differnce between facade and proxy

[Rachna Chaturvedi]

Hi all,
i feel there is not much difference between a facade and proxy pattern, and they can be exchanged for each other in some cases ., can someone provide light on the diffence in these patterns and when is facade more appropriate to using proxy.
For eg, in my FBN system, the controller talks to another object( facade or proxy or mediator ???) which talks to the data classes ??? what is this class between the controller & data classes , proxy or facade ???
THanks
Rachna

[Mark Spritzler]

A proxy can filter out bad requests, where as a facade doesn't filter anything, it justs acts as a way to make a complex subsystem easier to access for a client.
A proxy is a "Stand-in" it pretends to be the subsystem, taking requests and deciding if it is ok to really send it to the subsystem.
So while they are very much like "Fronts" for an underlying system, there really is two seperate purposes.
I always look at proxies, and think web server proxies to protect web servers for bad people.
Mark

[BJ Grau]

Proxies are a stand-in, Facades hide complexity.
Other uses for proxies are accessing remote resources like we are doing and deferring creation of expensive resources until they are actually needed.

[Hugo van Elk]

A proxy delegates to an instance of the same type as the proxy. A facade not.