Chain of Reponsibility

In this setting, a request is send to only one object, however there should be several related objects that take the responsibility. So a chain is build so as to create the final response.

The chain is usually created automatically when Composite pattern is used, since each object might keep a pointer to its parent. So the request sent to a leaf can be propagated further to its parent. The forwarding procedure can also be used to pass the request to who can handle it if the current object can not.