adeel's blog

Using Amazon S3 SDK Pre-signedURL function

2010-01-07T03:51:00.000-08:00

Today i was just exploring the amazon sdk. While using the presignedurl function of amazon sdk(C#), i was just curious that what is the server response time , zone. The amazon s3 returns the time in UTC. so simple but i was just curious that if we input time in GMT and it automatically convert it according to requestee IP time zone. i have tried to confirm but first i checked with UTC and it works 100% correctly. The second try i did is that i sent a GMT time and it works too. The amazon convert GMT to UTC according to client location. The sample code look like:

public string GetPreSignedURL(string bucketName, string key)
{
string url = string.Empty;
try
{
AmazonS3 client = Amazon.AWSClientFactory.CreateAmazonS3Client("ur access key", "secret key");

GetPreSignedUrlRequest request = new GetPreSignedUrlRequest().WithProtocol(Protocol.HTTPS).WithBucketName(bucketName).WithKey(key).WithExpires(DateTime.UtcNow.AddMinutes(1));
url = client.GetPreSignedURL(request);
}
catch { }
return url;
}

Increase IIS 5 connection limit on windows

2009-09-29T21:26:00.000-07:00

On a non server edition of window operating system, we often got the error.
There are too many people accessing the Web site at this time.
OR
HTTP 403.9 - Access Forbidden: Too many users are connected
Internet Information Services

To increase the connection limit, go to :
1 - Go to directory c:\inetpub\AdminScripts
2 - Execute the following command.
adsutil set w3svc/MaxConnections 40

Read or Write on Registry in C#

2009-08-26T00:36:00.000-07:00

Registry is a special place where applications stores its setting. Although Isolated storage for .net is a preferred way for storing
application settings yet registry has its own benefit. Normally it is difficult to find application created registry entries(if created carefully).
Below is a sample C# code.

//It will create a new subkey if not already created. otherwise it opens the existing one with write access.
RegistryKey objRegistryKey = Registry.CurrentUser.CreateSubKey("App_Name");
//Suppose i want to save last open time when application opened.
objRegistryKey.SetValue("LastOpenTime", DateTime.Now.ToString());

To get the value from registry, you use
string lastOpenDT = objRegistryKey.GetValue("LastOpenTime") as string;

The GetValue return the object type. you can than cast to the appropriate type.

Don't forget to add Microsoft.Win32 namespace.

For further reading,you can see the following two classess at msdn.
Registry,RegistryKey class.

multiple submit buttons and the enter key

2009-05-20T20:47:00.000-07:00

As you know it is the limitation of asp.net that it has only one form, so if you have another section which needs enter key submission, than you can use default button as used below.
The defaultButton property of Panel or Form is used to ensure Enter Key Submission. Typically people used to Enter Key submission and if it is disabled, it might be annoying certain times.

The defaultButton really provides a way to handle Enter Keys for respective portions of the page when the focus is there.

Example:

<form defaultbutton="button1" runat="server">
<asp:textbox id="textbox1" runat="server"/>
<asp:textbox id="textbox2" runat="server"/>
<asp:button id="button1" text="Button1" runat="server"/>

<asp:panel defaultbutton="button2" runat="server">
<asp:textbox id="textbox3" runat="server"/>
<asp:button id="button2" runat="server"/>
</asp:panel>
</form>

Extract links from html in C#

2009-04-24T03:25:00.000-07:00

private List ExtractLinks(string html)
{
List links = new List();

string startSquence = "<a";
string endSequence = "</a>";

html = html.ToLower();

while (html.IndexOf("<a") != -1)
{
int start = html.IndexOf(startSquence) ;
int end = html.IndexOf(endSequence, start+startSquence.Length);

//Extract the link, and add it to the list
if (end > start)
{
string link = html.Substring(start, end + endSequence.Length - start);

