Introduction

Last week I attended an interview with Infosys, Chennai. When I entered the compound, there were very many candidates. The atmosphere and culture in Infosys was very nice.Please find the original article here :http://sibeeshpassion.com/Infosys-Interview-Questions-For-DotNet-Professionals.htmlYou can read another series of interview questions here :http://www.c-sharpcorner.com/UploadFile/65794e/dot-net-interview-questions-for-experienced-and-fresher/

Background

I have attended many interviews in my life. But the interview with Infosys was something different. I thought to share that experience with you all.

Points to be remember

(There are some mistakes I made in the interview. I don't want you to do the same :) )1. Please ensure that you are maintaining eye contact with the interviewer.2. Be confident of what you say. Don't change your answer if the interviewer tries to make you do so.3. Please avoid the unwanted examples.4. Please never use any other technical terms that may provoke the interviewer into asking questions about.5. If you don't know the answer, please say "I don't know". It is always better to say so instead of going with the wrong answer.You can find more tips here:How to Prepare for a Job Interview

Questions asked and answers

(Here I am giving the answers that I answered .)

1. Tell me about yourself?

A. You can find many answers to this question in the internet. Please see the following link:

Tell me about yourself

2. What is your role in your project? What is the team size?

A. I said "My main role is coding, unit testing, big fixing and maintenance. My team size is 7".

3. What is the hierarchy of your team?

A. First I was confused by this question. Then I answered "Project Manager, Team Leader, Software Engineers, Trainees".

4. Describe the projects that you have worked on?

A. I described them. Please include the technologies you used in your projects and what kind of architecture (for example: 3-tire, n- tier) you used.

5. What is the employee size in your company? You don't need to be accurate. You can provide the approximate value.

A. I said "150 to 200".

Then he moved to the programming section.

6. Write an algorithm and program to determine whether or not a word is a palindrome.

We can do it in either of the following two ways:

a) Using a built-in function as in the following:1. stringstrRev,strReal=null;2. Console.WriteLine("Enterthestring..");3. strReal=Console.ReadLine();4. char[]tmpChar=strReal.ToCharArray();5. Array.Reverse(tmpChar);6. strRev=newstring(tmpChar);7. if(strReal.Equals(strRev,StringComparison.OrdinalIgnoreCase))8. {9. Console.WriteLine("Thestringispallindrome");10. }11. else12. {13. Console.WriteLine("Thestringisnotpallindrome");14. }15. Console.ReadLine();

Ref:To check string is palindrome or not in .NET (C#)

b) Without using a built-in function.

When I wrote the first program, the interviewer asked me to write the same without using a built-in function.1. privatestaticboolchkPallindrome(stringstrVal)2. {3. try4. {5. intmin=0;6. intmax=strVal.Length-1;7. while(true)8. {9. if(min>max)10. returntrue;11. charminChar=strVal[min];12. charmaxChar=strVal[max];13. if(char.ToLower(minChar)!=char.ToLower(maxChar))14. {15. returnfalse;16. }17. min++;18. max--;19. }20. }21. catch(Exception)22. {23. 24. throw;25. }26. }

Ref: You can find more here:C# Palindrome

7. Write a program to determine the count of a specific character in a string.

A.1. usingSystem;2. usingSystem.Collections.Generic;3. usingSystem.Linq;4. usingSystem.Text;5. 6. namespaceFindCountCharOccurance7. {8. classProgram9. {10. staticvoidMain(string[]args)11. {12. stringstrOccur,strChar=null;13. Console.WriteLine("Enterthestringinwhichyouneedtofindthecountofacharoccurance");14. strOccur=Console.ReadLine();15. 16. Console.WriteLine("Enterthechartobesearched..");17. strChar=Console.ReadLine();18. intintCnt=strOccur.Length-strOccur.Replace(strChar,string.Empty).Length;19. Console.WriteLine("Countofoccuranceis"+intCnt);20. Console.ReadLine();21. }22. }23. }

Please see this for more suggestions:count the number of characters in a string.

8. Next he gave me a program like the following and asked me what the output of this will be.1. publicclassA2. {3. publicintA()4. {5. Console.WriteLine("HiyouareinclassA");6. }7. }

A. I said "Here we have a constructor A; a constructor should not have a return type. So the code above will throw a compilation error."

9. What may be the output of the following program?1. usingSystem;2. usingSystem.Collections.Generic;3. usingSystem.Linq;4. usingSystem.Text;5. 6. namespaceRefClass7. {8. classProgram9. {10. staticvoidMain(string[]args)11. {12. BbObj=newB();13. Console.ReadLine();14. 15. }16. }17. publicclassA18. {19. publicA()20. {21. Console.WriteLine("HiyouareinclassA");22. }23. }24. 25. publicclassB:A26. {27. publicB()28. {29. Console.WriteLine("HiyouareinclassB");30. }31. }32. }

A. I said the output will be:

Hi you are in class A

Hi you are in class B

Even though you are creating an object of the derived class, it will invoke the base class first.

10. Write the output of the following program.1. classProgram2. {3. staticvoidMain(string[]args)4. {5. BbObj=newB(2);6. Console.ReadLine();7. 8. }9. }10. publicclassA11. {12. publicA()13. {14. Console.WriteLine("HiyouareinclassA");15. }16. 17. publicA(intx)18. {19. 20. }21. }22. 23. publicclassB:A24. {25. publicB()26. {27. Console.WriteLine("HiyouareinclassB");28. }29. }

A. It will throw a compilation error.

B does not contain a constructor that takes 1 argument. If you want to make this program run, you must create a parameterized constructor for class B also.

11. Abstract and interface real time examples

B.Please read it here:Real time example of interface

12. Describe authentication, types, differences?

A. Forms, Windows, Passport. Please read more here:ASP.NET authentication and authorization

13. Why DBMS? Why don't we save data in separate files?

A. I didn't know what exactly he meant, I got stuck there for a while. Finally I came up with the answer that "Normalization" is the main advantage of a DBMS.

Read more here:Why use a DBMS?

14. What is the differences between a Primary key and a Unique key?

A. Primary key doesn't allow NULL, a unique key does.

15. What exactly is happening when we make a field a primary key?

A. A clustered index will be created for that specific field.

16. How may clustered index we can create in table?

A. Basically we can create only one clustered index, but there is a way to have more. Please read here:Only one clustered index can be created on table . (Visual Database Tools)

17. What is the difference between a clustered and a non-clustered index?

A. I explained, please read here:Clustered and Non-Clustered Index in SQL 2005

18. What is a Distributed System?

A. A collection of autonomous computers.http://www.csc.villanova.edu/~schragge/CSC8530/Intro.html

Image Courtesy :http://msdn.microsoft.com/en-us/library/cc239737.aspx19.What will be the output for the below mentioned lines in JQuery? 1. alert('5'+5+5);2. alert(5+5+'5');3. alert(5+'5'+'5');4. alert(5+'5');

That was little tricky at that time. For a while I thought, and I just wrote the question to a paper, and replied. 1. alert('5'+5+5);Output=5552. alert(5+5+'5');Output=1053. alert(5+'5'+'5');Output=5554. alert(5+'5'); Output=55

Hmmm finally he said "You are selected for the next round" :)

Next was the direct HR round. That was a simple round. He just asked me to fill in some forms.

Finally they sent me an Offer Letter :)

Wish you good luck.

Lets Face my .NET InterviewThe title of this article is likely to make you curious and cause you to look at it. OK, let me explain the purpose of this article. Today I attended a .NET technical interview (and got clear in the first round though I am not at all interested to join there) in a company (I am not disclosing the company name). And while travelling by bus, I was thinking about what to write for another article in c-sharpcorner.com.

Then I decided that ok, let's write all my interview questions with my experiences and answers. Now it's the evening and I am providing my interview experiences from a few hours before.

Let's clarify some thing first. I have 9 months of experience and the interview questions have been that basic. So, if you are very much experienced or .NET savvy then it may seem that I am kidding with you.

OK, no more talking. Sit next to me and hear our conversation. It's only a 1:1 interview.

He offer me a chair when I enter in the room. I saw that he was reading my CV and highlighting a few portions with pencil (Hmm, loading ammunition for him to use). I took a seat and was waiting for his response.

He started with an ice-breaking question.

Tell me about yourself.

I told him a little of my background, my academics and a little bit about current and previous projects.

Have you used Infragestic and Telerik controls?

I said yes, as I said in my CV.

Which kind of control and version?

Q2 version, many controls like drop down list, combo box, list box, grid and so on and so on.Then he starts to ask questions about SQL Server.

