The other day my team was having a discussion about some software we were working on. During the discussion, several of the structural design patterns were mentioned, sometimes interchangeably. This is a brief overview of three of them for future reference.
The Facade
The Facade defines a single, simplified interface over one or more subsystems. Common usage of this is simplifying a remote system’s interface.
The Adapter
The Adapter changes (aka adapts) the interface of a class to match what is expected by a caller. I have used this in the past to provide a common interface for getting/setting the value of web controls.
The Proxy
The Proxy stands in for another class, intercepting the call and then usually passing the call on to the class the proxy is representing. Common usage of this is a proxy defined for WCF service or an NHibernate proxy for lazy loading. The end result is additional behavior, like remoting complexities or lazy tracking, are injected into the the call stack without the user of the proxy having to know about it.
