N-Tier Architecture

[Islamegy®]

Lately i started to use microsoft code block and read about N-tier model..
I got some templates which implement custom collection for each database
table, I used to use DataTable and DataView in my programs so the Entity is
Datarow or Datarowview and the collection is the Dataview it self..

This way i was able to do all tasks without go back to the database, i was
searching with findRows or use RowFilter to search using "Like" and other
sql expression [i notes later in my first windows application that RowFilter
is really slow in preformance].

For what reason people need to implement custom collections and write all
this code to reimplement something already exist!!
thanx

 

[shiv_koirala]

With Custom collection you can ensure that the whole group is of same
types. For example ClsCustomer type cam only be added in
CustomerCollection. Second i can write lot of central logic buisness
code to all the classes added in collection.

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[Islamegy®]

But You will have to write alot of code.. and implement something like
RowFilter is really hard.. how could i search for a Customer in
CustomerCollection with a part of the firstname (Like) or range of date
(Between) in custom collection..
say i want to use (like) expression then i must loop on my collection
implement search kind of
str.indexOf(input.ToString());
to return this customer if index >= 0;
Is this efficient way (from preformance view) if i have 500 customers in my
collection and better than using implemented Datatable and Dataview
methods??
thanx

 

[Karl Seguin]

I have an article which talks about custom entities in a fair amount of
details:
http://msdn.microsoft.com/asp.net/default.aspx?pull=/library/en-us/dnaspp/html/CustEntCls.asp

There's no doubt that you are right, you'll need to re-write a lot of the
code which the DataTables already have built-in. There are frameworks such
as CSLA.Net (http://www.lhotka.net/ArticleIndex.aspx?area=CSLA .NET) which
provide a lot of that core functionality. Additionally, you can use Code
Generators such as CodeSmith (www.codesmithtools.com) to automatically
generate a lot of the code for you.

Let's not forget, you can still use your data layer to *gasp* access the
data. DataTable's SELECT might be good, but it's no where as good as SQL
Server's. w

Karl

 

[PJ6]

Custom collections for each table violates the layer of abstraction that
needs to exist between the Object Oriented and Relational elements of your
project. It also over-complicates it and makes change management a
nightmare.

Do not put raw SQL in compiled code. The bulk of all business logic belongs
in the data layer - use stored procedures. Also it is generally better to
filter result sets servier-side.

Paul