Java

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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Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Dkim;

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the Dkim properties HeartbeatMs and AbortCurrent, which monitor and cancel a
        // long-running operation such as a DNS public-key lookup.

        Dkim dkim = new 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.setHeartbeatMs(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.setAbortCurrent(false);

        // PrefetchPublicKey performs a synchronous DNS lookup, which HeartbeatMs monitors and
        // AbortCurrent can cancel.
        try {
            dkim.prefetchPublicKey("myselector", "example.com");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Public key prefetched.");
    }
}