ASP.Net Free Short Notes

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What is ASP.Net?

ASP.Net is a web development platform provided by Microsoft. It is used for creating web-based applications. ASP.Net was first released in the year 2002.

The first version of ASP.Net deployed was 1.0. The most recent version of ASP.Net is version 4.6. ASP.Net is designed to work with the HTTP protocol. This is the standard protocol used across all web applications.

ASP.Net applications can also be written in a variety of .Net languages. These include C#, VB.Net, and J#.

The full form of ASP is Active Server Pages, and .NET is Network Enabled Technologies.

ASP.NET Architecture and its Components

ASP.Net is a framework which is used to develop a Web-based application. The basic architecture of the ASP.Net framework is as shown below.

ASP.NET Architecture Diagram

The architecture of the.Net framework is based on the following key components

  1. Language – A variety of languages exists for .net framework. They are VB.net and C#. These can be used to develop web applications.
  2. Library - The .NET Framework includes a set of standard class libraries. The most common library used for web applications in .net is the Web library. The web library has all the necessary components used to develop.Net web-based applications.
  3. Common Language Runtime - The Common Language Infrastructure or CLI is a platform. .Net programs are executed on this platform. The CLR is used for performing key activities. Activities include Exception handling and Garbage collection.

Below are some of the key characteristics of the ASP.Net framework

  1. Code Behind Mode – This is the concept of separation of design and code. By making this separation, it becomes easier to maintain the ASP.Net application. The general file type of an ASP.Net file is aspx. Assume we have a web page called MyPage.aspx. There will be another file called MyPage.aspx.cs which would denote the code part of the page. So Visual Studio creates separate files for each web page, one for the design part and the other for the code.
  2. State Management – ASP.Net has the facility to control state management. HTTP is known as a stateless protocol. Let's take an example of a shopping cart application. Now, when a user decides what he wants to buy from the site, he will press the submit button.The application needs to remember the items the user choose for the purchase. This is known as remembering the state of an application at a current point in time. HTTP is a stateless protocol. When the user goes to the purchase page, HTTP will not store the information on the cart items. Additional coding needs to be done to ensure that the cart items can be carried forward to the purchase page.

Such an implementation can become complex at times. But ASP.Net can do state management on your behalf. So ASP.Net can remember the cart items and pass it over to the purchase page.

  1. Caching – ASP.Net can implement the concept of Caching. This improve's the performance of the application. By caching those pages which are often requested by the user can be stored in a temporary location. These pages can be retrieved faster and better responses can be sent to the user. So caching can significantly improve the performance of an application.

ASP.Net is a development language used for constructing web-based applications. ASP.Net is designed to work with the standard HTTP protocol.

Overview of ASP.NET Controls

The ASP.NET Framework contains more than 90 controls. These controls can be divided into seven groups:

  • Standard Controls—Enable you to render standard form elements such as buttons, input fields, and labels.
  • Validation Controls—Enable you to validate form data before you submit the data to the server. For example, you can use a RequiredFieldValidator control to check whether a user entered a value for a required input field.
  • Rich Controls—Enable you to render things such as calendars, file upload buttons, rotating banner advertisements, and multistep wizards.
  • Data Controls—Enable you to work with data such as database data. For example, you can use these controls to submit new records to a database table or display a list of database records.
  • Navigation Controls—Enable you to display standard navigation elements such as menus, tree views etc.
  • Login Controls—Enables you to display login, change password, and registration forms.
  • HTML Controls—Enable you to convert any HTML tag into a server-side control.

Server: Web vs. Application

Server is a device or a computer program that accepts and responds to the request made by other program, known as client. It is used to manage the network resources and for running the program or software that provides services.

There are two types of servers:

  1. Web Server
  2. Application Server

Web Server

Web server contains only web or servlet container. It can be used for servlet, jsp, struts, jsf etc. It can't be used for EJB.

EJB is a server-side software component that encapsulates business logic of an application. An EJB web container provides a runtime environment for web related software components, including computer security, Java servlet lifecycle management, transaction processing, and other web services

It is a computer where the web content can be stored. In general web server can be used to host the web sites but there also used some other web servers also such as FTP, email, storage, gaming etc.

Examples of Web Servers are: Apache Tomcat and Resin.

Web Server Working

It can respond to the client request in either of the following two possible ways:

  • Generating response by using the script and communicating with database.
  • Sending file to the client associated with the requested URL.

The block diagram representation of Web Server is shown below:

Important points

  • If the requested web page at the client side is not found, then web server will sends the HTTP response: Error 404 Not found.
  • When the web server searching the requested page if requested page is found then it will send to the client with an HTTP response.
  • If the client requests some other resources then web server will contact to application server and data is store for constructing the HTTP response.

Application Server

Application server contains Web and EJB containers. It can be used for servlet, jsp, struts, jsf, ejb etc. It is a component based product that lies in the middle-tier of a server centric architecture.

It provides the middleware services for state maintenance and security, along with persistence and data access. It is a type of server designed to install, operate and host associated services and applications for the IT services, end users and organizations.

The block diagram representation of Application Server is shown below:

The Example of Application Servers are:

  1. JBoss: Open-source server from JBoss community.
  2. Glassfish: Provided by Sun Microsystem. Now acquired by Oracle.
  3. Weblogic: Provided by Oracle. It more secured.
  4. Websphere: Provided by IBM.

Web Forms

ASP.NET Web Forms is a part of the ASP.NET web application framework and is included with Visual Studio.Web Forms are pages that your users request using their browser. These pages can be written using a combination of HTML, client-script, server controls, and server code.

When users request a page, it is compiled and executed on the server by the framework, and then the framework generates the HTML mark-up that the browser can render. An ASP.NET Web Forms page presents information to the user in any browser or client device.

