Oshadha's Blog

Common Design Principles

2011-06-08T20:33:00.000-07:00

There are number of common design principles that, like design patterns, best practice over the years to build maintainable software.

I'm up to describe some widely used design principles though out the post.

Following common principle are extracted by the same book that I mentioned before (Professional ASP.Net Design Patterns - Scott Millet).

Principles are as follows:

Keep It Simple Stupid (KISS)

One common issue in software programming is over-complicating a solution. So main concern of this principle is keep the code simple but not simplistic. Eventually this will avoid unnecessary complexities.

Don't Repeat yourself (DRY)

Main concern of this principle is to avoid the repetition. In other words this is all about abstracting out the common functionalities into a single place.

Ex: If there is a price calculation method in a system. It should lay in a single place there.

Tell Don't Ask

The Tell, Don’t Ask principle is closely aligned with encapsulation and the assigning

of responsibilities to their correct classes. This principle state that you should tell the

object to what actions that you want to perform instead of checking the state of an object and performing the action by yourself. This avoids the tight coupling between classes.

You Ain’t Gonna Need It (YAGNI)

This is about putting of any features that are going to add having the idea in mind, that you gonna need this later. A design methodology that adheres to YAGNI is test-driven development (TDD). In brief TDD is all about righting the code only to pass the test.

Separation of Concerns (SoC)

SoC is the process of dissecting a piece of software into distinct features that encapsulate unique behavior and data that can be used by other classes. Generally, a concern represents a feature or behavior of a class. The act of separating a program into discrete responsibilities significantly increases code reuse, maintenance, and testability.

So this is it.

S.O.L.I.D Design Principles

2011-03-08T06:33:00.000-08:00

Hold on!!! Before this please read the common design principle post.

After a long time thought of writing a post. Actually these days I'm reading a book which is written by Scott Millet and the name of the book is "Professional ASP.Net Design Patterns". I can guarantee that this book give you a great knowledge on design stuffs.

Most of us are bit lazy to read things, so I thought of posting the things that I got form it. This is like the cream of what I got.

I'll start it with the S.O.L.I.D design principles:

The term S.O.L.I.D. comes from the initial letter of each of the five principles that were collected in the book Agile Principles, Patterns, and Practices in C# by Robert C. Martin, or Uncle Bob to his friends. Simply this is a collection of best practices for object-oriented design.

Following will explain all the principles:

Single Responsibility Principle (SRP)
This principle is closely aligned with a common design principle called Separation of Concerns. It says that every object should have one reason to change and single focus of responsibility. By applying this principle, you avoid the problem of monolithic class design. At the same time this principle gives readability and maintenance for a system.

Open-Closed Principle (OCP)
This principle says that classes should be open for extension and closed for modification, in that you should be able to add features and extend a class without it changing its internal behavior. In other words it avoids the possibilities of braking the system.

Liskov Substitution Principe (LSP)
The LSP says that you should be able to use any derived class in place of a base class and have it behave in the same manner without modification. In other words derived classes must be substitutable for their base classes.

Interface Segregation Principle (ISP)
The ISP is all about splitting the methods of a contract into groups of responsibility and assigning
interfaces to these groups to prevent a client from needing to implement one large interface and a host of methods that they do not use. The purpose behind this is so that classes wanting to use the same interfaces only need to implement a specific set of methods as opposed to a monolithic interface of methods.

Dependency Inversion Principle (DIP)
The DIP is all about isolating your classes from concrete implementations and having them depend on abstract classes or interfaces. It promotes the mantra of coding to an interface rather than an implementation, which increases flexibility within a system by ensuring you are not tightly coupled to one implementation.

This is about the S.O.L.I.D design principles. I hope this will you guys on the long way of design someday.

This is the first one of a series of articles. I'll be back with design patterns.

LINQ : Query expression vs Lambda Expression

2010-02-02T02:28:00.001-08:00

All the time I was using LINQ on projects I was wondering whether there is a performance difference between query expression and lambda expression.

So I decided to dig into it. I wanted to examine MSIL for both of these situations. I wrote small class which has two methods. One is using query expression and the other one is using lambda.

I complied this code and got the dll and view the MSIL using ildasm.exe. This following picture will show you the MSIL of GetFirst() method.

And this following picture will show you the MSIL of the GetSecond() method.

