Xojo Plugin

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. Xojo Plugin

Dim success As Boolean
success = False

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Dim sftp As New Chilkat.SFtp

// Set some timeouts, in milliseconds:
sftp.ConnectTimeoutMs = 5000
sftp.IdleTimeoutMs = 10000

// Connect to the SSH server.  
// The standard SSH port = 22
// The hostname may be a hostname or IP address.
Dim hostname As String
hostname = "sftp.example.com"
Dim port As Int32
port = 22
success = sftp.Connect(hostname,port)
If (success <> True) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

// Authenticate with the SSH server.  Chilkat SFTP supports
// both password-based authenication as well as public-key
// authentication.  This example uses password authenication.
success = sftp.AuthenticatePw("myLogin","myPassword")
If (success <> True) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

// After authenticating, the SFTP subsystem must be initialized:
success = sftp.InitializeSftp()
If (success <> True) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

// Open a remote file for writing on the SSH server.
// If the file already exists, it is overwritten.
// (Specify "createNew" instead of "createTruncate" to
// prevent overwriting existing files.)
Dim handle As String
handle = sftp.OpenFile("big.zip","writeOnly","createTruncate")
If (sftp.LastMethodSuccess <> True) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

// We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
// to the SFTP server.
Dim localFilePath As String
localFilePath = "qa_data/zips/big.zip"

// Rather than uploading in one shot, we'll read the local file in chunks
// and upload a chunk at a time.
Dim fac As New Chilkat.FileAccess

success = fac.OpenForRead(localFilePath)
If (success = False) Then
    success = sftp.CloseHandle(handle)
    System.DebugLog(fac.LastErrorText)
    Return
End If

// If we were to split the local file into 128K chunks, how many chunks (blocks) would
// we have, including the last partial block?
Dim blockSize As Int32
blockSize = 131072
Dim numBlocks As Int32
numBlocks = fac.GetNumBlocks(blockSize)
System.DebugLog("Number of blocks = " + Str(numBlocks))

Dim bd As New Chilkat.BinData
Dim i As Int32
i = 0
While i < numBlocks
    // Read the Nth block, which gets appended to the bd.  (which means
    // we must clear the contents of bd before the next iteration)
    success = fac.ReadBlockBd(i,blockSize,bd)
    If (success = False) Then
        success = sftp.CloseHandle(handle)
        System.DebugLog(fac.LastErrorText)
        Return
    End If

    // Upload this block to the open remote file.
    success = sftp.WriteFileBd(handle,bd)
    If (success = False) Then
        System.DebugLog(sftp.LastErrorText)
        Return
    End If

    // Clear the contents for the next iteration.
    success = bd.Clear()

    i = i + 1
Wend

// Close the local file.
fac.FileClose 

// -----------------------------------------------------------------------------
// This is important.  You must close the handle on the server.
// Otherwise open handles will accumulate on the server until eventually a limit
// is reached and the server will fail on a call to OpenFile.
// -----------------------------------------------------------------------------

// Close the remote file handle on the server.
success = sftp.CloseHandle(handle)
If (success <> True) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

System.DebugLog("Success.")