difference between facade and business delegate pattern

What is the difference between facade and business delegate design pattern?

Aren't both of them used for hiding business logic from the client开发者_运维技巧?

Delegation is standing between the client and the actual implementation, usually hiding/filtering/augmenting certain functionality of the implementation from the client.

Facade is providing a course-grained API hiding more complex logic and/or coordination, usually bundling up several implementations that work together, and usually as a convenience to the client.

Examples of each from java:

Delegation: The Collections.unmodifiableList() returns a List that keeps a reference to the original List and delegates to it for all methods, but throws Exceptions if its mutator methods are called.

Facade: If you've ever seen the ridiculous amount of code required to print a java DOM XML document, the first thing you do is create a utility method to hide all the ugliness - that method could be considered a facade.