public sealed class JobMessageEvent : ArcGIS.Core.Events.CompositePresentationEvent<JobMessageEventArgs<JobMessage>> 

{
  // Subscribe to the job message event to start receiving job and step notifications.
  // Use the subscription token to unsubscribe from the event.
  subscriptionToken = JobMessageEvent.Subscribe(e =>
  {
    var jobId = e.Message.JobId;
    var msgType = e.MessageType;
    var message = e.Message;
    // Include logic to process the job / step messages
  });

  // Subscribe to certain jobs. This will add these jobIds to the list of already subscribed jobs.
  var notifManager = WorkflowClientModule.NotificationManager;
  notifManager.SubscribeToJobs(jobIds);
}

{
  // Unsubscribe from the job message event using the subscription token
  JobMessageEvent.Unsubscribe(subscriptionToken);

  // Unsubscribe from jobs using the same instance of Notification Manager used to subscribe to jobs.
  // This will remove the jobs from the subscribed job list if no other clients are subscribed to those jobs.
  var notifManager = WorkflowClientModule.NotificationManager;
  notifManager.UnsubscribeFromJobs(jobIds);
}