Creating the Plug-in
Now that you have an idea of how and when plug-ins are called, you're ready to create one. A plug-in consists of a function wrapper, which instantiates a plug-in class as an object, and exposes its fields or methods. The classes and development techniques used to create a plug-in are described separately in these DevNet topics: Create .NET Plug-in and Create a Java Plug-in.
The .NET and Java classes are functional duplicates, though their method/field names differ. The topics linked above include source code examples for specific purposes.