//Check b
if (link.Substring(1).IndexOf(startSquence) != -1)
{
html = html.Substring(start + startSquence.Length);
continue;
}

if (link != string.Empty)
{
links.Add(link);
}
}
else if (end < start)
{
html = html.Substring(start + startSquence.Length);
continue;
}
//Trim the raw data
html = html.Substring(end + endSequence.Length);
}
return links;
}

how to modify web.config in asp.net using C#

2009-04-22T03:28:00.000-07:00

You can modify web.config at run time. For exmaple to add a property in app settings section of web.config, you can use the following c# code

Configuration myConfiguration = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
myConfiguration.AppSettings.Settings.Add("CommentsLimit", "10");
myConfiguration.Save();

To update the existing property:
Configuration myConfiguration = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
myConfiguration.AppSettings.Settings["CommentsLimit"].Value = "20";
myConfiguration.Save();

virtual keyword in C#

2009-04-09T21:40:00.000-07:00

If a base class method is to be overriden, it is defined using the keyword virtual
The class member method may be overriden even if the virtual keyword is not used, but its usage makes the code more transparent & meaningful.

When the override keyword is used to override the virtual method, in a scenario where the base class method is required in a child class along with the overriden method, then the base keyword may be used to access the parent class member. The following example will be helpful to understand.

public class Shape
{
string name;
public virtual void SetName(string name)
{ this.name = name; }
}

public class Circle : Shape
{
//This method is being overriden
public override void SetName(string name)
{
base.SetName("circle"); //We are calling parent class method
}
}

How to Backup MySQL Database automatically in linux

2009-04-08T21:34:00.000-07:00

The command for back up a mysql database is:

15 2 * * * root mysqldump -u root -pPASSWORD --all-databases | gzip > /mnt/disk2/database_`data '+%m-%d-%Y'`.sql.gz

The first part is "15 2 * * *". The five fields mean "minute, hour, day of month, month, day of week" respectively. The character '*' stands for "any".
The next, "root", means "run following command as root account".

You can use cron job so that it takes backup daily.

World Sleep Day 2009

2009-03-20T14:47:00.000-07:00

World Sleep Day is an international annual event, intended to be a celebration of sleep and a call to action on important issues related to sleep, including medicine, education, social aspects and driving. It aims to lessen the burden of sleep problems on society through better prevention and management of sleep disorders. World Sleep Day 2009 is being held on March 20^th, under the slogan ‘Drive alert, arrive safe’. This year’s theme is transportation, focussing on safety, travel and driving alertness.

The first World Sleep Day was launched on March 14^th 2008. Events involving local groups took place in public settings around the world and online with the unveiling of a declaration, presentation of educational materials, and exhibition of videos.

The World Sleep Day declaration is as follows:

Whereas, sleepiness and sleeplessness constitute a global epidemic that threatens health and quality of life,

Whereas, much can be done to prevent and treat sleepiness and sleeplessness,

Whereas, professional and public awareness are the firsts steps to action,

We hereby DECLARE that the disorders of sleep are preventable and treatable medical conditions in every country of the world.

The World Sleep Day Committee would like you to assist in raising awareness of World Sleep Day 2009 by carrying out related activities in your country. World Sleep Day Committee members:
Antonio Culebras, co-chair
Liborio Parrino, co-chair
Richard Allen,
Sudhansu Chokroverty,
Christian Guilleminault,
Mario Terzano,
Robert Thomas,
Claudia Trenkwalder,
Allan O’Bryan, WASM Executive Director.

Source:http://worldsleepday.wasmonline.org/

How to validate integer in c#

2009-03-05T03:41:00.000-08:00

In C#, we often need to validate that the value is an int. So most developers use try catch block as below.
try
{
int t = Convert.ToInt32("wrongval");
}
catch
{
}

while the best approach to test must be:

int num = 0;
Int32.TryParse("wrongval", out num); //It will not throw any exception, In case of failure, it set the value of num to zero and also return FALSE.

if you see the performance of above two methods, you will be amazed that the TryParse method is 1000 times faster than Convert.ToInt32.

force one instance of an application in .NET

2009-02-14T11:22:00.000-08:00

To force a single instance of an application, either fetch all processess and check your application process name that is it already there or not. Another option is to use Mutex class.

bool NoInstanceCurrently;
System.Threading.Mutex mutex = new System.Threading.Mutex(false, "applicationname", out NoInstanceCurrently);
if (NoInstanceCurrently == false)
{

MessageBox.Show("Another Instance is Running", "ApplicationName", MessageBoxButtons.OK, MessageBoxIcon.Stop);
return;
}

Play sound from Window Form in C#

2009-02-14T08:30:00.000-08:00

Playing a sound from window forms in C# is simple because of SoundPlayer class from System.Media namespace.

