In order to create InstallScript installations, you need to become familiar with event handlers.
InstallScript installations are driven by the InstallScript engine, which in turn generates a series of events in a specified order. Placing instructions in these events is how you build an InstallScript installation. Shortly after an installation program is executed, an event called Begin is fired. Begin triggers the event handler called OnBegin, and this handler specifies instructions to carry out when the Begin event is fired. There are other instructions in other event handlers that will be executed when their event handlers are fired.
There are four main event handlers you need to be familiar with, and these contain the dialog box functions that are displayed at run time:
OnFirstUIBefore – contains the dialog boxes to be displayed before the data transfer in a first-time installation.
OnFirstUIAfter – contains the dialog boxes to be displayed after the data transfer in a first-time installation.
OnMaintUIBefore – contains the dialog boxses to be displayed before the data transfer in a maintenance-mode installation.
OnMaintUIAfter – contains the dialog boxes to be displayed after the data transfer in a maintenance-mode installation.
If you would like to dive more into event handlers, then you should know that there are four groups of event hanlders, Global Event Handlers, Feature Event Handlers, Miscellaneous Event Handlers, and Advanced Event Handlers. Global and Feature event handlers are always called in a specific order. Miscellaneous Event Handlers respond to events that may not happen during an installation, so they are not called in a specific order like Global and Feature event handlers are.
Global Event Handlers carry out processes required before and after feature installation and uninstallation. Feature Event Handlers carry out processes required just before and after the installation or uninstallation of a single feature. Miscellaneous Event Handlers are triggered by unscheduled events during an installation, such as the end user exiting the installation. And finally, Advanced Event Handlers are triggered under special circumstances.
When you create an InstallScript project, a set of default global event handlers are generated. In addition, when you add features to your installation project, a set of default event handlers are generated for that feature.
One last thing. In an event-driven script, event-handler functions are called even if they do not explicitly appear in the InstallScript view. Of course, this is necessary, because the installation still has to function, even when you are not familiar with the ins and outs of the InstallScript event handlers.
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