With Active Page Item Developer (APID), you can convert your solution to an encrypted form that is disguised as a plug-in, or embedded into a document. These encrypted scripts are not open for inspection.
For optional copy protection, APID provides a licensing system that ties into the InDesign serial number. The end-user needs a proper license from you before the scripts can be executed. You can also provide your potential customers with a time-limited demo of your solution.
Standard ExtendScripts without APID are 'naked' - i.e. if you create a solution in ExtendScript without APID, your users would be able to freely open, inspect, copy, modify the scripts.
APID defines an 'event model', where one page item can 'observe' another, and page items can 'listen' to events like open, close, save, idle, context menu,... For example, simply moving one page item can automatically trigger the execution of a script that, for example, makes other page items 'follow'. Without APID, ExtendScripts are 'static' entities - i.e. they need to be launched by the user via the Scripts palette, and are cannot be activated in an event-driven way.
Active Page Item Developer opens up functionality that is not available in ExtendScript - for example, version 1.0 makes it possible to attach context menus to individual page items from ExtendScript. Future versions will add more functionality - e.g. creating floating palettes from ExtendScript,...
ExtendScript has a number of substantial advantages compared to using C++ for software development. It's easy to learn and use, it allows for fast development, it's cross-platform (Mac/Win), and there is no need to create different versions to support CS as well as CS2. And there are no endless run/compile/debug cycles!
Active Page Item Developer allows you to create your own Scripted Plug-Ins. To get a good idea of what can be achieved: check out some of our 'freebie' Plug-Ins - they were all created using this technology.