iPhone 4

If you are a iPhone lover then your next dream is in stores.

Apple had released iPhone 4 with many improvements.

Go and have look into it at Apple.

Unable to start debugging on the web server

Recently a set of developers who are working in one of my projects started getting an error while trying to debug the web application under development using ASP.Net. The targeted framework was .Net 4.0 and they were using Visual Studio 2010 in 64bit machines. The problem was whenever they tried to run/debug the application they gets an error saying unable to start debugging on the web server even though there are no compile errors as shown below.

It gave an error HTTP Error 500.21 - Internal Server Error Handler "PageHandlerFactory-Integrated" has a bad module "ManagedPipelineHandler" in its module list when ran direct from IIS. The error page is shown below.

Later I found the reason for this is ASP.Net 4 was not properly installed on the machine. To fix this get an administrative privileged command prompt.

Then type in the following,

aspnet_regiis -ir

You can find the aspnet_regiis.exe at the folder,

[Windows Dir]\Microsoft.NET\Framework64\v4.0.xxxxx

for example,

C:\Windows\Microsoft.NET\Framework64\v4.0.30319

This will register ASP.Net 4.0 in your machine, the -ir option will keep the existing applications unchanged. If you want them to be changed to use the new version use -i instead -ir.

When the installer ends type iisreset to restart the IIS service.

Now your applications will work fine without any complains.

Enable Hibernation and Sleep in Windows Server 2008 R2

Normally when you install Hyper-V role in your server, it will disable sleep and hibernate facilities provided by Windows.

But you can avoid this by doing some alterations to Windows.

Hibernate and seep features are disabled when the Hyper-V service is started, so you can regain hibernate and sleep by changing the start parameter of the Hyper-V service (hvboot).

To change,

1. Open the registry editor by typing “regedit” in the run window.

Locate the key,

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\hvboot and then set the start value of it to 3.

Start property can hold the following values.

0	Boot (Not supported by hvboot.)
1	System
2	Auto
3	On Demand
4	Disabled

Now you will have the hibernate and sleep facilities until you start the Hyper-V services in your machine.

2. Type the following command in a command prompt window with administrative rights.

sc config hvboot start= demand

Note that there needs to be a space between the = sign and the word demand.

Enabling Hibernate in Windows

Some server versions of Windows are having the hibernate feature disabled by default. So if you need to change the hibernation do the following simple steps.

1. Click start and type “cmd” or type command in the search box.

2. Then in the search results, right click the Command Prompt and click on Run as Administrator.

3. If you are prompted by the user account control click continue.

4. Then,

To turn hibernation on in your machine type -

“powercfg.exe /h on” or “powercfg.exe /hibernate on”

To turn hibernation off in your machine type -

“powercfg.exe /h off” or “powercfg.exe /hibernate off”

5. Lastly you can exit the command prompt by typing “exit”.

 

Sometimes you might get an error similar to the following while trying to enable hibernation.

Hibernation failed with the following error: The request is not supported. The following items are preventing hibernation on this system.         An internal system component has disabled hibernation.

 

This means your machine is running roles or services that are disabling hibernation feature. One such a role is Hyper-V. If your version of Windows 2008 is running Hyper-V then you cannot enable hibernation. This is not an error but is deliberately done since hibernating a server running virtual machines is a very complicated and rarely requiring service in an enterprise server.

But there is a way to enable hibernation on a Hyper-V installed machine, which you will be able to find in my next article.

Changing the Shared Feature Directory in SQL Server Setup

Today when I tried to install SQL Server 2008 R2 I couldn’t change the shared feature installation directory in the setup. Both the textbox and browse button were disabled restricting me to select the desired path.

After sometime I found the cause for this. It is because there were some SQL related programs already installed in my computer, because they are there the SQL setup uses the same directory to setup the rest of the programs.

If you need to relocate the install directory then simply you need to uninstall all the SQL related programs using Programs and Features and re-run the SQL Server setup. Then the browse buttons will be active enabling you to select an alternate location.

How to Make a Bootable Flash Drive

Recently I installed Windows using a flash (Pen/Thumb) drive, since I couldn’t get hold of a blank DVD to burn the ISO into.

It might be helpful to you as well. Because we don’t need to burn DVDs to install OSs that are coming as ISOs anymore.

Follow the steps below.

1. Find a good USB Flash drive with required space.

Make sure you have backed up all the required data in the flash drive because the flash drive will be formatted.

2. Get a command prompt by typing “cmd” in the run window.

3. Type “diskpart” and press enter.

This will open up a new window for DiskPart utility, you need to use the following commands within the diskpart utility to make the flash drive bootable.

