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Why so much emphasis on Business Delegate or Intercepting Filter

Sam Gehouse
Ranch Hand

Joined: Jul 21, 2003
Posts: 281
I am not sure why so much emphasis is placed on Business Delegate and Intercepting Filter in SCEA postings.

The reality is, WebClient app and think client apps are two separate apps which are deployed separateley.

However, they will use the same SLSB and DAO.

If they are two separate apps, where is the need for Business delgate?

No delegation is necessary as one app (web app) will hit Servlet and the web UI will hit Servlet and the other app (thick client) will hit POJO.

Am I missing anything?
Jacek Ostrowski
Greenhorn

Joined: Feb 09, 2007
Posts: 23
Hi Sam,

From http://java.sun.com/blueprints/corej2eepatterns/Patterns/BusinessDelegate.html

Reduces Coupling, Improves Manageability
The Business Delegate reduces coupling between the presentation tier and the business tier by hiding all business-tier implementation details. It is easier to manage changes because they are centralized in one place, the Business Delegate.


This is why BD is so important.

Jacek


SCEA, SCWCD, SCJP, OCA AS10g
Sam Gehouse
Ranch Hand

Joined: Jul 21, 2003
Posts: 281
I agree with you and fully understand the benefit of Business delegate.

I should have asked the question differently. My question is:

As two separate applications are deployed (one web, another Swing) with both using the same SLSB and DAO; I think I do not have to use Business Delegate.

Any input?
Jacek Ostrowski
Greenhorn

Joined: Feb 09, 2007
Posts: 23
It doesn't matter how many apps you have.
For some apps BD is useful, for others is not.

Here I would use BD to reduce coupling between tiers and
I would share BD between both apps.

Jacek
Yi Meng
Ranch Hand

Joined: May 07, 2003
Posts: 270
As you may already be aware that Business Delegate is used between Systems ...not just between UI and Business layers..

Therefore, what if FBN switches to a different credit card gateway later on?


Meng Yi
Francesco Bianchi
Greenhorn

Joined: May 06, 2007
Posts: 5
Does it means that the BD and the Service Locator are a part of the Java Application client?
Meghana Reddy
Ranch Hand

Joined: Jan 29, 2002
Posts: 76
Originally posted by Francesco Bianchi:
Does it means that the BD and the Service Locator are a part of the Java Application client?


Nope , they ain't part of either the app client/web client or the business app.

BD is the point of seperation of Client and the enterprise/biz app. BD completely abstracts the app client of any of the biz app changes.
BD is the one that would undergo changes if Business interface changes.

SL just implements a lookup mechanism for remote objects.

So, these are not part of the app client as they can serve any of the Client applications.


Meghana Reddy
Pham Huy Anh
Ranch Hand

Joined: Aug 23, 2006
Posts: 41
Hello,

As I understand, Business Delegate is like interface, which expose the "contract", the face of functionality. And the change of implementation doesn't impact (very much) BD.

In other word, Business Delegate is the front part of component.
Is that right?
[ May 10, 2007: Message edited by: Pham Huy Anh ]
Frank Kuepper
Ranch Hand

Joined: Mar 16, 2007
Posts: 45
In a way, yes.
A Business Delegate is a proxy (see GoF pattern) for the ejb hiding the complexity of lookup and access (remote or local).


SCEA (93%/93%)
 
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