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

dao/README.md

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+---
+layout: pattern
+title: Data Access Object
+folder: dao
+permalink: /patterns/dao/
+categories: Persistence Tier
+tags:
+ - Java
+ - Difficulty-Beginner
+---
+
+## Intent
+Object provides an abstract interface to some type of database or
+other persistence mechanism.
+
+![alt text](./etc/dao.png "Data Access Object")
+
+## Applicability
+Use the Data Access Object in any of the following situations
+
+* when you want to consolidate how the data layer is accessed
+* when you want to avoid writing multiple data retrieval/persistence layers
+
+## Credits
+
+* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)