SQL SERVER and DOT NET: Asp.Net Interview Questions

1. Describe the role of inetinfo.exe, aspnet_isapi.dll and aspnet_wp.exe in the page loading process.

inetinfo.exe is the Microsoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received (usually a file with .aspx extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.

2. What’s the difference between Response.Write() and Response.Output.Write()?

Response.Output.Write() allows you to write formatted output.

3. What methods are fired during the page load?

Init() - when the page is instantiated
Load() - when the page is loaded into server memory
PreRender() - the brief moment before the page is displayed to the user as HTML
Unload() - when page finishes loading.

4. When during the page processing cycle is ViewState available?
After the Init() and before the Page_Load(), or OnLoad() for a control.

5. What namespace does the Web page belong in the .NET Framework class hierarchy?

System.Web.UI.Page

6. Where do you store the information about the user’s locale?
System.Web.UI.Page.Culture

7. What’s the difference between Codebehind="MyCode.aspx.cs" and Src="MyCode.aspx.cs"?

CodeBehind is relevant to Visual Studio.NET only.

8. What’s a bubbled event?

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

9. Suppose you want a certain ASP.NET function executed on MouseOver for a certain button. Where do you add an event handler?

Add an OnMouseOver attribute to the button. Example: btnSubmit.Attributes.Add("onmouseover","someClientCodeHere();");

10. What data types do the RangeValidator control support?
Integer, String, and Date.

11. Explain the differences between Server-side and Client-side code?
Server-side code executes on the server. Client-side code executes in the client's browser.

12. What type of code (server or client) is found in a Code-Behind class?
The answer is server-side code since code-behind is executed on the server. However, during the code-behind's execution on the server, it can render client-side code such as JavaScript to be processed in the clients browser. But just to be clear, code-behind executes on the server, thus making it server-side code.

13. Should user input data validation occur server-side or client-side? Why?
All user input data validation should occur on the server at a minimum. Additionally, client-side validation can be performed where deemed appropriate and feasable to provide a richer, more responsive experience for the user.

14. What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client's browser. This provides a faster response with a little less overhead on the server. Server.Transfer does not update the clients url history list or current url.

Response.Redirect is used to redirect the user's browser to another page or site. This performas a trip back to the client where the client's browser is redirected to the new page. The user's browser history list is updated to reflect the new address.

Response.Redirect should be used when:

we want to redirect the request to some plain HTML pages on our server or to some other web server
we don't care about causing additional roundtrips to the server on each request
we do not need to preserve Query String and Form Variables from the original request
we want our users to be able to see the new redirected URL where he is redirected in his browser (and be able to bookmark it if its necessary)

Server.Transfer should be used when:

we want to transfer current page request to another .aspx page on the same server
we want to preserve server resources and avoid the unnecessary roundtrips to the server
we want to preserve Query String and Form Variables (optionally)
we don't need to show the real URL where we redirected the request in the users Web Browser

15. Can you explain the difference between an ADO.NET Dataset and an ADO Recordset?

· A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.

· A DataSet is designed to work without any continuing connection to the original data source.

· Data in a DataSet is bulk-loaded, rather than being loaded on demand.

· There's no concept of cursor types in a DataSet.

· DataSets have no current record pointer You can use For Each loops to move through the data.

· You can store many edits in a DataSet, and write them to the original data source in a single operation.

· Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.

16. What is the Global.asax used for?
The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.

17. What are the Application_Start and Session_Start subroutines used for?
This is where you can set the specific variables for the Application and Session objects.

18. Can you explain what inheritance is and an example of when you might use it?
When you want to inherit (use the functionality of) another class. Example: With a base class named Employee, a Manager class could be derived from the Employee base class.

19. Whats an assembly?
Assemblies are the building blocks of the .NET framework. Overview of assemblies from MSDN

20. Describe the difference between inline and code behind.
Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

21. Explain what a diffgram is, and a good use for one?
The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.

22. Whats MSIL, and why should my developers need an appreciation of it if at all?
MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.

23. Which method do you invoke on the DataAdapter control to load your generated dataset with data?
The Fill() method.

24. Can you edit data in the Repeater control?
No, it just reads the information from its data source.

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

26. How can you provide an alternating color scheme in a Repeater control?
Use the AlternatingItemTemplate.

27. What property must you set, and what method must you call in your code, in order to bind the data from a data source to the Repeater control?
You must set the DataSource property and call the DataBind method.

28. What base class do all Web Forms inherit from?
The Page class.

29. Name two properties common in every validation control?
ControlToValidate property and Text property.

30. 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 property.

31. Which control would you use if you needed to make sure the values in two different controls matched?
CompareValidator control.

