Query on .net

Fix issue HTTP/1.1 200 OK Server: Microsoft-IIS/7.5 Error with a SharePoint 2010 Web Application

2012-01-23T17:32:00.001+05:30

Generally, such error comes when we try to browse web-application url. There could be many problems around this problem and depends on it there are different solution for it.

First most common issue around this is that, web application does not contain any site collection at web application root level url, to resolve this you can create site collection from central admin ->Application Management ->Create Site Collection. During creation of site collection, please select your web application where you would like to create.

Second scenario, if you have already site collection created and still this problem occurs. To overcome such problem you have choice to restart IIS, reattach your content database, check services on your pc whether “work station” service is started.

Hope this will help!!

Prerequisites could not be found for bootstrapping (while upgrading from VS 2005, 2008 to VS 2010)

2012-01-12T15:25:00.002+05:30

Latest IDE by Microsoft for .net application is VS 2010. Most of applications are upgraded to newer version of IDE, some are in the process and some are already done. The thing create problem during upgrade is that most of time targeted framework does not change, it just refer older version.

When you try to add prerequisites, you will be surprised that it will not find your older version any more. Many forums said that Microsoft has disabled it and you need to upgrade to higher version of prerequisites.

You can see that in the given below images that shows unavailability.

To resolve this issue you need to copy boots trapper files.

Older version of VS files can be found at

C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bootstrapper\Packages

You need to copy files from above location to below location and once you copy required folders, you will be able to access those in prerequisites.

C:\Program Files\Microsoft SDKs\Windows\v7.0A\Bootstrapper\Packages

Cheers!!

Adding Footer to SharePoint 2010 Custom Master Page

2012-01-11T15:57:00.000+05:30

When you are going to develop custom layout of your SharePoint site, it could be requirement of having footer in the page. V4 master page does not contain any options to set footer in page.

You need to add footer manually to your custom master page.

If you check your master page you will find below line

Just above that line you can add your custom footer section as below sample markup.

Style for above div

*Customized foooter */

#s4-customfooter{

clear: both;

padding: 10px;

color: #ffffff;

background-color: #4F5E85;

}

Hope this will help!!

The Project Item "module1" cannot be deployed through a Feature with Farm Scope

2012-01-05T15:25:00.000+05:30

You might have faced such error sometime during your deployment of SharePoint projects. Usually this error comes due to lack of availability of particular item in the scope. You have limited items that can be deployed in the scope of web, site, web application and farm level.

Microsoft has prepared a very nice article to list out it. You can check out here

OOB: Change master page from SharePoint 2010

2011-12-26T17:08:00.000+05:30

Most of time we don’t prefer to use conventional user interface provided by SharePoint when we configure it. We want our separate identity when we try to publish our site on base of SharePoint framework.

When you try to find out Changing of master page in your SharePoint, you may not get that options in your Site Settings, first you need to do is to Enable “SharePoint Server Publishing Features”.

To enable above features follow below steps..

Go to Site SettingsàSite Collection Administration à Site Collection Features à Activate SharePoint Server Publishing Features.

Now you may able to see Master pages menu in the Site setting under Look and Feel depends on the version you have installed on your machine.

Alternatively you can directly go to change master page with _layouts/ChangeSiteMasterPage.aspx , just add below url with your site and you will be redirected to change master page for your site.

How to get public key token for my dll or exe?

2011-12-26T12:11:00.000+05:30

Sometime we need to find our dll or exe’s public token when we have strongly signed out. There is a very nice tool given by .net is sn.exe

Just go to command prompt of visual studio, and type following command. Here please note that you need to set your application folder path where your dll or exe assembly is stored.

Sn – T abc.dll

This will give us public token of abc.dll like below message

Public key token is c8903c1b3f99ec16

Install SharePoint 2010 on windows 7 64 bit

2011-12-14T19:47:00.002+05:30

Most of time in case of development It would require to install sharepoint on the non-server os, As we know sharepoint 2010 can only be installed on the 64bit operating system. Now we have one choice to create environment on the Windows 7 64bit os.

If we don’t dig more on it, we have choice to install as standalone sharepoint but instead of that we would like to have sharepoint farm configuration and we don’t wish to install SQL express by Sharepoint installation but we have our own SQL server then?

Also to enable installation on Windows 7, we require changing in configuration file and that is to add one setting for it.

Below things require to add at ..\files\Setup\Config.xml

If you don’t add above setting, setup will give you error and you won’t be go further.

Next thing for using your own SQL server installation is to create Sharepoint Configuration database and that can be done with help of Powershell command named SP-NewConfiguationDatabase

Once you use above command in the powershell you will be asked to enter required details for your server and database creation.

To use above command please note that, you are going to use your windows user in it, so you need to give full qualified name.

Like mypc\user, if you don’t give full name it will give you error.

Reference:

http://msdn.microsoft.com/en-us/library/ee554869.aspx -for Installing Sharepoint

http://technet.microsoft.com/en-us/library/ff607838.aspx -for configuration database creation.

http://spdeveloper.net/2010/06/errors-when-installing-sharepoint-2010-in-windows-7-development-environment/ --for possible error we could have in creating configuration database.

How to Resolve Activate disabled Sandbox solution in SharePoint 2010

2011-11-30T18:15:00.001+05:30

This problem mainly occurs when you start to develop sandbox solution and upload you solution to fresh SharePoint farm, if you have already developed some sandbox solution and some admin is maintaining SharePoint farm, you may never come to such problem.

Situation was, I was able to add solution to my site and I was also able to see SharePoint WSP and all was looking great, but when I was going to activate it, it didn’t seem to work and it was showing me user right tooltip, which usually comes up when we have not enough permission to access anything.

I wonder about my permission and I doubled check my permission but there was not an issue, then after checking about other problem if there could be.. but nothing was there.

After google, I found that there was issue of service named “Microsoft SharePoint Foundation Sandboxed Code Service” required to start prior to activating any sandboxed solution. This service can be activated from Central admin ->System Settings ->Server -> Manage Service on Server-> Start Service Microsoft SharePoint Foundation Sandboxed Code Service start

Reference: I found that useful information here

Connected WebParts in SharePoint 2010

2011-11-30T16:35:00.000+05:30

SharePoint has very cool features of connected Web Parts, It simply means that two different web parts are connected and they can share data between them.

In Connected Web Parts there are basically two things required at least, one is Consumer Web Parts and Provider Web Parts. Consumer Web Parts gets data from Provider Web Parts, and this data passing is usually done with use of interface.

Connected web parts are best when we have two different web parts and we want to change web parts activity based on external events happen in another web part exist in the same web page.

Here, MSDN contains very nice walk through for creating connected web parts.

In above article, two attributes plays role for connecting web parts

ConnectionProvider:

It should be attached to any one method which returns data, it does not necessary that it must have some value specified in the bracket, what so ever you write there will be displayed when you access web parts from SharePoint site.

ConnectionConsumer

It should be attached to any one method which gets data from another web part.

NOTE: when you use this connected web parts in Web Part page added in sharepoint, you will have option to connect with consumer web parts. But in case of default page you may require to turn to edit mode of your page and then click on edit of web part and then you will have this options of connecting to another consumer web part.

