Winsock Examples

[MikkyThomeon]

I have often seen many ugly tutorials on the web where people use doevents in a loop while waiting for a response from the remote server. VB is event driven - and the winsock control has enough events to handle things without needing a loop.

The code below is part of a pop3 server class that uses the winsock control. Just thought this contribution could make a difference to sonebody looking to reduce the processor usage from 100% to almost nothing while their program sits in a loop doing nothing useful. Maybe more posts will spurn this thing on a bit... Any comments...?

Forward the request to the remote server if the command is an
'authentication command, otherwise get the popclient to process
'the command locally(as the popclient has already downloaded and
'filtered messages)
Private Sub mwsServer_DataArrival(ByVal bytesTotal As Long)
    Dim strRequest As String
    Dim strArg As String
    Dim strParts() As String
    Dim lngNumber As Long
    Dim PassThrough As POP3SyntaxEnum
    mwsServer.GetData strRequest, , bytesTotal
    
    'these commands are allowed to authenticate the
    'mail client on the network and to initiate
    'the client server communication
    PassThrough = POP_USER Or POP_PASS Or _
                    POP_QUIT Or POP_NOOP
    
    mpopState = MessageToCommand(strRequest)
    strParts = Split(strRequest, " ")
    If UBound(strParts) > 0 Then
        If IsNumeric(strParts(1)) Then
            lngNumber = CLng(strParts(1))
            mlngMessage = lngNumber
        Else
            strArg = strParts(1)
        End If
    End If
        
    If (mpopState And PassThrough) = mpopState Then
        mobjPOPClient.ProcessRequest strRequest
    Else
        'the other commands issued really act on the mail
        'store object which contains messages that have been
        'received by this server.
        Select Case mpopState
        Case mpopState = POP_RSET
            mlngListPtr = 0
            mstrList = mobjMessages.GetRSETMsg
            mwsServer.SendData mstrList(mlngListPtr)
            mlngListPtr = mlngListPtr + 1
        Case mpopState = POP_STAT
            mlngListPtr = 0
            mstrList = mobjMessages.GetSTATMsg
            mwsServer.SendData mstrList(mlngListPtr)
            mlngListPtr = mlngListPtr + 1
        Case mpopState = POP_DELE
            mlngListPtr = 0
            mstrList = mobjMessages.GetDELEMsg(lngNumber)
            mwsServer.SendData mstrList(mlngListPtr)
            mlngListPtr = mlngListPtr + 1
        Case mpopState = POP_LIST
            mlngListPtr = 0
            mstrList = mobjMessages.GetLISTMsg(lngNumber)
            mwsServer.SendData mstrList(mlngListPtr)
            mlngListPtr = mlngListPtr + 1
        Case mpopState = POP_RETR   'must be able to handle chunked data!!!
            mlngListPtr = 0
            mstrList = mobjMessages.GetRETRMsg(lngNumber)
            mwsServer.SendData mstrList(mlngListPtr)
            mlngListPtr = mlngListPtr + 1
        End Select
    End If
End Sub