Ray.Aop package provides method interception. This feature enables you to write code that is executed each time a matching method is invoked. It's suited for cross cutting concerns ("aspects"), such as transactions, security and logging. Because interceptors divide a problem into aspects rather than objects, their use is called Aspect Oriented Programming (AOP). A Matcher is a simple interface that either accepts or rejects a value. For Ray.AOP, you need two matchers: one that defines which classes participate, and another for the methods of those classes. To make this easy, there's factory class to satisfy the common scenarios.