How many categories are there in SQL command?

Three, DDL, DML ,TCL and a few examples about them.

Structure of join query

I had drawn a tree structure to show various types of joins with Venn diagram.What is self join and their uses?

A self join is needed when we want to make a join of one table with itself. Then I gave a small example.

Difference between left and left outer join

Left and left outer join are the same, there is no difference between them.

Is the outer keyword mandatory?

No.

Implement a try catch block in PL/SQL

I gave a small structure of a try catch block.

How to define transactions?

I gave an exmple of beginning a transaction and ending a transaction within a try catch block, if the try raises an error then a rollback will occur within the catch.

Find the third highest salary from a table.

It's a very popular one. I provided an answer with a nested query. First fetch the top 3 highest salaries from the table then filter and pick the minimum one from them. He asked me to find another method, but at that moment I could not think of an alternative.

Give an example of a nested query.

I have referred to the previous example (of the third highest salary) sinceI wrote it using a nested query.

Temporary table and table variable syntax

I provided an example with # and @ symbols.

Difference between local temp table and global temp table

Local temp table (starts with #) has the current user's session scope wherea a global temp table (starts with ##) has all user's scope.

Save point of transactionA Save point is needed to rollback up to a certain point.

One insert statement to enter multiple rows.

Written using the following insert command.

Insert into values(1,'a')(2,'b')I had forgotten to provide a comma between each value pair. He point it out and corrected me.

What are ldf and mdf files

They are two files of SQL Server and I explained a little about them.

Syntax of function and trigger

I wrote the basic syntax of them. I made the mistake of not writing returns in the functions. He pointed it out and told me.

Types of trigger

I explained two types of triggers (instead of and after) and a little explanation about them, when they fire and so on and group by and and having clauses.

I gave an answer with one example to calculate the sum of a salary group by department. Where we can add a having clause to filter it again.

Find duplicate records

After a little struggle, I wrote one but it was not perfect. (Hmm,. my grip had slipped a little.)

What is a view?

I answered with a small example and also added how to make an index on a view.Difference between primary key and unique key

It's a very common and popular question. I provided two differences. That is what he was expecting.

What is a candidate key?

I answered with a small example of a student table. Where roll is the primary key and registration number is the candidate key.

Then he began to ask about .NET and C# (though it was very basic).

Draw architecture of .NET framework

I had drawn a complete architecture. He told me to point out the location of Entity Framework and how LINQ provides abstraction on ADO.NET classes.

Latest version of C#

I directly came to the point that he wanted. Yes, asynchronous programming.

What is CLSand CTS?

Discuss them with a little technical knowledge.

How tosee IL code?

Answered about ILDASM.

How to collect garbage?

Started to talk about GC.Collect() (it's an overloaded function) and about generation, how objects are promoted from one generation to another generation and so on.

Is there any other method?

I was taking time to find an alternate to GC.Collect(). After a few moments I suddenly discovered, hey the finalize dispose pattern is there to collect garbage (although it's not collection , it's nothing but disposing after use). And he was waiting for that.

How can multiple inheritance problems be overcome?

I provided a small structure and implementation of a class of multiple interfaces.

What is polymorphism and itsTypes?

I gave a definition of polymorphism with a classic example. The following is the example.

"Let's think about me. Now I am giving an interview, so you are my interviewer and I am the interviewee. Now when I go to my room, with respect to my roommate, I am his friend. And I talk to my mother after dinner on the phone (it's my daily routine for the past 7 years).

I am her son. So, I am not changing but my identity is changing with respect to people and places. It's nothing but polymorphism. The technical definition is "Ability to take more than one form". At first I was wondering what is its type but then it came to me, okay runtime and compile time. Actually I had forgotten the terminology. Then I showed an example of function overloading and overriding.

Then a few more was there but I have forgotten them, uh oh; no it is not coming to mind.

Then we started to talk about ASP.NET but not much.

What is MVC pattern?

Though, I am new to it and currently learning. I have drawn a picture with three bubble shapes ( yes, a classic MVC model picture, green, yellow and red colors, do you remember?) and began to discuss them little. Then I was trying to bring him into my safe zone. (Ha Ha, in ASP.Net web forms.)

How does viwestate work? Internally how does it store data?

I answered with the basic mechanism and how it stores data in key and value pairs and it's disadvantages when the page is heavy.

How to bind DataTable in grid and how to allow pagin

I answered the dataSource property but forgot about the paging properly. I answered, most probably it's Allow Paging.

Difference between DataView and DataGrid?

I was thinking and wondering for the answer of how they are related with each other. What is Dataview? I asked, sir, what is the Dataview? Is it a control? He replied, yes it's a control in the data section. Again I started to think and fnally I said sir, there is no control like this. (Or at least I have not used it). Then we discovered that he was a little incorrect and instead of DataView it is a Data Pager.

What is 3-tier architecture?

I showed a diagram with data flow from layer to layer and the forms of data.

Which namespace is used to make platform independent data access mechanisms?

I answered System.data.commn. Yes, it contains the DBFactory class.

How to solve the jQuery conflict problem?

I am hearing this question for the very first time, so obviously I was unable to provide an answer. He said something about a noconflict method. (I need to check that.)

A few more were there but at this moment they are not coming to mind.

So, it ended peacefully and I got confirmation for the next round within a few minutes.

So dear reader, here I have tried to show one motion picture of an interview session from my experience and knowledge.

The answer I have written here is not a complete and full answer. I have just tried to touch each and every question with important keywords. If you find any wrong question or answer then please correct me.C# and ASP.Net Question and AnswersIntroduction

This article provides a collection of numerous .Net, C#, ADO.NET, Web Services, .Net Framework questions and answers for which a reader must normally look around the entire internet in various community web sites. Most of the questions and answers you likely have already read. The purpose of this article is to consolidate most of the study material related to .Net in one single place.

ASP.NET

What is view state and the use of it?

The current property settings of an ASP.NET page and those of any ASP.NET server controls contained within the page. ASP.NET can detect when a form is requested for the first time versus when the form is posted (sent to the server), that allows you to program accordingly.

What are user controls and custom controls?

Custom controls

A control authored by a user or a third-party software vendor that does not belong to the .NET Framework class library. This is a generic term that includes user controls. A custom server control is used in Web Forms (ASP.NET pages). A custom client control is used in Windows Forms applications.

User Controls

In ASP.NET: A user-authored server control that enables an ASP.NET page to be re-used as a server control. An ASP.NET user control is authored declaratively and persisted as a text file with an .ascx extension. The ASP.NET page framework compiles a user control on the fly to a class that derives from the System.Web.UI.UserControl class.

What are the validation controls?

A set of server controls included with ASP.NET that tests user input in HTML and Web server controls for programmer-defined requirements. Validation controls perform input checking in server code. If the user is working with a browser that supports DHTML then the validation controls can also perform validation using a client script.

What's the difference between Response.Write() andResponse.Output.Write()?

The latter one allows you to write formatted output.

What methods are fired during the page load? Init ()

When the page is instantiated, Load() when the page is loaded into server memory; PreRender() for the brief moment before the page is displayed to the user as HTML and Unload() when the page finishes loading.

Where does the Web page belong in the .NET Framework class hierarchy?

System.Web.UI.Page

Where do you store the information about the user's locale?

System.Web.UI.Page.Culture

What's the difference between Codebehind="MyCode.aspx.cs" and src="MyCode.aspx.cs"?

CodeBehind is relevant to Visual Studio.NET only.

What's a bubbled event?

When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button, row and so on) is quite tedious. The controls can bubble up their event handlers, allowing the main DataGrid event handler to take care of its constituents.

Suppose you want a certain ASP.NET function executed on MouseOver over a certain button.

Where do you add an event handler?

It's the Attributes property, the Add function of that property. For example:btnSubmit.Attributes.Add("onMouseOver","someClientCode();")

What data type does the RangeValidator control support?

Integer, String and Date.

What are the various types of caching?

Caching is a technique widely used in computing to increase performance by keeping frequently accessed or expensive data in memory. In the context of a web application, caching retains the pages or data across HTTP requests and reuses them without the expense of recreating them. ASP.NET has 3 kinds of caching, strategiesOutput, CachingFragment and CachingData.

CachingOutput Caching:Caches the dynamic output generated by a request. Some times it is useful to cache the output of a website even for a minute, which will result in a better performance. For caching the entire page the page should have OutputCache directive.

