I save to a file by adding a FileStream variable to the WebRequestState, then initialize it with something like
outFile = new FileStream(fileName, FileMode.Create, FileAccess.Write, FileShare.None);
in the ctor and a
reqState.outFile.Write(reqState.bufferRead, 0, bytesRead);
into the ReadCallback() function.

Works fine, even with doing multiple consecutive downloads (the labels and progress bar don’t handle it, but that’s easy to fix).

Thanks a lot for this article. It’s been invaluable in understanding the shady depths of asynchronous execution of HttpWebRequest’s in .NET.

Keep up the awesome work!

Cheers

You might also look at this articles:
http://www.codeproject.com/KB/aspnet/Download_Track.aspx

or take a look at the All-In-One Code Framework for ASP.NET, at:
http://1code.codeplex.com/wikipage?title=ASP.NET

any help will be appreciated

Only one problem, no send zip files…
Can you help-me? I send total bytes in ftp, but my file is damaged…more people have the same problem but any solutions…

Dim reqState As WebRequestState = DirectCast((asyncResult.AsyncState), WebRequestState)
Dim requestStream As Stream = reqState.streamResponse

Dim stream As FileStream = reqState.filestreamup
Dim bytesRead As Integer = stream.EndRead(asyncResult)

If bytesRead > 0 Then

Dim buffer() As Byte = New Byte(bytesRead) {}
requestStream.Write(buffer, 0, bytesRead)

‘ reqState.uploadfile(reqState.iforloop, bytesRead, False, reqState.bufferRead, requestStream)
reqState.iforloop = CInt(reqState.iforloop + 1)
‘ Report some progress, including total # bytes read, % complete, and transfer rate
reqState.bytesRead += bytesRead
Dim pctComplete As Double = (CDbl(reqState.bytesRead) / CDbl(reqState.totalBytes)) * 100.0F
‘ Note: bytesRead/totalMS is in bytes/ms. Convert to kb/sec.
Dim totalTime As TimeSpan = DateTime.Now – reqState.transferStart
Dim kbPerSec As Double = (reqState.bytesRead * 1000.0F) / (totalTime.TotalMilliseconds * 1024.0F)
reqState.progCB(reqState.bytesRead, pctComplete, kbPerSec)
‘ Kick off another read

Dim ar As IAsyncResult = stream.BeginRead(reqState.bufferRead, 0, BUFFER_SIZE, New AsyncCallback(AddressOf ReadCallback1), reqState)

Exit Sub
Else

I you can help-me, I apologise….

In this link, have code for upload async, but the in true, the upload is not async because use do while…

Here I think that is write file here…
Private Sub teste1(ByVal lopps As Integer, ByVal bufer As Integer, ByVal valida As Boolean, ByVal bufferRead As Byte(), ByVal reqstated As FileStream)
If Me.InvokeRequired Then
Dim del As New teste1Delegate(AddressOf teste1)
Me.Invoke(del, New Object() {lopps, bufer, valida, bufferRead, reqstated})
Else
Dim buffer As Byte() = New Byte(bufer) {}
If lopps = “0″ Then
‘ Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)
‘FileStreamm.Write(bufferRead, 0, bufer)
Else
If valida = True Then
‘ FileStreamm.Close()
Else
‘ FileStreamm.Write(bufferRead, 0, bufer)
End If
End If
End If
End Sub

Here, I get de file size and pass ithis to reqstate.toltalbytes…

Private Sub sendfile()
Try

conecte.Text = “Conectado…”
lblDownloadComplete.Visible = False
Dim req As WebRequest = Nothing
Dim reqState As WebRequestState = Nothing
‘Dim buffer As Byte() = New Byte(1448) {}
reqState = New FtpWebRequestState(BUFFER_SIZE)
Dim fileURI As New Uri(txtURI.Text & “/” & TextBox2.Text)
req = DirectCast(FtpWebRequest.Create(fileURI), FtpWebRequest)
req.Credentials = New NetworkCredential(campousuario.Text, camposenha.Text)
DirectCast(req, FtpWebRequest).KeepAlive = False
DirectCast(req, FtpWebRequest).Method = WebRequestMethods.Ftp.UploadFile
reqState.FTPMethod = WebRequestMethods.Ftp.UploadFile

Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)
reqState.totalBytes = FileStreamm.Length
reqState.streamResponse = FileStreamm

If req IsNot Nothing Then
reqState.fileURI = fileURI
reqState.respInfoCB = New ResponseInfoDelegate(AddressOf SetResponseInfo)
reqState.progCB = New ProgressDelegate(AddressOf Progress)
reqState.doneCB = New DoneDelegate(AddressOf Done)
reqState.getlist1 = New teste1Delegate(AddressOf teste1)
reqState.transferStart = DateTime.Now

reqState.request = req

Dim result As IAsyncResult = DirectCast(req.BeginGetResponse(New AsyncCallback(AddressOf ReadCallback1), reqState), IAsyncResult)

‘ Start the asynchronous request.

