Applicability and examples

What follows is the applicability and examples of the chain-of-responsibility pattern:

• Event handlers: For example, most GUI frameworks use the chain-of-responsibility pattern to handle events. Let's say, for example, a window contains a panel that contains some buttons. We have to write the event handler of the button. If we decide to skip it and pass it on, the next one in the chain will be able to handle the request: the panel. If the panel skips it, it will go to the window.
• Log handlers: Similar to the event handlers, each log handler will log a specific request based on its status, or it will pass it on to the next handler.
• Servlets: In Java, javax.servlet.Filter (http://docs.oracle.com/javaee/7/api/javax/servlet/Filter.html) is used to filter requests or responses. The doFilter method also receives the filter chain as a parameter, and it can pass the request on.