In above scenario it is assumed that firstly we have added both consumer and provider web parts in the page and then we will have option to connect web parts.

Thoughts on Web Parts in SharePoint 2010

2011-11-29T12:32:00.000+05:30

SharePoint 2010 has many inbuilt functionality and features. One can leverage on it and take advantage of out of box SharePoint development. But business is all about having information in the right way and at a certain moment easy to catch.

Most of case Web parts serve many business needs for showing up information in the customized forms when SharePoint out of box development does not provide enough information.

At the time of Web Parts creation in SharePoint 2010, one has two choices Visual Web Parts and Standard Web Parts.

Both of these are much useful on their way and most of asp.net developers are much familiar with Standard Web Parts because it is very much similar to that of asp.net developers. Visual Web parts allows developer to just drag and drop control as they do in most of asp.net pages, you will have availability of all standard web controls, you don’t need to take care of setting underlying properties of controls. On the other hand Standard web parts allows developer to set each and every property at run time, you can have more controls on each controls. You can create as many controls as you need; you can dispose your control when you don’t need it.

There can be debate of using Standard Web Parts and Visual Web Parts, but certainly it depends on the choice of developer and business nature. Sometimes it is noted that Standard Web parts gives good performance compared to Visual Web Parts, and at the same time you need to take care of many things when you develop Standard Web Parts compared to Visual Web Parts.

It is good that now developer has choice to choose which type of web parts they want to develop, in earlier developer has to create user control and then they can add that visual element in standard web parts, but now they can directly add visual elements with use of Visual Web Parts.

To take decision of using any web parts is based on the time and resource it requires and also many other parameters need to consider for business activity.

Connect office 365 SharePoint online with SharePoint client object model

2011-11-28T16:06:00.001+05:30

When you create any SharePoint client object model application there are choices to connect with SharePoint either in LAN or SharePoint server. But now days there are much hype in office 365 provided by Microsoft, it does allow SharePoint online. You don’t need to manage your own SharePoint server if your organization is not much big and many companies are planning to move their work to office 365.

So it’s naturally necessary that your client object model should support this office 365 SharePoint online connection. Here there is a trick to connect with it, it’s not direct way to connect with SharePoint online. You need to consider many things for it like cookies and your id, password etc.

Here, it is very nicely explained how to authenticate with office 365 and make connection to SharePoint online with client object model.

Calendar (datetime picker) type column in windows grid

2011-11-17T17:57:00.001+05:30

Usually when we try to find some out of use column in default grid provided by .net, we are not able to do it. We require inheriting base class and then we need to put information inside of it.

Say for example, you require adding datetime picker column to your windows form grid, if you check all supported column types in grid, you won’t find such in it. We require writing custom code for it and then adding that columns in our grid control.

Here is some code for creating date time picker column, please make sure that you can add this code in separate component code and then you can access this column in whole project when ever needs.

using System;

using System.Windows.Forms;

public class CalendarColumn : DataGridViewColumn

{

public CalendarColumn() : base(new CalendarCell())

{

}

public override DataGridViewCell CellTemplate

{

get

{

return base.CellTemplate;

}

set

{

// Ensure that the cell used for the template is a CalendarCell.

if (value != null &&

!value.GetType().IsAssignableFrom(typeof(CalendarCell)))

{

throw new InvalidCastException("Must be a CalendarCell");

}

base.CellTemplate = value;

}

public class CalendarCell : DataGridViewTextBoxCell

{

public CalendarCell()

: base()

{

// Use the short date format.

this.Style.Format = "d";

}

public override void InitializeEditingControl(int rowIndex, object

initialFormattedValue, DataGridViewCellStyle dataGridViewCellStyle)

{

// Set the value of the editing control to the current cell value.

base.InitializeEditingControl(rowIndex, initialFormattedValue,

dataGridViewCellStyle);

CalendarEditingControl ctl =

DataGridView.EditingControl as CalendarEditingControl;

// Use the default row value when Value property is null.

if (this.Value == null)

{

ctl.Value = (DateTime)this.DefaultNewRowValue;

}

else

{

ctl.Value = (DateTime)this.Value;

}

public override Type EditType

{

get

{

// Return the type of the editing control that CalendarCell uses.

return typeof(CalendarEditingControl);

}

public override Type ValueType

{

get

{

// Return the type of the value that CalendarCell contains.

return typeof(DateTime);

}

public override object DefaultNewRowValue

{

get

{

// Use the current date and time as the default value.

return DateTime.Now;

}

class CalendarEditingControl : DateTimePicker, IDataGridViewEditingControl

{

DataGridView dataGridView;

private bool valueChanged = false;

int rowIndex;

public CalendarEditingControl()

{

this.Format = DateTimePickerFormat.Short;

}

// Implements the IDataGridViewEditingControl.EditingControlFormattedValue

// property.

public object EditingControlFormattedValue

{

get

{

return this.Value.ToShortDateString();

}

set

{

if (value is String)

{

try

{

// This will throw an exception of the string is

// null, empty, or not in the format of a date.

this.Value = DateTime.Parse((String)value);

}

catch

{

// In the case of an exception, just use the

// default value so we're not left with a null

// value.

this.Value = DateTime.Now;

}

// Implements the

// IDataGridViewEditingControl.GetEditingControlFormattedValue method.

public object GetEditingControlFormattedValue(

DataGridViewDataErrorContexts context)

{

return EditingControlFormattedValue;

}

// Implements the

// IDataGridViewEditingControl.ApplyCellStyleToEditingControl method.

public void ApplyCellStyleToEditingControl(

DataGridViewCellStyle dataGridViewCellStyle)

{

this.Font = dataGridViewCellStyle.Font;

this.CalendarForeColor = dataGridViewCellStyle.ForeColor;

this.CalendarMonthBackground = dataGridViewCellStyle.BackColor;

}

// Implements the IDataGridViewEditingControl.EditingControlRowIndex

// property.

public int EditingControlRowIndex

{

get

{

return rowIndex;

}

set

{

rowIndex = value;

}

// Implements the IDataGridViewEditingControl.EditingControlWantsInputKey

// method.

public bool EditingControlWantsInputKey(

Keys key, bool dataGridViewWantsInputKey)

{

// Let the DateTimePicker handle the keys listed.

switch (key & Keys.KeyCode)

{

case Keys.Left:

case Keys.Up:

case Keys.Down:

case Keys.Right:

case Keys.Home:

case Keys.End:

case Keys.PageDown:

case Keys.PageUp:

return true;

default:

return !dataGridViewWantsInputKey;

}

// Implements the IDataGridViewEditingControl.PrepareEditingControlForEdit

// method.

public void PrepareEditingControlForEdit(bool selectAll)

{

// No preparation needs to be done.