ASP.NET and Visual Studio documentation spans several versions. Topics that highlight features from previous versions may be useful for your current tasks and scenarios using the latest versions.

ASP.NET Web Forms are:

  • Based on Microsoft ASP.NET technology, in which code that runs on the server dynamically generates Web page output to the browser or client device.
  • Compatible with any browser or mobile device. An ASP.NET Web page automatically renders the correct browser-compliant HTML for features such as styles, layout, and so on.
  • Compatible with any language supported by the .NET common language runtime, such as Microsoft Visual Basic and Microsoft Visual C#.
  • Built on the Microsoft .NET Framework. This provides all the benefits of the framework, including a managed environment, type safety, and inheritance.
  • Flexible because you can add user-created and third party controls to them.

ASP.NET Web Forms offer:

  • Separation of HTML and other UI code from application logic.
  • A rich suite of server controls for common tasks, including data access.
  • Powerful data binding, with great tool support.
  • Support for client-side scripting that executes in the browser.
  • Support for a variety of other capabilities, including routing, security, performance, internationalization, testing, debugging, error handling and state management.

Features of ASP.NET Web Forms

  • Server Controls- ASP.NET Web server controls are objects on ASP.NET Web pages that run when the page is requested and that render markup to the browser. Many Web server controls are similar to familiar HTML elements, such as buttons and text boxes. Other controls encompass complex behavior, such as a calendar controls, and controls that you can use to connect to data sources and display data.
  • Master Pages- ASP.NET master pages allow you to create a consistent layout for the pages in your application. A single master page defines the look and feel and standard behavior that you want for all of the pages (or a group of pages) in your application.
  • Working with Data- ASP.NET provides many options for storing, retrieving, and displaying data. In an ASP.NET Web Forms application, you use data-bound controls to automate the presentation or input of data in web 0page UI elements such as tables and text boxes and drop-down lists.
  • Membership- ASP.NET Identity stores your users' credentials in a database created by the application. When your users log in, the application validates their credentials by reading the database. Your project's Account folder contains the files that implement the various parts of membership: registering, logging in, changing a password, and authorizing access.
  • Client Script and Client Frameworks- You can enhance the server-based features of ASP.NET by including client-script functionality in ASP.NET Web Form pages. You can use client script to provide a richer, more responsive user interface to users. You can also use client script to make asynchronous calls to the Web server while a page is running in the browser.
  • Routing- URL routing allows you to configure an application to accept request URLs that do not map to physical files. A request URL is simply the URL a user enters into their browser to find a page on your web site. You use routing to define URLs that are semantically meaningful to users and that can help with search-engine optimization (SEO).
  • State Management- ASP.NET Web Forms includes several options that help you preserve data on both a per-page basis and an application-wide basis.
  • Security- An important part of developing a more secure application is to understand the threats to it. Microsoft has developed a way to categorize threats: Spoofing, Tampering, Repudiation, Information disclosure, Denial of service, Elevation of privilege (STRIDE). In ASP.NET Web Forms, you can add extensibility points and configuration options that enable you to customize various security behaviors in ASP.NET Web Forms.
  • Performance- Performance can be a key factor in a successful Web site or project. ASP.NET Web Forms allows you to modify performance related to page and server control processing, state management, data access, application configuration and loading, and efficient coding practices.
  • Internationalization- ASP.NET Web Forms enables you to create web pages that can obtain content and other data based on the preferred language setting for the browser or based on the user's explicit choice of language. Content and other data is referred to as resources and such data can be stored in resource files or other sources. In an ASP.NET Web Forms page, you configure controls to get their property values from resources. At run time, the resource expressions are replaced by resources from the appropriate localized resource file.
  • Debugging and Error Handling- ASP.NET includes features to help you diagnose problems that might arise in your Web Forms application. Debugging and error handling are well supported within ASP.NET Web Forms so that your applications compile and run effectively.
  • Deployment and Hosting- Visual Studio, ASP.NET, Azure, and IIS provide tools that help you with the process of deploying and hosting your Web Forms application.

Web Form control

Client side HTML control : HTML controls are the native elements of browser. These are client side controls which is accessible only in the HTML page and not executed in server side. In this senerio user requests the page, receive the page from the server, then display the HTML and process the Javascript.The client side validation can be done using the Javascript or vb script. Client side validation is processed the client side before submitting the form. The advantage of using the client side validation is it reduces the network trafiic since the validation is processed in the client machine itself. So Client side HTML control will improve the performance of the web page. 
 
HTML Server Controls : when we can add the attribute runat="server" to any HTML control, such cases it will be an HTML server control. These controls map directly to html tags and without runat="server" it cannot be accessed from code behind.
 
ASP.Net Web Controls: Web Server Controls or ASP.NET controls Web Server Controls are group of controls derived directly from the System.Web.UI.WebControls base class. They are executed on the server side and output HTML sent back to the client browser. If you use a textbox web control in webform, what happens when the webform runs is the textbox server control is converted to html control(just like html client side control). This is extra headache when we can have simple html controls in hand.So it is better to not use these web controls where performace is an impotant parameter.

 

using System.Web.UI.WebControls;

Because All Web Forms Controls comes Under this Namespace .

Web Forms Controls:-

 

There are some Web Forms Controls which is given below with Real Time Example:-

  1. Label Control
  2. TextBox control
  3. Button control
  4. Literal control
  5. PlaceHolder control
  6. HiddenField control
  7. FileUpload control
  8. Image control
  9. ImageButton control
  10. ImageMap control

    1.) Label Control:-

The Label Control is basically used to display the Information(Text) on Web Forms. Any end User can not Edit(change) the Label Information.

Properties of Label Control:-
There are some important properties of Label controls.