SoundPlayer objSoundPlayer = new SoundPlayer("sound1.wav");
objSoundPlayer .Play();

Single line If Statement.

2009-01-31T11:49:00.001-08:00

string name = Session["UserName"];

if(string.isNullOrEmpty(name))
Response.Write("welcome guest");
else
Response.Write("welcome "+name);

You can write it in single line as below.

Response.Write((string.isNullOrEmpty(name)) ? "Welcome guest" : "Welcome "+name);

The HTML Label Tag Benifits

2009-01-31T11:44:00.000-08:00

Make your forms accessible to screen readers
Make your forms easy to click on
Give your CSS more to hold on to

To see more detail, check this Link

Use generics with drop down list

2009-01-31T11:40:00.000-08:00

You can use generice to bind with drop down list. Suppose you have a class Country.

public class Country
{
int id;
string countryName;

public int ID
{
get { return id; }
}

public string CountryName
{
get { return countryName; }
set { countryName = value; }
}
}

List objCountry = new List();
objCountry = objCountry.FetchCountries();
ddlCountryList.DataSource = objCountry;
ddlCountryList.DataTextField = "CountryName";
ddlCountryList.DataValueField = "ID";
ddlCountryList.DataBind();

The ddlCountryList is an asp.net drop down list control.

Designing a GUI

2009-01-21T21:58:00.000-08:00

A tip for designing a GUI(Graphical user interface) is that the items in the menu is in the range of 5 to 9. The reason is the famous rule of George A. Miller Seven plus or minus two. it states that the human minds at a time remember seven plus or minus two items. so it is a good practice to not make more than seven items in a menu.

Compiling C# and VB code together in asp.net

2008-12-03T02:34:00.000-08:00

Yesterday i was working on a web application which uses vb classes. I have added a c# class added but asp.net compiler does not compile it as app_code folder becomes a single assembly so it allows only vb or C#.

Tip:
To compile both C# and VB, add this in web.config.

<compilation debug="false">
<codesubdirectories>
<add directoryname="VBCode">
<add directoryname="CSCode">
</add>
</add></codesubdirectories></compilation>

For more information, see this post.

The Eight Commandments of Source Code Control

2008-12-01T09:24:00.000-08:00

Yesterday I read source code control tips which are helpful for developers working in a team environment. Link was sent by my friend Awais. I am posting here to share this.

1. You shall check in early and check in often. You anger your coworkers when you check out a file and insist on keeping it checked out until some future point in time that is measured using variables that exist solely in your brain.

2. You shall never check in code that breaks the build. If you code does not compile, it does not belong in the source control repository.

3. You shall not go home for the day with files checked out, nor shall you depart for the weekend or for a vacation, with files checked out.

4. You shall leave a descriptive comment when checking in your code. You need not include your name or the date in the comment as that information is already tracked.

5. You shall use the 'Undo Checkout' option if you check out a file and do not make any changes. It displeases your coworkers when you check in code that has not changed at all from the original.

6. You shall not use comments to 'save' defunct code. Fear not, for the code you delete still exists in the source control code history and can be retrieved if needed.

7. You shall use source control for more than archiving just code. The source code control repository makes an excellent storage for technical docs, SQL scripts, and other documents and files related to the project.

8. You shall religiously backup your source code control database on a regular basis and store a copy in an off-site location.

Source: http://scottonwriting.net/sowblog/posts/13581.aspx

fedora 10 released

2008-11-25T21:09:00.000-08:00

Yesterday the fedora 10 released. click Here to download it.

