ASP.NET Exclusive Interview Questions and Answers (348) - Page 17

This is a great  and the most asked ASP.NET interview question. Out of 100 .NET interviews atleast 70 interviewer will ask this question. The answer is very simple but the problem with the answer is that developers forget the  sequence of ASP.NET page life cycle.

The best way to remember this answer is by remembering the word SILVER.

S (Well this word is just to make up the word , you can just skip this.)
I (Init)
L (Load)
V (Validate)
E (Event)
R (Render)

This is a simple a .NET Interview question .Its a two step process.

First create a class which implements Ihttphandler

public class clsHttpHandler : IHttpHandler
{

    public bool IsReusable
    

{
        get { return true; 

}
    }

    public void ProcessRequest(HttpContext 

context)
    {
       // Put 

implementation here.
    }
}

Step 2 make a entry in the web.config file.

<httpHandlers>
<add verb="*" path="*.gif" 

type="clsHttpHandler"/>
</httpHandlers>

Again a simple .NET Interview question Writing a HttpModule is a two step process.

Create a class which implements IhttpModule.

public class clsHttpModule : IHttpModule
{

    public void Init(HttpApplication 

context)
    {
       

this.httpApp = context;
       

httpApp.Context.Response.Clear();
       

httpApp.AuthenticateRequest += new 

EventHandler(OnAuthentication);
       

httpApp.AuthorizeRequest += new 

EventHandler(OnAuthorization);
 ....
 ....
 ....
   


    }
    void OnAuthorization(object 

sender, EventArgs a)
    

{
        

//Implementation
    }
    void 

OnAuthentication(object sender, EventArgs a)
    

{
       


        

//Implementation
    }
    
}

Make a entry in the web.config file.

<httpModules>
<add name="clsHttpModule" 

type="clsHttpModule"/>
</httpModules>

Authentication:  Who the user is? or Authentication is process of Identifying the user is valid or not from the database.
Authorization:    To Identify what kind of authority or rights does user has.

Different Types:

In ASP.NET there are three way to do Authentication and Authorization.

1)Windows Authentication:
                                    In this methadology ASP.NET web pages will use local windows users and groups to authenticate and authorize resources.

2)Forms Authentication:
                                   This is a cookie based authentication where user name and password stored on client machine as cookie files or they are sent to URL for every request. Form-based authentication presents the users with an HTML-based web page that prompts the user for credentials.In case browser doesnot support cookies then username and password passed via URL string for every request.

3)Passport Authentication:
                                     Passport authentication is based on passport website provided by the microsoft.So when user logins with credentials it will be reached to the passport website(i.e. hotmail,devhood,windows live etc) where authentication will happen.If authentication is successful it will return a token to your website.

Following is the video for Authentication and Authorization

Regards,

In ASP.NET there are three way to do Authentication and Authorization.

Windows Authentication:
                             In this methadology ASP.NET web pages will use local windows users and groups to authenticate and authorize resources.

<authentication mode="Windows"> 
  <forms name=" 

AuthenticationDemo" loginUrl="logon.aspx" protection="All" path="/" timeout="30" 

/> 
</authentication>

Deny access to the anonymous user in the Aauthorization section as follows:

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


</authorization>

Forms Authentication:
                             This is a cookie based authentication where user name and password stored on client machine as cookie files or they are sent to URL for every request.Form-based authentication presents the users with an HTML-based web page that prompts the user for credentials.In case browser doesnot support cookies then username and password passed via URL string for every request.

<authentication mode="Forms"> 
<forms name=" AuthenticationDemo" 

loginUrl="logon.aspx" protection="All" path="/" timeout="30" /> 


</authentication>
<credential 

passwordFormat=”SHA1”>
<username="admin" 

password="admin">
</credential>

Deny access to the anonymous user in the Aauthorization section as follows:

<authorization>
    <deny users ="?" 

/>
</authorization>

Passport Authentication:
                                Passport authentication is based on passport website provided by the microsoft.So when user logins with credentials it will be reached to the passport website(i.e. hotmail,devhood,windows live etc)where authentication will happen.If authentication is successful it will return a token to your website.

<authentication mode= "Passport"/>

Regards,

Regards,

Regards,

Regards,

A validator is a computer program used to check the validity or syntactical correctness of a fragment of code or text.

IN ASP.NET there are six different types of Validators.

Required Field Validator.
Regular Expression Validator.
Compare Validator.
Range Validator.
CustomValidator.
Validation Summary

RequiredFieldValidator:-Ensure that the control has a value to assign in it or user does not skip an entry.