Fragment Caching:Caches the portion of the page generated by the request. Some times it is not practical to cache the entire page, in such cases we can cache a portion of page

Data Caching:Caches the objects programmatically. For data caching ASP.Net provides a cache object for eg: cache["States"] = dsStates;

What do you mean by authentication and authorization?

Authentication is the process of validating a user on the credentials (username and password) and authorization performs after authentication. After Authentication a user will be verified for performing the various tasks, It access is limited it is known as authorization.

What are various types of directives in .NET?

@Page: Defines page-specific attributes used by the ASP.NET page parser and compiler. Can be included only in .aspx files @Control: Defines control-specific attributes used by the ASP.NET page parser and compiler. Can be included only in .ascx files. @Import: Explicitly imports a namespace into a page or user control. The Import directive cannot have more than one namespace attribute. To import multiple namespaces, use multiple @Import directives. @Implements: Indicates that the current page or user control implements the specified .NET framework interface.@Register: Associates aliases with namespaces and class names for concise notation in custom server control syntax.@Assembly: Links an assembly to the current page during compilation, making all the assembly's classes and interfaces available for use on the page. @OutputCache: Declaratively controls the output caching policies of an ASP.NET page or a user control contained in a page@Reference: Declaratively indicates that another user control or page source file should be dynamically compiled and linked against the page in which this directive is declared.

Note: A few of the references are were taken from other sites/sources.

How do I debug an ASP.NET application that wasn't written with Visual Studio.NET and that doesn't use code-behind?

Start the DbgClr debugger that comes with the .NET Framework SDK, open the file containing the code you want to debug, and set your breakpoints. Start the ASP.NET application. Go back to DbgClr, choose "Debug Processes" from the Tools menu, and select "aspnet_wp.exe" from the list of processes. (If "aspnet_wp.exe" doesn't appear in the list then check the "Show system processes" box.) Click the "Attach" button to attach to "aspnet_wp.exe" and begin debugging.

Be sure to enable debugging in the ASPX file before debugging it with DbgClr. You can enable ASP.NET to build debug executables by placing a:

statement at the top of an ASPX file or a:

statement in a Web.config file.

Can a user browsing my Web site read my Web.config or Global.asax files?

No. The section of Machine.config, which holds the master configuration settings for ASP.NET, contains entries that map ASAX files, CONFIG files, and selected other file types to an HTTP handler named HttpForbiddenHandler, which fails attempts to retrieve the associated file. You can modify it by editing Machine.config or including a section in a local Web.config file.

What's the difference between Page.RegisterClientScriptBlock and Page.RegisterStartupScript?

RegisterClientScriptBlock is for returning blocks of client-side script containing functions. RegisterStartupScript is for returning blocks of client scripts, not packaged in functions. In other words, code that's to execute when the page is loaded. The latter positions script blocks near the end of the document so elements on the page that the script interacts with are loaded before the script runs.

Is it necessary to lock application state before accessing it?

Only if you're performing a multi-step update and want the update to be treated as an atomic operation. Here's an example:Application.Lock ();Application["ItemsSold"] = (int) Application["ItemsSold"] + 1;Application["ItemsLeft"] = (int) Application["ItemsLeft"] - 1;Application.UnLock();

By locking application state before updating it and unlocking it afterwards, you ensure that another request being processed on another thread doesn't read application state at exactly the wrong time and see an inconsistent view of it. If I update session state then should I lock it, too?Are concurrent accesses by multiple requests executing on multiple threads a concern with session state?

Concurrent accesses aren't an issue with session state, for two reasons. One, it's unlikely that two requests from the same user will overlap. Two, if they do overlap then ASP.NET locks down session state during request processing so that two threads can't touch it at once. Session state is locked down when the HttpApplication instance that's processing the request fires an AcquireRequestState event and unlocked when it fires a ReleaseRequestState event.

Do ASP.NET forms authentication cookies provide any protection against replay attacks? Do they, for example, include the client's IP address or anything else that would distinguish the real client from an attacker?

No. If an authentication cookie is stolen then it can be used by an attacker. It's up to you to prevent this from happening by using an encrypted communications channel (HTTPS). Authentication cookies issued as session cookies, do, however, include a time-out valid that limits their lifetime. So a stolen session cookie can only be used in replay attacks as long as the ticket inside the cookie is valid. The default time-out interval is 30 minutes. You can change that by modifying the timeout attribute accompanying the element in the Machine.config or a local Web.config file. Persistent authentication cookies do not time-out and therefore are a more serious security threat if stolen.

How do I send e-mail from an ASP.NET application?MailMessage message =newMailMessage ();message.From = ;message.To = ;message.Subject ="Scheduled Power Outage";message.Body ="Our servers will be down tonight.";SmtpMail.SmtpServer ="localhost";SmtpMail.Send(message);

MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's System.Web.Mail namespace. Due to a security change made to ASP.NET just before it shipped, you need to set SmtpMail's SmtpServer property to "localhost" even though "localhost" is the default. In addition, you must use the IIS configuration applet to enable localhost (127.0.0.1) to relay messages through the local SMTP service.

What are VSDISCO files?

VSDISCO files are DISCO files that support dynamic discovery of Web services. If you place the following VSDISCO file in a directory on your Web server, for example then it returns references to all ASMX and DISCO files in the host directory and any subdirectories not noted in elements:

How does dynamic discovery work?

ASP.NET maps the file name extension VSDISCO to an HTTP handler that scans the host directory and subdirectories for ASMX and DISCO files and returns a dynamically generated DISCO document. A client who requests a VSDISCO file gets back what appears to be a static DISCO document.

Note that VSDISCO files are disabled in the release version of ASP.NET. You can reenable them by uncommenting the line in the section of Machine.config that maps *.vsdisco to System.Web.Services.Discovery.DiscoveryRequestHandler and granting the ASPNET user account permission to read the IIS metabase. However, Microsoft is actively discouraging the use of VSDISCO files because they could represent a threat to Web server security.

Is it possible to prevent a browser from caching an ASPX page?

Just call SetNoStore on the HttpCachePolicy object exposed through the Response object's Cache property, as demonstrated here:

SetNoStore works by returning a Cache-Controll; a private, no-store header in the HTTP response. In this example, it prevents caching of a Web page that shows the current time.

What does AspCompat="true" mean and when should I use it?

AspCompat is an aid in migrating ASP pages to ASPX pages. It defaults to false but should be set to true in any ASPX file that creates apartment-threaded COM objects; that is, COM objects registered with ThreadingModel=Apartment. That includes all COM objects written with Visual Basic 6.0. AspCompat should also be set to true (regardless of threading model) if the page creates COM objects that access intrinsic ASP objects such as Request and Response. The following directive sets AspCompat to true:

Setting AspCompat to true does two things. First, it makes intrinsic ASP objects available to the COM components by placing unmanaged wrappers around the equivalent ASP.NET objects. Second, it improves the performance of calls that the page places to apartment-threaded COM objects by ensuring that the page (actually, the thread that processes the request for the page) and the COM objects it creates share an apartment. AspCompat="true" forces ASP.NET request threads into single-threaded apartments (STAs). If those threads create COM objects marked ThreadingModel=Apartment then the objects are created in the same STAs as the threads that created them. Without AspCompat="true," request threads run in a multithreaded apartment (MTA) and each call to an STA-based COM object incurs a performance hit when it's marshaled across apartment boundaries.

Do not set AspCompat to true if your page uses no COM objects or if it uses COM objects that don't access ASP intrinsic objects and that are registered ThreadingModel=Free or ThreadingModel=Both.

Explain the differences between Server-side and Client-side code?

Server-side scripting means that all the script will be executed by the server and interpreted as needed. ASP doesn't have some of the functionality like sockets, uploading, and so on. For these you need to make custom components usually in VB or VC++. Client-side scripting means that the script will be executed immediately in the browser such as form field validation, clock, email validation, and so on. Client-side scripting is usually done in VBScript or JavaScript. Download time, browser compatibility, and visible code, since JavaScript and VBScript code is included in the HTML page, then anyone can see the code by viewing the page source. Also possible security hazards for the client computer.

What type of code (server or client) is found in a Code-Behind class?

C#.

Should validation (such as did the user enter a real date) occur server-side or client-side? Why?

Client-side validation because there is no need to request a server-side date when you could obtain a date from the client machine.

What are ASP.NET Web Forms? How is this technology different than what is available though ASP?

Web Forms are the heart and soul of ASP.NET. Web Forms are the User Interface (UI) elements that provide your Web applications their look and feel. Web Forms are similar to Windows Forms in that they provide properties, methods, and events for the controls that are placed onto them. However, these UI elements render themselves in the appropriate markup language required by the request, for example HTML. If you use Microsoft Visual Studio .NET then you will also get the familiar drag-and-drop interface used to create your UI for your Web application.

