Re: Java Client beginner question
Re: Java Client beginner question
- Subject: Re: Java Client beginner question
- From: Arturo Pérez <email@hidden>
- Date: Wed, 5 Feb 2003 21:38:24 -0500
On Wednesday, February 5, 2003, at 05:32 PM, Kenny Sabarese wrote:
i'm new to java client web objects, i have 5.2 on osx and am trying to
develop a simple 3 tier app to be used over the net.
I've done that.
i'm just having a bit of confusion when setting up my EOModel and
setting attributes to be client side or server side class properties.
my idea is that in a 3 tiered app is that the client never talks to the
database directly. it will request things from the server which then
supplies the client with the information it requests.
In a WO client (even a WO non-client) the "application" never talks
directly
to the database. It always goes through EOF (assuming no raw SQL). So
that's
not really a concern.
The way I think about it: Some properties make no sense on the client
side.
For example, say you need to log most recent access times but never
need to
display them on the client side.
so am i right when i say that adding client side properties allows the
client direct access to the DB? and if i want to build a thin client
application, i will have to code things myself?
No, see above. Your second question leads to not needing WO at all.
Which may
be the correct answer but I don't know.
What WO provides in this situation is a mechanism for making business
logic objects. That's what you manipulate on both the client and
server sides, not database objects. Some people can't see the
difference and others refuse to see the difference. WO also allows for
the business logic to be different on the client vs the server side.
For example, the client business objects might want to enforce stricter
validation in order to conserve bandwidth.
i want a thin client in order to achive the best performance over the
internet. so say instead of the client having to go find the results
of a query itself instead of just asing a server for a list of strings.
(i would assume that the second way would consume less bandwidth)
Maybe maybe not. If you do the typical thing of converting integers to
strings for "portability" reasons then the second would consume more
bandwidth. WO has a lot of mechanisms built-in to help with bandwidth
management issues.
What you need to do is get a copy of the Apple WWDC videos and watch
the one on
doing java clients. After that you'll be in a much better position to
judge the
proper course of action for your needs.
Another thing you could look at are EJB design patterns. One (somewhat
flawed)
way of looking at the client side business object is to think of them
as EJB value objects.
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