The source for most of the Rapise implementation is available for you to read and modify. You may find it useful to look at if you decide to create a library customized for your application or wish to extend the testing platform to meet your needs.
Microsoft's Component Object Model (COM) is a standard for communication between separately engineered software components (source). Any object with a COM interface can be created and used remotely:
var doc = new ActiveXObject("Word.Application");
Using this approach, any external Dynamic Linked Libraries (DLLs) can be involved to expand the testing capabilities of Rapise. Rapise has built in support for both types of DLLs: