all index.md files renamed to README.md for more compatibility with github

chain/README.md

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+---
+layout: pattern
+title: Chain of responsibility
+folder: chain
+permalink: /patterns/chain/
+categories: Behavioral
+tags:
+ - Java
+ - Gang Of Four
+ - Difficulty-Intermediate
+---
+
+## Intent
+Avoid coupling the sender of a request to its receiver by giving
+more than one object a chance to handle the request. Chain the receiving
+objects and pass the request along the chain until an object handles it.
+
+![alt text](./etc/chain_1.png "Chain of Responsibility")
+
+## Applicability
+Use Chain of Responsibility when
+
+* more than one object may handle a request, and the handler isn't known a priori. The handler should be ascertained automatically
+* you want to issue a request to one of several objects without specifying the receiver explicitly
+* the set of objects that can handle a request should be specified dynamically
+
+## Real world examples
+
+* [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29)
+* [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html)
+
+## Credits
+
+* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)