Generate properties from class variables

2008-11-25T05:56:00.000-08:00

One of the nice thing about Visual studio is its macro support. You can create and use macros in visaul studio .net to increase the productivity. One feature which most developers wants a quick property generation from list of class variables but Visual Studio .NET has no shortcut for it. To achieve this, you have record or create a macro.

So below is the Macro that generate the automatic properties from the member variables.

Just copy the text below and then open VS.NET.Go to Tools-> Macro->Macros IDE menu item.
A new window will be open. click on mymacros and paste the below text and build it.

After building, open your VS project. Go to Tools->Options. A dialog will be appeard. click on keyboard in Environment. Select your macro and assign a shortcut. For example Shift + F2.

Imports System
Imports EnvDTE
Imports EnvDTE80
Imports EnvDTE90
Imports System.Diagnostics
Imports System.Text

Public Module Expand
Public Sub ExpandPrivateMembersFronSelection()
Dim TS As TextSelection =

DTE.ActiveDocument.Selection
Dim strResult As String, Line As String
Dim Lines() As String =

TS.Text.Split(vbNewLine)
For Each Line In Lines
strResult &= GetstrResult(Line)
Next
TS.EndOfLine()
TS.NewLine()
TS.Insert(vbCrLf & "#region ""Public

Properties""" & vbCrLf & strResult &

"#endregion" & vbCrLf)

DTE.ExecuteCommand("Edit.FormatDocument")
End Sub

Private Function GetstrResult(ByVal text As

String) As String
Try
If (text.Contains("private")) Then
text = text.Replace("private",

"")
End If
If (text.Contains(";")) Then
text = text.Replace(";", "")
End If
Dim words() As String =

text.Trim.Split()

'System.Windows.Forms.MessageBox.Show(words(1))
If words.Length < 2 Then
Return ""
Else
Dim strResult As New

StringBuilder
strResult.AppendLine()

strResult.AppendLine(String.Format("public {0}

{1}", words(0), StrConv(words(1)(0),

VbStrConv.ProperCase)) & words(1).Substring(1))
strResult.AppendLine(vbTab & "{

get { ")
strResult.AppendLine(vbTab &

vbTab & "return " & words(1) & ";")
strResult.AppendLine(vbTab &

"}")

strResult.AppendLine(String.Format(vbTab &

"set"))
strResult.AppendLine(vbTab &

vbTab & " { " & words(1) & " = value;")
strResult.AppendLine(vbTab &

"}")
strResult.AppendLine("}")
Return strResult.ToString
End If
Catch ex As Exception

System.Windows.Forms.MessageBox.Show(ex.ToString

)
End Try

End Function

End Module

Issues:
Currently it will gives you incorrect result if the input is

string p = string.Empty;

You can customize macro according to your needs. The valid inputs are

string p;

private string q;

Just select and press your assigned shortcut.

Microsoft flashes Silverlight for Linux

2007-09-05T06:05:00.000-07:00

Microsoft is to make its recently unveiled Silverlight 'Flash killer' plug-in available on Linux.

The commercial release of Silverlight 1.0 is a cross-browser, cross-platform plug-in for delivering richer user experiences on the web.

Microsoft confirmed that it will work with Novell to deliver Silverlight support for Linux, called Moonlight, based on the project started on mono-project.com.

The Redmond giant unveiled Silverlight at the 2007 National Association of Broadcasters conference in April and released the beta version to the public in May.

Silverlight claims to significantly reduce development and deployment costs, and provides enhanced web audio and video streaming and playback using Windows Media.

Ray Ozzie, chief software architect at Microsoft, said: "With today's release of Silverlight 1.0, we are making it possible for developers and designers to deliver to individuals the kind of high-def experiences they crave by integrating data and services in rich and unique ways."

Ozzie added that Silverlight 1.0 will offer developers and designers new options for delivering content across multiple platforms including web, PC, phone and other devices.

The decision to work with Novell to offer Silverlight support for the Linux platform is in direct response to customer feedback, both companies said.

Microsoft is also rolling out the Silverlight Partner Initiative. More than 35 companies have already signed up to support Silverlight.

Reference: vnunet.com