  • Text:-It is used to change the Label control information(text).
  • Font:- It is used to sets the font of the Label text.
  • ForeColor:- It is used to sets the text color in the Label.
  • Height:- It is used to Specify the height of the Label Control.
  • BackColor :-It is used to Sets the Background color of the Label control.
  • BorderWidth:-It is used to Sets the Border color of the Label control.
  • BorderStyle:-It is used to Sets the Style of the Label control.
  • AccessKey:-It is used to Navigate the Web Server control.

There are some steps to implement the Label control on  the Web Form which is given below:

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-->Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-->Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop Label and Button control  from Toolbox on  the Web Form as Given below:


Step :2 Now Double Click on Click Button and Write the following codes which is shown below:

 

using System;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

 

public partial class labelcontrol : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

 

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        Label2.Text = "You can easily display any information inside it";

    }

}



Step :3 Now Run The Program(Press F5) and Press the Click Button.
Output:



     2.) TextBox Control:-


The TextBox control is used to input the Data(text).Any end user can easily enter the text in this control.
Properties of TextBox Control:-
There are some important properties of TextBox controls.

  • Text:-It is used to sets the text in TextBox Control.
  • TextMode:- It is used to sets the mode of the TextBox Control as Single Mode,Multiline or Password.
  • Rows:-It is used to sets the number of rows display in a TextBox(Multiline).
  • MaxLength:->It is used to sets the maximum number of character alloweded in a TextBox control.
  • ReadOnly:-It is used to read the contents by the end used but can not change it.
  • Columns:-It is used to sets the width of character in TextBox.
  • AutoCompleteType:-It is used to sets a value that indicates the Auto Complete behavior of the TextBox control.
  • AutoPostBack:-It is used to handle the event when the TextBox control lose focus.
  • CauseValidation:-It is used to set a value that validate the TextBox control(client,server).
  • TextChange:-It is an event.It occurs when the end user change the text of the TextBox control.

·        3.) Button Control:-> The Button control is used to create an Event and send request to the web server. Properties of Button Control:- There are some important properties of Button controls.

·        Text:- It is used to sets the text to be displayed on the Button Control. Click:-It is an Event that occurs when the Button is clicked.

·        Command:- It is also an Event that occurs when the Button is clicked.It is used whenever we are using multiple Button on one page.

·        CommandName:-It is used to sets the command Name associated with the Button control that is passed to the command event.

·        OnClientClick:-It is used to sets the client side script that executes when a Button click event is fired.

·        CauseValidation:- It is used to sets the validation that is perform or not when we click the Button control. There are some steps to implement the TextBox and Button controls on the Web Form which is given below:

·        Step :1 First Open Your Visual Studio-->File-->New-->Web Site-->Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-->Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop TextBox,Label and Button control from Toolbox on the Web Form as Given below

·        Step

 

 

Step :2 Now Double Click on Button Control and Write the following which is given below:

 using System;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

 

public partial class _Default : System.Web.UI.Page

{

 protected void Page_Load(object sender, EventArgs e)

 {

 

 }

 

 protected void Button1_Click(object sender, EventArgs e)

{

 String str = TextBox1.Text; Label2.Text = str;

}

}

 

Step :3 Now Run The program(press F5) and click the Button. output:

 

 

4.) Literal control:-

It is similar to Label control but there are some differences and similarities which is given below.

Literal and Label control both are used to display the text(information) on the web form.

On Browser side Label control is converted to HTML 'Span' tag ‘span’ but Literal control is not converted in any HTML tag. 

We can provide formatting to the Label control but not to the Literal control.

If we want to show some HTML code and java script code the we used mainly Literal control ,not Label control.Encoding Mode is used with Literal control only.

 

Properties of Literal Control:-

There are some important properties of Literal controls.

·       Mode: - IT IS A Literal control property called Mode which can be changed as Transform,Encode and Pass Through.

·       Text: - It is used to sets the caption displayed in the Literal.

 

There are some steps to implement the Literal and Label controls on the Web Form which is given below:

 

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-- >Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-- >Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop Literal,Label and Button control from Toolbox on the Web Form as Given below:

 

 

Step : 2 Now Double click on Click button and write the following codes which is given below:

using System;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

 

public partial class Literal_and_label_controls_ : System.Web.UI.Page

{

 protected void Page_Load(object sender, EventArgs e)

{

 

 }

 protected void Button1_Click(object sender, EventArgs e)

{

 Literal1.Text = "Hello Asp.net Website I am Literal Control";

Label2.Text = "Hello Asp.net Website I am Label Control";

}

 }

 

Step :3 Now Run the program(press F5) and press the click button. output:-

 

 

 

Now you see browser source code,you will see Label control converted to HTML span tag

see it:

 

 

 

 

5.) PlaceHolder control:-

 

It is known as container control in Asp.Net.It is mainly used to store the value of other controls.You can Add controls to a Web Form by using the Controls.Add() Method.

There are some steps to implement the PlaceHolder control on the Web Form which is given below:

 

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-- >Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-- >Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop PlaceHolder and Button control from Toolbox on the Web Form as Given below:

 

 

Step :2 Now Double click on Click button and write the following codes which is given below:

 

using System;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

 

public partial class placeHoldercontrol : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

 

 }

protected void Button1_Click(object sender, EventArgs e)

{

 PlaceHolder1.Controls.Add(TextBox1);

}

}

Step :3 Now Run The Program(Press F5) and Press the Click Button. Output:

6.) HiddenField control:-

 

It is used to display the value stored in the HiddenField control in the Label control.It stores the information in the form of Strings. There are some steps to implement the HiddenField control on the Web Form which is given below:

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-- >Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-- >Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop HiddenField,TextBox,Label and Button control from Toolbox on the Web Form as Given below:

 

 

 

Step :2 Now Double click on Click button and write the following codes which is given below:

 

using System;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

public partial class HiddenFieldcontrol : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void Button1_Click(object sender, EventArgs e)

{

 HiddenField1.Value = TextBox1.Text;

Label2.Text = HiddenField1.Value;

}

 }

 

Step :3 Now Run The Program(Press F5) and Press the Click Button. Output:

 

7. FileUpload Control

It is basically used to Upload the File on the server using SaveAs() method on the click Event.When user browse a File and after browse click the Upload button then File is automatically Upload on the Server.