32. How many classes can a single .NET DLL contain?
It can contain many classes.

Web Service Questions

33. What is the transport protocol you use to call a Web service?
SOAP (Simple Object Access Protocol) is the preferred protocol.

34. True or False: A Web service can only be written in .NET?
False

35. What does WSDL stand for?
Web Services Description Language.

36. Where on the Internet would you look for Web services?
http://www.uddi.org

37. True or False: To test a Web service you must create a Windows application or Web application to consume this service?
False, the web service comes with a test page and it provides HTTP-GET method to test.

38. What is ViewState?
ViewState allows the state of objects (serializable) to be stored in a hidden field on the page. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. ViewState is used the retain the state of server-side objects between postabacks.

39. What is the lifespan for items stored in ViewState?
Item stored in ViewState exist for the life of the current page. This includes postbacks (to the same page).

40. What does the "EnableViewState" property do? Why would I want it on or off?
It allows the page to save the users input on a form across postbacks. It saves the server-side values for a given control into ViewState, which is stored as a hidden value on the page before sending the page to the clients browser. When the page is posted back to the server the server control is recreated with the state stored in viewstate.

41. What are the different types of Session state management options available with ASP.NET?
ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session in memory on the web server. This requires the a "sticky-server" (or no load-balancing) so that the user is always reconnected to the same web server. Out-of-Process Session state management stores data in an external data source. The external data source may be either a SQL Server or a State Server service. Out-of-Process state management requires that all objects stored in session are serializable.

Describe the role of inetinfo.exe, aspnet_isapi.dll and aspnet_wp.exe in the page loading process.
inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received (usually a file with .aspx extension),the ISAPI filter aspnet_isapi.dll takes care of it by passing the request to the actual worker process aspnet_wp.exe.

42.       What is CLS (Common Language Specificaiton)?
It provides the set of specificaiton which has to be adhered by any new language writer / Compiler writer for .NET Framework. This ensures Interoperability. For example: Within a ASP.NET application written in C#.NET language, we can refer to any DLL written in any other language supported by .NET Framework. As of now .NET Supports around 32 languages.

43.       What is CTS (Common Type System)?
It defines about how Objects should be declard, defined and used within .NET. CLS is the subset of CTS.

44.       What is Boxing and UnBoxing?
Boxing is implicit conversion of ValueTypes to Reference Types (Object) .
UnBoxing is explicit conversion of Reference Types (Object) to its equivalent ValueTypes. It requires type-casting.

45.       What is the difference between Value Types and Reference Types?
Value Types uses Stack to store the data where as the later uses the Heap to store the data.

46.       What are the different types of assemblies available and their purpose?
Private, Public/shared and Satellite Assemblies.

Private Assemblies : Assembly used within an application is known as private assemblies

Public/shared Assemblies : Assembly which can be shared across applicaiton is known as shared assemblies. Strong Name has to be created to create a shared assembly. This can be done using SN.EXE. The same has to be registered using GACUtil.exe (Global Assembly Cache).

Satellite Assemblies : These assemblies contain resource files pertaining to a locale (Culture+Language). These assemblies are used in deploying an Gloabl applicaiton for different languages.

47.       Is String is Value Type or Reference Type in C#?
String is an object (Reference Type).

48.       Which controls do not have events?
Ans:Timer control.

49.       What is the maximum size of the textbox?
Ans:65536.

50.       Which property of the textbox cannot be changed at runtime?
Ans:Locked Porperty.
51.       Which control cannot be placed in MDI?
Ans:The controls that do not have events.
52.       Difference between a sub and a function.
Ands -A Sub Procedure is a method will not return a value
-A sub procedure will be defined with a “Sub” keyword
Sub ShowName(ByVal myName As String)
Console.WriteLine(”My name is: ” & myName)
End Sub

-A function is a method that will return value(s).
-A function will be defined with a “Function” keyword
Function FindSum(ByVal num1 As Integer, ByVal num2 As Integer) As Integer
Dim sum As Integer = num1 + num2
Return sum
End Function

53.       Explain manifest & metadata.

Manifest is metadata about assemblies. Metadata is machine-readable information about a resource, or “”data about data.” In .NET, metadata includes type definitions, version information, external assembly references, and other standardized information.

54.       Difference between imperative and interrogative code
Ans. There are imperative and interrogative functions and I think they are talking about that. Imperative functions are the one which return a
value while the interrogative functions do not return a value.

55.       What are the two kinds of properties
Ans. Two types of properties in .Net: Get & Set
Two kind of properties are scalar properties and indexed properties

56.       Explain constructor
Ans. Constructor is a method in the class which has the same name as the class (in VB.Net its New()). It initialises the member attributes whenever an instance of the class is created.

