Page History

...

In this pattern, an existing service is decorated with a filter. The filter will delegate to the service, but has the chance to alter or replace parameters before invoking the method, and can perform operations before returning. This is similar to chain of command, but differs in that there are two interfaces (the service interface and the filter interface) and that each filter invokes the next filter via the service interface. In chain of command, the chain invokes each method, which must return before the next command in the chain is invoked.

...