}

// Implements the IDataGridViewEditingControl

// .RepositionEditingControlOnValueChange property.

public bool RepositionEditingControlOnValueChange

{

get

{

return false;

}

// Implements the IDataGridViewEditingControl

// .EditingControlDataGridView property.

public DataGridView EditingControlDataGridView

{

get

{

return dataGridView;

}

set

{

dataGridView = value;

}

// Implements the IDataGridViewEditingControl

// .EditingControlValueChanged property.

public bool EditingControlValueChanged

{

get

{

return valueChanged;

}

set

{

valueChanged = value;

}

// Implements the IDataGridViewEditingControl

// .EditingPanelCursor property.

public Cursor EditingPanelCursor

{

get

{

return base.Cursor;

}

protected override void OnValueChanged(EventArgs eventargs)

{

// Notify the DataGridView that the contents of the cell

// have changed.

valueChanged = true;

this.EditingControlDataGridView.NotifyCurrentCellDirty(true);

base.OnValueChanged(eventargs);

}

Secure asp.net website URL with global.asax

2011-08-16T12:37:00.000+05:30

Once any one has installed SSL certificate in their server, there is need to redirect old http url to https protocol. If we don’t write any custom code for redirection it will continue to browse by both of url.

There are many ways to redirection of page, we are going to take a look on global.asax file. We all are much familiar with Global.asax file in asp.net application, it handles out most of application related events.

We can use following code snippet to redirect http to https

protected void Application_BeginRequest(Object sender, EventArgs e)

{

if (HttpContext.Current.Request.IsSecureConnection.Equals(false))

{

HttpContext.Current.Response.Redirect(HttpContext.Current.Request.Url.AbsoluteUri.Replace("http://", "https://"));

}

Sharepoint Core Classes

2011-07-30T12:49:00.003+05:30

Sharepoint is collaborative product developed by microsot, many organizations adopting this product for their business activity. There are many benefits to use and implement to it. It becomes around 10 years of this product, one can say it become matured product for business automation.

Today I am going to give you brief development core classes and it’s structure in sharepoint environment.

Basically, any sharepoint environment can have one or more SharepointFarm, SharepointFarm can have one or more WebApplication, WebApplication have one or more SiteCollection, Sitecollection have one or more SubSite.

This SubSite is called your end where most of items are manipulated and shown to users.

At the Site level we can have List, Document Library.

Furthermore List is can have or more list items and Document Library can have files and Folder.

Above all are the basic terms one should know before they start to develop or implement sharepoint in their business.

For the development in sharepoint, we should understand classes being used in each of entity I told above.

For the Sharepoint Fam SPFarm

Farm’s WebApplication SPWebApplication

WebApplication’s SiteCollection SPSite

SiteCollection’s WebSite SPWeb

WebSite’s List SPList

List Item SPListItem

WebSite’s Document Library SPDocumentLibrary

WebSite’s Folder SPFolder

WebSite’s file SPFile

NOTES: I have considered that you have development machine for sharepoint and you are going to develop in it, to access above all classes you require to have sharepoint on your machine.

Redirect old page to new page with use of web.config

2011-07-04T15:04:00.005+05:30

Recently we found that some of our old links were broken as we have changed our page name to make it seo friendly. Suddenly, over the night our site’s page rank was down. It was really embarrassed situation for all of us.

There were below reason for it.

As we have moved our server from linux to windows platform and there were no idea of page rename, and lack of technical availability to use htaccess redirection in windows platform.

After some work around it, finally I came across following things which is very good and needs to use when we rename any page and don’t want old link should be break.

Here, please not that following things will work on IIS 7.0+

First block will resolve canonical issue of prefix www before any domain name.

Second block will redirect my old page link to new mapped page.

</conditions>

<rule>

</rule>

Which datatype is good for my database field?

2011-06-17T16:04:00.000+05:30

Every time at the designing of new database table we stuck for the choosing right datatype for the particular field.

It has been said that if there is right database design have been done, it’s easy to accomplish changes in the application. If you require to change database field type or require to add new field in the table, it costs a lot at later stage.

So with this confusion of choosing right database, I have some check list what to use for the string type field.

Consider following points for your string data field.

àWhat will be max size of field, how many characters could be there?

àIs there any fix length I will have?

àDoes field require using Unicode character?

There are basic for three types of datatype are supported.

Char : this datatype can be used when we know our field’s data. We have prior idea of value. It will be good to use this type.

Varchar: when we are not firm about the value come in the field, this can be the choice.

Now one interesting datatype

Nvarchar: this is same as varchar expect it stores value as Unicode character.

Unicode character are especially useful when we would like to support Multilanguage in application else there is not much reason to use it without any purpose.

Nvarachar datatype occupies double space than the varchar, it should be considered when there will be large amount of data will be feed in the system.

You can check it with following sample

After running query you will notice that varchar datatype takes less space compared to others.

declare @na char(30)

SET @na = 'shailesh'

declare @nam nvarchar(30)

SET @nam = 'shailesh'

declare @name varchar(30)

SET @name = 'shailesh'

select datalength(@na)

select datalength(@nam)

select datalength(@name)

LightSwitch the new approach for RAD

2011-06-13T15:59:00.001+05:30

Light Switch is the new technology or you can say new development IDE provided by the Microsoft. It’s based on the .net framework seats on the silverlight, through which you can build out desktop as well as web application.

Currently it’s available in the beta version and you can download it from here.

All the required software and hardware configuration are listed out on the page.

Languages Supported: Currently light switch support vb.net and c#.

Core parts of Light Switch

Data: this is one of the very basic parameter we use for any light switch application. During the development we should use any of the data store to be used in the application.

Screen: As it names implied it deals with the User interface of the application. In light switch user interface can be created from the underlying data structure. We can also customize the screen at the runtime. This would be best features so far we get facility at the runtime.

Queries: in the data store we can use customized query too. It’s not necessary to use plain data for the application, we can attach query that is created from more than on data store.

Code: As we have told that we can built out application without writing single line of code, but sometime it requires to change basic functionality provided by framework. We can do it so. It includes adding customize list from the code, different validation as per the business needs.

User Permission: in application we can place role based security and only authorized user can have access to system. There are so many types of user permission we could use in it.

Office Integration: many of the office features are integrated and we can directly use it. We don’t require writing custom code for it.

Deployment: Light switch application can be deployed on desktop as well as on the remote server as per the need. Light switch screen is built on the silverlight so there would be no extra item we require apart from silverlight when we use it on the web.

Apart from above mentioned parts there are so many features are available like we can place different validation on the input fields without writing any code, can customize look of application, can export data to the excel sheet, can search data in the grid, different look for the editing of record, tab panel layout for the data objects and screens.

Where it can be useful?

Light switch could be the one the best choice when we require to develop in very short period of time and for the small scale industry. It also supports various data sources behind the scene. You can use any of the data source including SQL Azure, SQL server etc.

We can say now with use of light switch developer can totally focus on the business logic and they don’t need to spend time in the insert/update and other basic coding. Even they don’t need to design screen layout.

After all business needs to have solid business logic and security.

Some useful resources

http://www.lightswitchtutorial.com/

http://msdn.microsoft.com/en-us/lightswitch/ff938857

Pass CSV parameter in SQL Stored procedure

2011-04-27T14:17:00.000+05:30

Recently, I have been asked to prepare query that accept CSV value and parse that value in stored procedure.

In early, I didn’t give much attention as I thought it was just like the Where clause with IN. If we prepare dynamic query and execute it works well. But we don’t want to do that, we want some solution that should work every time when we pass CSV value.

The solution was to create function and it returns list of value. Here is the function; I have found this function during my search.

