<pedrocorreia.net ⁄>
 

<DAO - it's not about Layering, it's about Abstraction! ⁄ >




clicks: 3002 3002 2009-02-18 2009-02-18 goto misc myNews misc  Bookmark This Bookmark This


Again there were some interesting debates in the near past, which once again discussed the role of the DAO within enterprise applications, especially based on JEE and EJB 3. One main argument for the dissapearance of DAOs is the very unlikely probability to exchange or replace your once chosen persistence technology, so that you may directly rely on EJBs Entity Manager within your Business Services (since it's in fact very unlikely that your underlying persistence technology will change). This argument is mostly accompanied with the concern, that the introduction of a DAO Layer might increase complexity and introduce some performance penalties, while direct usage of the Entity Manager let collapse two separate Layers into one.

All in all, those statements raise the impression, that DAOs form a kind of Layer in their own right, or represent at least the main part of your data access Layer.

Let me give you some counter arguments (using some input from 'J2EE Design and Development' as well as 'Domain Driven Design') which will show you that DAOs aren't so much about Layers but more importantly about Abstraction and domain specific Encapsulation (that said, with the disappearance of the DAO, collapsing two Layers into one as suggested, there is STILL a data access Layer, you only just jumbled business and data access logic).



este é só um excerto do artigo, para aceder ao artigo completo, clique no link em baixo:
this is just a small excerpt from the article, to access the full article please click in the link below:

http://gleichmann.wordpress.com/2009/02/17/dao-its-not-about-layering-...




Subscribe News RSS  Subscribe News Updates by E-mail





myNews <myNews show="rand" cat="misc" ⁄>

Adobe Photoshop CS6: Improvements for Web and UI Designers new ...

Photoshop CS6 has been hailed as a huge improvement for web and UI designers. I'm going to share wit (...)

clicks: 17025 17025 2012-05-14 2012-05-14 goto url (new window) webdesign.tutsp... goto myNews misc


Camera Exposure Modes Explained new ...

If you're just getting started with photography, the letters on your camera's dial might feel like h (...)

clicks: 14971 14971 2012-05-13 2012-05-13 goto url (new window) photo.tutsplus.... goto myNews misc


45 Fresh Collection of High Quality Free PSD Files new ...

What else can be so great for a designer than finding out high quality Photoshop PSD files? This is (...)

clicks: 9218 9218 2012-05-09 2012-05-09 goto url (new window) smashingapps.co... goto myNews misc


15 Free High Quality ToolTip PSD's new ...

A tooltip or infotip can be defined as a graphical hint that is incorporated with the website design (...)

clicks: 10813 10813 2012-05-07 2012-05-07 goto url (new window) smashingapps.co... goto myNews misc


40+ Elegant Examples of River Photography

River photography is one of the beautiful type of photography, photographers take pleasure in this w (...)

clicks: 6674 6674 2012-05-04 2012-05-04 goto url (new window) smashingbuzz.co... goto myNews misc


40 Fresh And High Quality Free Icon Sets In PSD Format

Here is yet another exciting collection of high quality Free Icon PSD files for the designers that t (...)

clicks: 7257 7257 2012-02-19 2012-02-19 goto url (new window) smashingapps.co... goto myNews misc


15 jQuery Calendar Date Picker Plugins

In this collection, you will see some of the best jQuery Calendar Date Picker Plugins that will allo (...)

clicks: 7165 7165 2012-02-18 2012-02-18 goto url (new window) smashingapps.co... goto myNews misc


50 Beautiful Yet Free HTML5 And CSS3 Templates

HTML5 templates are getting very popular these days because all professional HTML5 templates are com (...)

clicks: 7746 7746 2012-02-17 2012-02-17 goto url (new window) smashingapps.co... goto myNews misc