I was looking at your site and want to know if you allow for customizable HTTP responses back to your application and then generate an action based on this response.

In the HTTP(S) monitor settings you may specify a list of HTTP response codes. Generally, all server response codes starting with 400 are considered erroneous. If the server replies with such a response code, the resource being requested is considered unavailable and the monitor enters the Down state. However you can accept such response codes by adding them to the comma-separated list of Accepted Response Codes (see HTTP Monitor properties).

Another option is to use the Response Validation and String to Match parameters to specify whether a particular string should be searched in the HTTP response and whether it should or should not be present. If the condition fails the monitor enters the Down state. You may configure IPHost to send different notifications once the monitor goes Down and once it returns back to OK.

If you need more fine graned behaviour you may use the Script or Program monitor to invoke external custom VBScript which would use the returned HTTP response code as a monitor performance value (see Script or Program Monitor properties).

Create Script or Program monitor and configure it. Script may be customized to switch monitor to one of the OK, Down, Performance Problem and Performance Warning states depending on the HTTP response code, and notifications may be configured to be sent upon entering and exiting from any of these states.