‘ End If

‘ While True
‘ bytesread = FileStream.Read(buffer, 0, buffer.Length)
‘ MsgBox(bytesread.ToString)
‘ If bytesread = 0 Then
‘Exit While
‘ Else
‘ requestStream.Write(buffer, 0, bytesread)
End If
‘ End While
Catch ex As Exception
MsgBox(String.Format(“EXC in button1_Click(): {0}”, ex.Message))
End Try
End Sub

Here I get the first bytes of file…
Public Shared Sub ReadCallback1(ByVal asyncResult As IAsyncResult)
Try
Dim reqState As WebRequestState = DirectCast((asyncResult.AsyncState), WebRequestState)
Dim req As WebRequest = reqState.request
Dim statusDescr As String = “”
Dim contentLength As String = “”

‘ Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)

Dim resp As FtpWebResponse = DirectCast((req.EndGetResponse(asyncResult)), FtpWebResponse)
reqState.response = resp

statusDescr = resp.StatusDescription
‘ reqState.totalBytes = FileStreamm.Length
‘ # bytes
contentLength = reqState.totalBytes

‘ Get this info back to the GUI — max # bytes, so we can do progress bar
If statusDescr “” Then

reqState.respInfoCB(statusDescr, contentLength)
End If

‘ Dim responseStream As Stream = FileStreamm
Dim responseStream As Stream = reqState.streamResponse
reqState.streamResponse = responseStream

‘ Begin reading contents of the response data

Dim ar As IAsyncResult = responseStream.BeginRead(reqState.bufferRead, 0, BUFFER_SIZE, New AsyncCallback(AddressOf ReadCallback2), reqState)
Catch ex As Exception
MsgBox(String.Format(“EXC in ReadCallback(): {0}”, ex.Message))
End Try
End Sub
And here I make a loop…call the teste1 fo write file…
How Can I finish this code for finaly write in ftp?

Public Shared Sub ReadCallback2(ByVal asyncResult As IAsyncResult)

Try
Dim reqState As WebRequestState = DirectCast((asyncResult.AsyncState), WebRequestState)
Dim responseStream As Stream = reqState.streamResponse
‘ Get results of read operation
Dim bytesRead As Integer = responseStream.EndRead(asyncResult)

Dim buffer As Byte() = New Byte(bytesRead) {}

reqState.getlist1(reqState.iforloop, bytesRead, False, reqState.bufferRead, reqState.streamResponse)
reqState.iforloop = CInt(reqState.iforloop + 1)
‘ Got some data, need to read more
If bytesRead > 0 Then
‘ Report some progress, including total # bytes read, % complete, and transfer rate
reqState.bytesRead += bytesRead
Dim pctComplete As Double = (CDbl(reqState.bytesRead) / CDbl(reqState.totalBytes)) * 100.0F
‘ Note: bytesRead/totalMS is in bytes/ms. Convert to kb/sec.
Dim totalTime As TimeSpan = DateTime.Now – reqState.transferStart
Dim kbPerSec As Double = (reqState.bytesRead * 1000.0F) / (totalTime.TotalMilliseconds * 1024.0F)
reqState.progCB(reqState.bytesRead, pctComplete, kbPerSec)
‘ Kick off another read
Dim ar As IAsyncResult = responseStream.BeginRead(reqState.bufferRead, 0, BUFFER_SIZE, New AsyncCallback(AddressOf ReadCallback2), reqState)
Exit Sub
Else
MsgBox(“dentro do else”)
reqState.getlist1(reqState.iforloop, bytesRead, True, reqState.bufferRead, reqState.streamResponse)
‘Dim ms As FileStream = New FileStream(“d:\testestream.doc”, FileMode.Create)
‘ ms.Write(reqState.bufferRead, 0, BUFFER_SIZE)
‘ reqState.getlist(reqState.iforloop, bytesRead, True, reqState.bufferRead)
‘ responseStream.Write(, 0, BUFFER_SIZE)
‘memStream.Close()

‘ EndRead returned 0, so no more data to be read
responseStream.Close()
reqState.response.Close()
reqState.doneCB()
End If

