As you know, Simon is a website and server monitoring tool. This mouthful is to try to describe two of the levels at which Simon operates. At the very basic level, Simon is a very simple utility to watch web pages, and let you know when they change or go down. But Simon has much more depth to it — it enables you to monitor all sorts of internet servers and services, local applications, disk volumes, and more.

The Preview pane has this duality, too. When used with a web-based test (i.e. one using the Web Page service), it displays the rendered web page and graphics on the left (which can be interacted with like in a web browser), and the HTML source, web page headers, and filter output on the right:

This is really handy, both to quickly see the page while in Simon, without having to switch to a web browser (which is easy too, via the File ▸ Visit Site command), and when setting up the test in the first place.

The service and filter output are useful, too; you can see the HTML (or other) output, and the output of each filter.

The filters are one of Simon’s key features. This is a page of the test editor, where you can tell Simon to only look at the HTML source between two blocks of text, or find required text, or evaluate numbers, or reformat text, and much more. This enables you to focus on the part of the page you care about, and avoid dynamic portions like banner ads etc. You can easily set this up via the Preview window. With the test editor open, after entering the URL, show the Preview to display the preview of the page. Then search through the HTML source for interesting portions of the text (click in the HTML then press ⌘F to find text), select it, copy the relevant text, and paste into filter fields.

For example, here’s Apple’s RSS feed, with filters to extract and format the title and body text of the latest news:

As useful as this is, it’s not done yet. The Preview is also supported by many other services, in a slightly different way. For non-web services, the Preview looks much the same, but without the rendered content. Instead of the HTML source, it shows the output of the service. This is all plain text, since that’s what these services deal with.

For example, here’s the preview of a Ping test:

These services support the filters, too: just like with web pages, you can use filters to analyze the output and extract interesting nuggets.

I hope you’ll use the Preview to good advantage when configuring and using Simon.

A useful feature of Simon is how it handles the situation when your computer loses its internet connection.

People sometimes ask me what Simon does in this situation, concerned that it would count as a failure for tests. Simon is smarter than that, though. Every time it starts a check, it first checks if the computer has a current internet connection, and only then performs the check.

If it determines that your internet connection has been disrupted, it places the test in an “offline” state, where it shows a blinking “lightning bolt” for the status icon until the connection is restored. This offline state doesn’t count as a failure (or success).

Simon works out if you have a connection by seeing if it can resolve one of two popular domain names; if either work, your connection is probably fine, but if both fail, it is likely disconnected. Using two domains avoids a temporary outage of either one.

You can disable this internet connection check on a per-test basis via the Can check when offline checkbox on the test editor’s Options page. This is useful if you want to create a test to notify you when your connection goes down, or for tests that don’t require an internet connection (e.g. using the Application or Script service kinds):

I sometimes receive a question from a potential customer, asking whether Simon has the ability to send a notification via email.

Although I do mention it in a number of places, this isn’t an unreasonable question, particularly if you just download Simon and start playing with it, as no email options appear in the list of available notifiers in the Edit Test pane by default.

Why is this? Because unlike the Speech and Sound kinds of notifiers, the Email one requires some configuration before it can be used, so it can’t be offered by default.

The way notifiers work is (I hope) pretty intuitive, but a little indirect. Simon provides a number of notifier kinds that do the work of notifications, and you configure notifiers to use those, then choose notifiers for each test.

These levels of abstraction allow easy re-use of notifiers: a single kind of notifier can be used by multiple notifiers, and a single notifier can be used by multiple tests, without having to set up the same things over and over again.

For example, you can add a notifier to email yourself for some failures, another email notifier to your clients for other failures, another one for recoveries, and so on, and use whichever ones of those are desired in tens or hundreds of tests, as required, as simply as choosing them from a pop-up menu.

So, as I said, there is no email notifier set up by default, since it needs configuration, but you can easily add one. If you’re editing a test and realize that you want to receive an email when this test changes, fails, and/or recovers, you can click the New Notifier… button in the Notifiers section of the Edit Test pane, which will switch to the Notifiers page, and start editing a new notifier. You can then choose Email from the Notifier Kind pop-up menu, and the controls below will change to those for an email, with a sample email pre-populated, which you can edit as desired:

You can then configure the email To etc fields, plus switch to the Name page to give the notifier a name, and perhaps the Options page to indicate whether this notifier is available for changes, failures and/or recoveries.

Once it all looks good, click Done to save the notifier. You can check that it is set up correctly by choosing the File ▸ Notify Now menu command; that will send an email with placeholder values. If you don’t receive the email, check the notifier settings.

The new notifier will then be available for that test and any others you want to use it in:

Easy!