# Guide to OpenIG
Chapter 12. Customizing OpenIG

Sidebar | Prev | Up | Next

## 12.1. Key Extension Points

The two primary extension points are the interfaces: Filter (for processing a request and/or response en route) and Handler (for generating responses from requests). These interfaces are similar to the Java Enterprise Edition `Filter` and `Servlet` interfaces, with some differences in the semantics of messages. While you can simply implement these interfaces, there are also included convenience classes: GenericFilter and GenericHandler that you can use if you intend to make your extensions configurable through the OpenIG configuration resource.

OpenIG also allows standard Java Enterprise Edition servlets and servlet filters to be embedded in the gateway, with initialization parameters supplied through through the OpenIG configuration resource.