Subject: Session - > DAO - > CMP 2004-06-10 - By Amit Angerkar
Back
Hi,
Example at sun site shows you two ways of implementing the DAO with XMLDAO and
JDBCDAO as samples :
http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html
Cheers,
~Amit
Koala wrote:
> ashraf galal wrote:
>
> > It is a good approach based on good OO design principles. It uses
> > ordinary java interfaces rather than special infrastructure such as
> > that associated with entity beans.
> >
> >
> >
> > DAO uses an abstraction layer of ordinary java interfaces between
> > business logic and persistence components.
> >
> > The implementation of this interfaces handle persistence logic.
> >
> >
> >
> > Entity beans provide a similar abstraction between business logic and
> > persistence storage, but they lock us into one way of accessing data
> > and one particular O/R mapping solution.
> >
> >
> >
> > DAO pattern leaves us a choice, we can use JDO, JDBC, or entity beans
> > to implement DAO interfaces.
> >
> >
> >
> > With DAO, we can work inside or outside an EJB container, so we can
> > use same DAO implementations in any location, that means flexibility.
> >
> >
> >
> > We are not handle transaction or security, leaving this to business
> > logic components.
> >
> >
> >
> > You can find good information in the http://www.corej2eepatterns.com
> > <http://65.54.187.250/cgi-bin/linkrd?_lang=EN&lah
=38c68bcbcd405911ed54e61b76d97d5e&lat=1086804232&hm___action=http%3a%2f%2fwww
%2ecorej2eepatterns%2ecom>
> >
> >
> >
> > DAO can be used anywhere in a J2EE application.
> >
> >
> >
> >
> >
> >
> > Ashraf Galal
> > (416)804-8359
> >
> > -- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
> > Free yourself from those irritating pop-up ads With MSN Premium
> > <http://g.msn.com/8HMBENCA/2734??PS=47575> Get 2 Months FREE*
>
> So, if my application use only EJB for persistence it makes no sense use
> DAO.
>
> But, as you said above, if this is not the case (I have persistence
> layer implemented in EJB, SQL, JDO etc) I can use this solution.
>
> At this point the question is: is it possible have an application with a
> persistence layer implemented with EJB, SQL, JDO, Hibernate and so on?
>
> I know that in some EJB application could be useful use SQL for BULK
> operations. In this case what should be the approach? I mean, is DAO
> sufficient
> for abstraction or I need others patterns?
>
> Again, is it possible use EJB, JDO and Hibernate (or other persistent
> mechanism) at the same time? If, so can you tell me an example?
>
> ====================================================================
> Companion Site: http://www.corej2eepatterns.com
> J2EE BluePrints: http://java.sun.com/blueprints/corej2eepatterns
> List Archive: http://archives.java.sun.com/archives/j2eepatterns-interest.html
> Unsubscribing: email "signoff J2EEPATTERNS-INTEREST" to listserv@(protected)
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<html>
Hi,
<p>Example at sun site shows you two ways of implementing the DAO with
XMLDAO and JDBCDAO as samples :
<br><A HREF="http://java.sun.com/blueprints/corej2eepatterns/Patterns
/DataAccessObject.html">http://java.sun.com/blueprints/corej2eepatterns/Patterns
/DataAccessObject.html</A>
<p>Cheers,
<br>~Amit
<p>Koala wrote:
<blockquote TYPE=CITE>ashraf galal wrote:
<p>> It is a good approach based on good OO design principles. It uses
<br>> ordinary java interfaces rather than special infrastructure such
as
<br>> that associated with entity beans.
<br>>
<br>>
<br>>
<br>> DAO uses an abstraction layer of ordinary java interfaces between
<br>> business logic and persistence components.
<br>>
<br>> The implementation of this interfaces handle persistence logic.
<br>>
<br>>
<br>>
<br>> Entity beans provide a similar abstraction between business logic
and
<br>> persistence storage, but they lock us into one way of accessing data
<br>> and one particular O/R mapping solution.
<br>>
<br>>
<br>>
<br>> DAO pattern leaves us a choice, we can use JDO, JDBC, or entity beans
<br>> to implement DAO interfaces.
<br>>
<br>>
<br>>
<br>> With DAO, we can work inside or outside an EJB container, so we can
<br>> use same DAO implementations in any location, that means flexibility.
<br>>
<br>>
<br>>
<br>> We are not handle transaction or security, leaving this to business
<br>> logic components.
<br>>
<br>>
<br>>
<br>> You can find good information in the <a href="http://www
.corej2eepatterns.com">http://www.corej2eepatterns.com</a>
<br>> <<a href="http://65.54.187.250/cgi-bin/linkrd?_lang=EN&lah
=38c68bcbcd405911ed54e61b76d97d5e&lat=1086804232&hm___action=http%3a%2f%2fwww
%2ecorej2eepatterns%2ecom">http://65.54.187.250/cgi-bin/linkrd?_lang=EN&lah
=38c68bcbcd405911ed54e61b76d97d5e&lat=1086804232&hm___action=http%3a%2f
%2fwww%2ecorej2eepatterns%2ecom</a>>
<br>>
<br>>
<br>>
<br>> DAO can be used anywhere in a J2EE application.
<br>>
<br>>
<br>>
<br>>
<br>>
<br>>
<br>> Ashraf Galal
<br>> (416)804-8359
<br>>
<br>> -- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
<br>> Free yourself from those irritating pop-up ads With MSN Premium
<br>> <<a href="http://g.msn.com/8HMBENCA/2734??PS=47575">http://g.msn.com
/8HMBENCA/2734??PS=47575</a>>
Get 2 Months FREE*
<p>So, if my application use only EJB for persistence it makes no sense
use
<br>DAO.
<p>But, as you said above, if this is not the case (I have persistence
<br>layer implemented in EJB, SQL, JDO etc) I can use this solution.
<p>At this point the question is: is it possible have an application with
a
<br>persistence layer implemented with EJB, SQL, JDO, Hibernate and so
on?
<p>I know that in some EJB application could be useful use SQL for BULK
<br>operations. In this case what should be the approach? I mean, is DAO
<br>sufficient
<br>for abstraction or I need others patterns?
<p>Again, is it possible use EJB, JDO and Hibernate (or other persistent
<br>mechanism) at the same time? If, so can you tell me an example?
<p>====================================================================
<br>Companion Site: <a href="http://www.corej2eepatterns.com">http://www
.corej2eepatterns.com</a>
<br>J2EE BluePrints: <a href="http://java.sun.com/blueprints/corej2eepatterns"
>http://java.sun.com/blueprints/corej2eepatterns</a>
<br>List Archive: <a href="http://archives.java.sun.com/archives/j2eepatterns
-interest.html">http://archives.java.sun.com/archives/j2eepatterns-interest.html
</a>
<br>Unsubscribing: email "signoff J2EEPATTERNS-INTEREST" to listserv@(protected)
.com</blockquote>
<p>--
<br>NOTICE: If received in error, please destroy and notify sender.
Sender does not waive confidentiality or privilege, and use is prohibited.
<br> </html>
====================================================================
Companion Site: http://www.corej2eepatterns.com
J2EE BluePrints: http://java.sun.com/blueprints/corej2eepatterns
List Archive: http://archives.java.sun.com/archives/j2eepatterns-interest.html
Unsubscribing: email "signoff J2EEPATTERNS-INTEREST" to listserv@(protected)
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