For Example:- 

 <asp:Textbox id="txtMobileNumber" runat="server"></asp:Textbox>
 <asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server"
 ControlToValidate="txtMobileNumber"
 ErrorMessage="Mobile Number is a required field."
 ForeColor="Red">
 </asp:RequiredFieldValidator>

RegularExpressionValidator:-Ensure that the value of the control matches the expression of validator that is specified.This type of validation enables you to check for sequence of character, such as e-mail address,telephone number,postal code and so on.

For Example:- 

 <asp:TextBox ID="txtE-Mail" runat="server"></asp:TextBox>
 <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" 
 ControlToValidate="txtPassword"
 ErrorMessage="Please Enter a Valid E-Mail" 
 ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"> // for internet E-Mail.
 </asp:RegularExpressionValidator>

CompareValidator:-Ensure that the value of one control should be equal to value of another control.which is commonly used in password,less than,greater than or equal to.

For Example:-

<asp:TextBox ID="txtPassword" runat="server"></asp:TextBox>
<asp:TextBox ID="txtConfirmPassword" runat="server"></asp:TextBox>
<asp:CompareValidator ID="CompareValidator1" runat="server" 
ControlToCompare="txtPassword" ControlToValidate="txtConfirmPassword" 
ErrorMessage="Password does not match">
</asp:CompareValidator>

RangeValidator:-Ensures that the value of the control is in specified lower and upper boundaries or specified range.  You can check ranges within pairs of numbers, alphabetic characters.

For Example:- 

<asp:TextBox ID="txtAmount" runat="server"></asp:TextBox>
<asp:RangeValidator ID="RangeValidator1" runat="server" 
ControlToValidate="txtPassword"
ErrorMessage="RangeValidator" MaximumValue="5000" 
MinimumValue="100">
</asp:RangeValidator>>

CustomValidator:-This control is used to perform user defined validations.

ValidationSummary:-This validator is used to displays a detailed summary on the validation errors that currently exist.

Regards,

            Session["MySession"] = TextBox1.Text;// Here Session is declared.
            Cache.Insert("MyCache", TextBox2.Text);// Here Cache is declared.

Regards,

Application and Cache both help to share global data and cache data across the users.but cache object is proactive and you can define dependency.In application object you can't define depenency.

Below is the code for declaring application and cache object.

CacheDependency objCacheDependency = new CacheDependency(Server.MapPath("Banner.txt"));
 

Cache.Insert("Banner", strBanner, objCacheDependency);

Application["Banner"] = "strBanner";

In the above code, for Cache object you can define dependency but in Application object you can't define dependency.when the banner file is changed the Cache object can be refreshed but the application remain static and holds the old text of banner file.

Regards

Output Cache is used to Cache an ASP.NET page.

Output Cache is called as directives.

The below diagram shows, how exactly the caching is done.

                               Diagram of Caching.

Caching can be done in three ways as followings.

1. Cache the complete page.
   
2. Cache the portion of the page.
   
3. Cache the complete page but a portion is static.

The below diagram will give an idea of Caching different forms.

                           Different types of Caching.

The below code snippet shows how to Cache the complete page.

<%@ OutputCache Duration="20" Location="Server"  VaryByParam="none" %> 

To Cache the portion of the page.we have to add web user control page and the directive is placed at the top of user control page.(.ascx file).

<%@ OutputCache Duration="20" VaryByControl="LiveScore" VaryByParam="*"%>

Now, for Caching the complete page but a portion should be static. we have to add web user control page and later you can define the output cache in the source of the web user control page.

Regards,

Let's see an Simple example to understand.

Assuming that we have a TextBox and Button on the ASP.NET page like below.

<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClientClick="return validate()" />

Now, Add the below code snippet on the page source.

<script language="javascript" type="text/javascript">
function ValidateTextBox()     

{
    if(document.getElementById("<%=txtName.ClientID%>").value == "")        

   {             

    alert("Name Field Cannot be Empty");
    document.getElementById("<%=txtName.ClientID%>").focus();
    return false;       

   }
    return true;
}
</script>

Once you have completed the above steps, just run the project and see the result.

Regards,

Remoting are basically used when we are sure that both Server and Client are based on .NET platform.

WebServices are used when the Server and Client are in different platform like .NET and Java etc.

Regards,

SOAP(Simple Object Access Protocol) is a standard XML format for communicating between Server and Client in WebServices.

The below diagram dipicts an simple request and response using SOAP.

Regards,

Regards,