Yes!!! you can see that there is no different between these 2 MSIL. Will there be a performance difference???

reCAPTCHA for ASP.NET

2009-10-16T01:25:00.000-07:00

I was looking for this reCAPTCHA recently and this is what I found on my way. Hope this will help you in someway. To get an idea about reCAPTCHA watch the following video

and the following link will explain you how to implement it in your ASP.net web site.

reCAPTCHA for ASP.NET

Mihidum Dumaraye ( Kolapata helunu etha nimnaye) - Kasun Kalhara

2009-07-06T22:43:00.000-07:00

You can find this song on this link
http://www.elakiri.com/forum/showpost.php?p=3006516&postcount=18

I was trying to find this and I finally found it.

You and Me..

2009-06-17T03:03:00.000-07:00

Cool breeze wraps around…….
Slight showers of tiny drops
Eager to kiss the rosy petals……
Green smiles at the drizzle…….
And the golden beams illuminated…
Craft a gorgeous little world
Of hopes and dreams…..
It’s You and Me………..
Only both of us play the adoring role
In our devoted
Story of Love…………

By Thilini©

Dream

2009-06-17T02:54:00.000-07:00

Red and blue green and yellow,
Gorgeous picture was painted,
In the vast sky of thoughts,
Hills and Dews, Wings and hopes,
Added extra brightness,
To the beautiful scenery of thoughts.
Buds and flowers, Mist and breeze,
Brought cool fresh intimacy.
Fairy queen was lost in,
One big dream.
Fresh and sweet, pretty and cool,
Little world of dreams,
Could never call Her out.
She was enjoying,
The beautiful dream,
For years……………….
And years………………
Smiles and laughter;
The bosom friends,
Who shared Her joys,
Never let the Fairy Queen,
See no tears or sorrows.
She was totally lost in
The dream fairy world,
Of which She couldn’t
See the harsh reality.
But, revealing the truth of Life,
Gloomy shadows started,
Palling on the sweet little painting.
Red, blue colors were fading,
Dark shadows were capturing,
The gorgeous dream of the fairy queen,
Bright shiny dream was leaving,
Wet little drops of tears,
Started shining at the edge
Of Her little eye lids.
But still, She is struggling,
To survive in Her cute pretty dream,
Of which She never wants to come out.
No matter what sort of a dream it is,
Be with innocent hearts forever,
Whose only happiness is a dream.

By THILINI©

Not for you

2009-06-16T22:06:00.000-07:00

Golden Beams of ruthless radiance
Calling out a drop less drought
No damp neither live adjoining
Magical spell of kismet
Looking upon the rainbow lights
It was the same ruthless radiance
But comes up with rainbow shadows
That is for your name……………
Tiny tear droplets Shower cool smiles
That is for your name……………
Each second and each minute
Live and full to the utmost ecstasy
That is for your name……………
Sky catching castles of dreams
And floating clouds to put your name on it
The magical world of ecstasy
Live and true to the fullest
That is coz of you and only you
But……………………………
At the end of the day
Waken up but shattered dreams
Realization but broken promises
Soothing comfort but endless pain
Thousand words but trapped up voice
Tiny droplets but awful warmth
Sleepless dream but a dreadful nightmare

By Thilini©

Exit a T-SQL Cursor When Condition is met

2009-03-26T03:35:00.000-07:00

Have you ever wanted to exit from a cursor when a condition is met? I wanted to do it. So this is how I did it.

DECLARE @Field1 AS INT
DECLARE @Field2 AS INT

DECLARE CursorName CURSOR READ_ONLY
FOR

SELECT
Field1,
Field2
FROM TableName

OPEN CursorName

FETCH NEXT FROM CursorName
INTO @Field1, @Field2

WHILE @@FETCH_STATUS = 0
BEGIN

IF @Field1 = 1
BEGIN
GOTO ENDCURSOR
END

FETCH NEXT FROM CursorName
INTO @Field1, @Field2

END

ENDCURSOR:
CLOSE CursorName
DEALLOCATE CursorName

I have set my fonts to bold where you want to notice.

So that's all I hope you will get something out of it and it is true that this is not a big deal. :)

Populate Modal popup data which is bind to a link button - ASP.net

2009-02-05T20:30:00.000-08:00

I wanted to do a POC to my client to show modal popup functionality. So I did a simple page with one Button and a TextBox. That Button is responsible to popup the modal window. On that ModalPopup I implemented a search mechanism. I used Girdview control to show the search result.