4. In the diskpart utility select the flash drive by typing “select disk 2”.

Use extra caution when selecting the flash disk since if you select the wrong disk you will loose all data of that disk. You can use “list disk” command within the diskpart utility to list all the disks attached to your computer. Note the disk referred here is a physical disk attached to the computer not a partition.

5. Clean the disk by using the command “clean”.

6. Create a primary partition inside the flash drive by typing in “create partition primary”.

7. Select the newly created partition by using command "select partition 1”.

8. Make the selected partition active by typing in the command “active”.

9. Then you need to format the partition by using the command “format fs=fat32” inside the diskpart.

Note that we are formatting the disk using FAT32 file system.

10. Use the command “assign” to assign a drive letter for the newly formatted drive, since we are not giving a drive letter it will get the next available drive letter automatically. Then exit the diskpart utility by typing in “exit”.

11. Now we need to copy the setup files to the flash drive.

For this we can use the good old xcopy command as of below.

“xcopy F:\*.* /s/e/f G:\”

In the above command I am coping the contents of the drive F (which is a virtual drive created by Power ISO) to drive G which is the flash drive I created.

The meanings of the flags I used are as follows.

“xcopy F:\*.* /s/e/f G:\”

F:\ – Source Drive

*.* – All Contents

/s – Copies directories and sub directories which are not empty

/e – This will add the empty directories also so now all the directories and sub directories will be copied even though they are empty

/f  – Will show the source and destination file names while copying.

G:\ – Destination Drive

When xcopy completes you will have a flash drive which you can boot your computer, in my case I had a Windows 2008 R2 installer. You may even be able to copy the OS files to your flash drive and boot an OS with this method.

Then you may need to change your BIOS options and/or press function keys to let you boot from the flash drive.

Connecting to MySQL in Visual Studio 2010

If you need to access MySQL databases using Visual Studio you have to install MySQL connector into your machine.

Currently only mysql-connector-net-6.3.1 is supporting Visual Studio 2010 which is still an alpha product.

To download it, use this link and switch to Development Releases tab.

Preserving State in ASP.Net

As you know a main challenge in web development is preserving the state of the application. We say web is stateless because web server treats each HTTP request for a page as an independent request. The server will not know any knowledge of variable values that were set/used during the previous requests. For example in Windows applications after we start the application if we set a variable to a certain value in a form it will be there until we close the form. But in web since the page is getting posted back the value will be normally lost.

To overcome this limitation in web ASP.Net provides two main methods and they are having different options under them.

1. Client Side State Management
   1. View State
   2. Cookies
   3. Query String
2. Server Side State Management
   1. Session State
   2. Application State
   3. Profile Properties

1.1- View State

Viewstate is a technique used in ASP.Net to preserve the state changes during the page postbacks. The viewstate data is always belong to the page, so this needs to be used when we want to store data at page level and retrieve them on the same page. Viewstate data will not be available from another page.

Viewstate uses a hidden form field named __VIEWSTATE as default to store the state information. When the “EnableViewstate” property of a control is set to true ASP.Net will start saving the control state in the viewstate. If we enable this property for many controls then soon the viewstate hidden variable will be large, and that may slow our application since this needs to be transferred at each postback. For example each time we submit a page the viewstate will go from our machine to server and from server to our machine. Due to this reason we should consider whether it is really required before enabling viewstate for a control. One advantage viewstate has is that it is not using server resources.

Apart from the viewstates of the controls in the form we can also add the values we need to preserve to the viewstate.

Adding a value -

1. ViewState["Text"] = value;

1. ViewState.Add("Text", value);

Retrieving a value -

1. object o = ViewState["Text"];

1. string str = (string) ViewState["Text"];

Read more at http://msdn.microsoft.com/en-us/library/bb386448.aspx.

1.2- Cookies

We use cookies to store frequently changed small amount of data at client side. We can control the life span of a cookie. For example we can create a cookie which expires when the session is over or which exists indefinitely in the client machine.

Cookies are light weight since they are text based structures having key value pairs. They are not taking any server resources since they are at client, but this also adds a disadvantage on security because users/hackers can tamper them. To prevent this we can encrypt cookies but this will reduce application performance. There is also a limit to the amount of data which we can be stored in a cookie. Also if cookies are blocked in browser the application will fail.

Adding a value -

1. Response.Cookies["userData"]["Name"] = "Arjuna";
2. Response.Cookies["userData"]["lastVisit"] = DateTime.Now.ToString();
3. Response.Cookies["userData"].Expires = DateTime.Now.AddDays(1);

1. HttpCookie aCookie = new HttpCookie("userData");
2. aCookie.Values["Name"] = "Arjuna";
3. aCookie.Values["lastVisit"] = DateTime.Now.ToString();
4. aCookie.Expires = DateTime.Now.AddDays(1);
5. Response.Cookies.Add(aCookie);

Retrieving a value -

1. HttpCookie cookie = Request.Cookies["userData"];
2. if (cookie == null)
3. {
4.     lblCookieText.Text = "Cookie not found.";
5. }
6. else
7. {
8.     lblCookieText.Text = cookie.Values[0] + ", " + cookie.Values["lastVisit"];
9. }

Read more at http://msdn.microsoft.com/en-us/library/ms178194.aspx.

