3-tier approach

[Daniela Roman]

can someone explain to me please how to develop a 3-tier project?
Is each of the layers parta of a different dll (class library) project?

Thank you

 

[Scott M.]

They could be, but most likely, each layer is represented by a class or
series of classes.

 

[Jay Riggs]

can someone explain to me please how to develop a 3-tier project?
Is each of the layers parta of a different dll (class library) project?

Thank you

Daniela,

There's plenty of material out there on the subject (perhaps my
favorite:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/BOAGag.asp)

-Jay

 

[Bob]

Hi Daniela,
My understanding (And it is only that) is that it is dividing your
functionality into three separate catagories.
i.e. User Interface, Business Logic and DataTransport.
The BL and /or the DT could be separate assemblies but it is not mandatory.
To me it is more about the functionality of the classes that make up the
application.
So...
I usually put all my Database accesses in one class.(DT)
The Business Layer consists of whatever classes are required to make the
application perform its function(s) eg a Widget class is a business layer
object.
Business layer objects interact with the database by having an instantiation
of the DT class.
The UI instantiates and manipulates business layer objects.

eg A widget maintenance application. based on a Database

DT Class contains methods for
WriteNewWidget
GetWidgetList

Business Layer contains
Class Widget
Class Factory (Which has a collection of Widgets)

UI Layer
Form instantiates a Factory object and has a list box which displays the
Factory's Widget Collection.

FWIW
Bob

 

[Cor Ligthert [MVP]]

Daniel,

You have to create an extra Window services for that running on your server.

The bussiness Tier is communicating with your clients on one side and on the
other side with the data tier.
The dataTier is by instance the SQL Sever. (This is the approach as standard
in ASP.Net).

It is a very difficult method in windows forms. It is easier to go for a
multi layer approach, where the layers are classes that you use in your
program.

However those are than an integrated part of your client programs and in my
opinion not real tiers.

I hope this gives an idea,

Cor

 

[AAJ]

Hi Cor

I suppose its down to the terminology of tier and layer. I have found that
lots of people use tier and layer Interchangeably.

I dont know if its of any use for Daniela, but I found

http://www.asp.net/learn/dataaccess/default.aspx?tabid=63

to be a really good starting point particularly for .NET ( although they
class it as Tier rather than layer)

Personally, I have a physical database layer (which I suppose is a tier)
then a Data access Layer, a Business layer and a user layer (which I suppose
are all in one tier), and certainly for the smaller projects I've been
working on, they all exist in one project. I'm not sure how the bigger
companies arrange theirs though.


Andy

 

[sloan]

Daniela,

http://sholliday.spaces.live.com/?_...ogview&_c=blogpart&partqs=amonth=5&ayear=2006
5/24/2006
http://sholliday.spaces.live.com
Custom Objects/Collections and Tiered Development


This blog entry will actually bring some code samples and implementation to
all the tutorials out there.

And show some common mistakes.

I do interviews for my company, and alot of people know the key words and
some concepts, but coding it up well is a little different sometimes.

At the bottom of that blog entry is:
And a reference to read from start to finish, aka, very informative for a
bird's eye view:
*
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/BOAGag.asp

I have that bookmarked, and if you just getting into it, I'd read that thing
once a month for the next 4 or 5 months.

..........................

If you're doing 2.0 development, there is a June 2006 blog entry also.

 

[Daniela Roman]

than you