How to download from ftp without form lag vb.net

Question

I just made a ftp chat in vb.net and it update message from a file from a ftp server so i add a timer with interval 1000 with this code

 Try
            Dim client As New Net.WebClient
            client.Credentials = New Net.NetworkCredential("fnet_1355****", "******")
            RichTextBox1.Text = client.DownloadString("ftp://185.**.***.**/htdocs/chat.txt")
        Catch ex As Exception
        End Try

so .. the file is downloaded and it update the text successful but there is a problem .. every time he download the form have a bit lag ... and i dont like that :D what i can do ?

You need to run the download operation on different thread to avoid UI thread lag. — Arpit, Aug 29 '13 at 15:07
possible duplicate of [How to use the WebClient.DownloadDataAsync() method in this context?](http://stackoverflow.com/questions/1585985/how-to-use-the-webclient-downloaddataasync-method-in-this-context) — Yuriy Galanter, Aug 29 '13 at 15:10
FTP chat. Wow. Should have entered that in the DWTF contest. — , Aug 29 '13 at 15:17
@BcComputersRO Check my Ans. It is doing same but using the async method. — Arpit, Aug 29 '13 at 15:36

Arpit · Accepted Answer · 2013-08-29T15:48:52.737

3

RichTextBox1.Text = client.DownloadString("ftp://185.**.***.**/htdocs/chat.txt")

Instead of this try async method.

client.DownloadStringAsync(new Uri("ftp://185.**.***.**/htdocs/chat.txt"))

and then handle download string completed event.

Sample Code

client.DownloadStringAsync(new Uri("ftp://185.**.***.**/htdocs/chat.txt"));
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted); 

void client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
     RichTextBox1.Text =e.Result;
}

You can also add progress indicator by handling progress change event.

edited Aug 29 '13 at 15:48

answered Aug 29 '13 at 15:12

Arpit

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i got this error on client.DownloadStringAsync("ftp://185.**.***.**/htdocs/chat.txt") ---> Value of type string cannot be converted to uri ... – Bc Computers RO Aug 29 '13 at 15:44
With a little code modification i got it Thank you , it's work perfectrly ! – Bc Computers RO Aug 29 '13 at 20:11

Parimal Raj · Answer 2 · 2013-08-29T15:15:55.013

The best way you can do it would be to use ThreadPool provided by the Framework to I/O bound operation on different thread.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    ThreadPool.QueueUserWorkItem(New WaitCallback(AddressOf DownloadFromFtp))
End Sub

Private Sub DownloadFromFtp()
    Try
        Dim client As New Net.WebClient
        client.Credentials = New Net.NetworkCredential("fnet_1355****", "******")
        Dim response As String = client.DownloadString("ftp://185.**.***.**/htdocs/chat.txt")

        Me.Invoke(New MethodInvoker(Function() RichTextBox1.Text = response))
    Catch ex As Exception
    End Try
End Sub

Why? When WebClient has its own Async methods – Yuriy Galanter Aug 29 '13 at 15:16 — Yuriy Galanter, Aug 29 '13 at 15:16

score 0 · Answer 3 · answered Aug 29 '13 at 16:30

This program was the exact one I design before i learned PHP.

Here try this:

Dim thrd As Threading.Thread
Dim tmr As New Timer
Dim tempstring As String
Private Sub thread_start()
    thrd = New Threading.Thread(Sub() check_for_changes())
    tmr.Interval = 50
    AddHandler tmr.Tick, AddressOf Tick
    tmr.Enabled = True
    tmr.Start()
    thrd.Start()
End Sub
Private Sub Tick(sender As Object, e As EventArgs)
    If Not thrd.IsAlive Then
        tmr.Stop() : tmr.Enabled = False
        RichTextBox1.Text = tempstring
    End If
End Sub
Private Sub check_for_changes()
    Try
        Dim client As New Net.WebClient
        client.Credentials = New Net.NetworkCredential("fnet_1355****", "******")
        tempstring = client.DownloadString("ftp://185.**.***.**/htdocs/chat.txt")
    Catch ex As Exception
    End Try
End Sub

Hope It Helps.

Remember, you have to use the 'thread_start' function, not 'check_for_changes' itself. — aliqandil, Aug 29 '13 at 16:35

How to download from ftp without form lag vb.net

3 Answers3