Monitoring ftp file download progress in VB

Question

I have this working fine -

Using client As New Ftp()
    client.Connect("OnlineTarget")
    client.Login("Login", "Password")
    client.Download(TargetFile, MyFolder & "\" & TargetFile)
    client.Close()
End Using

However I need to monitor and show the progress of large file downloads. I have read the "Ftp Download and Upload Progress Event" blog item but I still need some advice to get my ProgressBar operating. I see it needs to be a separate thread, so please can you explain (in VB) what I need to do?

Thanks

Answer 1

If you want to track progress you need to subscribe to Progress event.

Take a look at this sample:

Imports System.Windows.Forms
Imports System.IO
Imports Limilabs.FTP.Client
Imports System.Threading

Public Class MainForm
    Inherits Form
    Private ReadOnly _btnUpload As Button
    Private ReadOnly _progressBar As ProgressBar
    Private ReadOnly _listBox As ListBox

    Public Sub New()
        _btnUpload = New Button()
        _btnUpload.Text = "Upload"
        AddHandler _btnUpload.Click, AddressOf btnUpload_Click
        _progressBar = New ProgressBar()
        _listBox = New ListBox()
        _btnUpload.Dock = DockStyle.Bottom
        _listBox.Dock = DockStyle.Fill
        _progressBar.Dock = DockStyle.Top
        Me.Controls.Add(_listBox)
        Me.Controls.Add(_progressBar)
        Me.Controls.Add(_btnUpload)
    End Sub

    Private Sub Ftp_Progress(ByVal sender As Object, ByVal e As
ProgressEventArgs)
        Me.BeginInvoke(Sub()
                           _progressBar.Value = CInt(e.Percentage)
                           _progressBar.Update()
                           _listBox.Items.Add(e.Percentage)
                       End Sub)
        Thread.Sleep(TimeSpan.FromSeconds(0.1))
    End Sub

    Private Sub btnUpload_Click(ByVal sender As Object, ByVal e As EventArgs)
        Dim thread As New Thread(AddressOf BackgroundThread)
        thread.Start()
    End Sub

    Private Sub BackgroundThread()

        Try
            Using ftp As New Ftp()
                AddHandler ftp.Progress, AddressOf Ftp_Progress
                ftp.Connect("localhost")
                Log("Connected. Logging in...")
                ftp.Login("ftptest", "cypher")
                Log("Logged in.")
                For Each fileName As String In Directory.GetFiles(".")
                    Log("Uploading: " + fileName)


                    ftp.Upload(Path.GetFileName(fileName), fileName)
                Next
                ftp.Close()
            End Using
        Catch ex As Exception
            Log(ex.ToString())
        End Try
    End Sub

    Private Sub Log(ByVal entry As String)
        Me.BeginInvoke(Function() _listBox.Items.Add(entry))
    End Sub

    <STAThread()> _
    Public Shared Sub Main()
        Application.EnableVisualStyles()
        Application.SetCompatibleTextRenderingDefault(False)
        Application.Run(New MainForm())
    End Sub
End Class

Comments

Thank you, very helpful - I will get into this next.
NickB

---

Hello again,
Thanks for this - well understood. In one instance however I have to download a single large file (an occasional App update of 10MB+), and I want to display the percentage received with a 1-100 progress bar as the download progresses. The answer above works fine to monitor successive discrete file ops within a series, but how do I monitor and show the receipt progress of one large file as it is downloaded?

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Ftp class has 2 events: Progress and BatchProgress. First is  to monitor progress on the single file, second to monitor where in the batch the process currently is.

The sample above is using Progress event - this is the one you are interested in.

---

Excellent, thank you - working fine.

One question: if the user wants to kill a large single-file up/download in mid-process your advice to someone was:

"You simply need to use Ftp.Abort method. It is thread safe. You can use it from any thread."

but once the ftp.Download(remote-address) operation is in progress - where would you put this Ftp.Abort instruction to intercept the working thread and safely stop that process? Sorry if this is a dumb question, but I can't see how to make it work.

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Put in in the method that is invoked when user cancels the transfer.

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But this will be outside the thread, where you can't refer to the ftp operation that is running in the thread -

    Private Sub BtnDownload_Click(ByVal sender As Object, ByVal e As EventArgs) _
    Handles _BtnDownload.Click
        Dim thread As New Thread(AddressOf BackgroundThread)
        thread.Start()
    End Sub

    Private Sub BackgroundThread()
        Try
            Using ftp As New Ftp()
                ftp.Connect("ftp-loc")
                ftp.Login("login", "password")
                ftp.Download(path-of-one-big-file)
                ftp.Close()
            End Using
        Catch ex As Exception
            
        End Try
    End Sub

    Private Sub Btn_Stop_Click(sender As System.Object, e As System.EventArgs) _
    Handles Btn_Stop.Click
        ' What goes here? Not Ftp.Abort() as this can't work ...
    End Sub

??

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Please ask a separate question.