Xojo Plugin

Async Methods Returning an Object

See more Async Examples

Demonstrates how to call an asynchronous method that returns an object. This example reads email from a POP3 server using the Async versions of the Chilkat methods. 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.

success = False

Dim mailman As New Chilkat.MailMan

// Set the POP3 server's hostname
mailman.MailHost = "pop.example.com"

// Set the POP3 login/password and any other requirements..
mailman.PopUsername = "myLogin"
mailman.PopPassword = "myPassword"
mailman.PopSsl = True
mailman.MailPort = 995

// Connect to the POP3 server:
Dim task As Chilkat.Task
task = mailman.Pop3BeginSessionAsync()
If (mailman.LastMethodSuccess = False) Then
    System.DebugLog(mailman.LastErrorText)
    Return
End If

// Start the background task.
success = task.Run()
If (Not success) Then
    System.DebugLog(task.LastErrorText)

    Return
End If

// Wait for the POP3 connect task to finish.
// The True/False returned by Wait applies to the Wait method call, not the task.
Dim maxWaitMs As Int32
maxWaitMs = 30000
success = task.Wait(maxWaitMs)
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.
        System.DebugLog(task.LastErrorText)
    Else
        // The ResultErrorText applies to the underlying task method call (i.e. the Pop3BeginSession)
        System.DebugLog(task.Status)
        System.DebugLog(task.ResultErrorText)
    End If

    Return
End If

// Get the number of messages in the mailbox.
task = mailman.GetMailboxCountAsync()

// 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(maxWaitMs)
Dim numMessages As Int32
numMessages = task.GetResultInt()

If (numMessages = 0) Then
    Return
End If

Dim email As New Chilkat.Email

Dim i As Int32
For i = 1 To numMessages

    task = mailman.FetchByMsgnumAsync(i)
    If (mailman.LastMethodSuccess = False) Then
        System.DebugLog(mailman.LastErrorText)
        Return
    End If

    success = task.Run()
    success = task.Wait(maxWaitMs)
    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.
            System.DebugLog(task.LastErrorText)
        Else
            // The ResultErrorText applies to the underlying task method call (i.e. the FetchByMsgnum)
            System.DebugLog(task.Status)
            System.DebugLog(task.ResultErrorText)
        End If

        Return
    End If

    // Each Chilkat object that can be a return value of an asynchronous task will
    // have a method named LoadTaskResult.  The object returned in the underlying
    // asynchronous method call is retrieved by calling LoadTaskResult. 

    // To say it another way: The application will provide a pre-existing object of
    // the desired return type (in this case it is an email object).  This object is
    // loaded by calling LoadTaskResult.  

    success = email.LoadTaskResult(task)

    If (Not success) Then
        System.DebugLog(email.LastErrorText)
        Return
    Else
        System.DebugLog(email.From + ": " + email.Subject + EndOfLine.Unix)
    End If

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