What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?

In earlier versions of IIS, if we wanted to send a user to a new Web page then the only option we had was Response.Redirect. While this method does accomplish our goal, it has several important drawbacks. The biggest problem is that this method causes each page to be treated as a separate transaction. Besides making it difficult to maintain your transactional integrity, Response.Redirect introduces some additional headaches. First, it prevents good encapsulation of code. Second, you lose access to all of the properties in the Request object. Sure, there are workarounds, but they're difficult. Finally, Response.Redirect necessitates a round trip to the client, which, on high-volume sites, causes scalability problems.

As you might suspect, Server.Transfer fixes all of these problems. It does this by performing the transfer on the server without requiring a roundtrip to the client.

How can you provide an alternating color scheme in a Repeater control?

AlternatingItemTemplate Like the ItemTemplate element, but rendered for every other row (alternating items) in the Repeater control. You can specify a different appearance for the AlternatingItemTemplate element by setting its style properties.

Which template must you provide, in order to display data in a Repeater control?

ItemTemplate.

What event handlers can I include in Global.asax?

Application_Start, Application_End, Application_AcquireRequestState, Application_AuthenticateRequest, Application_AuthorizeRequest, Application_BeginRequest, Application_Disposed, Application_EndRequest, Application_Error, Application_PostRequestHandlerExecute, Application_PreRequestHandlerExecute,Application_PreSendRequestContent, Application_PreSendRequestHeaders, Application_ReleaseRequestState, Application_ResolveRequestCache, Application_UpdateRequestCache, Session_Start andSession_End.

You can optionally include "On" in any of the method names. For example, you can name a BeginRequest event handler Application_BeginRequest or Application_OnBeginRequest. You can also include event handlers in Global.asax for events fired by custom HTTP modules. Note that not all of the event handlers make sense for Web Services (they're designed for ASP.NET applications in general, whereas .NET XML Web Services are specialized instances of an ASP.NET app). For example, the Application_AuthenticateRequest and Application_AuthorizeRequest events are designed to be used with ASP.NET Forms authentication.

What is different between webconfig.xml and Machineconfig.xml?

Web.config and machine.config both are configuration files. Web.config contains settings specific to an application whereas machine.config contains settings to a computer. The Configuration system first searches settings in machine.config file and then looks in application configuration files. Web.config can appear in multiple directories on an ASP.NET Web application server. Each Web.config file applies configuration settings to its own directory and all child directories below it. There is only a Machine.config file on a web server.

If I'm developing an application that must accomodate multiple security levels using a secure login and my ASP.NET web appplication is spanned across three web-servers (using round-robbin load balancing) then what would be the best approach to maintain login-in state for the users?

Use the state server or store the state in the database. This can be easily done through a simple setting change in the web.config.

You can specify mode as "stateserver" or "sqlserver".

Where would you use an iHTTPModule, and what are the limitations of any approach you might use in implementing one?

"One of ASP.NET's most useful features is the extensibility of the HTTP pipeline, the path that data takes between client and server. You can use them to extend your ASP.NET applications by adding pre-processing and post-processing to each HTTP request coming into your application. For example, if you wanted custom authentication facilities for your application then the best technique would be to intercept the request when it comes in and processes the request in a custom HTTP module.

How do you turn off cookies for one page in your site?

Since no Page Level directive is present, I am afraid that can't be done.

How do you create a permanent cookie?

Permanent cookies are available until a specified expiration date, and are stored on the hard disk. So set the "Expires" property to a value greater than DataTime.MinValue with respect to the current datetime. If you want the cookie that never expires set its Expires property equal to DateTime.maxValue.

Which method do you use to redirect the user to another page without performing a round trip to the client?

Server.Transfer and Server.Execute

What property do you need to set to tell the grid which page to go to when using the Pager object?

CurrentPageIndex

Should validation (such as did the user enter a real date) occur server-side or client-side? Why?

It should occur both at client-side and server-side. By using an expression validator control with the specified expression, in other words, the regular expression provides the ability to only validatate the date specified that it is in the correct format. For checking the date, whether it is the real data or not should hoever be done at the server-side, by getting the system date ranges and checking the date whether it is between that range or not.

What does the "EnableViewState" property do? Why would I want it on or off?

Enable ViewState turns on the automatic state management feature that enables server controls to re-populate their values on a round trip without requiring you to write any code. This feature is not free, however, since the state of a control is passed to and from the server in a hidden form field. You should be aware of when ViewState is helping you and when it is not. For example, if you are binding a control to data on every round trip, then you do not need the control to maintain it's view state, since you will wipe out any re-populated data in any case. ViewState is enabled for all server controls by default. To disable it, set the EnableViewState property of the control to false.

What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?

Server.Transfer():the client is shown as it is on the requesting page only, but all the content is of the requested page. Data can be persisted accros the pages using a Context.Item collection, which is one of the best way to transfer data from one page to another keeping the page state alive.Response.Redirect():client knows the physical location (page name and query string as well). Context.Items loses the persisitance when nevigating to the destination page. In earlier versions of IIS, if we wanted to send a user to a new Web page, the only option we had was Response.Redirect While this method does accomplish our goal, it has several important drawbacks. The biggest problem is that this method causes each page to be treated as a separate transaction. Besides making it difficult to maintain your transactional integrity, Response.Redirect introduces some additionalproblens. First, it prevents good encapsulation of code. Second, you lose access to all of the properties in the Request object. Sure, there are workarounds, but they're difficult. Finally, Response.Redirect necessitates a round trip to the client, which, on high-volume sites, causes scalability problems. As you might suspect, Server.Transfer fixes all of these problems. It does this by performing the transfer on the server without requiring a roundtrip to the client.

Can you give an example of when it would be appropriate to use a web service as opposed to a non-serviced .NET component? Communicating through a Firewall when building a distributed application with 100s or 1000s of users spread over multiple locations, there is always the problem of communicating between client and server because of firewalls and proxy servers. Exposing your middle tier components as Web Services and invoking them directly from a Windows UI is a very valid option. Application Integration When integrating applications written in various languages and running on disparate systems. Or even applications running on the same platform that have been written by separate vendors. Business-to-Business Integration. This is an enabler for B2B intergtation that allows one to expose vital business processes to authorized suppliers and customers. An example would be exposing electronic ordering and invoicing, allowing customers to send you purchase orders and suppliers to send you invoices electronically. Software Reuse. This takes place at multiple levels. Code Reuse at the Source code level or binary componet-based resuse. The limiting factor here is that you can reuse the code but not the data behind it. Webservice overcomes this limitation. A scenario could be when you are building an app that aggregates the functionality of serveral other Applicatons. Each of these functions could be performed by individual apps, but there is value in perhaps combining the the multiple apps to present a unifiend view in a Portal or Intranet. When not to use Web Services: Single-machine applicatons are applicatons running on the same machine and that need to communicate with each other using a native API. You also have the options of using component technologies such as COM or .NET Componets since there is very little overhead. Homogeneous Applications on a LAN. If you have Win32 or Winforms apps that want to communicate with their server counterpart. It is much more efficient to use DCOM in the case of Win32 apps and .NET Remoting in the case of .NET Apps.Can you give an example of what might be most appropriately placed in the Application_Start and Session_Start events?

The Application_Start event is guaranteed to occur only once throughout the lifetime of the application. It's a good place to initialize global variables. For example, you might want to retrieve a list of products from a database table and place the list in application state or the Cache object. SessionStateModule exposes both Session_Start and Session_End events.

What are the advantages and disadvantages of viewstate?

The primary advantages of the ViewState feature in ASP.NET are:1. Simplicity. There is no need to write possibly complex code to store form data between page submissions.2. Flexibility. It is possible to enable, configure, and disable ViewState on a control-by-control basis, choosing to persist the values of some fields but not others.There are, however a few disadvantages that are worth pointing out:1. Does not track across pages. ViewState information does not automatically transfer from page to page. With the sessionapproach, values can be stored in the session and accessed from other pages. This is not possible with ViewState, so storingdata into the session must be done explicitly.2. ViewState is not suitable for transferring data for back-end systems. That is, data must still be transferred to the backend using some form of data object.Describe session handling in a webfarm, how does it work and what are the limits?

ASP.NET Sessions support storing of session data in 3 ways, i] In-Process (in the same memory that ASP.NET uses) , ii] Out-of-Process using a Windows NT Service (in memory separate from ASP.NET) or iii] in SQL Server (persistent storage). Both the Windows Service and SQL Server solutions support a webfarm scenario where all the web-servers can be configured to share a common session state store.

