Do we need Business Logic Layer.vb files?

cJeffreywang · January 9th, 2008, 04:53 PM

On Microsoft Data Access Tutorials, instead of just creating datasets in App_Code, Business Logic Layer (BLL) classes were created as a proxy for the presentation layer to access the Data Access Layer data.

Is BLL a new, advanced class to program the Web database applications? If we can use datasets directly, why we need the BLL.vb files?

TIA,
Jeffrey

Imar · January 9th, 2008, 05:10 PM

Hi Jeffrey,

An additional business layer gives you flexibility and functionality in a lot of different areas, including centralized business logic and the possibility to switch databases.

You may want to take a look here: http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=416 for some ideas about business layers in ASP.NET applications.

Cheers,

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

planoie · January 9th, 2008, 05:30 PM

Also, by decoupling your business logic from your user interface, you promote reuse of your business logic code for other programs. It may gain you much with simple "one-off" database web apps, but it's a vital piece of application architecture design for larger business apps.

Yet another reason for these "separation of concerns" is to provide the capability to use unit testing frameworks. These frameworks are very difficult if not impossible to use when your business logic lives in web project classes or the pages themselves. By building atomic business logic units you can automate tests against them using a unit testing framework.

-Peter

cJeffreywang · January 9th, 2008, 07:23 PM

I believe you both are right.

First thing first. On P. 4,the Tutorial-02 showed some Methods after creating a BLL.vb file. My question is how to 'add' these methods to the BLL classes. By typing the vb codes? Moving the methods created in Datasets.xsd files to here? How?

Any examples showing how to add the Methods to a BLL class?

Thanks.
Jeffrey

Bob Bedell · January 9th, 2008, 10:50 PM

Hi Imar,

Definitely excited to have stumbled across the QuikDoc you referenced today. Looking forward to playing with it for hours!

I downloaded and ran the C# version, and just noticed one odd behavior. Try this:

1. Run the app.
2. Click the button fields on gvContactPersons in exactly this sequence:

Imar Spaanjaars - Email
Some other Dude - Addresses
Some other Dude - Email

Some other dude has got your e-mail address!

Or try any version of that sequence:

Imar Spaanjaars - Phonenumbers
Some other Dude - Email
Some other Dude - Phonenumbers

Imar Spaanjaars - Addresses
Some other Dude - Email
Some other Dude - Addresses

Some other Dude's info isn't displayed. Imar Spaanjaars info appears instead. When I click the Some other dude ButtonField the second time in any of these sequences, WhateverManager.GetList isn't firing. A round-trip to the database isn't happening, so a new Some other Dude business object isn't getting returned. It looks like the View is still bound to the old Imar Spaanjaars object, or something.

Are you seeing what I'm seeing??

Thanks for putting this together. Have to poke around on your site more often!!

Best,

Bob

Imar · January 10th, 2008, 01:54 AM

I don't know what code you are referring to exactly, but yes, usually you "add" methods into a class by typing in code, copying and pasting it from somewhere else, use built in code generation tools (the Class Designer / Create Method Stub etc) or use external tools like Code Rush.

I don't know what's relevant / referred to in your situation...

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

cJeffreywang · January 10th, 2008, 04:55 PM

Thanks.

As I expect, we need to type in codes, use Class Designer, or other tools to add the methods to a BLL.vb file.

Jeffrey

Imar · January 10th, 2008, 05:10 PM

Hi Bob,

Thanks for catching that. Seems like a bug to me. The fix is easy though; just DataBind the relevant GridView controls whenever you choose a new option:

Code:

switch (e.CommandName.ToLower())
{
  case "addresses":
    gvContactPersons.SelectedIndex = Convert.ToInt32(e.CommandArgument);
    MultiView1.ActiveViewIndex = 0;
    gvAddresses.DataBind();
    break;
  case "emailaddresses":
    gvContactPersons.SelectedIndex = Convert.ToInt32(e.CommandArgument);
    MultiView1.ActiveViewIndex = 1;
    gvEmailAddresses.DataBind();
    break;
  case "phonenumbers":
    gvContactPersons.SelectedIndex = Convert.ToInt32(e.CommandArgument);
    MultiView1.ActiveViewIndex = 2;
    gvPhoneNumbers.DataBind();
    break;
  case "edit":
    ....
}

Will try to update the article ASAP....

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

Bob Bedell · January 10th, 2008, 10:13 PM

Thanks Imar. Works great.

Bob

cJeffreywang · January 11th, 2008, 12:58 PM

Just finished reading Part I and get ready for the Part 2.
While trying to recreate the database in SQL Server 2000, I was not sure which download link is for the T-SQL scripts. quickdoc=?

TIA,
Jeffrey

Quote:

quote:Originally posted by Imar
Hi Jeffrey,

An additional business layer gives you flexibility and functionality in a lot of different areas, including centralized business logic and the possibility to switch databases.

You may want to take a look here: http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=416 for some ideas about business layers in ASP.NET applications.

Cheers,

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.