Sending Messages Using Winsock

[SteveCRM]

How do I send messages using Winsock. Also, how do I recieve them?

[Chris]

Is this the coomand that you looking for?

Winsock1.SendData "My Test Data"

[SteveCRM]

yeah, but If I am sending more than one thing, how will the other computer know which is which? Can I name each or something?

[Chris]

Do you mean more than one diffrence string/message?

Then you may need to define your own Message TAG and make use of the standard communication message format like:

[STX]+[Message TAG]+[Message Body]+[ETX]

Where STX = Start Of Text ,normally is Chr(2)
ETX = End Of Text ,normally is Chr(3)
Message TAG = Your own define TAG to differentiate
each message type.
Message Body = Your real message that to be transfer.

After send this, you should wait for the ACK (Acknowledgement) or NAK from the remote terminal

Then in your

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
  Dim strHold As String
  Dim MsgTAG As String
  Dim MsgBody As String

  Winsock1.GetData ClientData, vbString
  'Search for the STX
  strHold = left(strHold, InStr(1,StrHold, Chr(2),vbBinaryCompare)-1)

  'Search for the ETX 
  strHold = Mid(strHold, 1, InStr(1,StrHold, Chr(3),vbBinaryCompare)-1)

  'Get the Message Tag and Message Body 
  'Assume the first Character is your Message  TAG
  Select case Mid(strhold,1,1)
  Case TAG1
      Debug.Pring "Message With TAG1 received - " & Mid(strHold,2)
  Case TAG2
      Debug.Pring "Message With TAG2 received - " & Mid(strHold,2)
  Case Else
      Debug.Pring "Unknown Message TAG received" 
  End Select
End Sub

Hope this can help you.

[Edited by Chris on 06-18-2000 at 09:55 PM]

[SteveCRM]

That helped a lot, but I still am having a really hard time with this. If it isn't too much trouble, can you show me what to do. Like make a demo. If you can't thats fine. Thanks for your help!

[Chris]

Hi SteveCRM, I just wrote a sample program & hope this can help you understand what I mention in the early post.

Code under frmClient.frm
Option Explicit
Private MsgType As Integer
Private Sub chkType_Click(Index As Integer)
MsgType = Index
End Sub

Private Sub cmdAction_Click()
'Setup Winsock Control
Winsock1.RemoteHost = "127.0.0.1"
Winsock1.RemotePort = 1234
Winsock1.Connect
End Sub

Private Sub BuildMessage()
Dim BodyMsg As String
Select Case MsgType
Case 0 'TAG 1 "A"
    BodyMsg = "A" & txtBodyMsg
Case 1 'TAG 2 "D"
    BodyMsg = "D" & txtBodyMsg
Case 2 'TAG 3 "C"
    BodyMsg = "C" & txtBodyMsg
Case 3 'unknow TAG "x"
    BodyMsg = "x" & txtBodyMsg
End Select

'Append the STX + ETX in the Body Message
BodyMsg = Chr(2) & BodyMsg & Chr(3)

'Send Message back to Server.
Winsock1.SendData BodyMsg
End Sub

Private Sub cmdSend_Click()
BuildMessage
End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
If Winsock1.State <> sckClosed Then Winsock1.Close
End Sub

Private Sub OptType_Click(Index As Integer)
MsgType = Index
End Sub

Private Sub Winsock1_Error(ByVal Number As Integer, Description As String, ByVal Scode As Long, ByVal Source As String, ByVal HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)
MsgBox "Error (" & Number & "), " & Description, vbExclamation + vbOKOnly
End Sub

Code under the frmServer.frm
Private Sub Winsock1_ConnectionRequest(ByVal requestID As Long)
If Winsock1.State <> sckClosed Then Winsock1.Close
Winsock1.Accept requestID
ShowData "Connection Establish with ID: " & requestID
End Sub

Private Sub ShowData(ByVal MyData As String)
txtRx = txtRx & MyData & vbCrLf
txtRx.SelStart = Len(txtRx)
End Sub

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
Dim ClientData As String
Dim Tmp As String
'Retrieve the data from WinSock Control
Winsock1.GetData ClientData, vbString

'Remove the STX and ETX
DoEvents
Do While Len(ClientData) <> 0
    Select Case Asc(ClientData)
    Case 2 'STX
        'reset the buffer
        Tmp = ""
    Case 3 'ETX
        'clear all the ClientData
        ClientData = ""
        Exit Do
    Case Else
        Tmp = Tmp & Mid(ClientData, 1, 1)
    End Select
    ClientData = Mid(ClientData, 2)
Loop

'Analyze the client's send data.
'Check Message TAG
Select Case Mid(Tmp, 1, 1)
Case "A" 'TAG 1
    ShowData "TAG 1 message received [A]"
Case "B" 'TAG 2
    ShowData "TAG 2 message received [D]"
Case "C" 'TAG 3
    ShowData "TAG 3 message received [C]"
Case "x" 'Unknown TAG
    ShowData "Unknown TAG message received [x]"
Case Else 'Empy message TAG
    ShowData "Unknown TAG message received [" & Mid(Tmp, 1, 1) & "]"
End Select
    
'Display the body message
ShowData "Body Message : " & Mid(Tmp, 2)

End Sub

If you need the sample program source file, do let me know & i'll send it to you.

[Edited by Chris on 06-18-2000 at 10:00 PM]

[SteveCRM]

Error, connection forcefully refused.

[SteveCRM]

Im sorry I don't understand much of this, could you send it to [email protected]? Thanks!