I wanted to populate the id value of that search result which was binded to a link button. This gridview and the text box and button was in a AJAX update panel control. I did this because I wanted to have the smothness of the UI.

Now I met a new problem. Because I wanted to get that value out of that LinkButton control and show it in a TextBox control which was out of the ModalPopup.

So what I did was, I just assign that LinkButton's text property to a HiddenField and I used a JavaScript function to populate that HiddenField value the TextBox.

As you all know we need a Panel control to show our ModalPopup. This is gonna be a <div> on the HTML. So I used the onblur event to call my JavaScript function.

So my problem is solved. :D

I think this will help you all one day.

Programmatically add the META tags to an ASP.NET page

2008-11-16T01:36:00.000-08:00

Do you want to programmatically add the META tags to an ASP.NET page? You can try to the below code:

HtmlMeta metaDesc = new HtmlMeta();
metaDesc.Name = "description";
metaDesc.Content = "Your Description goes here";
Page.Header.Controls.Add(metaDesc);

HtmlMeta metaKey = new HtmlMeta();
metaKey.Name = "keywords";
metaKey.Content = "Your keywords here";
Page.Header.Controls.Add(metaKey);

Adding a separator image to ASP.Net Menu Control

2008-11-06T20:17:00.000-08:00

This what I did to add a separator to ASP.Net menu. I used Web.sitemap to bind the data to menu control. This how Web.sitemap looks like.

<sitemap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0">
<sitemapnode>
<sitemapnode url="~/Pages/DatingHome.aspx" title="Home" description="" separatorImageUrl="../../Images/but_blueSlice.jpg">
<sitemapnode url="~/Pages/Inbox.aspx" title="Inbox" description="" separatorImageUrl="../../Images/but_blueSlice.jpg">
</sitemapnode>
</sitemapnode>

This separatorImageUrl will tell you the image path of the separator. This event handler will do the rest of it.

protected void Menu2_MenuItemDataBound(object sender, System.Web.UI.WebControls.MenuEventArgs e)
{
SiteMapNode smNode = (SiteMapNode)e.Item.DataItem;

if (smNode["seperatorImageUrl"] != null)
e.Item.SeparatorImageUrl = smNode["seperatorImageUrl"];

}

This is it. Hope you all have something to get from it. :)

Dynamically Setting Master Page Body OnLoad Event script from a Child Page - ASP.net

2008-10-20T05:28:00.000-07:00

I wanted to dynamically set master page body onLoad event and I was searching the web for a solution. This link helped to find me the solution. :)

http://forums.asp.net/p/1310519/2584110.aspx

How to configure SQL Server Session State with Custom Database

2008-10-09T09:16:00.000-07:00

There are two steps got to follow to enable the SQL Server Session state to work

1. Configuring the database to support the SQL Server Session state.
2. Configuring your application to use SQL Server Session state.

1. Configuring the database to support the SQL Server Session state.

.Net framework has a tool aspnet_regsql which you can use to add the table and stored procedure to support SQL Server Session state. You can find this tool in the following folder.

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\ aspnet_regsql.exe

You can run this exe from window command prompt or you can directly run from SDK Command prompt.

Executing the following command enables SQL Server Session state for a database server named local and store it in a custom database called CustomSessionDB.

aspnet_regsql -C "Data Source=local;User Id=sa; Password=Sql2005" -ssadd -sstype c -d CustomSessionDB

Executing this command creates a new database named CustomSessionDB that contains both the tables and stored procedures for storing Session state.

2. Configuring your application to use SQL Server Session state.

To Configuring your application to use SQL Server Session state change the session state session as follows:

Simulate Table Lock situation using a Select statement - SQL Server 2005

2008-08-15T04:05:00.000-07:00

Today I wanted simulate a table lock situation in my database using a select statement. It was bit hard for me to do it. I was searching it in web, but couldn't find useful thing. May be I didn't do it in right way. ;)

Anyway I could do it. This is how I did it.

You can write your SQL statement with (TABLOCKX) at the end of SQL statement.

ex: Select * From table_name (TABLOCKX)

I assume you all know how to do the rest of it.

How to use DataBinder.Eval in HyperLink NavigationUrl - ASP.net

2008-07-22T03:01:00.000-07:00

I wanted to append page Url with DataBinder.Eval value in ASP.NET hyperlink control on ASP.NET HTML source. I was trying it using many ways and also search for resources on web but I could not find any useful thing.

