BD,SL and TO Patterns

I had read this line about BD,SL and TO patterns in Peabody on scwcd patterns

BD Reduces coupling between presentation and business tiers (TO, SL)

See Business delegate reduces coupling between Controller and remote java services.
From what i know that presentation tier is JSPs, htmls while business tier is servlets
Then how can BD reduce coupling between presentation and business tiers.


Similarily, SL reduces coupling between BD and JNDI server.
Then how can BD reduce coupling between presentation and business tiers.

And TO I don't understand how it can do this either.

What i understand is this can only be done by MVC.

From what i know that presentation tier is JSPs, htmls while business tier is servlets

The Business tier consists of EJBs while the Web-tier (presentation layer) consists of Servlets and JSPs (according to Sun)

And TO I don't understand how it can do this either.

The Transfer object lives on the edge between the business layer and the presentation layer. The presentation layer should not know about EJBs.

Did this answer all your questions?

Regards,
Frits

Ya, about BD,SL and TO I understand.

But in case of MVC presentation tier is JSPs, htmls while business tier is servlets and data tier is model(EJBs)
isn't it?

But in case of MVC presentation tier is JSPs, htmls while business tier is servlets and data tier is model(EJBs)
isn't it?

To my understanding it was like this:
Model consists of the EJBs
View consists of JSPs
Controller is a Servlet

Regards,
Frits

hmm.. ok ...
may be its not about tiers in case of MVC..

i understood Bd,TO and SL
thanks..