Eric D Nielsen on 26/03/08 15:31, wrote:
Adam Hardy on 26/03/08 00:28:43
Eric D Nielsen on 25/03/08 14:29, wrote:
Its a Struts2/Spring2/JPA(Hibernate) based project. I'm using a slightly
modified version of the Generic DAO pattern shown in the Java persistence
with Hibernate book and/or the IBM ThoughtWorks very similar example.
(Modified to allow Spring Based Injection of the JPA EntityManger, while
falling back to a native Hibernate session inside the DAOs to allow a few
more optimizations).
So its basically
Business Objects (POJOs) <---1:1---> DAOs
which is a relatively normal pattern I beleive.
Is it normal with that Generic DAO pattern to name the DAOs 'services'? In the
Domain-Driven-Design paradigm that I generally follow, the services are objects
which carry out operations that you don't want to specifically assign to one
domain object.
I'm willing to admit a LOT of confusion about DAOs v (Services | Managers) v
business logic on POJOs. I will say that my Actions are taking things named
"services" but typed as DAOs since I thought I would eventually migrate towards
this extra tier, but have let to really understand what belongs there. I think
a large part of my confusion comes from most examples I've seen where just
about 100% of the method in the vast majority of service classes are proxied
calls from the DAO. With only 1-2 methods added to a small percentage of the
services. However we are getting quite far afield for Struts matters here.....
I'd be very happy to receive further enlightenment, but if its better to move
this part of the discussion elswhere, please let me know...
I guess you want the Spring design paradigm. It's relatively straight-forward
although you're right - in alot of cases, the managers just wrap the dao calls
with no added functionality.
just use POJOs there. I believe this approach would work with the
Model-Driven idea, but it feels a little odd to me to mark up the domain
object with HTTP-specific details....
Yes it would do, but what do you mean by 'mark up the domain object with
HTTP-specific details'? I don't think you have to touch the domain objects to
code the re-construction of your incoming Bug POJO.
Yay! Back to Struts matters... I haven't written any type converters yet, but
from the examples I'd been seeing I thought you had to add a @TypeConversion
annotation to accessors that wanted custom type conversion.
http://struts.apache.org/2.x/docs/typeconversion-annotation.html
So if I was using Model Driven, would this mean putting these annotation on the
model. (much like the Vistor pattern for Validation)
You don't have to use annotations if you don't want to. You can use property
files instead.
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