VB 2005 and Three Tier Solution Development

[Bob Palank]

Deae Dr. GUI, MVPs and others
Features of VB.Net 2005 makes it so easy to access mdb tables directly from
the form's controls. This makes me wonder how and if I should restrict the
communication to and from a database tables to a separate data tier which
is reached through a business process logic tier which passes data back to
the presentation tier.
1. Is three tier separation a best practice and recommended in all
solutions
for systems with a complexity level of seven or more classes ?
2. Doesn't the application of the point and click convenient access to the
DB Tables somewhat negate three tier
application solutions?
3. Sheepishly, could I say a new direction is for the presentation tier to
engulf the business
rules tier as well as the data access tier ?
BR
Bob

 

[Cor Ligthert [MVP]]

Bob,

I have seen in these newsgroups and on website a complete different
perception of multi tier applications than my perseption.

In my perception it is as this.
http://en.wikipedia.org/wiki/Three_tier

This is not about seperating program logic in different classes as by
instance a datalayer.

Can you tell us what your perception is.

(Be aware that a nTier application is a hell of a job and you should have to
do all checking and corresponding using managed pipes or remoting or
whatever method)

Cor

 

[Bob Palank]

Doke, Satzinger et al describe a three tier application as having a
User Interface ( aka Presentation Tier)
Web Server ( aka Busines Logic)
Data Base Server ( aka DBMS)
For example, all forms fit in the User Interface, separate from the
Business Logic code, which is separate from the Data Base code.
How would I follow the above as I develop an application if when I drop a
combo box onto a form, it nicely provides me with an efficient way to
immediately link and define the data that is to be displayed in the user
interface.
I'm confused.
Bob

 

[Cor Ligthert [MVP]]

Bob,

Doke, Satzinger et al describe a three tier application as having a
User Interface ( aka Presentation Tier)
Web Server ( aka Busines Logic)
Data Base Server ( aka DBMS)

This is exactly as ASPNET is working in it standard way.
The webbrowser accessing the given HTML code created by the applications as
the UI
The Dll on the webserver created by te application accessing all commands
from the UI
The DataBase server.

However a window forms application is build as a two tier, and I see not any
reason any more to use the three tier for that while I saw in past enormous
advantages.

Althouhg when you have a lot of sources for your data, than you can start
thinking of one single entry point.

Just my thought,

Cor

 

[Cor Ligthert [MVP]]

Bob,

I forgot, to fullfill what you want you can use a WebService, what gives the
same idea as the ASPNET handling. The Webservice is your supplier of the
information the user want to use and the application that does the updating.

You can of course as well use normal services, however around that are not
those tools in VS Net as there are around the webservice.

I hope this helps,

Cor

 

[Michel van den Berg]

Dear Bob Palank,

I recommend you to take a look at Lhotka's site: he has written two great
books (c# and vb.net editions) from where he build CSLA .NET
In his book he describes n-tier very well, plus you can see the
implementation in code (= CSLA .NET)
He also has some great articles.

Hope it helps,

Michel van den Berg