Catch ex As Exception
MsgBox(String.Format(“EXC in ReadCallback(): {0}”, ex.Message))
End Try
End Sub

Here I think that is write file here…
Private Sub teste1(ByVal lopps As Integer, ByVal bufer As Integer, ByVal valida As Boolean, ByVal bufferRead As Byte(), ByVal reqstated As FileStream)
If Me.InvokeRequired Then
Dim del As New teste1Delegate(AddressOf teste1)
Me.Invoke(del, New Object() {lopps, bufer, valida, bufferRead, reqstated})
Else
Dim buffer As Byte() = New Byte(bufer) {}
If lopps = “0″ Then
‘ Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)
‘FileStreamm.Write(bufferRead, 0, bufer)
Else
If valida = True Then
‘ FileStreamm.Close()
Else
‘ FileStreamm.Write(bufferRead, 0, bufer)
End If
End If
End If
End Sub

Here, I get de file size and pass ithis to reqstate.toltalbytes…

Private Sub sendfile()
Try

conecte.Text = “Conectado…”
lblDownloadComplete.Visible = False
Dim req As WebRequest = Nothing
Dim reqState As WebRequestState = Nothing
‘Dim buffer As Byte() = New Byte(1448) {}
reqState = New FtpWebRequestState(BUFFER_SIZE)
Dim fileURI As New Uri(txtURI.Text & “/” & TextBox2.Text)
req = DirectCast(FtpWebRequest.Create(fileURI), FtpWebRequest)
req.Credentials = New NetworkCredential(campousuario.Text, camposenha.Text)
DirectCast(req, FtpWebRequest).KeepAlive = False
DirectCast(req, FtpWebRequest).Method = WebRequestMethods.Ftp.UploadFile
reqState.FTPMethod = WebRequestMethods.Ftp.UploadFile

Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)
reqState.totalBytes = FileStreamm.Length
reqState.streamResponse = FileStreamm

If req IsNot Nothing Then
reqState.fileURI = fileURI
reqState.respInfoCB = New ResponseInfoDelegate(AddressOf SetResponseInfo)
reqState.progCB = New ProgressDelegate(AddressOf Progress)
reqState.doneCB = New DoneDelegate(AddressOf Done)
reqState.getlist1 = New teste1Delegate(AddressOf teste1)
reqState.transferStart = DateTime.Now

reqState.request = req

Dim result As IAsyncResult = DirectCast(req.BeginGetResponse(New AsyncCallback(AddressOf ReadCallback1), reqState), IAsyncResult)

‘ Start the asynchronous request.

‘ End If

‘ While True
‘ bytesread = FileStream.Read(buffer, 0, buffer.Length)
‘ MsgBox(bytesread.ToString)
‘ If bytesread = 0 Then
‘Exit While
‘ Else
‘ requestStream.Write(buffer, 0, bytesread)
End If
‘ End While
Catch ex As Exception
MsgBox(String.Format(“EXC in button1_Click(): {0}”, ex.Message))
End Try
End Sub

Here I get the first bytes of file…
Public Shared Sub ReadCallback1(ByVal asyncResult As IAsyncResult)
Try
Dim reqState As WebRequestState = DirectCast((asyncResult.AsyncState), WebRequestState)
Dim req As WebRequest = reqState.request
Dim statusDescr As String = “”
Dim contentLength As String = “”

‘ Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)

Dim resp As FtpWebResponse = DirectCast((req.EndGetResponse(asyncResult)), FtpWebResponse)
reqState.response = resp

statusDescr = resp.StatusDescription
‘ reqState.totalBytes = FileStreamm.Length
‘ # bytes
contentLength = reqState.totalBytes

‘ Get this info back to the GUI — max # bytes, so we can do progress bar
If statusDescr “” Then

reqState.respInfoCB(statusDescr, contentLength)
End If

‘ Dim responseStream As Stream = FileStreamm
Dim responseStream As Stream = reqState.streamResponse
reqState.streamResponse = responseStream

‘ Begin reading contents of the response data

Dim ar As IAsyncResult = responseStream.BeginRead(reqState.bufferRead, 0, BUFFER_SIZE, New AsyncCallback(AddressOf ReadCallback2), reqState)
Catch ex As Exception
MsgBox(String.Format(“EXC in ReadCallback(): {0}”, ex.Message))
End Try
End Sub
And here I make a loop…call the teste1 fo write file…
How Can I finish this code for finaly write in ftp?

