Running WinSCP from VB.NET

WinSCP .NET assembly mostly deprecates techniques demostrated in this article. Using the assembly is now preferred approach for advanced automation tasks with WinSCP.

Following is more robust alternative to simple example contained in guide to SFTP file transfers in .NET.

Imports System
Imports System.IO
Imports System.Diagnostics
Imports System.Xml
Imports System.Xml.XPath
Imports System.Configuration.ConfigurationManager
 
Public Class SFTP
    ' SFTP support, built on WinSCP
    Public Shared Function PutSFTP(ByRef filename As String, ByRef remotehost As String, ByRef username As String, ByRef password As String,
                           Optional outfilename As String = Nothing, Optional output As String = Nothing,
                           Optional ByRef errmsg As String = Nothing) As Boolean
 
        ' Run hidden WinSCP process
        Dim winscp As Process = New Process()
        Dim logname As String = Path.ChangeExtension(Path.GetTempFileName, "xml")
        With winscp.StartInfo
            ' SFTPExecutable needs to be defined in app.config to point to winscp.com
            Try
                .FileName = AppSettings("SFTPExecutable")
                If .FileName Is Nothing OrElse .FileName.Length = 0 Then Throw (New Exception("from PutSFTP: SFTPExecutable not set in config file."))
            Catch ex As Exception
                errmsg = ex.Message
                Return False
            End Try
            .Arguments = "/xmllog=" + logname
            .UseShellExecute = False
            .RedirectStandardInput = True
            .RedirectStandardOutput = True
            .CreateNoWindow = True
        End With
        Try
            winscp.Start()
        Catch ex As Exception
            errmsg = "from PutSFTP:  Could not run the WinSCP executable " & winscp.StartInfo.FileName & Environment.NewLine & ex.Message
            Return False
        End Try
 
        ' Feed in the scripting commands
        With winscp.StandardInput
            .WriteLine("option batch abort")
            .WriteLine("option confirm off")
            .WriteLine("open sftp://" & username & ":" & password & "@" & remotehost & "/")
            If outfilename Is Nothing Then .WriteLine("put " & filename) Else .WriteLine("put " & filename & " """ & outfilename & """")
            .Close()
        End With
        If output IsNot Nothing Then output = winscp.StandardOutput.ReadToEnd()
 
        ' Wait until WinSCP finishes
        winscp.WaitForExit()
 
        ' Parse and interpret the XML log
        ' (Note that in case of fatal failure the log file may not exist at all)
        If Not File.Exists(logname) Then
            errmsg = "from PutSFTP:  The WinSCP executable appears to have crashed."
            Return False
        End If
 
        Dim log As XPathDocument = New XPathDocument(logname)
        Dim ns As XmlNamespaceManager = New XmlNamespaceManager(New NameTable())
        ns.AddNamespace("w", "http://winscp.net/schema/session/1.0")
        Dim nav As XPathNavigator = log.CreateNavigator()
 
        ' Success (0) or error?
        Dim status As Boolean = (winscp.ExitCode = 0)
        If Not status Then
            errmsg = "from PutSFTP:  There was an error transferring " & filename & "."
            ' See if there are any messages associated with the error
            For Each message As XPathNavigator In nav.Select("//w:message", ns)
                errmsg &= Environment.NewLine & message.Value
            Next message
        End If
 
        Try
            My.Computer.FileSystem.DeleteFile(logname)
        Catch ex As Exception
            ' at least we tried to clean up
        End Try
 
        Return status
    End Function
End Class