57.       Describe ways of cleaning up objects
Ans. The run time will maintain a service called as garbage collector.
this service will take care of deallocating memory corresponding to
objects.it works as a thread with least priority.when application
demenads for memory the runtime will take care of setting the high
priority for the garbage collector,so that it will be called for execution
and memory will be released.the programmer can make a call
to garbage colector by using GC class in system name space.

58.       what are value types and reference types?
Ans. Value type - bool, byte, chat, decimal, double, enum , float, int, long, sbyte, short, strut, uint, ulong, ushort
Value types are stored in the Stack
Reference type - class, delegate, interface, object, string
Reference types are stored in the Heap

59.       How can you clean up objects holding resources from within the
code?
Ands Call the dispose method from code for clean up of objects

60.       Explain the life cycle of an ASP .NET page.
Life cycle of ASP.Net Web Form
Page Request >> Start >> Page Init >> Page Load >> Validation >> PostBack Event Handling >> Page Rendering >> Page Unload
Page Request - When the page is requested ASP.Net determines whether the page is to be parsed and compiled or a cached verion of the page is to be sent without running the page.

Start - Page propertied REQUEST and RESPONSE are SET, if the page is pastback request then the IsPostBack property is SET and in addition to this UICulture property is also SET.
Page Initilization - In this the UniqueID of each property is SET. If the request was postback the data is not yet loaded from the viewstate.
Page Load - If it was a postback request then the data gets loaded in the control from the ViewState and control property are set.
Validation - If any control validation present, they are performed and IsValid property is SET for each control.
PostBack Event Handling - If it was a postback request then any event handlers are called.
Page Rendering - Before this the viewstate is saved from the page and RENDER method of each page is called.
Page Unload - Page is fully rendered and sent to the client(Browser) and is discarded. Page property RESPONSE and REQUEST are unloaded.

61.       .Net architecture?
The order starting from the bottom
1. CLR (Common Language Runtime)
2. .Net framework base classe
3. ASP.Net Web Form / Windows Form

62.       What are object-oriented concepts?
Ans. Inheritance
Abstraction
Polymorphism
Encapsulation

63.       How do you create multiple inheritance in c# and .NET?
Ans. Use interfaces
public class MyTest: IPaidInterface, ISoldInterface

64.       When is web.config called?
Ans. Web.config is an xml configuration file. It is never directly called
unless we need to retrieve a configurations setting.

65.       How many weg.configs can an application have?
Ans. One.

66.       How do you set language in weg.config?
Ans. defaultLanguage=”vb”: This specifies the default code language.
debug=”true”: This specifies that the application should be run in debug
mode

67.       What does connection string consist of?
Ans. Server, user id, password, database name.

68.       Where do you store connection string?
Ans. Web.config

69.       What is abstract class?
An abstract class is a class that cannot be instantiated. Its purpose is to act as a base class from which other classes may be derived.

70.       What is difference between interface inheritance and class inheritance?
Ans. We can only inherit from one class but multiple interfaces. In addition, an interface does not contain any implementation it just contains a series of signatures.

71.       What are the collection classes?
Ans. Queue, Stack, BitArray, HashTable, LinkedList, ArrayList, Name ValueCollection, Array, SortedList , HybridDictionary, ListDictionary, StringCollection, StringDictionary

72.       What are the types of threading models?
Ans. Single Threading: This is the simplest and most common threading model where a single thread corresponds to your entire application’s process.

Apartment Threading (STA): This allows multiple threads to exist in a single application. In single threading apartment (STA), each thread is isolated in it’s own apartment. The process may contain multiple
threads (apartments) however when an object is created in a thread (i.e. apartment) it stays within that
apartment. If any communication needs to occur between different threads (i.e. different apartments) then we must marshal the first thread object to the second thread. Free Threading: The most complex threading model. Unlike STA, threads are not confined to their own apartments. Multiple treads can make calls to the same methods and same components at the same time.

73.       What inheritance does VB.NET support?
Ans. Single inheritance using classes or multiple inheritance using
interfaces.

74.       What is a runtime host?
Ans. The runtime host is the environment in which the CLR is started and managed.

75.       Describe the techniques for optimising your application?
Ans: Avoid round-trips to server. Perform validation on client. Save viewstate only when necessary.
. Employ caching.
. Leave buffering on unless there is a dire need to disable it.
. Use connection pooling.
. Use stored procedures instead of in-line SQL or dynamic SQL.

76.       Differences between application and session
Ans. The session object maintains state on a per client basis whereas the application object is on a per application basis and is consistent across all client requests.

77.       What is web application virtual directory?
Ans. A virtual directory appears to client browsers as though it were contained in a Web server’s root directory, even though it can physically Reside somewhere else.

