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| | | Pattern Composite Entity is still good for EJB 2.0 | Pattern Composite Entity is still good for EJB 2.0 2003-08-29 - By Deepak Alur
Back
Pradeep,
The Composite Entity pattern is still relevant to Entity bean design. It
would be a
misconception that this pattern is unnecessary now with EJB 2.x. We
introduced
a pattern called Business Object in the 2nd edition. Business Object
talks about
implementing your conceptual domain model and can be implemented as
POJOs (Plain old Java Objects) or entity beans. When you choose to go
with entity beans, you still need to consider a many things and that
is where the Composite Entity pattern comes in. Here are the
reasons why you should this pattern still applies regardless of whether
you are using EJB 1.x or 2.x:
1. It address is how to design entity beans that implement your business
objects
in the domain model regardless of EJB 1.x or 2.x.
2. It is applicable whether you choose to implement the dependent
objects as
local entity beans or as POJOs regardless of EJB 1.x or 2.x.
3. Some strategies (Lazy Loading, Store Optimization) outlined in this
pattern
are still applicable if you choose to use BMP (which is still widely in use
with entity beans) regardless of EJB 1.x or 2.x.
4. If you are using EJB 1.1 containers or if you wish to continue using
EJB 1.1 style entity beans, this pattern is still applicable.
5. (Reiterating what Sean said in his reply)
hope this helps,
-deepak
Pradeep Kumar wrote:
>This pattern was introduced only to address the drawbacks of EJB 1.1
>Now with EJB 2.0, this pattern must be outdated. I can't believe why this is
>still discussed in the 2nd edition of core patterns book.
>
> -- --Original Message-- --
>From: Sean Brydon [mailto:Sean.Brydon@(protected)]
>Sent: Friday, August 29, 2003 4:30 AM
>To: J2EEPATTERNS-INTEREST@(protected)
>Subject: Re: Pattern Composite Entity is still good for EJB 2.0
>
>Hi,
>Yes it is valid, especially for EJB2.0 and higher. Local EJBs make this
>a valuable design. This pattern is discussed and updated in the second
>edition of the patterns book, now available. An example of this strategy
>is at
>http://java.sun.com/blueprints/patterns/CompositeEntity.html
>and this is done in the petstore application.
>
>hope that helps,
>Sean
>Le Quang Tu wrote:
>
>
>
>>Hi all,
>>In "The Core J2EE pattern" book, the Composite Entity Pattern is
>>recommended for the Coarse-Grained Entity bean. But in another book -
>>"the EJB Pattern" which is available in theserverside.com, the author
>>recommends that "Don't Use the Composite Entity Bean Pattern", because
>>it is built for the 1.x specification. The problem with dependent
>>objects is that they are impossible to create, using your application
>>server's CMP engine and extremely difficult to implement using BMP.
>>Managing the life cycle of a set of dependent objects in BMP
>>is equivalent to writing your own persistence engine.
>>
>>EJB 2.0 can support the CMP EJB relationship among entity beans. With
>>this enhancement, including Local interface, entity bean can now be
>>used to domain objects in your design model as finely as you like.
>>
>>So is Composite Entity Pattern still good for EJB 2.0 now?
>>
>>Le Quang Tu
>>====================================================================
>>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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>
>
>
>
>DISCLAIMER:
>This message (including attachment if any) is confidential and may be
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<meta http-equiv="Content-Type" content="text/html;charset=ISO-8859 (See http://ISO-8859.ora-code.com)-1">
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Pradeep,<br>
The Composite Entity pattern is still relevant to Entity bean design. It
would be a <br>
misconception that this pattern is unnecessary now with EJB 2.x. We introduced
<br>
a pattern called Business Object in the 2nd edition. Business Object talks
about <br>
implementing your conceptual domain model and can be implemented as <br>
POJOs (Plain old Java Objects) or entity beans. When you choose to go <br>
with entity beans, you still need to consider a many things and that<br>
is where the Composite Entity pattern comes in. Here are the<br>
reasons why you should this pattern still applies regardless of whether<br>
you are using EJB 1.x or 2.x:<br>
1. It address is how to design entity beans that implement your business
objects <br>
in the domain model regardless of EJB 1.x or 2.x. <br>
2. It is applicable whether you choose to implement the dependent objects
as <br>
local entity beans or as POJOs regardless of EJB 1.x or 2.x. <br>
3. Some strategies (Lazy Loading, Store Optimization) outlined in this pattern
<br>
are still applicable if you choose to use BMP (which is still widely in use
<br>
with entity beans) regardless of EJB 1.x or 2.x. <br>
4. If you are using EJB 1.1 containers or if you wish to continue using<br>
EJB 1.1 style entity beans, this pattern is still applicable.<br>
5. (Reiterating what Sean said in his reply)<br>
hope this helps,<br>
-deepak<br>
<br>
Pradeep Kumar wrote:<br>
<blockquote type="cite"
cite="mid8A9E18385C536F40AFD9DFA8ED7BBEA90225C5B3@(protected)">
<pre wrap="">This pattern was introduced only to address the drawbacks of EJB
1.1
Now with EJB 2.0, this pattern must be outdated. I can't believe why this is
still discussed in the 2nd edition of core patterns book.
-- --Original Message-- --
From: Sean Brydon [<a class="moz-txt-link-freetext" href="mailto:Sean.Brydon
@(protected)">mailto:Sean.Brydon@(protected)</a>]
Sent: Friday, August 29, 2003 4:30 AM
To: <a class="moz-txt-link-abbreviated" href="mailto:J2EEPATTERNS-INTEREST
@(protected)">J2EEPATTERNS-INTEREST@(protected)</a>
Subject: Re: Pattern Composite Entity is still good for EJB 2.0
Hi,
Yes it is valid, especially for EJB2.0 and higher. Local EJBs make this
a valuable design. This pattern is discussed and updated in the second
edition of the patterns book, now available. An example of this strategy
is at
<a class="moz-txt-link-freetext" href="http://java.sun.com/blueprints/patterns
/CompositeEntity.html">http://java.sun.com/blueprints/patterns/CompositeEntity
.html</a>
and this is done in the petstore application.
hope that helps,
Sean
Le Quang Tu wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi all,
In "The Core J2EE pattern" book, the Composite Entity Pattern is
recommended for the Coarse-Grained Entity bean. But in another book -
"the EJB Pattern" which is available in theserverside.com, the author
recommends that "Don't Use the Composite Entity Bean Pattern", because
it is built for the 1.x specification. The problem with dependent
objects is that they are impossible to create, using your application
server's CMP engine and extremely difficult to implement using BMP.
Managing the life cycle of a set of dependent objects in BMP
is equivalent to writing your own persistence engine.
EJB 2.0 can support the CMP EJB relationship among entity beans. With
this enhancement, including Local interface, entity bean can now be
used to domain objects in your design model as finely as you like.
So is Composite Entity Pattern still good for EJB 2.0 now?
Le Quang Tu
====================================================================
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</pre>
</blockquote>
<pre wrap=""><!---->
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notify the sender by return e-mail and delete this message from your system.
Any unauthorized use or dissemination of this message in whole or in part is
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