There are some steps to implement the FileUpload control on the Web Form which is given below:

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-- >Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-- >Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop FileUpload,Label and Button control from Toolbox on the Web Form as Given below:

 

 

Step :2 Now Double click on Click button and write the following codes which is given below:

 

using System;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

public partial class Fileuploadcontrol : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

 }

protected void Button1_Click(object sender, EventArgs e)

{

 FileUpload1.SaveAs("I:/" + FileUpload1.FileName);

Label2.Text = "File"+" " + FileUpload1.FileName +" "+"is uploaded successfully";

}

}

 

 

Step :3 Now Run The Program(Press F5) ,Browse File from your computer and Press the Click Button.

Output:

 

 

8.) Image Control:-

It is used to display an image on a web page.

 

Properties of Image control:-

There are some important properties of Image control controls. 

·       Alternate Text: - It is used to display alternate text when the image is not present. 

·       ImageAlign:- It is used to sets the alignment of image control on the web page. 

·       ImageUrl:- It is used to sets the path to an image to display in the image control. 

·       Font:- It is used to increase or decrease font of the image control text.

·        DescriptionUrl:- It is used to set the location to a detailed description for the image.

There are some steps to implement the Image control on the Web Form which is given below:

 

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-- >Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-- >Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop Image control from Toolbox on the Web Form as Given below:

 

 

Step :2 Now copy the Image from computer and paste in the Website folder as shown below:

 

 

Step :3 Now Go Image Property-->click on ImageUrl Property-- >select your image

 

 

You will see following output:

 

9. ) ImageButton control:-

It is used to display the image on Button instead of text.Properties of ImageButton is same as Button property.

10.) ImageMap control:-

It is used to provide various links(hotspots) to navigate to other web page,depending on the place where the user clicks.

Properties of ImageMap Control:-

 

There are some important properties of ImageMap control.

Hotspots:- It obtains a group of Hotspot Object that is defined in a ImageMap. 

Target:- It is used to sets target window to show the web page when the ImageMap control clicked. 

Enabled:- It is used to sets a value indicating whether the control can respond to the user interaction.

 

 

There are some steps to implement the Image control on the Web Form which is given below:

Step :1 First Open Your Visual Studio-->File-->New-->Web Site-- >Select ASP.NET Empty Web Site-->OK-->Open Solution Explorer-- >Right Click on Web Site-->Add New Item -->Select Web Form--> click Add-->Now drag and drop ImageMap,ImageButton and Label control from Toolbox on the Web Form as Given below:

 

 

 

Step :2 Now copy the Image from computer and paste in the Website folder as shown below:

Step :3 Now Go properties of ImageMap and ImageButton and Select appropriate image by Clicking ImageUrl.

 

 

 

 

Step :4 Now go Properties of ImageMap control and select( Collection).Add new hotspots as shown below:

 

 

 

 

Step :5 Now Run the Program(Press F5) and Click the Image Button. output:

 

 


Multiple Project Method

If you separate the Web application into multiple Visual Studio .NET projects, you may find it easier to manage the development of large Web applications. You can separate a large development project into smaller projects, which you can manage and build separately. Your team can work on separate parts of a Web application by working on separate projects. You should still use source control software to coordinate work on project files.

Visual Studio .NET does not directly support this method because Visual Studio .NET Web projects are always created in their own IIS application root directories with their own assemblies. IIS Web applications cannot span multiple IIS application root directories.

The advantages of the multiple project method are as follows:

·        It is easier to manage smaller units of a large Web application.

·        You can build each project separately from the other projects, which shortens the build times during development.

·        You can divide a large Web application into logical units and have these units share common resources, such as controls.

The disadvantages of the multiple project method are as follows:


·        Visual Studio .NET does not directly support this method. You must perform additional steps so that separate Visual Studio .NET projects participate in the same Web application.

·        Assemblies that access each other's resources must set references to each other. Visual Studio .NET does not allow circular references.

·        This method is not ideal for small Web applications. For small Web applications, it is more complex to manage multiple projects than to manage a single project.

Create the IIS Application Root Project

To create the IIS application root project for the Web application, follow these steps:

1.     Start Visual Studio .NET.

2.     On the File menu, point to New, and then click Project.

3.     In the New Project dialog box, click the language that you want to use under Project Types, and then click ASP.NET Web Application under Templates.

4.     In the Location text box, replace the WebApplication# default name with MainWeb. If you are using the local server, you can leave the server name as http://localhost. The Location box should then appear as follows:

http://localhost/MainWeb

Create the Child Projects

To create the child projects, follow these steps:

1.     For each child project, right-click the solution in the Solution Explorer window, point to Add, and then click New Project.

2.     In the Add New Project dialog box, click ASP.NET Web Application under Templates.

3.     In the Location text box, type http://localhost/MainWeb/<subwebname>. This creates a child project named <subwebname> in a subdirectory of the root application directory.

4.     Click OK.

5.     Delete any files that are not needed for a non-application root directory from the project. Specifically, delete the Global.asax and the Web.config files. This child project will rely on the Global.asax and the Web.config files from the main project.

