Constructor
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Public Sub New(ByVal Ip As String, ByVal ControlPort As Integer)
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mHostIP = Ip
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mHostPort = ControlPort.ToString
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TryInitConnection()
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End Sub
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Private Sub OnEndTryingConnection(ByVal Ar As IAsyncResult)
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If Ar.IsCompleted Then
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If mTcpClient.Connected Then
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'The connection has been possible
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'Stream to send packets
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mStream = mTcpClient.GetStream()
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'Thread to read incoming packets
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mReceivingThread = New Thread(AddressOf ReadData)
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mReceivingThread.Start()
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'Start the connection status checking
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mTimerPing.Start()
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OnConnectionSuccessful()
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Else
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'The connection is not possible
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mTimerPing.Stop()
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OnConnectionFailed()
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'Let's try again
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TryInitConnection()
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End If
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End If
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End Sub
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Public Sub TryInitConnection()
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'Tries to establish a TCP connection with the E301 module
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Dim RequestCallback As AsyncCallback
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Dim State As Object
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Dim ReturnValue As IAsyncResult
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mTcpClient = New TcpClient()
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mTcpClient.ReceiveTimeout = 0 'Waits forever for incoming packets
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mTimerPing.Interval = CheckingTime
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RequestCallback = New AsyncCallback(AddressOf OnEndTryingConnection)
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State = New Object
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ReturnValue = mTcpClient.BeginConnect(HostIP, CInt(HostPort), RequestCallback, State)
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End Sub
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Public Sub Disconnect()
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mReceivingThread.Abort()
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mTimerPing.Stop()
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mStream.Close()
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mTcpClient.Close()
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End Sub
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Public Sub SendData(ByVal Data() As Byte)
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If Not (mStream Is Nothing) Then
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mStream.Write(Data, 0, Data.Length)
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End If
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End Sub
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Private Sub ReadData()
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Dim ReadBuffer() As Byte
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Dim BytesLeidos As Integer
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Dim Ex As System.Net.Sockets.SocketException
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While True
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Try
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ReadBuffer = New Byte(100) {}
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'Wait until data arrives
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BytesLeidos = mStream.Read(ReadBuffer, 0, ReadBuffer.Length)
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'Data has arrived...
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OnDataReceived(ReadBuffer, BytesLeidos)
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Application.DoEvents()
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Catch e As IOException
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'Some error... the conection is lost
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Ex = e.InnerException
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Console.WriteLine("ErrorCode: " & Ex.ErrorCode.ToString)
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Console.WriteLine("ERROR: " & Ex.ToString)
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OnConnectionTerminated()
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Exit While
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End Try
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End While
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End Sub
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Private Sub OnTimerPingFired(ByVal Sender As Object, ByVal e As System.Timers.ElapsedEventArgs) Handles mTimerPing.Elapsed
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'Send a ping and wait for a response at the most for the time between
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'checkings minus one second (and no more than 10 seconds).
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'This is done in order to not overlap the
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'processes when the connection is lost. If there is no connection, the waiting
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'process of one ping mus be terminated before sending a new one.
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Dim WaitingTime As Integer
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WaitingTime = CheckingTime - 1000
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If WaitingTime > 10000 Then WaitingTime = 10000
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Try
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mPingClient.SendAsync(mHostIP, WaitingTime, Nothing)
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Catch
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End Try
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End Sub
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Private Sub OnPingClientResponse(ByVal Sender As Object, ByVal e As System.Net.NetworkInformation.PingCompletedEventArgs) Handles mPingClient.PingCompleted
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'Treats the response of the ping agent
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Dim NoPingResponse As Boolean = False
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If e.Error Is Nothing Then
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If e.Reply.Status = IPStatus.TimedOut Then
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NoPingResponse = True
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End If
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Else
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NoPingResponse = True
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End If
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If NoPingResponse Then
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OnConnectionFailed()
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Disconnect()
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TryInitConnection()
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End If
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End Sub
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#End Region
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End Class
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