I thought this will help u guys to get an idea about appending two strings. Solution as follows.

<asp:HyperLink ID="customerHyperLink" runat="server"
Text= '<%# DataBinder.Eval(Container.DataItem, "Name") %>' NavigateUrl='<%# "~/Pages/YourPage.aspx?id=" + DataBinder.Eval(Container.DataItem, "id") %>'></asp:HyperLink>

You can see how I have appended these two value in NavigateUrl property.

Hope some one will get the advantage of this post.

How To Implement Forms-Based Authentication in Your ASP.NET Application by Using C# .NET

2008-07-17T21:32:00.000-07:00

These days I was so busy to find how to Implement form based authentication in my ASP.net application. I was looking for a resource that I can use on web. I found some and most of them are not that easy to understand. So I though to write an article so then any one can read and get the basic idea from it.

I will first explain what is my scenario. I have my own database table to keep user credentials. So I wanted to use it to authenticate the users who are trying to log in.

This has nothing more than configuring your Web.config and writing few codes authenticate the user.

If you have your own database table to keep user credential, obviously you have a method written to authenticate. We can use this method to validate user and based on the results of this method you can do the authentication part.

These are the configuration lines that you have to put in to our Web.config.

<authentication mode="Forms"> <authentication mode="Forms">
<forms loginurl="Login.aspx">
</authentication>

This part in the Web.config will help you to say that you are going to use form authentication and go to the URL in loginUrl attribute if the user not authenticated.

If you want to check this authentication part for all the pages except Login.aspx. You can simply add following part to the Web.config and it will do the job.

<authorization>
<deny users="?">
<allow users="*">
</allow></deny></authorization>

This tells to allow all users who are authenticated and will tell to deny those who are not authenticated. Simple as that.

I know what you are thinking now. What if i don't wanna check authentication for all pages. It is also simple. You have to tell Web.config that these are pages that I want to authenticate. You can ignore the Web.config part I explained you just now and this following part for each page that you want to authenticate.

<location path="Default.aspx">
<system.web>
<authorization>
<deny users="?"></deny>
</authorization>
</system.web>
</location>

So know you know what is happening here. It will not allow any unauthenticated users to access this page. Like wise you have to add this part for the all pages you want to authenticate.

Now time has come to do coding.

Choose the place that you going to authenticate your users. Think you have method called ValidateUser(string userName, string password) which returns a boolean value as result.

If you get this result as true that mean user is authenticated and it is good to go. Before we proceed to other pages we have do some stuffs to let the application know that this user has authenticated.

This can be done in 2 ways. First one will do the job through one line of code. Second will do the job with few lines of code but it give you more control than the first one.

First way:

if (ValidateUser(txtUserName.Value,txtUserPass.Value))
FormsAuthentication.RedirectFromLoginPage(txtUserName.Value, chkPersistCookie.Checked);
else
Response.Redirect("logon.aspx", true);

Do not get confused with these names I have given. You can use your control names here.
and this chkPersistCookie.Checked part will tell whether you want to remember this user and log him/her directly without asking anything next time.

Second way:

if (ValidateUser(txtUserName.Value,txtUserPass.Value) )
{
FormsAuthenticationTicket tkt;
string cookiestr;
HttpCookie ck;

tkt = new FormsAuthenticationTicket(1, txtUserName.Value, DateTime.Now,
DateTime.Now.AddMinutes(30), chkPersistCookie.Checked, "your custom data");
cookiestr = FormsAuthentication.Encrypt(tkt);

ck = new HttpCookie(FormsAuthentication.FormsCookieName, cookiestr);

if (chkPersistCookie.Checked)
 ck.Expires=tkt.Expiration;

ck.Path = FormsAuthentication.FormsCookiePath;
Response.Cookies.Add(ck);

string strRedirect;
strRedirect = Request["ReturnUrl"];
if (strRedirect==null)
      strRedirect = "default.aspx";
   Response.Redirect(strRedirect, true);
}
else
Response.Redirect("logon.aspx", true);

That's all. Now you are good to go. Your site if fully authenticated now.

I think you got some thing out of this. Please let me know if you want to know something more.(Comments)

Thanks.

How To: Use Forms Authentication with Active Directory in ASP.NET 2.0

2008-07-12T01:17:00.000-07:00

This post will show you how to use forms authentication with Microsoft Active Directory directory service by using the ActiveDirectoryMembershipProvider.