CREATE FUNCTION dbo.CSVToList (@CSV varchar(3000))

RETURNS @Result TABLE (Value varchar(30))

BEGIN

DECLARE @List TABLE

(

Value varchar(30)

)

DECLARE

@Value varchar(30),

@Pos int

SET @CSV = LTRIM(RTRIM(@CSV))+ ','

SET @Pos = CHARINDEX(',', @CSV, 1)

IF REPLACE(@CSV, ',', '') <> ''

BEGIN

WHILE @Pos > 0

BEGIN

SET @Value = LTRIM(RTRIM(LEFT(@CSV, @Pos - 1)))

IF @Value <> ''

INSERT INTO @List (Value) VALUES (@Value)

SET @CSV = RIGHT(@CSV, LEN(@CSV) - @Pos)

SET @Pos = CHARINDEX(',', @CSV, 1)

END

INSERT @Result

SELECT

Value

FROM

@List

RETURN

END

Now say for example you want to create stored procedure that should return you all state name where we passed id with CSV,

We can pass any number of state id in the @StateId parameter.

CREATE PROCEDURE State_Search

@StateId nvarchar(2000)

BEGIN

SELECT * FROM tblState

WHERE tblState.StateId IN (SELECT * FROM dbo.CSVToLIst(@StateId))

END

Allowing special character in xml with .net in built class

2011-03-29T21:03:00.000+05:30

Recently I was finding solution to allowing special character in xml, it can be done by replacing with replaced code. You can check here

But if you are using .net then we have one inbuilt class that replaces all of the special character with replaced code and you don’t need to worry for every special character replacement.

Code sample:

XMLstring = System.Security.SecurityElement.Escape(XMLstring)

Access to the path FileListAbsolute.txt is Denied (Error for TFS Project)

2011-03-25T12:34:00.004+05:30

Recently during our development we come to know very strange problem and stuck to find solution for it. We use TFS for source control system for our various projects that adds capability to work parallel. After getting this error we thought it could be problem of user right’s but all people where getting same error during the build.

After going through project checked in files in server we come to know that during check in some one has checked in obj folder and that was causing this issue around the development area. After deleting this from source control and commit these changes, error of access denied was gone.
We also found same solution in after searching on internet.

Allow special character in XML

2011-03-21T14:47:00.005+05:30

XML is very useful in any of the programming language. You have many controls of your data representation. One of the features of platform independent makes vital use of it.

In actual data we have different characters which are not supported in XML if we directly write in it. Here are some lists which can be used to replace actual character in XML.

Less than < can be replaced with &lt

Greater than > can be replaced with &gt

Ampersand & can be replaced with &amp

Quotation "can be replaced with &quot

Apostrophe ' can be replaced with &apos

At the end of replaced character we should keep one ;

Hope this list is useful when we want to use special character in XML.

Get next identity value in my table For SQL Server

2011-03-02T17:08:00.001+05:30

It may require some time to know what will be our identity value before we actually insert record in our table. Usually we tend to find our max id value by selecting max id from records. But it may be possible you deleted records and now you want to know next identity value. SQL server has given a very nice function for it.

SELECT IDENT_CURRENT(‘mytable’)

In above line, mytable is table name, in which we want to find next identity value. Very impressive function!!

Paging stored procedure for the SQL server 2000

2011-02-03T19:19:00.001+05:30

Before a while ago, I have posted query for the true paging but it does not work in SQL server as ROWNUM is not available in it.

Here, is the sample stored procedure for SQL Server 2000

CREATE PROCEDURE [dbo].[State_Search]

@SearchText nvarchar(50) = null

,@PageNo int

,@PageSize int

,@TotalRecords int OUTPUT

BEGIN

SET NOCOUNT ON;

DECLARE @StartFrom int

SET @StartFrom = @PageSize * (@PageNo - 1);

CREATE TABLE #tmpState (

RowNo int IDENTITY(1,1) PRIMARY KEY,

RowId int NOT NULL

);

INSERT INTO #tmpState(RowId)

SELECT CHECKSUM([State].StateGuid) FROM [State]

WHERE (@SearchText IS NULL OR StateCode LIKE @SearchText OR

StateName LIKE @SearchText OR StateDesc LIKE @SearchText)

SET @TotalRecords = (SELECT COUNT(*) FROM #tmpState);

SELECT

[State].*

FROM #tmpState

INNER JOIN [State] ON CHECKSUM([State].StateGuid) = #tmpState.RowId

WHERE #tmpState.RowNo > @StartFrom AND #tmpState.RowNo <= (@StartFrom + @PageSize)

ORDER BY #tmpState.RowNo;

SELECT @TotalRecords AS TotalRecords;

DROP TABLE #tmpState;

END

OCR In .net with MS-Office 2007 component (MODI)

2011-01-05T12:53:00.005+05:30

I have been just passed through requirement to implement OCR in one of my .net application. There are very less option available in .net to implement it. I thought to share with you what I have learned at that time.

In .net OCR can be done with Ms-Office component, it’s the Microsoft Office Document Imagining Library. It is required to have ms-office on your pc before you develop or run this application. This component is available in both ms-office 2003 and 2007.

Initially when we install our office, it does not install image library in our pc, we need to install it explicitly. When you start to add/remove features in your office you need to check following things should be included.

Once you have installed it, you can start to develop your application.

You can take any project type either windows or console. Now you need to add reference of Document Imaging Library to your project, that will be available in com tab of add reference dialog box. Please note down that this will be only shown if you have installed it correctly. If you don’t able to see it though you have installed, try to restart your system and then check it again.

Once you have added that com reference you can work with images and can read text from it.

Difference between build and rebuild

2010-09-07T16:12:00.000+05:30

In vs we find two options build and rebuild for our solution and very rarely we give attention what do we require.

There is very much difference between both of them, if you have noticed it, build takes less time compared to rebuild.

When we build application it complies files which has been changed it does not compile all files in project, while in case of rebuild it compiles all files weather it has been changed or not. Mainly rebuild should be done when so many files are changed and also it might possible some files are changed outside of IDE.

Hope this information will help to speed up your application when you choose rebuild instead of build.

Hide Tab Pages from Tab Control in Win forms

2010-08-10T11:21:00.001+05:30

Recently I come to know one requirement to hide tab pages on my tab control of windows form depends on some condition.

I thought there could be some properties like Visible as we have in other controls. But surprisingly there is no such properties exist.

At the end I have only one solution to remove my tabpage from tab control. Let’s go through some code.

I have following tabControls.

myTabControl is my Tab Controls and I have following sub tabs(tab Pages) in it.

tabPage1

tabPage2

tabPage3

At index of 0, 1 and 2 respectively.

To hide my tabPage1 on my UI I have following options.

myTabControl.TabPaegs.Remove(0)

myTabControl.TabPages.Remove(tabPage1)

I hope this could be helpful when we have some condition for showing tabs.

Call customize Main method in Vb.net

2010-07-20T19:18:00.000+05:30

If you have tried to find main method in vb.net, you would not able to find it because vb.net automatically generates that method at runtime. We don’t require writing it. Developer who have worked with C# may find this problem most.

You can write your own main method that can be used at runtime. You can write your main method in a class or a module like below.