6.     If the child project will only contain shared resources, such as user controls, delete the WebForm1.aspx file.

7.     Build the solution.

Validation

Validations can be performed on the server side or on the client side ( web browser). The user input validation take place on the Server Side during a post back session is called Server Side Validation and the user input validation take place on the Client Side (web browser) is called Client Side Validation. Client Side Validation does not require a postback. If the user request requires server resources to validate the user input, you should use Server Side Validation. If the user request does not require any server resources to validate the input , you can use Client Side Validation.

 

Server Side Validation

In the Server Side Validation, the input submitted by the user is being sent to the server and validated using one of server side scripting languages such as ASP.Net, PHP etc. After the validation process on the Server Side, the feedback is sent back to the client by a new dynamically generated web page. It is better to validate user input on Server Side because you can protect against the malicious users, who can easily bypass your Client Side scripting language and submit dangerous input to the server.

Client Side Validation

In the Client Side Validation you can provide a better user experience by responding quickly at the browser level. When you perform a Client Side Validation, all the user inputs validated in the user's browser itself. Client Side validation does not require a round trip to the server, so the network traffic which will help your server perform better. This type of validation is done on the browser side using script languages such as JavaScript, VBScript or HTML5 attributes.

For example, if the user enter an invalid email format, you can show an error message immediately before the user move to the next field, so the user can correct every field before they submit the form.

Mostly the Client Side Validation depends on the JavaScript Language, so if users turn JavaScript off, it can easily bypass and submit dangerous input to the server . So the Client Side Validation can not protect your application from malicious attacks on your server resources and databases.

As both the validation methods have their own significances, it is recommended that the Server side validation is more SECURE.ASP.NET validation controls validate the user input data to ensure that useless, unauthenticated, or contradictory data don't get stored.ASP.NET provides the following validation controls:

  • RequiredFieldValidator
  • RangeValidator
  • CompareValidator
  • RegularExpressionValidator
  • CustomValidator
  • ValidationSummary

BaseValidator Class

The validation control classes are inherited from the BaseValidator class hence they inherit its properties and methods. Therefore, it would help to take a look at the properties and the methods of this base class, which are common for all the validation controls:

Members

Description

ControlToValidate

Indicates the input control to validate.

Display

Indicates how the error message is shown.

EnableClientScript

Indicates whether client side validation will take.

Enabled

Enables or disables the validator.

ErrorMessage

Indicates error string.

Text

Error text to be shown if validation fails.

IsValid

Indicates whether the value of the control is valid.

SetFocusOnError

It indicates whether in case of an invalid control, the focus should switch to the related input control.

ValidationGroup

The logical group of multiple validators, where this control belongs.

Validate()

This method revalidates the control and updates the IsValid property.

RequiredFieldValidator Control

The RequiredFieldValidator control ensures that the required field is not empty. It is generally tied to a text box to force input into the text box.

The syntax of the control is as given:

<asp:RequiredFieldValidator ID="rfvcandidate"

   runat="server" ControlToValidate ="ddlcandidate"

   ErrorMessage="Please choose a candidate"

   InitialValue="Please choose a candidate">

  

</asp:RequiredFieldValidator>

RangeValidator Control

The RangeValidator control verifies that the input value falls within a predetermined range.

It has three specific properties:

Properties

Description

Type

It defines the type of the data. The available values are: Currency, Date, Double, Integer, and String.

MinimumValue

It specifies the minimum value of the range.

MaximumValue

It specifies the maximum value of the range.

The syntax of the control is as given:

<asp:RangeValidator ID="rvclass" runat="server" ControlToValidate="txtclass"

   ErrorMessage="Enter your class (6 - 12)" MaximumValue="12"

   MinimumValue="6" Type="Integer">

  

</asp:RangeValidator>

CompareValidator Control

The CompareValidator control compares a value in one control with a fixed value or a value in another control.

It has the following specific properties:

Properties

Description

Type

It specifies the data type.

ControlToCompare

It specifies the value of the input control to compare with.

ValueToCompare

It specifies the constant value to compare with.

Operator

It specifies the comparison operator, the available values are: Equal, NotEqual, GreaterThan, GreaterThanEqual, LessThan, LessThanEqual, and DataTypeCheck.

The basic syntax of the control is as follows:

<asp:CompareValidator ID="CompareValidator1" runat="server"

   ErrorMessage="CompareValidator">

  

</asp:CompareValidator>

RegularExpressionValidator

The RegularExpressionValidator allows validating the input text by matching against a pattern of a regular expression. The regular expression is set in the ValidationExpression property.

The following table summarizes the commonly used syntax constructs for regular expressions:

Character Escapes

Description

\b

Matches a backspace.

\t

Matches a tab.

\r

Matches a carriage return.

\v

Matches a vertical tab.

\f

Matches a form feed.

\n

Matches a new line.

\

Escape character.

Apart from single character match, a class of characters could be specified that can be matched, called the metacharacters.

Metacharacters

Description

.

Matches any character except \n.

[abcd]

Matches any character in the set.

[^abcd]

Excludes any character in the set.

[2-7a-mA-M]

Matches any character specified in the range.

\w

Matches any alphanumeric character and underscore.

\W

Matches any non-word character.

\s

Matches whitespace characters like, space, tab, new line etc.

\S

Matches any non-whitespace character.

\d

Matches any decimal character.

\D

Matches any non-decimal character.

Quantifiers could be added to specify number of times a character could appear.

Quantifier

Description

*

Zero or more matches.

+

One or more matches.

?

Zero or one matches.

{N}

N matches.

{N,}

N or more matches.

{N,M}

Between N and M matches.

The syntax of the control is as given:

<asp:RegularExpressionValidator ID="string" runat="server" ErrorMessage="string"

   ValidationExpression="string" ValidationGroup="string">

  

</asp:RegularExpressionValidator>

CustomValidator

The CustomValidator control allows writing application specific custom validation routines for both the client side and the server side validation.

