Why so much emphasis on Business Delegate or Intercepting Filter

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?

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

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?

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

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?

Does it means that the BD and the Service Locator are a part of the Java Application client?

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.

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 ]

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).