Private Sub sendfile()
Try

conecte.Text = “Conectado…”
lblDownloadComplete.Visible = False
Dim req As WebRequest = Nothing
Dim reqState As WebRequestState = Nothing
‘Dim buffer As Byte() = New Byte(1448) {}
reqState = New FtpWebRequestState(BUFFER_SIZE)
Dim fileURI As New Uri(txtURI.Text & “/” & TextBox2.Text)
req = DirectCast(FtpWebRequest.Create(fileURI), FtpWebRequest)
req.Credentials = New NetworkCredential(campousuario.Text, camposenha.Text)
DirectCast(req, FtpWebRequest).KeepAlive = False
DirectCast(req, FtpWebRequest).Method = WebRequestMethods.Ftp.UploadFile
reqState.FTPMethod = WebRequestMethods.Ftp.UploadFile

If req IsNot Nothing Then
reqState.fileURI = fileURI
reqState.respInfoCB = New ResponseInfoDelegate(AddressOf SetResponseInfo)
reqState.progCB = New ProgressDelegate(AddressOf Progress)
reqState.doneCB = New DoneDelegate(AddressOf Done)
‘ reqState.getlist = New testeDelegate(AddressOf teste)
reqState.transferStart = DateTime.Now

reqState.request = req

Dim result As IAsyncResult = DirectCast(req.BeginGetResponse(New AsyncCallback(AddressOf ReadCallback1), reqState), IAsyncResult)

‘ Start the asynchronous request.

‘ End If

‘ While True
‘ bytesread = FileStream.Read(buffer, 0, buffer.Length)
‘ MsgBox(bytesread.ToString)
‘ If bytesread = 0 Then
‘Exit While
‘ Else
‘ requestStream.Write(buffer, 0, bytesread)
End If
‘ End While
Catch ex As Exception
MsgBox(String.Format(“EXC in button1_Click(): {0}”, ex.Message))
End Try
End Sub

Public Shared Sub ReadCallback1(ByVal asyncResult As IAsyncResult)
Try
Dim reqState As WebRequestState = DirectCast((asyncResult.AsyncState), WebRequestState)
Dim req As WebRequest = reqState.request
Dim statusDescr As String = “”
Dim contentLength As String = “”

Dim FileStreamm As FileStream = File.Open(“d:\rel1.xls”, FileMode.Open)

Dim resp As FtpWebResponse = DirectCast((req.EndGetResponse(asyncResult)), FtpWebResponse)
reqState.response = resp

statusDescr = resp.StatusDescription
reqState.totalBytes = FileStreamm.Length
‘ # bytes
contentLength = reqState.totalBytes

‘ Get this info back to the GUI — max # bytes, so we can do progress bar
If statusDescr “” Then

reqState.respInfoCB(statusDescr, contentLength)
End If

Dim responseStream As Stream = FileStreamm
reqState.streamResponse = responseStream

‘ Begin reading contents of the response data

Dim ar As IAsyncResult = responseStream.BeginRead(reqState.bufferRead, 0, BUFFER_SIZE, New AsyncCallback(AddressOf ReadCallback2), reqState)
Catch ex As Exception
MsgBox(String.Format(“EXC in ReadCallback(): {0}”, ex.Message))
End Try
End Sub
Public Shared Sub ReadCallback2(ByVal asyncResult As IAsyncResult)

Try
Dim reqState As WebRequestState = DirectCast((asyncResult.AsyncState), WebRequestState)
Dim responseStream As Stream = reqState.streamResponse
‘ Get results of read operation
Dim bytesRead As Integer = responseStream.EndRead(asyncResult)

Dim buffer As Byte() = New Byte(bytesRead) {}
responseStream.Write(buffer, 0, bytesRead)

‘ Got some data, need to read more
If bytesRead > 0 Then
‘ Report some progress, including total # bytes read, % complete, and transfer rate
reqState.bytesRead += bytesRead
Dim pctComplete As Double = (CDbl(reqState.bytesRead) / CDbl(reqState.totalBytes)) * 100.0F
‘ Note: bytesRead/totalMS is in bytes/ms. Convert to kb/sec.
Dim totalTime As TimeSpan = DateTime.Now – reqState.transferStart
Dim kbPerSec As Double = (reqState.bytesRead * 1000.0F) / (totalTime.TotalMilliseconds * 1024.0F)
reqState.progCB(reqState.bytesRead, pctComplete, kbPerSec)
‘ Kick off another read
Dim ar As IAsyncResult = responseStream.BeginRead(reqState.bufferRead, 0, BUFFER_SIZE, New AsyncCallback(AddressOf ReadCallback2), reqState)
Exit Sub
Else
MsgBox(“dentro do else”)
‘Dim ms As FileStream = New FileStream(“d:\testestream.doc”, FileMode.Create)
‘ ms.Write(reqState.bufferRead, 0, BUFFER_SIZE)
‘ reqState.getlist(reqState.iforloop, bytesRead, True, reqState.bufferRead)
‘ responseStream.Write(, 0, BUFFER_SIZE)
‘memStream.Close()

‘ EndRead returned 0, so no more data to be read
responseStream.Close()
reqState.response.Close()
reqState.doneCB()
End If

Catch ex As Exception
MsgBox(String.Format(“EXC in ReadCallback(): {0}”, ex.Message))
End Try
End Sub

This code upload a file in FTP but not async.