But you need be aware of one thing on your project properties

Application->uncheck Enable application framework. In this case, your main method will be invoked instead of automatic generated one.

To Fix Label’s and other controls text are wrapping though it looks Okay in Designer

2010-07-20T19:16:00.000+05:30

Recently I have faced a very strange problem in my project, suddenly in some forms text of label wrapped when I run application.

I have not changed anything in my designer or code, though it was creating problem at runtime. I have compared my forms with older version, I also went through each of possible design property of forms but I didn’t find anything.

I had no idea what to do. Then I came to know that my project is in Vb.net and recently I have added my custom main method, if you have been using vb.net you would be aware there is no main method, framework create it runtime. But if you want to do something at startup you need to write main method in vb.net application.

So I got what the problem it was.

By default when runtime create main method it uses following setting for text render but if you are using your own main method at that time you need to add this line to your main method else it can create problem what I have faced.

Application.SetCompatibleTextRenderingDefault(False)

Bind Enum to windows dropdown box.

2010-07-17T11:30:00.000+05:30

Sometime our dropdown lookup value are fixed and we don’t have any database table. In such situation we mostly make enum of our look up value.

But most of the time we are used to bind datasource of tables or list to combbox. So we might be wonder how to bind our enum to combobox.

Here is the simple way to bind combobox.

Say for example you have RoleTypes Enum.

public enum RoleTypes

{

Owner = 1,

Manager = 2,

AssitManager = 3,

Employee = 4

}

Now, to bind this enum to our combo box.

this.cmbUserRole.DataSource = Enum.GetValues(typeof(RoleTypes));

Set value to combobox.

this.cmbUserRole.SelectedItem = (RoleTypes)1;

To get value from combobox.

Convert.ToInt32((RoleTypes) this.cmbUserRole.SelectedItem);

Change Local Working Folder Path in TFS…

2010-07-12T14:26:00.000+05:30

Hi, all

Before a few days ago, I was using TFS as our version control system. When I tried to get latest for first time, It asked me for local path where It would be copied from server.

Later on, I needed to change my local path to somewhere else and when I was looking in TFS window to change my local path, I was wondered there were no such options which leads me to change my local working path.

I tried to find in web and I got solution.

In VsàFile menuàSource ControlàWork Space this will leads you a dialog box which shows all workspace on your computer.

You can change any of the lists by editing it.

I hope this will be helpful.

Declare Guid as Constant.

2010-07-01T15:10:00.002+05:30

If you have tried to declare Guid constant with keyword, const you definitely come to error that Guid can’t be declared as constant.

We can only use Const keyword for the value type not for the Object type. Here Guid is object type. You can get to know your datatype is value type or object type by the color of it.

Like value type always shows in blue text(link) while reference type shows in skyblue.

We can use readonly keyword for object type.

We can declare constant of guid as

readonly Guid myId = Guid.NewGuid();

After all our goal is that nobody can change value of our variable and that can be achieved by above.

Graphics with .net (Part -3)

2010-05-26T14:19:00.000+05:30

Till now we got idea of how to create image and edit existing image. Now we are moving to add text data to our existing image or creating image where text is to be inserted as copyright logo or company’s initial.

To add text to any image, following things are required.

Object of Graphics

Object of Font

If require Object of Brush

Call Graphics.DrawString method and pass font and brush object.

Yes its very simple to add text to our image. Now let’s check out how to create Font object and how to write in image

Create object of Font
Font f = new Font(“Arial”,10,FontStyle.Bold);

Apart from above constructor Font class has more than 12 constructor, we can create FontFamily object and pass it to Font Constructor.

FontFamily ffm = new FontFamily(“Arial”);
Font f = new Font(ffm,10);

If we need to read type of font, we can do with help of FontConverter class. But their errors prone, as we don’t get any error at compile time. We don’t come to know any error till it throws Runtime exception.

FontConverter converter = new FontConverter();
Font f = (Font)converter.ConvertFromString("Arial, 12pt");

Write text To Image
Once font is created, we need to create object of brush to fill text with that color, or we can use Brushes if we don’t wish to create object of brush.

Graphics g = this.CreateGraphics();
Font f = new Font("Arial", 40, FontStyle.Bold);
g.DrawString("My Test String!", f, Brushes.Blue, 10, 10);

Above code will draw “My Test String!” in form with Blue color and bold style with Arial font family.

With help of StringFormat we can format string like its alignment, FormatFlags, LineAlignment, Traimming etc.

Alternatively, to add text to image saved in disk, load it by using any of the bitmap or image class then follow step to draw string on it.

After that call save method of image or bitmap class, that will store new modified image in disk.

Graphics with .net (Part -2)

2010-05-25T14:32:00.001+05:30

As we discussed in previous post, we required to modify existing image file or have to create new image, chart, edit image and back save to file.

Image and Bitmap class provides ability to modify existing image file or create new image file.

Image is an abstract class, but we can have instance of it by Image.FromFile or Image.FromStream methods. FromFile accept any image file, FromStream accepts stream of Image file. We can use whatsoever we have at hand when we are going to play with Image.

Bitmap class is inherited by Image, For still image we can use Bitmap class, For animated image we can use System.Drawing.Imaging.MetaFile. Bitmap class is widely used for image editing and creation compared to MetaFile.

Display Image in background.
To display image in the back ground of form or any control we have one or more techniques, we can choose any of them.

Take a picturebox control on the form, or create instance of picture box and set BackGroundImage property.

Image backImage = Image.FromFile(“@myImage.jpg”);
myPictureBox.BackGroundImage = backImage;

Here we have placed picturebox control and set its name myPictureBox. myImage.jpg is file available in our current directory else we can specify whole path of my image file.

In another method, we can set background image using Graphics.DrawImage method.

Bitmap backImage = new Bitmap(“@myImage.jpg”);
Graphics g = this.CreateGraphics();
g.DrawImage(backImage,1,1,this.Width,this.Height);

DrawImage methods has 30 around overloaded method, we can use any of them.

Create and Save Image

To create or edit any image first create object of Bitmap class, edit it using Graphics then with Bitmap.Save method, save it back to disk.

Bitmap bm = new Bitmap(600, 600);
Graphics g = Graphics.FromImage(bm);

Brush b = new LinearGradientBrush(new Point(1, 1), new Point(600, 600), Color.White, Color.Blue);

Point[] points = new Point[] {new Point(10, 10), new Point(77, 500), new Point(590, 100), new Point(250, 590), new Point(300, 410)};
g.FillPolygon(b, points);
bm.Save("bm.jpg", ImageFormat.Jpeg);

In above code we have created a polygon and filled it with Blue-while Gradient Brush. Once it done, we save it to disk by bm.jpg to our current directory.

To edit an image, just use another over load of Bitmap constructor that takes file as parameter.

Display Icon
Icon are transparent bitmap image with specific size and used to convey status to windows system. .Net have provided built in Icons with 40-40 size for Questions, Exclamation, Information etc.

To add Icon to Form or control just call Graphics.DrawIcon method, it will do rest for us.

Graphics g = this.CreateGraphics();
g.DrawIcon(SystemIcons.Information, 40, 40);

Above code will draw 40*40 Information Icon on our form.

