Which ServiceControl.Contracts messages should IHandle?

Question

I'm trying to make sure that 3rd party dependencies are running, and built a service to do this based on the Monitoring 3rd party Sample Application, which emits ServiceControl CheckResult messages.

This works fine; ServicePulse alerts me when I stop/start my local and remote windows services, Databases, Flux Capacitors, etc.

I now want to build a windows service / nServiceBus Endpoint, like ServicePulse, but with logic that can attempt recovery, send emails etc. I don't really want to put this code into the 3rdParty monitor.

I followed the servicecontrol/external-integrations and servicecontrol/contracts tutorials, and created my MendStuffOrEmail endpoint - But it doesn't work; It doesn't receive any messages.

I was going to ask "what am I doing wrong?", but I think I know; I'm using IHandleMessages<ServiceControl.Contracts.MessageFailed> which is for failed messages.

I need to listen for the "CheckResult" type messages - but what are they? I have looked through the ServiceControl and ServicePulse code, but cannot work out what is being sent/received. How can I find this out, or has anyone else actually done this and already knows?

UPDATE
After more extensive rummaging, I also subscribed to CustomCheckFailed and CustomCheckSucceeded messages. I implemented IHandle interfaces for them, but I'm still not getting any messages. The log shows autosubscriber has taken out a subscription to them. What should I check for next?

Answer 1

I compared my code to Sean's posted example and found the mistake: I had implemented two of the interfaces, IConfigureThisEndpoint and AsA_Server in the wrong class (a 2am cut 'n' paste error).

The example listens for failed messages, but for anyone else trying to do this, you do need to subscribe to CustomCheckFailed and CustomCheckSucceeded messages (nuget ServiceControl.Contracts).

public partial class MessageHandler : IHandleMessages<CustomCheckFailed>,
                                      IHandleMessages<CustomCheckSucceeded>
{
    public void Handle(CustomCheckFailed message)
    {
        this.HandleImplementation(message);
    }
    partial void HandleImplementation(CustomCheckFailed message);

    public void Handle(CustomCheckSucceeded message)
    {
        this.HandleImplementation(message);
    }
    partial void HandleImplementation(CustomCheckSucceeded message);

    public IBus Bus { get; set; }   
}

then the logic to do something with the messages. (I left in my original test - sending email - but our system has a library with all sorts of recovery & notification methods. You'll need something similar to stop an email flood):

public partial class MessageHandler
{
    partial void HandleImplementation(CustomCheckFailed message)
    {
        var messageBody = string.Format("Message with id {0} failed with reason {1}", message.CustomCheckId, message.FailureReason);
        MailMessageFactory.sendEmail("Failure Notification", messageBody);

        Console.Out.WriteLine(messageBody);
    }
}

And a similar file with the logic for recovery messages (CustomCheckSucceeded). You probably want a check in there to detect it is actually recovering from a failure, not just passing the test.

So anyway, fixed - on my dev pc.

The next problem was making it work on the server, which took a support call. It turns out ServiceControl ALSO needs a licence, available as part of the "Advanced", "Enterprise", and "Ultimate" editions - Not part of the platform on the standard licence.