I just started this week on a new project. The existing project uses
BEA Tuxedo as a second layer service broker. The clients make calls
to the Tux services which in turn retrieves data from an Oracle DB.

My job is to support the current application and possibly upgrade teh
client app to .Net. I have a few options:


I can rewrite the client desktop application .in Dot Net (FW3.0)
utilizing the same Tux calls or
Write a new desktop application using straight calls to the DB (make
it a two tier app)
Write a new ASP.Net application using straight calls to the DB
Write either a new Win form app or ASP.Net app utilizing WCF services
as a middle tier
Write a new front end (win form or web form) using BizTalk as a
replacement to Tux


Here are my questions:


Assuming the new application is stand alone, why would I need
BizTalk?
If the system isn't stand alone, I could still make calls to the Tux
services, so again would I need BizTalk?
What advantages does do I gain if I do use BizTalk over just WCF?
In the pass all of my calls to Web services were slow; wouldn't my
app
gain processing performance with less dependency on services (2 tier
vs 3 tier)?
Again what am I gaining with a 3 tier over a 2 tier?
Is there another solution I'm not seeing?

I've had some time to rethink what it is I'm trying to convey. My
question comes down to the architecture of a new application. Do I
really need a middle tier solution? For the purposes of replacing the
just existing application, I can build an ASP.Net site using ASP.AJAX,
JavaScript, and HTML on the Client side; the FileNet APIs, WCF and
ADO.Net on the Server-side. My short circuit is this solution seems
too easy. It also appears that by cutting out the middle tier, I will
gain performance. I'm wondering if there's some major architectural
black hole I'm missing here? Load balancing maybe? I don't know