1. Windows Service

We can start this service by "Start" | "Control Panel" | "Administrative Tools" | "Services". In that we service names ASP.NET State Service. We can start or stop a service manually or configure it to start automatically. Then we need to configure our web.config fileas in the following:

Here ASP.Net Session is directed to use a Windows Service for state management on the local server (the address127.0.0.1 is the TCP/IP loop-back address). The default port is 42424. We can configure it to any port but for that we need to manually edit the registry.

Use the following simple procedure: In a webfarm make sure you have the same config file in all your web servers. Also make sure your objects are serializable. For the session state to be maintained across various web servers in the webfarm, the application path of the web-site in the IIS Metabase should be identical in all the web-servers in the webfarm.Which template must you provide to display data in a Repeater control?

You need to use the ItemTemplate to display data. The syntax is as follows:

< ItemTemplate >< div class ="rItem" >< img src="images/" hspace="10" />< b > < /div >< ItemTemplate >

How can you provide an alternating color scheme in a Repeater control?

Using the AlternatintItemTemplate

What property must you set, and what method must you call in your code, to bind the data from some data source to the Repeater control?

Set the DataMember property to the name of the table to bind to. (If this property is not set then by default the first table in the dataset is used.)

The DataBind method uses this method to bind data from a source to a server control. This method is commonly used after retrieving a data set through a database query.

What method do you use to explicitly kill a user s session?You can dump (Kill) the session yourself by calling the method Session.Abandon.

ASP.NET automatically deletes a user's Session object, dumping its contents, after it has been idle for a configurable timeout interval. This interval, in minutes, is set in the section of the web.config file. The default is 20 minutes.

How do you turn off cookies for one page in your site?

Use the Cookie.Discard property, Gets or sets the discard flag set by the server. When true, this property instructs the client application not to save the Cookie on the user's hard disk when a session ends.

Which two properties are on every validation control?

We have two common properties for every validation controlas in the following:1. Control to Validate,2. Error Message.What tags do you need to add within the asp:datagrid tags to bind columns manually?

< asp:DataGrid id="dgCart" AutoGenerateColumns="False" CellPadding="4" Width="448px" runat="server" >< Columns >< asp:ButtonColumn HeaderText="SELECT" Text="SELECT" CommandName="select" >< /asp:ButtonColumn >< asp:BoundColumn DataField="ProductId" HeaderText="Product ID" >< /asp:BoundColumn >< asp:BoundColumn DataField="ProductName" HeaderText="Product Name" >< /asp:BoundColumn >< asp:BoundColumn DataField="UnitPrice" HeaderText="UnitPrice" >< /asp:BoundColumn >< /Columns >< /asp:DataGrid >

How do you create a permanent cookie?

Permanent cookies are the ones that are most useful. Permanent cookies are available until a specified expiration date, and are stored on the hard disk. The location of cookies differs with each browser, but this doesn't matter, as this is all handled by your browser and the server. If you want to create a permanent cookie called Name with a value of Nigel, that expires in one month then you'd use the following code:

Response.Cookies ("Name") = "Nigel"Response.Cookies ("Name"). Expires = DateAdd ("m", 1, Now ())What tag do you use to add a hyperlink column to the DataGrid?< asp:HyperLinkColumn >

Which method do you use to redirect the user to another page without performing a round trip to the client?

Server.transfer

What is the transport protocol you use to call a Web service SOAP ?

HTTP Protocol

Explain role based security

Role Based Security lets you identify groups of users to allow or deny based on their role in the organization. In Windows NT and Windows XP, roles map to names used to identify user groups. Windows defines several built-in groups, including Administrators, Users, and Guests.To allow or deny access to certain groups of users, add the element to the authorization list in your Web application's Web.config file. For example:

< authorization >< allow roles="Domain Name\Administrators" / > < !-- Allow Administrators in domain. -- >< deny users="*" / > < !-- Deny anyone else. -- >< /authorization >

How do you register JavaScript for webcontrols ?

You can register JavaScript for controls using the Attribtues.Add(scriptname,scripttext) method.

When do you set "" ?

Identity is a webconfig declaration under System.web, which helps to control the application Identity of the web applicaton. Which can be at any level (Machine, Site, application, subdirectory, or page). The attribute impersonates "true" as the value to specify that client impersonation is used.

What are various templates available in Repeater, DataList and Datagrid?

Templates enable one to apply complicated formatting to each of the items displayed by a control. The Repeater control supports five types of templates. HeaderTemplate controls how the header of the repeater control is formatted. ItemTemplate controls the formatting of each item displayed. AlternatingItemTemplate controls how alternate items are formatted. SeparatorTemplate displays a separator between each item displyed. FooterTemplate controls how the footer of the repeater control is formatted. DataList and Datagrid supports two templates in addition to the preceding five. The SelectedItem Template controls how a selected item is formatted and EditItemTemplate controls how an item selected for editing is formatted.

What is ViewState? How is it managed ?

ASP.NET ViewState is a new kind of state service that developers can use to track UI state on a per-user basis. Internally it uses an an old Web programming trick, roundtripping state in a hidden form field and bakes it right into the page-processing framework. It needs less code to write and maintain state in your Web-based forms.

What is the web.config file?

The Web.config file is the configuration file for the ASP.Net web application. There is one web.config file for one ASP.Net application that configures the specific application. The Web.config file is written in XML with specific tags having specific meanings. It includes data that includes connections, Session States, Error Handling, Security and so on.

For example:

< configuration >< appSettings >< add key="ConnectionString"value="server=localhost;uid=sa;pwd=;database=MyDB" / >< /appSettings >< /configuration >

What are the advantages and benefits of viewstate?When a form is submitted in classic ASP, all form values are cleared. Suppose you have submitted a form with a lot of information and the server returns an error. You will need to return to the form and correct the information. You click the back button, and what happens?Allform values arecleared, and you will need to start all over again! The site did not maintain your ViewState. With ASP .NET, the form reappears in the browser window together with all form values. This is because ASP .NET maintains your ViewState. The ViewState indicates the status of the page when submitted to the server.

What tags do you need to add within the asp:datagrid tags to bind columns manually?

Set the AutoGenerateColumns Property to false on the datagrid tag and then use the Column tag and an ASP:databound tag as in the following:

< asp:DataGrid runat="server" id="ManualColumnBinding" AutoGenerateColumns="False" >< Columns >< asp:BoundColumn HeaderText="Column1" DataField="Column1"/ >< asp:BoundColumn HeaderText="Column2" DataField="Column2"/ >< /Columns >< /asp:DataGrid >

Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?DataTextField and DataValueField

Which control would you use if you needed to ensure the values in two different controls matched?

CompareValidator is used to ensure that two fields are identical.

What is validationsummary server control? Where is it used?

The ValidationSummary control allows you to summarize the error messages from all validation controls on a Web page in a single location. The summary can be displayed as a list, a bulleted list, or a single paragraph, based on the value of the DisplayMode property. The error message displayed in the ValidationSummary control for each validation control on the page is specified by the ErrorMessage property of each validation control. If the ErrorMessage property of the validation control is not set then no error message is displayed in the ValidationSummary control for that validation control. You can also specify a custom title in the heading section of the ValidationSummary control by setting the HeaderText property.

You can control whether the ValidationSummary control is displayed or hidden by setting the ShowSummary property. The summary can also be displayed in a message box by setting the ShowMessageBox property to true.

What is the sequence of operations occuring when a page is loaded?

BeginTranaction: only if the request is transactedInit: every time a page is processedLoadViewState: Only on postbackProcessPostData1: Only on postbackLoad: every timeProcessData2: Only on PostbackRaiseChangedEvent: Only on PostbackRaisePostBackEvent: Only on PostbackPreRender: everytimeBuildTraceTree: Only if tracing is enabledSaveViewState: Every timeRender: Every timeEnd Transaction: Only if the request is transactedTrace.EndRequest: Only when tracing is enabledUnloadRecursive: Every request

What are some of the differences between ASP and ASP.Net?

"Active Server Pages (ASP) and ASP.NET are both server-side technologies for building web sites and web applications, ASP.NET is Managed compiled code, ASP is interpreted. and ASP.Net is fully Object Oriented. ASP.NET has been entirely re-architected to provide a highly productive programming experience based on the .NET Framework, and a robust infrastructure for building reliable and scalable web applications."