The client side validation is accomplished through the ClientValidationFunction property. The client side validation routine should be written in a scripting language, such as JavaScript or VBScript, which the browser can understand.

The server side validation routine must be called from the control's ServerValidate event handler. The server side validation routine should be written in any .Net language, like C# or VB.Net.

The basic syntax for the control is as given:

<asp:CustomValidator ID="CustomValidator1" runat="server"

   ClientValidationFunction=.cvf_func. ErrorMessage="CustomValidator">

  

</asp:CustomValidator>

Calender Control

The calendar control is a functionally rich web control, which provides the following capabilities:

  • Displaying one month at a time
  • Selecting a day, a week or a month
  • Selecting a range of days
  • Moving from month to month
  • Controlling the display of the days programmatically

The basic syntax of a calendar control is:

<asp:Calender ID = "Calendar1" runat = "server">

</asp:Calender>

 

 

The Calendar control has the following three most important events that allow the developers to program the calendar control. They are:

Events

Description

SelectionChanged

It is raised when a day, a week or an entire month is selected.

DayRender

It is raised when each data cell of the calendar control is rendered.

VisibleMonthChanged

It is raised when user changes a month.

Working with the Calendar Control

Putting a bare-bone calendar control without any code behind file provides a workable calendar to a site, which shows the months and days of the year. It also allows navigation to next and previous months.

Calendar controls allow the users to select a single day, a week, or an entire month. This is done by using the SelectionMode property. This property has the following values:

Properties

Description

Day

To select a single day.

DayWeek

To select a single day or an entire week.

DayWeekMonth

To select a single day, a week, or an entire month.

None

Nothing can be selected.

The syntax for selecting days:

<asp:Calender ID = "Calendar1" runat = "server" SelectionMode="DayWeekMonth">

</asp:Calender>

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="calendardemo._Default" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml" >
 
   <head runat="server">
      <title>
         Untitled Page
      </title>
   </head>
   
   <body>
      <form id="form1" runat="server">
      
         <div>
            <h3> Your Birthday:</h3>
            <asp:Calendar ID="Calendar1" runat="server  SelectionMode="DayWeekMonth" onselectionchanged="Calendar1_SelectionChanged">
            </asp:Calendar>
         </div>
         
         <p>Todays date is: 
            <asp:Label ID="lblday" runat="server"></asp:Label>
         </p>
         
         <p>Your Birday is: 
            <asp:Label ID="lblbday" runat="server"></asp:Label>
         </p>
         
      </form>
   </body>
</html>

The event handler for the event SelectionChanged:

protected void Calendar1_SelectionChanged(object sender, EventArgs e)
{
   lblday.Text = Calendar1.TodaysDate.ToShortDateString();
   lblbday.Text = Calendar1.SelectedDate.ToShortDateString();
}

When the file is run, it should produce the following output:

Ad Rotator Control

AdRotator is a control in ASP.NET that is all about ads in Web pages. It displays a number of ad images and rotates them or loads them when a page is refreshed. The ASP.NET AdRotator control uses an XML file to store the ads and their information. The XML file must begin and end with an <Advertisements> tag.

The basic syntax of adding an AdRotator is as follows:

<asp:AdRotator  runat = "server" AdvertisementFile = "adfile.xml"  Target = "_blank" />

The Advertisement File

The advertisement file is an XML file, which contains the information about the advertisements to be displayed.

It is a text-based markup language that enables you to store data in a structured format by using meaningful tags. The term 'extensible' implies that you can extend your ability to describe a document by defining meaningful tags for the application.

XML is not a language in itself, like HTML, but a set of rules for creating new markup languages. It is a meta-markup language. It allows developers to create custom tag sets for special uses. It structures, stores, and transports the information.

Following is an example of XML file:

<BOOK>
   <NAME> Learn XML </NAME>
   <AUTHOR> Samuel Peterson </AUTHOR>
   <PUBLISHER> NSS Publications </PUBLISHER>
   <PRICE> $30.00</PRICE>
</BOOK>
 
State Management

State Management Types

 

In ASP.NET there are the following 2 State Management methodologies:

 

 

 

Client-Side State Management

 

Whenever we use Client-Side State Management, the state related information will directly get stored on the client-side. That specific information will travel back and communicate with every request generated by the user then afterwards provides responses after server-side communication.

 

This architecture is something like the following,

 

 

 

Server-Side State Management

 

Server-Side State Management is different from Client-Side State Management but the operations and working is somewhat the same in functionality. In Server-Side State Management all the information is stored in the user memory. Due to this functionality there is more secure domains at the server side in comparison to Client-Side State Management.

 

The structure is something like the following,

 

 

 

State Management Scenario

 

It will be a little difficult to directly evaluate what will be better for our application. We cannot directly say that we will use client-side or server-side architecture of State Management.

 

State Management Techniques

 

State Management techniques are based on client side and server side. Their functionality differs depending on the change in state, so here is the hierarchy:

 

 

 

Client-side | Techniques

 

Client-Side State Management techniques are,

  • View State
  • Hidden field
  • Cookies
  • Control State
  • Query Strings

Server-side | Technique

 

Server-Side State Management techniques are,

  • Session State
  • Application State

Now I am defining each and every technique in detail with their reference example.

 

View State

 

In general we can say it is used for storing user data in ASP.NET, sometimes in ASP.NET applications the user wants to maintain or store their data temporarily after a post-back.. In this case VIEW STATE is the most used and preferred way of doing that.

 

This property is enabled by default but we can make changes depending on our functionality, what we need to do is just change the EnableViewState value to either TRUE for enabling it or FALSE for the opposite operation.

