(VB.NET) Wait for Async Method to Complete

Demonstrates using the Wait method to wait for an asynchronous method to complete. This example will do an SFTP upload (over SSH) and will use the Async version of each method. Obviously, waiting for the async method to complete is the same as making a synchronous call, but an application wouldn't typically do this. An application might, for example, do other things as a background task is running, and then later wait for the task to complete.

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' All Chilkat classes can be unlocked at once at the beginning of a program
' by calling UnlockBundle.  It requires a Bundle unlock code.
Dim chilkatGlob As New Chilkat.Global
Dim success As Boolean = chilkatGlob.UnlockBundle("Anything for 30-day trial.")
If (success <> True) Then
    Debug.WriteLine(chilkatGlob.LastErrorText)
    Exit Sub
End If


Dim sftp As New Chilkat.SFtp


' Set some timeouts, in milliseconds:
sftp.ConnectTimeoutMs = 15000
sftp.IdleTimeoutMs = 15000
Dim waitMaxMs As Integer = 30000

' Connect to the SSH server.  
' The standard SSH port = 22
' The hostname may be a hostname or IP address.
Dim port As Integer = 22
Dim hostname As String = "www.my-ssh-server.com"

Dim task As Chilkat.Task = sftp.ConnectAsync(hostname,port)
If (sftp.LastMethodSuccess = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If

' Start the background task.
success = task.Run()
If (Not success) Then
    Debug.WriteLine(task.LastErrorText)
End If


' Wait for the connect task to finish.
' The True/False returned by Wait applies to the Wait method call, not the task.
success = task.Wait(waitMaxMs)
If (Not success Or (task.StatusInt <> 7) Or (task.TaskSuccess <> True)) Then
    If (Not success) Then
        ' The task.LastErrorText applies to the Wait method call.
        Debug.WriteLine(task.LastErrorText)
    Else
        ' The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        Debug.WriteLine(task.Status)
        Debug.WriteLine(task.ResultErrorText)
    End If


    Exit Sub
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.
task = sftp.AuthenticatePwAsync("myLogin","myPassword")
' To keep the example short, we'll skip handling failures.
' The failures would be handled in the same way as shown above.

success = task.Run()
success = task.Wait(waitMaxMs)


' After authenticating, the SFTP subsystem must be initialized:
task = sftp.InitializeSftpAsync()
success = task.Run()
success = task.Wait(waitMaxMs)


' Upload from the local file to the SSH server.
' Important -- the remote filepath is the 1st argument,
' the local filepath is the 2nd argument;
Dim remoteFilePath As String = "hamlet.xml"
Dim localFilePath As String = "c:/temp/hamlet.xml"

task = sftp.UploadFileByNameAsync(remoteFilePath,localFilePath)
If (sftp.LastMethodSuccess = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


success = task.Run()
success = task.Wait(waitMaxMs)
If (Not success Or (task.StatusInt <> 7) Or (task.TaskSuccess <> True)) Then
    If (Not success) Then
        ' The task.LastErrorText applies to the Wait method call.
        Debug.WriteLine(task.LastErrorText)
    Else
        ' The ResultErrorText applies to the underlying task method call (i.e. the Connect)
        Debug.WriteLine(task.Status)
        Debug.WriteLine(task.ResultErrorText)
    End If


    Exit Sub
End If



Debug.WriteLine("File uploaded.")