Name the validation control available in ASP.Net

RequiredField, RangeValidator, RegularExpression, Custom Validator, Compare Validator.

What are the various ways of securing a web site that could prevent hacking and so on?1. Authentication/Authorization2. Encryption/Decryption3. Maintaining web servers outside the corporate firewall4. and so on.What is the difference between in-proc and out-of-proc?

An inproc is one that runs in the same process area as that of the client giving tha advantage of speed but the disadvantage of stability because if it crashes then it takes the client application also with it. Outproc is one that works outside the client's memory, thus giving stability to the client, but we need to compromise a bit on speed.

When you're running a component within ASP.NET, what process is it running within on Windows XP? Windows 2000? Windows 2003?

On Windows 2003 (IIS 6.0) running in native mode, the component is running within the w3wp.exe process associated with the application pool that has been configured for the web application containing the component.On Windows 2003 in IIS 5.0 emulation mode, 2000, or XP, it's running within the IIS helper process whose name I do not remember, it being quite a while since I last used IIS 5.0.

What does aspnet_regiis -i do?

Aspnet_regiis.exe is the ASP.NET IIS Registration tool that allows an administrator or installation program to easily update the script maps for an ASP.NET application to point to the ASP.NET ISAPI version associated with the tool. The tool can also be used to display the status of all installed versions of ASP. NET, register the ASP.NET version coupled with the tool, create client-script directories, and perform other configuration operations.

When multiple versions of the .NET Framework are executing side-by-side on a single computer, the ASP.NET ISAPI version mapped to an ASP.NET application determines which version of the Common Language Runtime is used for the application.

The tool can be launched with a set of optional parameters. Option "i" installs the version of ASP.NET associated with Aspnet_regiis.exe and updates the script maps at the IIS metabase root and below. Note that only applications that are currently mapped to an earlier version of ASP.NET are affected

What is a PostBack?

The process in which a Web page sends data back to the same page on the server.

What is ViewState? How is it encoded? Is it encrypted? Who uses ViewState?

ViewState is the mechanism ASP.NET uses to maintain server control state values that don't otherwise post-back as part of the HTTP form. ViewState Maintains the UI State of a Page.ViewState is base64-encoded.

It is not encrypted but it can be encrypted by setting EnableViewStatMAC="true" and setting the machineKey validation type to 3DES. If you want tonotmaintain the ViewState then include the directive < %@ Page EnableViewState="false" % > at the top of an .aspx page or add the attribute EnableViewState="false" to any control.

What is the < machinekey > element and what two ASP.NET technologies is it used for?

Configures keys to use for encryption and decryption of forms authentication cookie data and view state data, and for verification of out-of-process session state identification.Therefore 2 ASP.Net techniques in which it is used are Encryption/Decryption and Verification.

What three Session State providers are available in ASP.NET 1.1? What are the pros and cons of each?

ASP.NET provides three distinct ways to store session data for your application: in-process session state, out-of-process session state as a Windows service, and out-of-process session state in a SQL Server database. Each has it advantages.

1. In-process session-state mode

Limitations When using the in-process session-state mode, session-state data is lost if aspnet_wp.exe or the application domain restarts. If you enable Web Garden mode in the < processModel > element of the application's Web.config file then do not use in-process session-state mode. Otherwise, random data loss can occur.Advantage in-process session state is by far the fastest solution. If you are storing only small amounts of volatile data in session state, it is recommended that you use the in-process provider.2.The State Server simply stores session state in memory when in out-of-proc mode. In this mode the worker process talks directly to the State Server

3.SQL mode, session states are stored in a SQL Server database and the worker process talks directly to SQL. The ASP.NET worker processes are then able to take advantage of this simple storage service by serializing and saving (using .NET serialization services) all objects within a client's Session collection at the end of each Web request

Both these out-of-process solutions are useful primarily if you scale your application across multiple processors or multiple computers, or where data cannot be lost if a server or process is restarted.

What is the difference between HTTP-Post and HTTP-Get?

As their names imply, both HTTP GET and HTTP POST use HTTP as their underlying protocol. Both of these methods encode request parameters as name/value pairs in the HTTP request.

The GET method creates a query string and appends it to the script's URL on the server that handles the request.

The POST method creates name/value pairs that are passed in the body of the HTTP request message.

Name and describe some HTTP Status Codes and what they express to the requesting client.

When users try to access content on a server that is running Internet Information Services (IIS) through HTTP or File Transfer Protocol (FTP), IIS returns a numeric code that indicates the status of the request. This status code is recorded in the IIS log, and it may also be displayed in the Web browser or FTP client. The status code can indicate whether a specific request is successful or unsuccessful and can also reveal the exact reason why a request is unsuccessful. There are 5 groups ranging from 1xx - 5xx of HTTP status codes that exist as in the following:

101: Switching protocols.200: OK. The client request has succeeded302: Object moved.400: Bad request.500.13: Web server is too busy.

Explain < @OutputCache% > and the usage of VaryByParam, VaryByHeader.

OutputCacheis used to control the caching policies of an ASP.NET page or user control. To cache a page @OutputCache directive should be defined as follows < %@ OutputCache Duration="100" VaryByParam="none" % >

VaryByParam: A semicolon-separated list of strings used to vary the output cache. By default, these strings correspond to a query string value sent with GET method attributes, or a parameter sent using the POST method. When this attribute is set to multiple parameters then the output cache contains a different version of the requested document for each specified parameter. Possible values include none, *, and any valid query string or POST parameter name.

VaryByHeader: A semicolon-separated list of HTTP headers used to vary the output cache. When this attribute is set to multiple headers, the output cache contains a different version of the requested document for each specified header.What is the difference between repeater over datalist and datagrid?

The Repeater class is not derived from the WebControl class, like the DataGrid and DataList. Therefore, the Repeater lacks the stylistic properties common to both the DataGrid and DataList. What this boils down to is that if you want to format the data displayed in the Repeater then you must do so in the HTML markup.

The Repeater control provides the maximum amount of flexibility over the HTML produced. Whereas the DataGrid wraps the DataSource contents in an HTML < table >, and the DataList wraps the contents in either an HTML < table > or < span > tags (depending on the DataList's RepeatLayout property), the Repeater adds absolutely no HTML content other than what you explicitly specify in the templates.

While using the Repeater control, if we wanted to display the employee names in a bold font then we'd need to alter the "ItemTemplate" to include an HTML bold tag. Whereas with the DataGrid or DataList, we could have made the text appear in a bold font by setting the control's ItemStyle-Font-Bold property to True.

The Repeater's lack of style properties can drastically add to the development time metric. For example, imagine that you decide to use the Repeater to display data that needs to be bold, centered, and displayed in a specific font-face with a specific background color. While all this can be specified using a few HTML tags, these tags will quickly clutter the Repeater's templates. Such clutter makes it much harder to change the look at a later date. Along with its increased development time, the Repeater also lacks any built-in functionality to assist in supporting paging, editing, or editing of data. Due to this lack of feature-support, the Repeater scores poorly on the usability scale.

However, The Repeater's performance is slightly better than that of the DataList's, and is noticeably better than that of the DataGrid's. The following figure shows the number of requests per second the Repeater could handle versus the DataGrid and DataList.

Can we handle the error and redirect to some pages using web.config?

Yes, we can do this, but to handle errors, we must know the error codes; only then we can take the user to a proper error message page, else it may confuse the user.

CustomErrors Configuration section in web.config file:

The default configuration is:

< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >< error statusCode="404" redirect="Notfound.aspx" / >< /customErrors >

If the mode is set to Off then the custom error messages will be disabled. Users will receive detailed exception error messages.

If mode is set to On then custom error messages will be enabled.

If mode is set to RemoteOnly then then users will receive custom errors, but users accessing the site locally will receive detailed error messages.

Add an < error > tag for each error you want to handle. The error tag will redirect the user to the Notfound.aspx page when the site returns the 404 (Page not found) error.

[Example]

There is a page MainForm.aspx

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

'Put user code to initialize the page here

Dim str As System.Text.StringBuilderstr.Append("hi") ' Error Line as str is not instantiatedResponse.Write(str.ToString)End Sub

[Web.Config]

< customErrors mode="On" defaultRedirect="Error.aspx"/ >' a simple redirect will take the user to Error.aspx [user defined] error file.< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >< error statusCode="404" redirect="Notfound.aspx" / >< /customErrors >

'This will take the user to NotFound.aspx defined in IIS.

How do you implement Paging in .Net?

The DataGrid provides the means to display a group of records from the data source (for example, the first 10), and then navigate to the "page" containing the next 10 records, and so on through the data.