 


Figure: [View State Management]

  1. // Page Load Event  
  2. protected void Page_Load(object sender, EventArgs e)  
  3. {  
  4.     if (IsPostBack)  
  5.     {  
  6.         if (ViewState["count"] != null)  
  7.         {  
  8.             int ViewstateVal = Convert.ToInt32(ViewState["count"]) + 1;  
  9.             View.Text = ViewstateVal.ToString();  
  10.             ViewState["count"]=ViewstateVal.ToString();  
  11.         }  
  12.         else  
  13.         {  
  14.             ViewState["count"] = "1";  
  15.         }  
  16.     }  
  17. }  
  18.   
  19. // Click Event  
  20. protected void Submit(object sender, EventArgs e)  
  21. {  
  22.        View.Text=ViewState["count"].ToString();  
  23. } 

Points to Remember

 

Some of the features of view state are:

  • It is page-level State Management
  • Used for holding data temporarily
  • Can store any type of data
  • Property dependent

Hidden Field

 

A hidden field is used for storing small amounts of data on the client side. In most simple words it's just a container of some objects but their result is not rendered on our web browser. It is invisible in the browser.

 

It stores a value for the single variable and it is the preferable way when a variable's value is changed frequently but we don't need to keep track of that every time in our application or web program.

 

 
Figure: [Hidden Field Management]

  1. // Hidden Field  
  2.   
  3. int newVal = Convert.ToInt32(HiddenField1.Value) + 1;  
  4. HiddenField1.Value = newVal.ToString();  
  5. Label2.Text = HiddenField1.Value; 

Points to Remember

 

Some features of hidden fields are:

  • Contains a small amount of memory
  • Direct functionality access

Cookies

 

A set of Cookies is a small text file that is stored in the user's hard drive using the client's browser. Cookies are just used for the sake of the user's identity matching as it only stores information such as sessions id's, some frequent navigation or post-back request objects.

 

Whenever we get connected to the internet for accessing a specific service, the cookie file is accessed from our hard drive via our browser for identifying the user. The cookie access depends upon the life cycle or expiration of that specific cookie file.

 


Figure: [Cookie Management]

  1. int postbacks = 0;  
  2. if (Request.Cookies["number"] != null)  
  3. {  
  4.     postbacks = Convert.ToInt32(Request.Cookies["number"].Value) + 1;  
  5. }  
  6. // Generating Response  
  7. else   
  8. {  
  9.     postbacks = 1;  
  10. }  
  11. Response.Cookies["number"].Value = postbacks.ToString();  
  12.   
  13. Result.Text = Response.Cookies["number"].Value; 

Cookie | Types

 

 

 

Persistent Cookie

 

Cookies having an expiration date is called a persistent cookie. This type of cookie reaches their end as their expiration dates comes to an end. In this cookie we set an expiration date.

  1. Response.Cookies["UserName"].Value = "Abhishek";  
  2. Response.Cookies["UserName"].Expires = DateTime.Now.AddDays(1);  
  3.   
  4. HttpCookie aCookie = new HttpCookie("Session");  
  5. aCookie.Value = DateTime.Now.ToString();  
  6. aCookie.Expires = DateTime.Now.AddDays(1);  
  7. Response.Cookies.Add(aCookie); 

Non-Persistent Cookie

 

Non-persistent types of cookies aren't stored in the client's hard drive permanently. It maintains user information as long as the user access or uses the services. Its simply the opposite procedure of a persistent cookie.

  1. HttpCookie aCookie = new HttpCookie("Session");  
  2. aCookie.Value = DateTime.Now.ToString();  
  3. aCookie.Expires = DateTime.Now.AddDays(1);  
  4. Response.Cookies.Add(aCookie); 

Points to Remember

 

Some features of cookies are:

  • Store information temporarily
  • It's just a simple small sized text file
  • Can be changed depending on requirements
  • User Preferred
  • Requires only a few bytes or KBs of space for creating cookies

Control State

 

Control state is based on the custom control option. For expected results from CONTROL STATE we need to enable the property of view state. As I already described you can manually change those settings.

 

Points to Remember

 

Some features of query strings are:

  • Used for enabling the View State Property
  • Defines a custom view
  • View State property declaration
  • Can't be modified
  • Accessed directly or disabled

Query Strings

 

Query strings are used for some specific purpose. These in a general case are used for holding some value from a different page and move these values to the different page. The information stored in it can be easily navigated to one page to another or to the same page as well.

 


Figure: [Query Strings]

  1. // Getting data  
  2. if (Request.QueryString["number"] != null)   
  3. {  
  4.     View.Text = Request.QueryString["number"];  
  5. }  
  6.   
  7. // Setting query string  
  8. int postbacks = 0;  
  9.   
  10. if (Request.QueryString["number"] != null)   
  11. {  
  12.     postbacks = Convert.ToInt32(Request.QueryString["number"]) + 1;  
  13. }  
  14. else   
  15. {  
  16.     postbacks = 1;  
  17. }  
  18.   
  19. Response.Redirect("default.aspx?number=" + postbacks); 

Points to Remember

 

Some of the features are,

  • It is generally used for holding values
  • Works temporarily
  • Switches info from one to another page
  • Increase performance
  • Uses real and virtual path values for URL routing
 
 
Session State

As we all know, our web is "Stateless", in other words a new instance of a web page class, is recreated each time the page is posted to the server. HTTP is a stateless protocol and it can't hold the client information on the page. For example, if the user inserts some information on one page and then moves to the next page then that inserted data will be lost from the first page and moreover the user will not be able to retrieve that information.