Graphics with .net (Part -1)

2010-05-24T14:46:00.000+05:30

As a developer, we passed through requirement when we want some customize user interface. We want to draw various shapes, various charts, various diagram to output.

Thanks to System.Drawing namespace, we can play with output design. Graphics includes drawing various shapes circle, rectangle, triangle, ellipse etc, also fill shapes with different colors, modify image as per need. Font can be changed, various charts can be constructed.

System.Drawing includes classes Bitmap, Brush, Brushes, ColorCoverter, ColorTranslator, Font, FontConverter, Graphics, Icon, Image, Pen, Pens, Region, SolidBrush, StringFormat, SystemBrushes, SystemColors and many other classes which can be used at various task of graphics drawing.

Apart from classes System.Drawing namespace have structures CharacterChange, Color, Point, PointF, Rectangle, RectangleF, Size, SizeF. Here F in structure name specifies floating point value support.

Location of control: with help of Point we can set location of control

btnOkay.Location = new Point(50,50) will set btnOkay at (50,50) point.

Set Color, with Color structure
btnOkay.ForeColor = Color.Red;
bnkOkay.BackColor = Color.Blue;

We can specify color from another method FromArgb and passing value of RGB.
btnOkay.ForeColor = Color.FromArgb(10,200,200);
bnkOkay.BackColor = Color. FromArgb(5,20,50);

Draw on surface of form or control.

To draw shapes first we need to create object of Graphics, create object of pen, and now call various method of Graphics to draw shape with pen created earlier.

Graphics g = this.CreateGraphics();

Pen p = new Pen(Color.Blue, 5);

g.DrawLine(p,10,10,100,100);

Above code will draw a blue line with 5 pixel thick from point (10,10) to (100,100)

Pen’s style can be set with DashStyle enumeration.

p.DashStyle = DashStyle.Dot;

p.DashStyle = DashStyle.Dash;

p.DashStyle = DashStyle.DashDot;

p.DashStyle = DashStyle.Solid;

By default, pen draw with solid style. Pen.DashOffset and Pen.DashPattern used to customize dash pattern.

To control endcaps, create arrows or modify pen start cap and end cap, LineCap enumerations is helpful.

p.StartCap = LineCap.ArrowAnchor;
p.EndCap = LineCap.DiamondAnchor;

p.StartCap = LineCap.Flat;
p.EndCap = LineCap.Round;

Methods of Graphics which start with Draw needs to fill it with different brushes, Graphics also support fill methods, which does not create shape but also fill shape.

To fill shape, Brush is used. Brush class is abstract class so any of their child class’s instances can be initiated.

System.Drawing.Drawing2D.HatchBrush: A rectangular brush with a hatchstyle, a foreground color, and a background color

System.Drawing.Drawing2D.LinearGradientBrush: Encapsulates a brush with a lin-
ear gradient that provides a visually appealing, professional-looking fill

System.Drawing.Drawing2D.PathGradientBrush: Provides similar functionality to
LinearGradientBrush; however, you can define a complex fill pattern that fades
between multiple points

System.Drawing.SolidBrush: A brush of a single color

System.Drawing.TextureBrush: A brush made from an image that can be tiled across a shape, like a wallpaper design

Configuration in .net

2010-05-17T10:11:00.000+05:30

When ever .net application runs in any computer, it requires storing some user preference data, connection string if it’s interacting with database and setting for user’s custom control over application. To do so, user adds custom class that stores all information and retrieve when need arise. Usually system administrator wishes to change setting information.

If information is stored in XML file, its easy to store, edit and retrieve by application, with help of System.Configuration namespace that task can be fulfilled.

There are two types of configuration files exist. Machine.Config, it is one which stores information for all application running in a computer, that defines setting for machine. Application .cofing files which stores information for a particular application and which resides in executable folder of running assembly.

Some of the settings which are exists in Machine.Config can be overridden in application configuration but only whose setting allowDefination property set to MachineToApplication , whose property set to MachineOnly can’t be override in application configuration.

To play with setting files, System.Configuration require, we can add reference to it by selecting add reference to our project and once its added to our application, it can be used by Imports in vb.net and using in C#.

To edit Machine.Configue file following steps are useful.

Create instance of Configuration by calling ConfigurationMangaer.OpenMachineConfiguration();

Configuration machineConfig = ConfigurationManager.OpenMachineConfiguration();

There are different sections exist in it, let’s check ProtectedConfigurationSection.

ProtectedConfigurationSection pcs =

(ProtectedConfigurationSection)machineSettings.GetSection( "configProtectedData");

Its provider can be displayed as

MessageBox.Show(pcs.DefaultProvider);

Parameters of section can be accessed by.

MessageBox.Show(pcs.Providers[“DataProtectionConfigurationProvider”].Parameters[“description”]);

Configuration section has unique class, and that c

Each configuration section has a unique class. To determine which class a configuration section uses, call ConfigurationManager.OpenMachineConfiguration().GetSection(

"").ElementInformation.Type.ToString.

To edit application configuration file

Create instance of Configuration by method OpenExeConfiguration

Configuration config =

ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

Values can be added as

config.AppSettings.Settings.Add("MyKey", "MyValue");

Save new value to configuration file

config.Save(ConfigurationSaveMode.Modified);

After running above code check your configuration file, it should look like

Application settings can be read as ..

Configuration.AppSettings(“KeyName”);

Above code will return values of “KeyName” key.

Configuration.AppSettings return NameValueCollection, for database connection string we have ConnectionStringCollection.

The three most useful property of ConnectionStringClass are

Name -- defines name of connection string

ProviderName –type of database connection i.e sql servr, oracle, oledb etc

ConnectionString –defines a string how to connect with database.

We have following connection string in configuration file

Integrated Security=SSPI; AttachDBFilename=|DataDirectory|aspnetdb.mdf; User Instance=true"

providerName="System.Data.SqlClient" />

Though in above connections string split in many lines, in actual it can be placed in a single line.

We can access this connection as

ConfigurationManager.ConnectionStrings["mySqlServer"].ConnectionString

To create custom section in our application configuration there are two way to do that in first create a class that inherits from IConfigurationSectionHandler interface and create a class derived from ConfigurationSection class.

Show Tray Icon for your application In .net.

2010-05-14T17:24:00.002+05:30

In our daily life we see many applications that run in background; we can see them in system tray. Let me tell you, System Tray at the bottom right corner of the screen which shows datetime, network connection, firewall or any programs that running but not showing in taskbar.

We can also put our application’s Icon in system Tray. To achieve it, just go through below steps.

-->Drag NotifiyIcon to your main form (Form which is going to run at start up)

-->Wire up event for form’s resized and add code as...

if(this.WindowState == FormWindowState.Minimized)

this.Hide();

-->Now we have two choice to again show our application in taskbar, either simply clicking on notifyIcon just call this.Show() or add a context menu.

-->This context menu have one or more options like restore application, close application etc.

NotifyIcon control has Icon property to show Icon of your application, and ContextMenuStrip to set contextmenu when you right click on it at system tray.

Windows Service (Part-2)

2010-05-13T10:20:00.000+05:30

In last post we learn how to build windows service in Visual studio, but work does not complete here. Once windows service is developed we need to install it.

