gnue-dev
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Gnue-dev] New Architecture Drawing based on Whitepaper.


From: Reinhard Mueller
Subject: Re: [Gnue-dev] New Architecture Drawing based on Whitepaper.
Date: 05 Dec 2002 17:00:35 +0100

Am Don, 2002-12-05 um 09.16 schrieb Stanley A. Klein:
> However, there is a challenge in trying to do this that is evident from
> your terminology.  "Table and field names" implies a relational paradigm.
> "Class and property names" implies an object paradigm.  
[snip]
> However, if the front side is object and the back side is relational, I
> think there may be a problem.  These kinds of mappings tend to be complex
> and less easy to understand.  Objects can have structures that don't easily
> map into tables and fields.

A business object can basically have
* basic properties, which map to a database field 1:1
* calculated properties, which don't have a database mapping at all
* compound properties, where every element maps to a database field 1:1
* reference properties, which map to a database field 1:1 and
* list properties, which map to a field in another table 1:1

I don't see any problem in this.

The basic misunderstanding here seems to be that everybody seems to hear
"object" and thinks "oh, no, they are going to do inheritance,
polymorphism and all that stuff!!"

Please refer to the Appserver Whitepaper
(http://www.gnuenterprise.org/docs/whitepaper.html) for an explaination
of what we call a "business object". It is not "object" as in "object
oriented programming", it's more "object" as in "thing".

We use the terms "class" and "property" not because we want to refer to
OOP, but we use them because they fit best for what we mean.

Of course, there's some overlap between the classical OOP model and our
business object definition. The main part of the overlap is the concept
of "encapsulation", which means that we define the data elements and the
code to operate on them side by side.

I hope this brings some light into this issue.

Thanks,
-- 
Reinhard Mueller
GNU Enterprise project
http://www.gnue.org

Attachment: signature.asc
Description: Dies ist ein digital signierter Nachrichtenteil


reply via email to

[Prev in Thread] Current Thread [Next in Thread]