Re: Business Objects vs Data Objects [was Re: JXTemplates - what' s in a name?]

[Ugo Cei <u....@cbim.it>]

Ralph Goers wrote:
> In my environment a DAO is the object that is the result of reading from the
> database (or some other source).

You can call them anything you like, but the accepted meaning of DAO is 
an object that is used to read/store Value Objects from/to a persistent 
storage. A DAO has no attributes with business meaning. See [1].

 > Finally DataTransferObjects are the objects sent to the
 > presentation tier as the result of a request.

DTOs are used to transfer data in a single chunk between layers of a 
*distributed* application. That is, if you have a remote object (imagine 
an entity EJB) with many attributes, you'd rather copy the attribute 
values to a DTO and serialize it to the client rather than call many 
getters across the wire. [2]

If your presentation layer is remote, you can as well send DTOs to it.

	Ugo

[1]: 
http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html
[2]: 
http://java.sun.com/blueprints/corej2eepatterns/Patterns/TransferObject.html


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