We didn’t talk about how to give name to myservice or what property should be set when building it.

Firstly in windows service, we have ServiceBase if you look on designer view, check properties windows of it. Set ServiceName property, this will be our service name.

As we discussed we should write code in OnStart and OnStop method, we can even override other methods OnPause and OnContinue. Pause service is continued to serve users who are already consuming it, but don’t serve to new request. OnContinue is called when service is resumed from stop. To implement these methods set CanPauseAndContinue to true.

To override OnShutdown method, set CanShutdown to true. This method is called at the time of shutdown of computer.

To override OnPowerEvent method, set CanHandlePowerEvent to true. This method is invoked at the time of suspended mode of computer.

As we know to consume windows service, firstly we need to install it. To install it .net has provided ServiceInstaller and ServiceProcessInstaller classes.

ServiceInstaller class is used to define service description, display name, service name and startup type.

ServiceProcessInstaller class is used to define service account information.

àBy right clicking on designer of ServiceBase we can add ProjectInstaller.

àSet StartType property of ProjectInstaller from below list

Automatic: The service starts automatically after the computer starts, whether or not a user logs in.

Manual: A user must start the service manually. This is the default.

Disabled: The service does not start automatically, and users cannot start the service without first changing the start-up type.

àSet Description and DisplayName properties.

àSet ServiceDependedOn property. It may be possible service which we create is depends on some of serviced provided by operating system. We can add one more service in this list.

àSet Security Context of your service by specifying your Account property from one of the following value.

LocalService: Runs in the context of an account that acts as a nonprivileged user on the local computer, and presents anonymous credentials to any remote server. Use LocalService to minimize security risks.

NetworkService: Enables the service to authenticate to another computer on the network. This authentication is not required for anonymous connections, such as most connections to a Web server.

LocalSystem: The service runs with almost unlimited privileges and presents the computer’s credentials to any remote server. Using this account type presents a severe security risk; any vulnerabilities in your application could be exploited to take complete control of the user’s computer.

User: Causes the system to prompt for a valid user name and password when the service is installed. You can set values for both the Username and Password properties of your ServiceProcessInstaller instance. This is the default.

àSet your service project startup object as we have set as startup form in windows application.

Now last task is to install service on computer, we can do that either manually or by creating installer with .msi file.

To manually install service run InstallUtil “service.exe”. here “service.exe” is name of service assembly. InstallUtil is available in ...windows\Microsoft.Net\Framework\Versoion\Folder…

For installer, we can add installer project to our service solution as per other project give Primary output in installer. In primary output give output of windows service.

Once service is installed, we can start , stop from services. Services can be accessed from administrative tools in control panel or by right clicking on mycomputer and manage of it. One of manage list have node services, that is showing all available list of windows service.

By right clicking on service we can pause, run, restart, and stop service. We can even set start up type form there.

Windows Service (Part-1)

2010-05-12T14:34:00.001+05:30

Windows service are application that don’t have any visual element or visual effect, they run in back ground. Windows service run under particular user session as long as we have configured it.

Windows operating system it self provides many services we are familiar with IIS, telnet, Security Center services. We don’t use all services provided by operating system, sometime we require to have some application that run automatically and do work independently without interruption from user interaction. Application starts as we start our computer and run as long as computer don’t shutdown.

In such type of situation we can build up windows service application and host on our computer where we want to have automatic run and stop functionality.

Before we start to talk about how to develop windows service, we check how is it different from other application types?

We can’t run or debug windows service from visual studio development environment so there is no use of F5 and F11 in case of windows service project.

We have to create installer to run windows service, unlike other project we don’t have dll or exe files and can use easily. We need to install windows service by installing to a particular computer.

The main method of your windows service project must have run command, which loads service to service control manager on appropriate computer.

Unlike other application, you would not able to show message box when application crash, or something happened, it will run on background, you will not get any information once service start as after it fully controlled by operating system.

Windows services run on their own security context, we should take care of user account and security problem.

Creation of Windows service project

àChoose windows service template for windows project type.

àwrite your code on OnStart and OnStop procedures, we can override other methods too.

Once windows service started, we can’t have any control on it, we don’t get any thing, in that situation we can create timer object and start timer once windows service start. After that we can write event for timer time elapsed. In such a way we do useful work by using windows services.

Application Domain and its configuration (Part-2)

2010-05-10T10:02:00.000+05:30

In previous post we see how to create application domain, how to load and unload application domain. Sometime we don’t have idea of running assembly as we have loaded it from internet or some third party vendor. Such type of assembly may have possibly contains code, which create security vulnerabilities. Malicious code may corrupt your file system, application and damage to your hardware. To reduce this attack we can allow assembly to run in application domain but with limited privileges.

When you create an application domain, you have complete control over host evidence. Host evidence is the information of assembly, form which code group assembly belongs to.

With help of System.Security and System.Security.Policy you can provide evidence for particular application domain.

You can pass zone or code group for assembly when creating application domain with help of System.Security.Policy.Zone and System.Security.SecurityZone enumeration.

object[] hostEvidence = {new Zone(SecurityZone.Internet)};

Evidence internetEvidence = new Evidence(hostEvidence, null);

AppDomain myDomain = AppDomain.CreateDomain("MyAppDomain");

myDomain.ExecuteAssembly("myAssembly.exe", internetEvidence);

In above sample code we have created hostEvidence object with Internet code group and passed evidence object to ExecuteAssembly method.

Now “MyAppDomain” application domain will run “myAssembly.exe” with internet group privileges. As we know there is a very low control to run code which has been downloaded from internet or running directly from internet. By default Internet zone has very limited permission. There are other code groups are exist like “MyComputer” they can be useful when we want to give more permission to executable assembly in application domain.

We can pass evidence object when creating application domain as.

object [] hostEvidence = {new Zone(SecurityZone.Internet)};

Evidence appDomainEvidence = new Evidence(hostEvidence, null);

AppDomain d = AppDomain.CreateDomain("MyAppDomain", appDomainEvidence);

d.ExecuteAssembly("myAssembly.exe");

To fully customize application domain environment .net has provided AppDomainSetup class. By assigning various property and method to this class we can built up environment for new application domain.

AppDomainSetup has some properties like ApplicaitonBase which used to set root path for assembly, ApplicationName, ConfigurationFile, LicenceFile most of them are self describing from their name.

We can examine current application domains by using.

AppDomainSetup ads = AppDomain.CurrentDomain.SetupInformation;

Application Domain and its configuration (Part-1)

2010-05-08T18:06:00.002+05:30

In .net all application assembly run under an application domain that is created by default for each application, we don’t need to create it. Common Language Runtime does it for application.

Application domain is logical unit to run different application in a single process. IIS is the very good example of it, in IIS more than one website or application are hosted, still they run independent with out interfering to any other application, hosted on same IIS.

Application domain creates a separate layer for application; .net run time is responsible for the various application runtime, while operating system manage process. In a process, we can run more than one application domain and each application domain has one or more assembly, application running. Each of these application domains can’t access resource or memory used by another application domain.

To create an application domain is as simple as we create an object of a class. The benefit of application domain is that when we don’t require or our work has been completed we can unload resource occupied by application runtime.

