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Flexible server monitoring

Introducing Simon 5!

Simon version 5 is now available. It is a massive update, introducing a much-requested feature: syncing the Simon data between multiple Macs, plus a Simon Status service, a Link Checker filter, improved Find filter, iMessage and Speak Error notifiers, a new app icon, and much more.

Important: please note that Simon 5 requires a minimum of macOS 10.12 (Sierra), and is a paid upgrade from Simon 4. Purchasers since September 1, 2020 automatically get a version 5 license (that also works in previous versions).

Read the Simon What's New page for details.

What does a "Check" do?

In order to calculate how my using Simon is affecting the traffic stats on my site, I would like to know what, technically, does a Check of a website actually do?

Does it ping the server? Does it get? If so, what does it get? The home page? The whole home page, or does it cancel after xxx bytes? What is xxx?


Jerry Krinock

P.S. The Simon manual focuses on the user interface, but I can't find any answers to technical questions such as the above. Also, the FAQ item in Simon's Help menu goes to Page Not Found.

David Sinclair's picture

Re: What does a "Check" do?

What a check does depends on the service. A Ping service does a ping of the server. A Web (HTTP) service does a GET or POST of the page (as specified in the test settings). A Twitter service communicates with the Twitter site. And so on.

The Web (HTTP) service gets the whole page source that you specify (but not auxiliary resources like CSS and images). You can use a Head method to only get the header, if desired.

Thanks for the heads-up re the FAQ menu item. I've fixed it now.

Thanks, David. I only

Thanks, David. I only monitor one site. Simon reports that it was down for a couple minutes yesterday afternoon. But what if the failure was at my ISP -- say, that my computer was still connected to my modem and the local loop to the central office in San José was still up, but my ISP had a traffic overload and was dropping my packets. Would this show up as the same kind of failure as if my monitored site's web host in Atlanta lost electrical power?

David Sinclair's picture

Re: I only monitor one site.

Yes, that could look the same. Simon will put tests into an "offline" state if it detects that your internet connection is down, but if you are connected and the failure is further afield, Simon has no way of knowing exactly where the failure occurred... though the error may provide a clue.

You can use other tests to check for other situations, like your ISP load, if desired.

"your ISP load"?? I don't

"your ISP load"?? I don't see any test like that in Simon. Do you mean to call my ISP's tech support and ask about outages? [emoticons needed here]

One workaround would be that if I monitored two sites, one hosted on a "known reliable" different server in a different part of the world. Here's a suggestion. When Simon detects an http failure it should immediately try several other sites -- to try and guess whether it was the monitored site or the ISP/internet that failed.

David Sinclair's picture

Re: "your ISP load"??

I meant that you can use the Ping service or others to check other aspects of the server in question.

Re your suggestion, Simon automatically detects a local internet failure before each check. If that occurs, the test goes into an offline state until the connection is re-established.