PowerShell

Monitor and Cancel a Running DKIM Operation

Demonstrates the Chilkat Dkim.HeartbeatMs and Dkim.AbortCurrent properties, which monitor and cancel a long-running operation such as a DNS public-key lookup. HeartbeatMs sets how often an AbortCheck event fires, and AbortCurrent requests cancellation.

Background: Most Dkim work is instant, but anything touching DNS can stall on a slow or unresponsive server. HeartbeatMs makes the object emit a periodic AbortCheck callback during such calls so an application stays responsive and can show progress, and AbortCurrent — set from that callback or from another thread — breaks a blocked synchronous call out early. Together they turn an otherwise uninterruptible operation into a cancellable one.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  Demonstrates the Dkim properties HeartbeatMs and AbortCurrent, which monitor and cancel a
#  long-running operation such as a DNS public-key lookup.

$dkim = New-Object Chilkat.Dkim

#  Fire an AbortCheck event callback every 100 ms during method calls.  In programming languages
#  where Chilkat supports event callbacks, the callback can request cancellation.
$dkim.HeartbeatMs = 100

#  AbortCurrent may be set to $true to request cancellation of a running operation.  It is
#  typically set from another thread, or from within an AbortCheck callback.  Setting it $false
#  here ensures the operation is not pre-emptively aborted.
$dkim.AbortCurrent = $false

#  PrefetchPublicKey performs a synchronous DNS lookup, which HeartbeatMs monitors and
#  AbortCurrent can cancel.
$success = $dkim.PrefetchPublicKey("myselector","example.com")
if ($success -eq $false) {
    $($dkim.LastErrorText)
    exit
}

$("Public key prefetched.")