The event trigger is a complex and sensitive but also powerful way to monitor the system. Events in the system can cause your job to run if you want it. Let say your web server service dies and you want to know or act upon that.
Most events are based on WMI Windows Management Instrumentation. WMI is a new management technology allowing scripts to monitor and control managed resources throughout the network. Resources include hard drives, file systems, operating system settings, processes, services, shares, registry settings, networking components, event logs, users, and groups. WMI is built into clients with Windows 2000 or above, and can be installed on any other 32-bit Windows client.
Using a WMI based trigger, requires some common settings to control their behaviour. These common settings are located in the main Settings tab of the Event Trigger window.
Warning: Some event based triggers, like the File event type, can in some cases, trigger several times a second. This will run your job several times a second.
In the Triggers tab, clicking on Add -> Event trigger, a selection window for the different event trigger types is opened.
Main tab
A description is entered so you can distinguish the current trigger among others in the trigger list. You can also change the event trigger type in the combo box, which results in that only the tabs for the actual event trigger type is shown.
Active
Determines if this event should be active from start. If not, it can be reactivated later. Default is active.
Run delay
You can set a delay which means that the trigger will fire x number of times before executing. Default is 1 which means that the it will fire when the first time it has been triggered.
Polling interval
This value is only used by certain WMI events, otherwise grayed out. The polling interval defines how often VisualCron should check for changes in the system. Default is every 60 second. Setting it to a lower value than 10 will increase the load on the server. What's good is that you won't miss any events even though you are not checking it every second. Changes are stored and if something has happened you will be notified at your polling interval. What is important to know is that if you are watching for state "stopped" at a service and the service has started then stopped, any change has not occurred since the service was stopped in the first place. The service has to be started before monitoring a "stopped" change. Also, if the the service has started before monitoring and it turns from started to stopped within the polling interval no change is observed and you won't be notified.
Remote event
This value is only used by certain WMI events, otherwise grayed out. Can remotely monitor another computer in the network, specify the name or IP address of the remote computer. The computer has to be in the local network. Default is "." which means that VisualCron is monitoring the the local computer. A network credential must be specified when connecting to a remote computer. Also you must check so that the remote computer let's this computer or user access the WMI on the remote computer.
Timeout tab
You are able to control what happens if no event has triggered in a period of time. Specify number of hours, minutes and seconds for the timeout. When VisualCron reaches timeout it will fire the event.
Expires tab
You are able to set if a Trigger should be deleted or deactivated at a certain time or after a certain number of triggered times. Check Expiration enabled to activate this feature. Select either date or x time(s) the trigger has to fire before doing something.
Expire action
Select what you want to do when a Trigger has expired. Choose between Delete the Trigger or Inactivate the Trigger.