Hi,
I'm on the same boat as Mike and you. The discussion was about how can we
simplify the data transformation of a subset of POJOs following a strict
pattern without starting from a formal model such as XSD. I don't know any
JAXB implementation can handle a POJO without JAXB annotations. If there is
one with reasonable support of default Java/XML mapping (no XSD or
annotations are required), I would be happy to use it.
Thanks,
Raymond
----- Original Message -----
From: "Simon Nash" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, November 26, 2007 12:36 PM
Subject: Re: Data transformation from/to POJO
Mike has brought up a very good point. I don't think it would make
sense for Tuscany to invent yet another Java to XML mapping. What
are the issues if we were to go with what JAXB defines for this?
Simon
Mike Edwards wrote:
Raymond,
"Where angels fear to tread"
My initial thoughts about this mused on why people had spent so much time
on specs like SDO and JAXB. If mapping POJOs to XML was simple and
straightforward, why did we need those large specs?
Perhaps you are right in thinking that there are simple cases that can be
mapped simply. But then, what do you do about the more awkward cases?
What I'd like us to consider deeply first is whether we want to create
(yet) another Java <-> XML mapping specification and if so, what is its
relationship to the existing ones.
My initial 2 cents....
Yours, Mike.
Raymond Feng wrote:
Hi,
With the recent development of the online store tutorial, we encounter
quite a few issues around the transformation between POJO and other
databindings (such as XML, JSON).
Let's take the POJO <--> XML as an example. Here is a set of questions
to be answered.
1) Do we require the POJO to be a strict JavaBean or free-form class?
2) How to read properties from a java object?
The data in a java object can be accessed by the field or by JavaBean
style getter methods. There are different strategies:
a) Always use JavaBean-style getter method
b) Always use field access
c) A combination of a & b
The other factor is the modifier of a field/method defintion. What
modifiers are allowed? public, protected, default and private?
If a property only have getter method, should we dump the property into
the XML? How about transient fields?
3) How to write properties to populate the target POJO instance?
a) Use JavaBean setter?
b) Use field
c) Combination of a & b
When we convert XML element back to a POJO property, how do we
instantiate the property instance if the property type is an interface
or abstract class?
For example,
package com.example;
public class MyBean {
private MyInterface p1;
public void setP1(MyInterface p1) {
this.p1 = p1;
}
public MyInterface getP1() {
return p1;
}
}
Do we require the XML element contains xsi:type attribute which will be
generated from POJO-->XML to represent the concrete property type? Such
as:
<myBean xsi:type="ns1:MyBean" xmlns:ns1="http://example.com/";>
<p1 xsi:type="ns2:MyInterface" xmlns:ns2=http://example.com//>
</myBean>
Thanks,
Raymond
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