Using ADO.Net we can have explicit control over the number of records returned from the data source, as well as how much data is to be cached locally in the DataSetas in the following:1. Using the DataAdapter.fill method provides the value of the "Maxrecords" parameter

(Note:: Don't use it because the query will return all records but fill the dataset based on the value of the "maxrecords" parameter).2. For SQL Server databases, combine a WHERE clause and a ORDER BY clause with the TOP predicate.3. If data does not change often then just cache records locally in a DataSet and take some records from the DataSet to display.What is the difference between Server.Transfer and Response.Redirect?

Server.Transfer(): client is shown as it is on the requesting page only, but all the content is of the requested page. Data can be persisted across the pages using the Context.Item collection, that is one of the best ways to transfer data from one page to another keeping the page state alive.Response.Dedirect(): the client knows the physical location (page name and query string as well). Context.Items loses the persistence when navigate to destination page. In earlier versions of IIS, if we wanted to send a user to a new Web page then the only option we had was Response.Redirect. While this method does accomplish our goal, it has several important drawbacks. The biggest problem is that this method causes each page to be treated as a separate transaction. Besides making it difficult to maintain your transactional integrity, Response.Redirect introduces some additional headaches. First, it prevents good encapsulation of code. Second, you lose access to all of the properties in the Request object. Sure, there are workarounds, but they're difficult. Finally, Response.Redirect necessitates a round trip to the client, which, on high-volume sites, causes scalability problems. As you might suspect, Server.Transfer fixes all of these problems. It does this by performing the transfer on the server without requiring a roundtrip to the client.Response.Redirect sends a response to the client browser instructing it to request the second page. This requires a round-trip to the client, and the client initiates the Request for the second page. Server.Transfer transfers the process to the second page without making a round-trip to the client. It also transfers the HttpContext to the second page, enabling the second page access to all the values in the HttpContext of the first page.

Can you create an app domain?

Yes, we can create a user app domain by calling one of the following overload static methods of the System.AppDomain class:1. Public static AppDomain CreateDomain(String friendlyName)2. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo)3. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, AppDomainSetup info)4. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, String appBasePath, String appRelativeSearchPath, bool shadowCopyFiles)What are the various security methods that IIS Provides apart from .NET?

The various security methods that IIS provides are: Authentication Modes IP Address and Domain Name Restriction DNS Lookups DNS Lookups The Network ID and Subnet Mask SSLWhat is Web Gardening? How would using it affect a design?

The Web Garden Model

The Web Garden model is configurable through the machine.config file. Notice that the section is the only configuration section that cannot be placed in an application-specific web.config file. This means that the Web Garden mode applies to all applications running on the machine. However, by using the node in the machine.config source, you can adapt machine-wide settings on a per-application basis.

Two attributes in the section affect the Web Garden model. They are webGarden and cpuMask. The webGarden attribute takes a Boolean value that indicates whether or not multiple worker processes (one per each affinitized CPU) need to be used. The attribute is set to false by default. The cpuMask attribute stores a DWORD value whose binary representation provides a bit mask for the CPUs that are eligible to run the ASP.NET worker process. The default value is -1 (0xFFFFFF), which means that all available CPUs can be used. The contents of the cpuMask attribute is ignored when the webGarden attribute is false. The cpuMask attribute also sets an upper bound to the number of copies of aspnet_wp.exe that are running.

Web Gardening enables multiple worker processes to run at the same time. However, you should note that all processes will have their own copy of application state, in-process session state, ASP.NET cache, static data, and all that is needed to run applications. When the Web Garden mode is enabled, the ASP.NET ISAPI launches as many worker processes as there are CPUs, each a full clone of the next (and each affinitized with the corresponding CPU). To balance the workload, incoming requests are partitioned among running processes in a round-robin manner. Worker processes get recycled as in the single processor case. Note that ASP.NET inherits any CPU usage restriction from the operating system and doesn't include any custom semantics for doing this.

All in all, the Web Garden model is not necessarily a big win for all applications. The more stateful applications are, the more they risk to pay in terms of real performance. Working data is stored in blocks of shared memory so that any changes entered by a process are immediately visible to others. However, for the time it takes to service a request, working data is copied in the context of the process. Each worker process, therefore, will handle its own copy of working data, and the more stateful the application, the higher the cost in performance. In this context, careful and savvy application benchmarking is an absolute must.

Changes made to the section of the configuration file are effective only after IIS is restarted. In IIS 6, Web Gardening parameters are stored in the IIS metabase; the webGarden and cpuMask attributes are ignored.

What is view state? Where is it stored? Can we disable it?

The web is a state-less protocol, so the page is instantiated, executed, rendered and then disposed of on every round trip to the server. The developer's code to add "statefulness" to the page by using server-side storage for the state or posting the page to itself. When required to persist and read the data in a control on a webform, the developer must read the values and store them in a hidden variable (in the form), that were then used to restore the values. With the advent of the .NET Framework, ASP.NET offers the ViewState mechanism that tracks the data values of server controls on an ASP.NET webform. In effect, ViewState can be viewed as "hidden variable managed by the ASP.NET framework!". When an ASP.NET page is executed, data values from all server controls on a page are collected and encoded as a single string that is then assigned to the page's hidden atrribute "< input type=hidden >", that is part of the page sent to the client.

The ViewState value is temporarily saved in the client's browser. ViewState can be disabled for a single control, for an entire page or for an entire web application. The syntax is:

Disable ViewState for control (Datagrid in this example)

< asp:datagrid EnableViewState="false" ... / >Disable ViewState for a page, using Page directive< %@ Page EnableViewState="False" ... % >Disable ViewState for application through entry in web.config< Pages EnableViewState="false" ... / >

.NET FrameWork FAQ's

When was .NET announced?

Bill Gates delivered a keynote at Forum 2000, held June 22, 2000, outlining the .NET "vision". The July 2000 PDC had a number of sessions on .NET technology, and delegates were given CDs containing a pre-release version of the .NET Framework/SDK and Visual Studio.NET.

When was the first version of .NET released?

The final version of the 1.0 SDK and runtime was made publicly available around 6 PM PST on 15-Jan-2002. At the same time, the final version of Visual Studio.NET was made available to MSDN subscribers.

What platforms does the .NET Framework run on?

The runtime supports Windows XP, Windows 2000, NT4 SP6a and Windows ME/98. Windows 95 is not supported. Some parts of the framework do not work on all platforms; for example, ASP.NET is only supported on Windows XP and Windows 2000. Windows 98/ME cannot be used for development.

IIS is not supported on Windows XP Home Edition, and so cannot be used to host ASP.NET. However, the ASP.NET Web Matrixweb server does run on XP Home.The Mono project is attempting to implement the .NET framework on Linux.

What is the CLR?

CLR = Common Language Runtime. The CLR is a set of standard resources that (in theory) any .NET program can take advantage of, regardless of programming language. Robert Schmidt (Microsoft) lists the following CLR resources in his MSDN PDC# article: Object-oriented programming model (inheritance, polymorphism, exception handling, garbage collection) Security model Type system All .NET base classes Many .NET framework classes Development, debugging, and profiling tools Execution and code management IL-to-native translators and optimizersWhat this means is that in the .NET world, various programming languages will be more equal in capability than they have ever been before, although clearly not all languages will support all CLR services.

What is the CTS?

CTS = Common Type System. This is the range of types that the .NET runtime understands, and therefore that .NET applications can use. However note that not all .NET languages will support all the types in the CTS. The CTS is a superset of the CLS.

What is the CLS?

CLS = Common Language Specification. This is a subset of the CTS that all .NET languages are expected to support. The idea is that any program that uses CLS-compliant types can interoperate with any .NET program written in any language.In theory this allows very tight interop between various .NET languages, for example allowing a C# class to inherit from a VB class.

What is IL?

IL = Intermediate Language. Also known as MSIL (Microsoft Intermediate Language) or CIL (Common Intermediate Language). All .NET source code (of any language) is compiled to IL. The IL is then converted to machine code at the point where the software is installed, or at run-time by a Just-In-Time (JIT) compiler.

What does "managed" mean in the .NET context?

The term "managed" is the cause of much confusion. It is used in various places within .NET, meaning slightly different things. Managed code: The .NET framework provides several core run-time services to the programs that run within it, for exampleexception handling and security. For these services to work, the code must provide a minimum level of information to the runtime.

Such code is called managed code. All C# and Visual Basic.NET code is managed by default. Visual Studio 7 C++ code is not managed by default, but the compiler can produce managed code by specifying a command-line switch (/com+).

