---
layout: pattern
title: Data Access Object
folder: dao
permalink: /patterns/dao/
categories: Architectural
tags:
 - Data access
---

## Intent
Object provides an abstract interface to some type of database or
other persistence mechanism.

## Class diagram
![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)