ftp callback example C#

9 Jan 2006 4:27 AM

marfi95

Hello all,

I've looked all over the internet and am not having much luck. I'm
trying to implement a callback out of a ftpgetfile method so I can give
my users an indication of the progress of their download since the
files are pretty big. I'm having problems setting up the callback
using the InternetSetStatusCallback method. I found a VB6 version, but
having all kinds of problems converting it to C#. I'm new to C#, so
I'm not all that familiar with event handlers, but I don't understand
how to use InternetSetStatusCallback or what it passes to the callback
method.

Does anyone have an example of this in C# or vb.net ?

Any help would be most appreciated.

Thanks,
Mark

10 Jan 2006 3:50 PM

Dragon

Hello Mark,

Take a look at this:

~
#Region "Declarations"
    Friend Declare Function InternetSetStatusCallback Lib "wininet.dll"
( _
        ByVal hInternet As IntPtr, _
        ByVal lpfnInternetCallback As INTERNET_STATUS_CALLBACK _
    ) As Integer

    Friend Delegate Sub INTERNET_STATUS_CALLBACK( _
        ByVal hInternet As IntPtr, _
        ByRef dwContext As Integer, _
        ByVal dwInternetStatus As InternetStatus, _
        ByRef lpvStatusInformation As InternetState, _
        ByVal dwStatusInformationLength As Integer _
    )

    Friend Enum InternetStatus
        ResolvingName = 10
        NameResolved = 11
        ConnectingToServer = 20
        ConnectedToServer = 21
        SendingRequest = 30
        RequestSent = 31
        ReceivingResponse = 40
        ResponseReceived = 41
        CtlResponseReceived = 42
        Prefetch = 43
        ClosingConnection = 50
        ConnectionClosed = 51
        HandleCreated = 60
        HandleClosing = 70
        RequestComplete = 100
        Redirect = 110
        IntermediateResponse = 120
        StateChange = 200
    End Enum

    Friend Enum InternetState
        Connected = &H1
        Disconnected = &H2
        DisconnectedByUser = &H10
        Idle = &H100
        Busy = &H200
    End Enum
#End Region
    Protected Overrides Sub OnClick(ByVal e As System.EventArgs)
        MyBase.OnClick(e)
        InternetSetStatusCallback(hInternet, AddressOf
InternetSetStatusCallback)
    End Sub

    Friend Sub InternetStatusCallback( _
        ByVal hInternet As IntPtr, _
        ByRef dwContext As Integer, _
        ByVal dwInternetStatus As InternetStatus, _
        ByRef lpvStatusInformation As InternetState, _
        ByVal dwStatusInformationLength As Integer _
    )
        REM Handle callback
    End Sub
~

It wasn't tested but should work.
Hope it will,
Roman

10 Jan 2006 4:48 PM

marfi95

Thanks for the reply. I'll give it a try.

Temporarily, what I did was change to code to not use a FTPGetFile, but
InternetReadFile instead since I have control over the buffer size.
My preference was to use FTPGetFile, so I'll give this is a shot.
Thanks again.