dao design pattern - a core j2ee design pattern

7/29/2019 DAO Design Pattern - A Core J2EE Design Pattern

1/4


www.codefutures.com/j2ee-design-pattern/

Home

Products

Resources

Our Customers

Support

About CodeFutures

DAO Design Pattern: A Core J2EE Design

Pattern

DAO Design Pattern

Business applications almost always need access to data from relational or object databases and the Java

platform offers many techniques for accessing this data, the best of wich use the DAO Design Pattern. The oldes

and most mature technique is to use the Java Database Connectivity (JDBC) API, which provides the capability

to execute SQL queries against a database and then fetch the results, one column at a time. Although this API

provides everything a developer needs to access data and to persist application state, it is a cumbersome API todevelop against - which makes a code generator particularly useful.

Java 2 Enterprise Edition (J2EE) offers a newer persistence framework in the form of Entity Beans, a subset of

the Enterprise JavaBean (EJB) framework. Although there have been many improvements in the more recent

EJB 2.0 specification, many developers are now looking to alternative persistence frameworks, such as Java

Persistence API (JPA) and Hibernate DAO.

The Benefits of the DAO Design Pattern

The DAO Design Pattern provides a technique for separating object persistence and data access logic from anyparticular persistence mechanism or API. There are clear benefits to this approach from an architectural

perspective. The DAO Design Pattern approach provides flexibility to change an application's persistence

mechanism over time without the need to re-engineer application logic that interacts with the DAO Design

Pattern tier. For example, there may be performance benefits in changing an application's performance

mechanism from using Entity Beans to using direct JDBC calls from a session bean, or even a move to an

alternative persistence framework, such as Hibernate. Without a DAO Design Pattern tier in place, this sort of

transition would require extensive re-engineering of existing code.

The DAO design pattern also provides a simple, consistent API for data access that does not require knowledge
http://www.codefutures.com/company/about/http://www.codefutures.com/customers/http://www.codefutures.com/database-products/http://www.codefutures.com/http://www.dbshards.com/http://www.codefutures.com/http://www.codefutures.com/http://www.codefutures.com/hibernate/http://www.codefutures.com/company/about/http://www.codefutures.com/support/http://www.codefutures.com/customers/http://www.codefutures.com/library/http://www.codefutures.com/database-products/http://www.codefutures.com/http://www.codefutures.com/weblog/corporate/atom.xmlhttp://www.dbshards.com/http://www.codefutures.com/


2/4



of JDBC or EJB interfaces. A typical DAO Design Pattern interface is shown below.

public interface CustomerDAO

{

public void insert(Customer customer)

throws CustomerDAOException;

public void update(CustomerPK pk, Customer customer)


public void delete(CustomerPK pk)


public Customer[] findAll()


public Customer findByPrimaryKey(String email)


public Customer[] findByCompany(int companyId)


}

It is important to note that DAO J2EE Design Pattern does not just apply to simple mappings of one object to

one relational table, but also allows complex queries to be performed and allows for stored procedures and

database views to be mapped into Java data structures.

Additional useful information on Data Access Objects J2EE Design Pattern is available here;

http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html

http://www.corej2eepatterns.com/Patterns2ndEd/DataAccessObject.htm

Minimizing the Impact of Moving to DAO

CodeFutures' objective is to minimize the importance of the main argument against using DAO Design Pattern:

the fact that it requires a significant amount of repetitive source code to be produced for no immediate advantage

over using JDBC or EJB directly. For many developers, this disadvantage is good enough reason to ignore the

long-term benefits of using a framework-neutral API, especially where there are strict project deadlines. Without

the code generation advantages of FireStorm/DAO, it is not easy to justify to a project manager or project

sponsor the time and cost of manually writing DAO code, regardless of any future benefits they may see.

DAO Design Pattern Code Generation

CodeFutures' solution to the manual coding problem is to automate the production of a DAO Design Pattern tier

as well as automating the actual implementation logic for whichever persistence framework is deemed
http://www.corej2eepatterns.com/Patterns2ndEd/DataAccessObject.htmhttp://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html


3/4



appropriate for an application. This approach is easy to adopt because almost all databases use a standard

language for defining their structure (SQL).