Managed data: This is data that is allocated and de-allocated by the .NET runtime's garbage collector. C# and VB.NET data is always managed. Visual Studio 7 C++ data is unmanaged by default, even when using the /com+ switch, but it can be marked as managed using the __gc keyword. Managed classes: This is usually referred to in the context of Managed Extensions (ME) for C++. When using ME C++, a class can be marked with the __gc keyword. As the name suggests, this means that the memory for instances of the class is managed by the garbage collector, but it also means more than that. The class becomes a fully paid-up member of the .NET community with the benefits and restrictions that brings. An example of a benefit is proper interop with classes written in other languages, for example, a managed C++ class can inherit from a VB class. An example of a restriction is that a managed class can only inherit from one base class.

What is reflection?

All .NET compilers produce metadata about the types defined in the modules they produce. This metadata is packaged along with the module (modules in turn are packaged together in assemblies), and can be accessed by a mechanism called reflection. The System.Reflection namespace contains classes that can be used to interrogate the types for a module/assembly.

Using reflection to access .NET metadata is very similar to using ITypeLib/ITypeInfo to access type library data in COM, and it is used for similar purposes, for example determining data type sizes for marshaling data across context/process/machine boundaries.Reflection can also be used to dynamically invoke methods (see System.Type.InvokeMember ) , or even create types dynamically at run-time (see System.Reflection.Emit.TypeBuilder).

What is the difference between Finalize and Dispose (Garbage collection) ?

Class instances often encapsulate control over resources that are not managed by the runtime, such as window handles (HWND), database connections, and so on. Therefore, you should provide both an explicit and an implicit way to free those resources. Provide implicit control by implementing the protected Finalize Method on an object (destructor syntax in C# and the Managed Extensions for C++). The garbage collector calls this method at some point after there are no longer any valid references to the object. In some cases, you might want to provide programmers using an object with the ability to explicitly release these external resources before the garbage collector frees the object. If an external resource is scarce or expensive, better performance can be done if the programmer explicitly releases resources when they are no longer being used. To provide explicit control, implement the Dispose method provided by the IDisposable Interface. The consumer of the object should call this method when it is done using the object.

Dispose can be called even if other references to the object are alive. Note that even when you provide explicit control by way of Dispose, you should provide implicit cleanup using the Finalize method. Finalize provides a backup to prevent resources frompermanently leaking if the programmer fails to call Dispose.

What is Partial Assembly References?

Full Assembly reference: A full assembly reference includes the assembly's text name, version, culture, and public key token (if the assembly has a strong name). A full assembly reference is required if you reference any assembly that is part of the commonlanguage runtime or any assembly located in the Global Assembly Cache.

Partial Assembly reference: We can dynamically reference an assembly by providing only partial information, such as specifying only the assembly name. When you specify a partial assembly reference, the runtime looks for the assembly only in the applicationdirectory.

We can make partial references to an assembly in your code in one of the following ways: Use a method such as System.Reflection.Assembly.Load and specify only a partial reference. The runtime checks for the assembly in the application directory. Use the System.Reflection.Assembly.LoadWithPartialName method and specify only a partial reference. The runtime checks for the assembly in the application directory and in the Global Assembly Cache.Changes to which portion of version number indicates an incompatible change?

Major or minor. Changes to the major or minor portion of the version number indicate an incompatible change. Under this convention, then version 2.0.0.0 would be considered incompatible with version 1.0.0.0. Examples of an incompatible change would be a change to the types of some method parameters or the removal of a type or method altogether.Build. The Build number is typically used to distinguish between daily builds or smaller compatible releases.Revision. Changes to the revision number are typically reserved for an incremental build needed to fix a specific bug. You'll sometimes hear this referred to as the "emergency bug fix" number in that the revision is what is often changed when a fix to a specific bug is shipped to a customer.What is side-by-side execution? Can two applications, one using private assembly and the other using Shared assembly be started as side-by-side executables? Side-by-side execution is the ability to run multiple versions of an application or component on the same computer. You can have multiple versions of the Common Language Runtime, and multiple versions of applications and components that use a version of the runtime, on the same computer at the same time. Since versioning is only applied to shared assemblies, and not to private assemblies, two applications, one using private assembly and one using shared assembly cannot be started as side-by-sideexecutables.

Why are strings called an immutable data type?

The memory representation of a string is an Array of Characters, so on re-assigning the new array of Char is formedand the start address is changed, thus keeping the old string in memory for the Garbage Collector to dispose.

What does assert() method do?

In debug compilations, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition is true.

What's the difference between the Debug class and Trace class?

The documentation looks the same. Use the Debug class for debug builds, use the Trace class for both debug and release builds.

Why are there five tracing levels in System.Diagnostics.TraceSwitcher?

The tracing dumps can be quite verbose. For applications that are constantly running you run the risk of overloading the machine and the hard drive. Five levels range from None to Verbose, allowing you to fine-tune the tracing activities.

Where is the output of TextWriterTraceListener redirected?

To the Console or a text file depending on the parameter passed to the constructor.

How do assemblies find each other?

By searching directory paths. There are several factors that can affect the path (such as the AppDomain host, and application configuration files), but for private assemblies the search path is normally the application's directory and its sub-directories. For shared assemblies, the search path is normally the same as the private assembly path plus the shared assembly cache.

How does assembly versioning work?

Each assembly has a version number called the compatibility version. Also each reference to an assembly (from another assembly) includes both the name and version of the referenced assembly.The version number has four numeric parts (for example 5.5.2.33). Assemblies with either of the first two parts different are normally viewed as incompatible. If the first two parts are the same, but the third is different, the assemblies are deemed as "maybe compatible". If only the fourth part is different then the assemblies are deemed compatible. However, this is just the default guideline, it is the version policy that decides to what extent these rules are enforced. The version policy can be specified via the application configuration file.

What is garbage collection?

Garbage collection is a system whereby a run-time component takes responsibility for managing the lifetime of objects and the heap memory that they occupy. This concept is not new to .NET. Java and many other languages/runtimes have used garbage collection for some time.

Why doesn't the .NET runtime offer deterministic destruction?

Because of the garbage collection algorithm. The .NET garbage collector works by periodically running through a list of all the objects that are currently being referenced by an application. All the objects that it doesn't find during this search are ready to be destroyed and the memory reclaimed. The implication of this algorithm is that the runtime doesn't get notified immediately when the final reference on an object goes away, it only determines during the next sweep of the heap.Futhermore, this type of algorithm works best by performing the garbage collection sweep as rarely as possible. Normally heap exhaustion is the trigger for a collection sweep.

Is the lack of deterministic destruction in .NET a problem?

It's certainly an issue that affects component design. If you have objects that maintain expensive or scarce resources (for example database locks), you need to provide some way for the client to tell the object to release the resource when it is done. Microsoft recommends that you provide a method called Dispose() for this purpose. However, this causes problems for distributed objects, in a distributed system who calls the Dispose() method? Some form of reference-counting or ownership-management mechanism is needed to handle distributed objects, unfortunately the runtime offers no help with this.

What is serialization?

Serialization is the process of converting an object into a stream of bytes. Deserialization is the opposite process of creating an object from a stream of bytes. Serialization / Deserialization is mostly used to transport objects (for example during remoting), or to persistobjects (for example to a file or database).

Does the .NET Framework have in-built support for serialization?

There are two separate mechanisms provided by the .NET class library, XmlSerializer and SoapFormatter/BinaryFormatter. Microsoft uses XmlSerializer for Web Services, and uses SoapFormatter/BinaryFormatter for remoting. Both are available for use in your own code.

Can I customise the serialization process?

Yes. XmlSerializer supports a range of attributes that can be used to configure serialization for a specific class. For example, a field or property can be marked with the [XmlIgnore] attribute to exclude it from serialization. Another example is the [XmlElement]attribute, that can be used to specify the XML element name to be used for a specific property or field.Serialization via SoapFormatter/BinaryFormatter can also be controlled to some extent by attributes. For example, the [NonSerialized] attribute is the equivalent of XmlSerializer's [XmlIgnore] attribute. Ultimate control of the serialization process can be acheived by implementing the the ISerializable interface on the class whose instances are to be serialized.

Why is XmlSerializer so slow?

There is a once-per-process-per-type overhead with XmlSerializer. So the first time you serialize or deserialize an object of a given type in an application, there is a significant delay. This normally doesn't matter, but it may mean, for example, that XmlSerializer is a poor choice for loading configuration settings during startup of a GUI application.

Why do I get errors when I try to seriali