Windows® Script Component technology consists of three pieces:
The most commonly used interface handlers, including the COM Automation interface handler, an ASP interface handler, and a handler for DHTML Behaviors, are already built into the script component run-time. Others are available as add-on components, or embedded into specific applications.
The script component run-time serves as an entry point for the host application. The complexities of COM, including the implementation of such COM-standard interfaces as IUnknown, are embedded in the various interface handlers. Your script component contains only the script required to implement the functionality of the COM component.
For example, one of the most common types of COM components is an Automation component, which is a component with properties and methods that can be called from other applications. The low-level COM interfaces required to implement this functionality such as dispatching to the correct function when a method is called are built into an Automation interface handler. In your script component file, you define the properties, methods, and events you want to expose, and the Automation handler makes sure they are called correctly when the host application needs them.