System.AppDomain class provides many methods and property to manipulate application domain.

-->Create an application domain
AppDomain ad = new AppDomain(“myAppDomain”);

We can run our assembly under this newly created Application domain.
ad.ExecuteAssembly(“myAssembly.exe”);

We can either call ExecuteAssemblyByName method to run assembly, in that case we need to pass name of assembly.
ad.ExecuteAssembly(“myAssembly.exe”);

There are so many properties and methods provide by AppDomain which gives ability to specify ID to process, friendlyname etc. Methods like Load, ApplyPolicy,CreateIntance etc.

If you notice in above code, we don’t have any constructor to create application domain, we are using static method of AppDomain class.

We can access current domains by ..

AppDomain myCurrentDomain = AppDomain.CurrentDomain;
To unload application domain, call Unload method of AppDomain

AppDomain.Unload(ad);

Threading in .net (Part -2)

2010-05-07T09:40:00.000+05:30

In previous post, we have got idea of what is threading and how it can be done easily by calling ThreadPool.QueueUserWorkItem. But threading is not that mean only we need more control on our threading activity.

Like we need to ensure that all thread must work, give priority to my thread than other once, weather my thread has been completed or not, what is status of my thread etc.. all thing can be done by various type of mechanism provided by .net. Yes it’s surely a tedious and complex task to implement but if we do it carefully it not only reduces response time but application behaves very nicely and manages resources.

ThreadPool.QueueUserWorkItem provides a way to run thread in back ground and let it run until it finish. For more control on thread we can create instance of thread, we can even control start, pause, abort, priority. We can handle ThreadAbortException when thread has been aborted.

àCreate thread instance

Thread myThread = new Thread(new ThreadStart(myWork));

àStart thread

myThread.Start();

àWait for some time to run myThread

Thread.Sleep(2000);

àAbort myThread

myThread.Abort();

myWork method has following implementation

public static void myWork()

{

Console.WriteLine("myWork is running on another thread.");

try

{

Thread.Sleep(5000);

}

catch (ThreadAbortException ex)

{

Console.WriteLine("myWork was aborted.");

}

finally

{

Console.WriteLine("Use finally to close all open resources.");

}

Console.WriteLine("myWork has ended.");

}

In above code “myWork has ended” will never display as I have aborted thread. If I comment that line that it will be displayed.

We can call Thread.Suspend and Thread.Resume to stop and resume thread execution but sometime they can create problem. Say for example I am stopping a thread which has acquired my printer, so it will create deadlock condition as my other thread may need printer.

We can set thread priority before starting thread by ThreadPriority enumeration. Enumeration has following values.

àHighest

àAboveNormal

àNormal

àBelowNormal

àLowest

By default foreground and background run on normal priority.

Thread’s state can be checked with Thread.ThreadState property. There are various types of it like Unstarted, Running, Stopped, Suspended, Aborted etc. At a time a thread may have one or more thread state.

Sometime there is requirement to know status of thread which is running in background we want to pass some data to thread and let us know what is the output of that data after certain time elapsed. We can achieve this task by creating delegate and callback. For that we need to create a delegate at class level and a method to handle that delegate. Create a class for which you want to run in background, add delegate to class. Create an instance of class and in constructor pass delegate with appropriate method.

When there are more than one thread runs simultaneously, situation may happen it acquires resource and in turn deadlock. So it means instead of improvement in performance our application become slow and unresponsive. At that time we need to manage resource by synchronizing thread resource.

Use lock keyword in C# and SynLock keyword in vb.net. It does not allow using resource of any other thread till it completes it work. One thing should be kept in mind that these keywords work only with reference type not on value type.

When there is requirement of separate read and write lock on resource we can use ReaderWriterLock class. Create instance of this class and use separate read and write lock.

ReaderWriterLock rwl = new ReaderWriterLock()

To acquire read lock

rwl.AcquireReaderLock(10000);

Release reader lock

rwl.ReleaseReaderLock();

Acquire writer lock and release it.

rwl.AcquireWriterLock(10000);

rwl.ReleaseWriterLock();

Another method to synchronize thread is to use object of Interlocked class. It will add numeric value to thread. It also provides various numeric methods.

There are also so many things to wait for thread to complete and start another thread once complete previous one.

NOTE: In visual basic we need to add attribute to main method to run main thread as multithread. MTA (Multithread Apartment) is by default provided in C#, so there is no need to add it. MTA supports calling WaitHandle.WaitAll.

Threading in .net (Part -1)

2010-05-06T09:51:00.000+05:30

Most of the time developer chooses to develop program in linear way. In this mechanism user would need to wait sometime in some situation like application is going to download page from server, application is going to print document, applications is going to access remote database. Those cases are time consuming, user needs to wait till main thread completes work, sometime user get frustrated by response time, and application does not response to user till task has been completed.

To overcome, .net has provided threading mechanism. Our main thread executes as and in background we can execute process. So user will not feel that application is not responding, in background thread method executes and once result will be available, it would be shown to user.

Threading means in a single process execute more than one task among different processors. Now days most of computers are more than one core, we can use another core when main core is busy to complete task. We can distribute work task among different processors.

Though multithreading seems to be very complex, .net has provided a simple way to implement in programming. At a time there can be more than 250 threads run in back ground. We can even change it to more if require.

To work with thread we need to add System.Threading namespace to our application. We can run background thread by using ThreadPool.QueueUserWorkItem and passing method name or address of in vb.net.

static void Main(string[] args)

{

int workerThreads;

int completionPortThreads;

ThreadPool.GetAvailableThreads(out workerThreads, out completionPortThreads);

ThreadPool.QueueUserWorkItem(ThreadProc, "Thread 1");

ThreadPool.QueueUserWorkItem(ThreadProc, "Thread 2");

ThreadPool.QueueUserWorkItem(ThreadProc, "Thread 3");

ThreadPool.QueueUserWorkItem(ThreadProc, "Thread 4");

ThreadProc("ForgroundThread");

Thread.Sleep(1000);

Console.WriteLine("Worker Threads: {0} CompletePortThreads: {1}", workerThreads, completionPortThreads);

ThreadPool.QueueUserWorkItem(ThreadProc, "Thread 5");

ThreadPool.QueueUserWorkItem(ThreadProc, "Thread 6");

Console.WriteLine("Now main is continue");

}

Above code shows how many threads can be run, default value is 250. We have used ThreadProc method which will run in background thread. When main thread has no work at that time background thread will run and execute code. We can add as many threads as we wish as per limit of 250 and if required we can increase this maximum thread limit.

Thread which runs first is called Forground and other called background.

static void ThreadProc(object msg)

{

string threadMsg = (string)msg;

if (Thread.CurrentThread.IsBackground)

{

Console.WriteLine("Background Thread");

Console.WriteLine("My Threading method with:" + threadMsg);

}

else

{

Console.WriteLine("Forground Thread");

Console.WriteLine("My Threading method with:" + threadMsg);

}

We can check weather thread is background or not with Thread.CurrentThread.IsBackGround property.

Some time threading also overheads on processors, so need to take care while implementing threading as it distribute loads to different processor, more memory is required to manage resource.

Wise use of threading may improve application’s performance. It depends on requirement and application problem to use of Threading.