1.3- Query String

A query string is the information added at the end of the URL. This is supported by all the browsers and does not consume server resources. But this has limited capacity and security problems.

Adding a value -

1. Response.Redirect("Webform2.aspx?Name=" +
2. this.txtName.Text + "&LastName=" +
3. this.txtLastName.Text);

Retrieving a value -

Using Webform2.

1. this.TextBox1.Text = Request.QueryString[0];
2. this.TextBox2.Text = Request.QueryString["LastName"];

 

2.1- Session State

Session state (variables) needs to be used to store session specific data. For example the logged in user information can be stored in session. Session variables are accessible by the entire set of pages in an application within the same session.

Session is created once a user visits a site and the session will end when the user leaves a site or when user becomes idle. Session variables are stored in a SessionStateItemCollection object that is exposed through the HttpContext.Session property. In an ASP.NET page, the current session variables are exposed through the Session property of the Page object. One disadvantage is that the session variables are taking server resources.

Adding a value -

1. Session["Name"] = “My Name”;

Retrieving a value -

1. string str = (string) Session["Name"];

Read more at http://msdn.microsoft.com/en-us/library/ms178581.aspx.

2.2- Application State

Application state (variables) are used to store application specific data. Application state will be accessible to any users connected to the application. Normally global data which are infrequently changed, having no security concerns are stored in an application state.

The HttpApplicatioState instance is created at the first time a user accesses any URL resource in an application and the application state is lost when the application is ended. For example if the web server is restarted. If the value is required after application restart then before application end the required values needs to be transfered to a non volatile medium such as a database for later retrieval. The HttpApplicationState class is most often accessed through the Application property of the HttpContext class. When using the application state we need to remove any unnecessary items as soon as it is not required to maintain the site performance.

Adding a value -

When adding a value to an application variable it is always good to lock it before adding data since application state data can be accessed by multiple threads at the same time. Otherwise invalid data or erroneous data will appear. The loack needs to be removed after adding or changing the value to make the application state available for other threads.

1. Application.Lock ();
2. Application["NumberofViews"] = 1;
3. Application.UnLock ();

Retrieving a value -

1. string str = (string)Application["NumberofViews"];

Read more at http://msdn.microsoft.com/en-us/library/ms178594.aspx.

2.3 Profile Properties

Profile properties uses an ASP.Net profile and is user specific. This is similar to session state except that the data stored in profile properties are not lost when session is ended.

We can store the profile data in a place that we like. If we are using SQL Server to store them then we can use SqlProfileProvider, if not we can write our own profile provider classes so the profile data will be stored in custom formats and in a custom storage mechanisms, such as an XML file, or even to a Web service. But performance will be less since the data is stored in a data store. Also to use it additional configurations and to keep it in a fully optimized level maintenance activities are required.

Adding a value -

First we need to add the required provider and the properties to the web.config file.

1. <profile enabled="true">
2.   <providers>
3.     <clear/>
4.     <add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" applicationName="/"/>
5.   </providers>
6.   <properties>
7.     <add name="UserName" />
8.   </properties>
9. </profile>

Retrieving a value -

1. TextBox1.Text = System.Web.Profile.DefaultProfile.Properties["UserName"].DefaultValue.ToString();

Read more at http://msdn.microsoft.com/en-us/library/2y3fs9xs.aspx.

Read more on ASP.Net state managements at http://msdn.microsoft.com/en-us/library/75x4ha6s.aspx.

"Login failed. The login is from an untrusted domain and cannot be used with Windows authentication."

If you are getting the above error while trying to connect to a database, the reason is you are using Windows Authentication to login to the SQL Server while being in another untrusted domain.

For example if the SQL Server machine is a member of the CompanyDomain and if you are in MyDomain or if you are in a Workgroup the you will face the above issue while trying to connect to the SQL Server.

The connection string used in the web.config while the above error is generated is as follows.

1. <connectionStrings>
2.   <add name="cnnStr" connectionString="Data Source=BI-SVR;Initial Catalog=BBIDatabase;Integrated Security=True"/>
3. </connectionStrings>

 

There are three ways to fix this problem.

1. Use the SQL Authentication to login to the SQL Server.

You can get this done by changing the connection string to use SQL authentication while connecting. But you need to know the credentials of an account which is having permissions to your required database or the System Administrator (SA) password. For simplicity I will use SA account details in the connection string.

