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RE: "Uh, what do I need this for" (was RE: XML.COM: How I Learne dtoLov

• From: Nicolas LEHUEN <nicolas.lehuen@u...>
• To: 'Leigh Dodds' <ldodds@i...>,'Michael Brennan' <Michael_Brennan@a...>
• Date: Thu, 23 Aug 2001 15:18:09 +0200

Why not use XML in the DAO layer with XML document as immutable Values, then
? It could be reusable in non-EJB contexts and it would solve your SOAP
serialization problem.

Regards,
Nicolas

>-----Message d'origine-----
>De : Leigh Dodds [mailto:ldodds@i...]
>Envoyé : jeudi 23 août 2001 15:07
>À : Michael Brennan; Nicolas LEHUEN
>Cc : 'xml-dev'
>Objet : RE: "Uh, what do I need this for" (was RE: XML.COM: How I
>Learned toLove daBomb)
>
>
>
>> -----Original Message-----
>> From: Michael Brennan [mailto:Michael_Brennan@a...]
>> Sent: 22 August 2001 21:35
>> To: 'Nicolas LEHUEN'
>> Cc: 'xml-dev'
>> Subject: "Uh, what do I need this for" (was RE: XML.COM: How 
>I Learned
>> toLove daBomb)
>
>[...comments on EJB DAO layers...]
>
>> You'll also notice in Sun's J2EE Blueprints white papers, they
>> encourage the notion of "value objects" that can encapsulate 
>the state of
>an entity bean
>> in a lightweight object that permits interaction with EJBs at a more
>> coarse-grained level. These objects are just data.
>
>We use a separate DAO layer and immutable Value objects, and they work
>very well. One advantage of a separate Data Access Object layer is that
>if you're writing a non-EJB oriented application (e.g. batch
>update/processing)
>that doesn't need to run in a full application server, you can 
>reuse this
>code. In this way Entity beans become adapters to plug your business
>logic into the DAO layer.
>
>One side effect of immutable Value objects I noted recently when
>adding a SOAP interface to one of our components, was that I couldn't
>take advantage of the Apache SOAP support for automated 
>(de-)serialisation
>of JavaBeans. Value objects aren't JavaBeans because everything is
>done in the constructor, and there are no set methods.
>
>No great loss, but it did mitigate one of the possible 
>benefits of using
>the Apache SOAP framework: I still had to write Serializers and
>Deserializers
>the same as I would have had to do with a custom XML messaging
>format.
>
>Cheers,
>
>L.
>
>
>--
>Leigh Dodds, Research Group, ingenta | "Pluralitas non est ponenda
>http://weblogs.userland.com/eclectic |    sine necessitate"
>http://www.xml.com/pub/xmldeviant    |     -- William of Ockham
>

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