To create a Web application with a logon page

Start Microsoft Visual Studio® .NET development system, and then create a new ASP.NET Web site called FormsAuthAD.
Use Solution Explorer to add a new Web form to the site called Login.aspx.
Add a Login control to Login.aspx.
By default, this control displays a user name field, a password field, and a Remember me next time checkbox. If the user selects this checkbox, a persistent authentication cookie is created and the user's browser stores the cookie on the user's computer.
For security reasons, you should avoid creating persistent authentication cookies; therefore, disable this feature by setting the DisplayRememberMe property of the Login control to false.
Note that when a user clicks Login on the Login control, it automatically validates the user by calling the configured membership provider, creates a forms authentication ticket, and then redirects the user back to the page he or she originally requested.
If you are working in a test environment and have a service account with permissions to create new user accounts in Active Directory, add a CreateUserWizard control beneath the Login control so that users can register with your site and create new accounts.
Note If you do not have the permissions to create new users, you will need to test authentication with an existing account.

You have to config your Web.Config with following settings

Locate the <authentication> element, and then change the mode attribute to Forms.

Add the following <forms> element as a child of the <authentication> element, and then set the name and timeout attributes as shown in the following example.

authentication>

Add the following <authorization> element beneath the <authentication> element in your Web.config file.

authorization>

Add configure ASP.Net for membership

In the Web.config file, add a connection string similar to the following, and modify it so that it points to your Active Directory users container.

connectionStrings>

Note The connection string shown above connects to the user's container within a domain called domainname. Update this string to point to the relevant users container within your domain.

Add a <membership> element after your <authorization> element, as shown in the following example.

<add

name="MyADMembershipProvider"

type="System.Web.Security.ActiveDirectoryMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

connectionStringName="ADConnectionString" attributeMapUsername="sAMAccountName"/>

providers>

membership>

Test Forms Authentication

Add a Page_Load Event Handler

Add the following code to the Page_Load event handler of your Default.aspx page. This page should be displayed only to authenticated users. To prove that this is the case, the code displays information obtained from the forms authentication ticket that is issued to authenticated users.

protected void Page_Load(object sender, EventArgs e)

{

Response.Write("Hello, " + Server.HtmlEncode(User.Identity.Name));

FormsIdentity id = (FormsIdentity)User.Identity;

FormsAuthenticationTicket ticket = id.Ticket;

Response.Write("

TicketName: "

+ ticket.Name);

Response.Write("
Cookie Path: " + ticket.CookiePath);

Response.Write("
Ticket Expiration: " +

ticket.Expiration.ToString());

Response.Write("
Expired: " + ticket.Expired.ToString());

Response.Write("
Persistent: " + ticket.IsPersistent.ToString());

Response.Write("
IssueDate: " + ticket.IssueDate.ToString());

Response.Write("
UserData: " + ticket.UserData);

Response.Write("
Version: " + ticket.Version.ToString());

}

To logon as an existing user

Browse to your application's Default.aspx page.
The earlier configuration of the <authorization> element prevents unauthenticated users from accessing any pages in your application. They are redirected to your Login.aspx page.
Enter valid credentials for an account in your domain, and then click Login.
The format of the user name depends on the attributeMapUsername attribute of the <membership> element. The default configuration for the ActiveDirectoryMembershipProvider uses User Principal Names (UPNs) for name mapping as shown in the following example.

attributeMapUsername="userPrincipalName"

Because of this, all user names must have the format UserName@DomainName; for example: mary@testdomain.com or steve@testdomain.com.
You can change the name mapping so that it uses simple user name format by setting the following attribute in the Membership Provider configuration in the Web.config file.
attributeMapUsername="sAMAccountName"

This is how it is look like when you done with Web.Config.

connectionStrings>

<system.web>

authentication>

authorization>

<add

name="MyADMembershipProvider"

type="System.Web.Security.ActiveDirectoryMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

connectionStringName="ADConnectionString" attributeMapUsername="sAMAccountName"/>

providers>

membership>

system.web>

configuration>

What is life

2008-07-04T03:42:00.000-07:00

Do we know what is it really?

Most of the ppl don't know... We all think that we understand it and also think that we know the truth.. Do we? Are u sure ur feelings telling u the truth? No it is not.

Real truth is not at anywhere else. It's inside u. If some have the courage to start to find it and keep that courage until u find it.. That person is a winner.. All others are losers, no matter what ever they have achieved in their so called life.....