1. <connectionStrings>
2.   <add name="cnnStr" providerName="System.Data.OleDb" connectionString="Data Source=BI-SVR;Persist Security Info=True;Password=YourPassword;User ID=sa;Initial Catalog=BBIDatabase"/>
3. </connectionStrings>

 

2. Login to your machine using the same Domain.

If you login to your machine using a domain account which the SQL Server is added to, then this error will vanish. But for this you need to add your machine to the same domain which the SQL Server machine is added to (CompanyDomain) also to properly get authenticated the account used should have proper permissions set to access the database in the SQL Server.

3. Make the account trusted in SQL Server.

By making the account you use to login to your machine trusted account in SQL Server and giving it appropriate permissions to access databases will also permit you to fix this error.

Windows XP Mode in Windows 7 – Knowing, Installing and Using

There is a cool feature provided by Microsoft for Windows 7 named Windows XP Mode. Simply this is an improved virtual machine which you can use to install applications that are not compatible with Windows 7.

Some advantages of this over Virtual PC are,

• Use of virtually installed applications are faster and easy.
• Virtual applications are performing faster.
• Your Windows 7 start menu can be used to access all the applications that are installed on Windows XP Mode.
• No need to start the virtual machine your self.
• Application is run in normal Windows 7 not in another virtual environment.
• Copy Paste is supported between applications without needing to install any other software addons.

To setup Windows XP Mode you need to download and install Windows XP Mode from Microsoft site. You can use the following link for that.

http://www.microsoft.com/windows/virtual-pc/download.aspx

There you need to download and install,

1. Windows XP Mode (WXPM)
2. Windows Virtual PC
3. WXPM Update

Note - If you have installed Microsoft Virtual PC you need to uninstall that first, other wise WXPM will not work.

After you installed WXPM, it will be in your start menu.

Setting up Windows XP Mode

1. Start WXPM by clicking on the start menu item.

2. Select an appropriate path for the installation of WXPM and give a suitable password, this password will be the password used for the Virtual PC (VPC) user. If you needed to manually connect to the VPC then you need this.

3. Use the next screen to enable the Windows Updates on the VPC.

4. Start the setup to initiate the configuration.

5. After the completion of the configuration WXPM will start a of shown below.

6. All your physical drives will be available on the WXPM as well so you will be able to select and install applications from either of them.

7. For the demonstration I installed “Stellar Phoenix Windows Data Recovery” software since it takes less time to setup.

8. After successfully installing the application on WXPM it will appear on your Windows 7 start menu so you will be able to invoke it directly from Windows 7.

9. As you see there is no difference to the way application is running or shown, and you will even not notice that the application is running in VPC.

Notes – Even though you don’t need, you can even connect to external networks or browse internet using the WXPM, if you do connect the VPC, remember to install a virus guard and enable the firewall for maintaining your computer safety.

Windows Update Error

Today I faced an error when trying to install few updates for Windows. The message Windows was showing was “Windows update encountered an unknown error.”. So it was not helpful in resolving the issue.

This is happening due to either update not getting downloaded properly, getting corrupt while downloading, space issues in your hard disk, errors while applying updates, etc.

To my satisfaction one thing I did, fixed the issue. If you are also getting similar error I recommend you to first browse to your SoftwareDistribution folder inside Windows installation folder. For example I found it in “C:\Windows\SoftwareDistribution”.

Then delete all the folders in the folder (make sure the Windows Update is closed before doing this) and restart your computer.

After making sure your Windows installation partition is having enough free space (about 1 GB) try running Windows Update again. This time the updates will get installed successfully.

Error Installing Windows 7

Recently I tried installing Windows 7 64 bit version in to my HP Pavilion laptop, and I continuously got a problem while installing.

Installer was generating a blue screen with a message Page_Fault_in_NonPaged_Area referring to the file “wimfsf.sys” after coping files and showing the new Windows logo for about 10 seconds.

Since it is mentioning about a page fault and also I am trying with a 64 bit version of Windows I thought this is due to a problem related to hardware of my laptop, so I tried many alterations which included things like, flashing BIOS to various versions including new and old, plugging memory in different ways, installing other OSs to try setup Windows from within them, but nothing helped me to sort the issue except replacing the DVD.

Yes indeed, it was an issue with the installation media (DVD), if you also get a similar error when installing Windows 7, I suggest you to first try installing with a different media.

If you still get an error then try running Windows 7 Upgrade Advisor which can be downloaded from Microsoft. This will analyze your machine and will report you the compatibility details.

Also,

- updating your BIOS to the latest version,

- installing with only one memory module when you are having more,

- disabling special processor (virtualization) and memory (memory caching) functionalities,

- changing hard disk drive options,

will help you getting Windows installed successfully.