So basically here we need someone to hold the state of our application. Here is the privitage role of our "session state". Basically a session is a variable used between the client and the server that is stored on the server side. Now it can be stored either on an Internet Information Service (IIS) server that is by default our "inproc" mode or it can be stored in a state or SQL Server that is our "outproc" mode. We will discuss both, the inproc and outproc modes in detail later in the article.

 

So a session helps to maintain the user state and data all over the application by storing the information on the server memory. Also a session can store any kind of information or object on the server side and is accessible in the entire website.

Every object is stored in the application on the basis of the Key value. We can see both the application and session start up events by adding a "Global.asax" file in our project.

 

The process of maintaining the session state proceeds in the following manner. First the client hits the website and the information is stored in the session. Then a Session table will be made by default on the IIS server and in the session IDs of all the users visiting the website will be stored by the server. Now the next time the client requests some information with the unique session ID from the server, the server looks in the session providers and retrieves the serialized data from the state server and type casts the object. 

 

 

FIG: PROCESS FOR MAINTAINING THE SESSION STATE IN THE APPLICATION

 

Now let us see how to store and retrieve values in a session.

 

STORING AND RETRIEVING VALUES FROM SESSION

 

The following code is used for storing a value in a session:

  1. // Storing Username in session.Session[ "UserName" ] = txtUser.Text;  
  2. // Retreiving  
  3. values  
  4. from  
  5. session.// Check whether session variable null  
  6. or not if(Session[ "UserName" ] != null) { // Retreiving UserName  
  7. from  
  8. session lblWelcome.text = "Welcome: +Session[" UserName "];  
  9. }  
  10. else  
  11. {  
  12. //Do something else  
  13. }  

As we know all these values will be stored and retreived from the session on the IIS server by default.

 

Now for maintaining the load balance we need to free the IIS server. So we require an "Outproc" mode of the session state. Now we will study both the "Inproc" and "Outproc" modes of the session state in detail.

 

    

 

FIG: INPROC AND OUTPROC MODES IN SESSION STATE AND THEIR RESPECTIVE STATE PROVIDERS

                                              

INPROC SESSION MODE IN SESSION STATE

 

 

 

FIG: INPROC SESSION MODE

 

This is the default session mode in ASP.Net. It stores the information in a memory object in the current application domain. So it is easily and quickly available and is best suited for web application performance but the main disadvantage is that because all the information is stored on the server side in the same application domain, if we will restart the server all the data will be lost. When the client requests data, the State Provider reads the data from an in-memory object and return it to the client. In web.config, we need to specify the session mode and also set the time out.

 

 

Advantages

  • It stores session data in a memory object of the current application domain. So accessing data is very fast and data is easily available.
  • There is not a requirement for serialization to store the data in InProc session mode.
  • Implementation is very easy, similar to using the ViewState.

Disadvantages

Although an InProc session is the fastest, common and default mechanism, it has many limitations as in the following:

  • If the worker process or application domain is recycled, all session data will be lost.
  • Though it is the fastest, more session data and more users can affect performance, because of memory usage.
  • We can't use it in Web Garden scenarios.
  • This session mode is not suitable for web Farm scenarios.

As in the preceding discussion, we can conclude that InProc is a very fast session storing mechanism but suitable only for small web applications. InProc session data will be lost if we restart the server, or if the application domain is recycled. It is also not suitable for Web Farm and Web Garden scenarios.

Now we will have a look at the other options available to overcome these problems. First is the StateServer mode.

Application State

Introduction

Application State is a state management technique. Application State is stored in the memory of the the server and is faster than storing and retrieving information in a database. Session sate is specific for a single user session, but Application State is for all users and sessions. Application State does not have a default expiration period. When we close the worker process the application object will be lost. Technically the data is shared amongst users by a HTTPApplcationState class and the data can be stored here in a key/value pair. It can also be accessed using the application property of the HTTPContext class.

Application State Life Cycle

Step 1 : When the Browser sends a request to the web server and the server receives the the request it first checks the extension to determine whether or not it is ISAPI because this request can only be handled by the ISAPI extension; if the extension is different then the request is handled by the server itself.

Step 2 : After receiving the request the Application Manager creates an application domain. In the application domain an instance of the class HostingEnvironment is created that provides access to information about all application resources.



Step 3 : After creating the application domain, ASP.NET initializes the basic objects as HTTPContext, HTTPRequest and HTTPResponse. HTTPContext holds objects to the specific application request as HTTPRequest and HTTPResponse.HTTPRequest contains all the information regarding the current request like cookies, browser information and so on and the HTTPResponse contains the response that is sent to the client.

Step 4 : Here all the basic objects are being initialized and the application is being started with the creation of the HTTPApplication class.

Step 5 : Then events are executed by the HTTPApplication class for any specific requirement. Here is a list of events:

Global.asax file: the Global.asax file is used for handling application events or methods. It always exists in the root level. Events are one of the following of the 2 types in the Global application:

  1. Events that will be raised on a certain condition.
  2. Events that will be raised on every request.

The application will be started only once; if 10 users send a request then 10 user sessions are created. The events of the Global.asax file are:

  1. Application_Start() : This method is invoked initially when first application domain is created.
  2. Session_Start() : This method is called every time a session is start.
  3. Application_BeginRequest() : After an application has started the first method Application_BeginRequest() is executed for every user.
  4. Application_AuthenticateRequest() : It checks to determine whether or not the user is valid.
  5. Application_Error() : Whenever an unhandled exception occurs then this event will be called.
  6. Session_End() : When a user session is ended and all the data related to a specific user is cleared then the Session_End() event is called.
  7. Application_End() : This method is called before the application ends. This can take place if IIS is restarted or the application domain is changing.
  8. Application_Disposed() : This event is called after the application will be shut down and the .NET GC is about to reclaim the memory it occupies. Although this is very late to perform any clean-up but we can use it for safety purposes.

 

 


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