Else
ListBox1.Items.Add(BUFFER_SIZE.ToString)

Dim buffer As Byte() = New Byte(bufer) {}

ListBox2.Items.Add(bufer.ToString)

If lopps = “0″ Then
memstream = New FileStream(“d:\testestream.doc”, FileMode.Create)
memstream.Write(buffer, 0, bufer)
Else
If valida = True Then
memstream.Close()
Else
memstream.Write(buffer, 0, bufer)
End If
End If
End If
End Sub

But, I have one problem, my doc is a word document but not recognised, I receive a messenge box question me if I want convert my doc…

Sorry my english…
I like much your code…very cool…

But I have a problem to save the doenload file.
I dont understanding all code because I am study and I have difficult.

Can you show mw how I can save file? Not programing…Only any step that I need…

Thanks…

Excellent question! I should have been more clear in the code, or added a comment to this effect: In the Stream.Read and Stream.BeginRead methods, the Offset parameter specifies an offset into the buffer that you’re writing into (1st parameter), rather than into the stream. You don’t need to specify an offset into the stream, because when you read from a stream, the Stream object automatically advances the position into the source buffer after each Read operation. In other words, you can just do a bunch of consecutive Stream.Read operations and you’ll automatically march through the data in the stream.

Sean

with 0 as offset parameter ? should it be the actual offset of current reading block ?

thanx very much

This is just what i was looking. You did mention you have not implemented following feature
“Allow the user to actually store the data to a local file ”

Can you advise
a.

which function i can open the file and save the asynchronous bytes.

b. How can i cancel the download

Any ideas? If I force the request to http 1.0, the server won’t chunk the response, and things work great, but I really don’t like that work-around.

Maybe if you shared some more details on what about the example code doesn’t work for you, I could help you.

Sean

Nothing jumps out at me, but I think I’d try swapping out a few different things to see if you get consistent behavior, e.g.

- Do you get the same error, no matter the FTP site and file?
- Try a shorter path in FTP url and simpler filename
- Have you tried a file that just requires anonymous access, rather than using a specific user?
- If using your own FTP server, try a simpler password, e.g. w/no special characters
- Any sort of firewall or security software that would be blocking port 21? Try turning opening up access to port 21, or turning everything temporarily off
- If you have access to the server, what do the logs on the server-side say?
- Try running as a privileged (e.g. Administrators group) user
- Try using a network monitor or packet sniffing tool to look at the actual traffic and see if you can see the difference between your working and non-working situation
- Everything in the FtpWebRequest is really the same, i.e. the only difference between fail/no-fail is GetResponse vs. BeginGetResponse?

I’d be very interested to hear what you run into..

Great site and great explanation. I’ve implemented your code near verbatum, with the only changes being the default text values for the ftp server / file name and the credentials. Without exception, as the BeginGetResponse is started, I get a 550 error (File Unavailable, no access).

I am able to download the file with synchronus code and any standard FTP client, but no matter what form of Async code I use (i.e. BeginGetResponse, yours and other examples), I always get this error. I’ve tried umpteen different combos of the file name / URI, but I get the same thing every time.

Any ideas?

Thanks, Sean!

Carl

HTTP:
http://mschnlnine.vo.llnwd.net/d1/pdc08/PPTX/BB01.pptx

http://www.microsoft.com/downloads/info.aspx?na=90&p=&SrcDisplayLang=en&SrcCategoryId=&SrcFamilyId=6ef71415-646f-4279-8b6b-193435ab2d80&u=http%3a%2f%2fdownload.microsoft.com%2fdownload%2f9%2f9%2f2%2f992ba2c9-21fe-4f7c-98dc-b830c14963a6%2fIE8-WindowsVista-x86-ENU.exe

(or http://tinyurl.com/5rpcsd)

(The 2nd one is the IE8 beta for Vista).

FTP:

ftp://ftp.uci.edu/mirrors/fedora/linux/releases/10/Fedora/i386/iso/Fedora-10-i386-disc1.iso