Additional Reading on Design Patterns

EJB Design Patterns by Floyd Marinescu

http://www.theserverside.com/books/wiley/EJBDesignPatterns/index.tss

The Hillside Group

http://hillside.net/patterns/onlinepatterncatalog.htm

JavaWorld list of design pattern articles

http://www.javaworld.com/columns/jw-java-design-patterns-index.shtml

The Design Patterns Java Companion

http://www.patterndepot.com/put/8/JavaPatterns.htm

Data and Object Factory

http://www.dofactory.com/patterns/Patterns.aspx

A Learning Guide To Design Patterns

http://www.industriallogic.com/papers/learning.html

Design Patterns (good quality personal page)

http://home.earthlink.net/huston2/dp/patterns.html

Additional Resources

FireStorm/DAO is a database access tool based on the Data Access Object design pattern.

Download FireStorm/DAO

CodeFutures provides a free program to analyze the performance of your MySQL database.

Free MySQL Performance Analysis

Read about how Database Sharding helps many major companies to linearly scale their database applications.

Request Database Sharding White Paper

dbShards economically scales large, high transaction volume databases using Database Sharding.

View Introduction to dbShards Video

Products
http://www.codefutures.com/dbshards-product-presentation/http://www.codefutures.com/database-sharding/http://www.codefutures.com/database-sharding-white-paper/http://www.codefutures.com/database-sharding/http://www.codefutures.com/database-performance-analysis/http://www.codefutures.com/products/firestorm/download/http://www.codefutures.com/data-access-object/http://www.codefutures.com/products/firestorm/http://home.earthlink.net/huston2/dp/patterns.htmlhttp://www.industriallogic.com/papers/learning.htmlhttp://www.dofactory.com/patterns/Patterns.aspxhttp://www.patterndepot.com/put/8/JavaPatterns.htmhttp://www.javaworld.com/columns/jw-java-design-patterns-index.shtmlhttp://hillside.net/patterns/onlinepatterncatalog.htmhttp://www.theserverside.com/books/wiley/EJBDesignPatterns/index.tss


4/4



dbShards

FireStorm/DAO

FireStorm/DAO

FireStorm/DAO Overview

DAO Benefits

FireStorm/DAO FeaturesFireStorm/DAO Architecture

FireStorm/DAO FAQs

DAO Design Pattern

DAO Tutorial

DAO Download

FireStorm/DAO Editions

Product Range

Architect Edition

OEM Edition

Free

MySQL

Performance

Analysis

Click Here

DATABASE PERFORMANCE TOOLS

dbShards economically scales large, high transaction volume databases using Database Sharding, dramatically

improving the response times and scalability of OLTP databases, Software as a Service applications, and any

database application with many concurrent users.

FireStorm/DAO is a database access tool that generates Data Access Objects based on Java DAO, JDBC

DAO, Hibernate DAO, and Spring DAO.

Site Map | Legal | Site Search

Technologies Supported:Database Sharding | Data Access ObjectSpring DAO

Hibernate DAO | JDBC DAO | Java DAO | DAO Code

Copyright 2003-2009 CodeFutures Corporation. All rights reserved.

dbShards, FireStorm/DAO, FireStorm/SDO, and CodeFutures are trade marks of CodeFutures

Corporation.
http://www.codefutures.com/dao-code/http://www.codefutures.com/java-dao/http://www.codefutures.com/jdbc-dao/http://www.codefutures.com/hibernate/http://www.codefutures.com/spring-dao/http://www.codefutures.com/data-access-object/http://www.codefutures.com/database-sharding/http://www.codefutures.com/search/http://www.codefutures.com/company/legal/http://www.codefutures.com/company/sitemap/http://www.codefutures.com/spring-dao/http://www.codefutures.com/hibernate/http://www.codefutures.com/jdbc-dao/http://www.codefutures.com/java-dao/http://www.codefutures.com/data-access-object/http://www.codefutures.com/products/firestorm/http://www.codefutures.com/database-sharding/http://www.codefutures.com/http://www.codefutures.com/database-performance-analysis/http://www.codefutures.com/database-performance-analysis/http://www.codefutures.com/database-performance-analysis/http://www.codefutures.com/products/firestorm/editions/oem/http://www.codefutures.com/architect/http://www.codefutures.com/products/firestorm/editions/http://www.codefutures.com/products/firestorm/download/http://www.codefutures.com/products/firestorm/tutorial/http://www.codefutures.com/products/firestorm/benefits/http://www.codefutures.com/products/firestorm/faq/http://www.codefutures.com/products/firestorm/architecture/http://www.codefutures.com/products/firestorm/editions/matrix.htmlhttp://www.codefutures.com/dao-benefits/http://www.codefutures.com/products/firestorm/http://www.codefutures.com/products/firestorm/http://www.codefutures.com/dbshards/

dao design pattern - a core j2ee design pattern

Documents