Velocity and Data Access Layer Questions...

[Jeff Duska <Je...@noaa.gov>]

I'm using VelocityServlet project. My goal is to create a several 
Velocity Library Tools that are implement the business objects.

I was using the model suggest by Martin Fowler called Row Data Gateway. 
I tweaked this for the recommendation from Block in Effective Java to 
use static factor instead of a constructor. In my case, I have 
findbyRandomNumber(String rnd).

In my test code I just would have

	PurchasedProduct pp=PurchasedProduct.findbyRandomNumber...

I wanted to have something like this for my template users

	#set ($pp= PurchaseProduct.findyRandomNumber...)

	$pp.isFree

The problem is that this doesn't work with VelocityServlet, because 
there isn't a public construtor. I could change from a factory to a 
method, since the object already exists. What happens when I want to 
create another instance of the object?

I could refactor this into two classes. The business object and another 
object that is the factory. My only concern is that I know have quite a 
few classes.

Right now it does findbyRandomNumber
		
  creates a ProductPurchaseFinder (does all the db stuff)
  uses the ProductPruchaseFinder to create the ProductPurchaseGateway
  ProductPurchase would then have function for the business rules
    using a the private instance of ProductPurchaseGateway to stored the
    data

I use the wrapper on ProductPurchase, because I like to replace my 
database code with something like JDO, Torque or Castor at a later date.
At this point, I would need to create ProductPurchaseFactory to hold the
factory functionality. Does this make sense? I'm worried I've made this 
too confusing. I really do expect to rip out the database code in future 
release.

What are you suggestions?

Regards,

Jeff Duska



	
			




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