[Opensource] JDO

[Peter A. Pilgrim]

Geeta Ramani wrote:
> Hey, that's *exactly* what I have been wondering about too!!  Expresso gurus,
> would sure appreciate and answer to this.. especially since Mike has been
> rethinking component architecture..?
> 
> Thanks, and happy new year to you too!
> Geeta
> 
> Marc Schipperheyn wrote:
> 
> 
>>Hi all,
>>
>>Best wishes for the New Year. I've been using my time off to read up on JDO
>>(Java Data Objects). This looks to be very promising and I was wondering is
>>this were at all a candidate for replacing DBObjects by a JCP standard?

Hi

It depends on how on far the data object architecture is going a long?
There is already a new package `com.jcorporate.expresso.core.dataobject'
with java interfaces. There is a implementation package also
`com.jcorporate.expresso.core.dataobject.jdbc'

In theory you should able to write your own implementation in terms
JDO. However the whole way that data objects are constructed internally
in the Expresso Framework and outside will have to change.


First, a way has to separate the data object manipulaton from the
data object access, I believe `DataExecutorInterface' does this from
design. So you must avoid direct JDBC code in your own DBObject
classes. You cant call stored procedure for example.


Second, a factory design pattern is a possible the key to the design.

	DataObject x = DataObjectFactory.create("jdbc",
			com.acme.dbobg.SalesPerson,
			requestContext );

	DataObject x = DataObjectFactory.create("jdo",
			com.acme.dbobg.SalesPerson,
			requestContext );

Every new Expresso application will have use these API and not
the current ``new SecuredDBObjectType( RequestContext r )''

Third, it is not clear whether you would use the interface `DataObject'
or the `DBObject' in your web application. What type will the factory
return depends on how well the DBObject divorces it data manipulation
from it access operation ? In other how generic is the new data object
interface.

Fourth, the current code base will need a secured data object possibly?
So may be we will have

	SecuredDataObject s = DataObjectFactory.create("jdbc",
				com.acme.dbobg.SalesPerson,
				requestContext );

	s.validateSomeRole( "Admin" )

I will let Mike R chip in with the rest?

--////--

-- 
Peter Pilgrim
ServerSide Java Specialist

My on-line resume and for interview videos about myself, J2EE
Open Source, Struts and Expresso.
    ||
    \\===>  `` http://www.xenonsoft.demon.co.uk/no-it-striker.html ''