78.       What is isPostback property?
This property is used to check whether the page is being loaded and accessed for the first time or whether the page is loaded in response to the client postback.
Example:-
Consider two combo boxes In one lets have a list of countries In the other, the states. Upon selection of the first, the subsequent one should be populated in accordance. So this requires postback property in combo boxes to be true.

79.       Where do you store connection string?
Ans. Database connection string can be stored in the web config file. The connection string can be stored in the WEB.Config file under element

80.       What does connection string consist of?
Ans. The connection string consists of the following parts:
In general:
Server: Whether local or remote.
Uid: User Id (sa-in sql server)
Password: The required password to be filled-in here
Database: The database name.

81.       What are the collection classes?
Ans. The .NET Framework provides specialized classes for data storage and retrieval. These classes provide support for stacks, queues, lists, and hash tables.

83.       What are Abstract base classes?
Ans. Abstact Class is nothing but a true virtual class.This class cannot be instantiated instead it has to be inherited. The method in abstract class are virtual and hence they can be overriden in the child class.

84.       What is difference between interface inhertance and class inheritance?
Ans. Interface inheritance: -
1. The accessibility modifier in Interface is public by defalut.
2. All the methods defined in the interface class should be oveririden in the child class.
Class Inheritance -
1. There is not restriction on the acessibility modifier in a class.
2. Only the method that are defined virtual should be overriden.

85.       ASP.NET OBJECTS?
Ans. Application,Request,Responce,server and session

86.       How do you get the value of a combo box in Javascript?
Ans. document.form_name.element_name.value

87.       Why do we use Option Explicit?
Ans:- Correct answer is - This statement force the declaration of
variables in VB before using them.

88.       How do you create a recordset object in VBScript?
Ans.
//First of all declare a variable to hold the Recordset object,
ex-Dim objRs
//Now, Create this varible as a Recordset object, ex- Set objRs=Server.CreateObject(ADODB.RECORDSET)

89.       What is a class in CSS?
Ans. A class allows you to define different style characteristics to the same HTML element. class is a child to the id, id should be used only once, a css class can be used multiple times:
div id=”banner”
p class=”alert”

90.       When inserting strings into a SQL table in ASP what is the risk and
how can you prevent it?
Ans. SQL Injection, to prevent you probably need to use Stored Procedures instead of inline/incode SQL

91.       what is boxing?
what is unboxing?
what is deep copy & shallow copy?
Ans. Converting the value type into reverence type is call boxing.
Ans. Converting the reference type into value type is call unboxing.

When an object of value type is assigned with another, the data itself is
copied from one object to another. Suppose there are two integer

variables, count1 and count2. Further suppose that count1 contains the value 5 and that count2 is assigned the value of count1.
count1 = 5;
count2 = count1;
Both count1 and count2 now contain their own copies of the data, in this case, the value 5. They are independent. If count1 is now assigned the value 6, count2 will still contain the value 5. This type of copy is referred to as a deep copy. The value itself is copied.
If count1 is now assigned the value 6, count2 will still contain the value 5. This type of copy is referred to as a deep copy.
For reference types copies work differently. Remember that a reference type consists of two parts: the data on the heap and the address of the data stored in the reference variable itself on the stack. When one reference variable is assigned to another, the address stored in the first is copied to the second. They both then refer to the same data content on the heap. This is referred to as a shallow copy.

92.       What will be output for the given code?
Dim I as integer = 5
Do
I = I + 2
Response.Write (I & \” \”)
Loop Until I > 10
Ans. o/p: It generates error because of \” \”. (VB.NET)

93.       What is the output for the following code snippet:
public class testClass
{
public static void Main(string[] args)
{
System.Console.WriteLine(args[1]);
}//end Main
}//end class testClass

2. What is a user control?

• An ASP.NET user control is a group of one or more server controls or static HTML elements that encapsulate a piece of functionality. A user control could simply be an extension of the functionality of an existing server control(s) (such as an image control that can be rotated or a calendar control that stores the date in a text box). Or, it could consist of several elements that work and interact together to get a job done (such as several controls grouped together that gather information about a user's previous work experience).
Source: 15seconds.com

3. What are different types of controls available in ASP.net?
• HTML server controls HTML elements exposed to the server so you can program them. HTML server controls expose an object model that maps very closely to the HTML elements that they render.
• Web server controls Controls with more built-in features than HTML server controls. Web server controls include not only form-type controls such as buttons and text boxes, but also special-purpose controls such as a calendar. Web server controls are more abstract than HTML server controls in that their object model does not necessarily reflect HTML syntax.
• Validation controls Controls that incorporate logic to allow you to test a user's input. You attach a validation control to an input control to test what the user enters for that input control. Validation controls are provided to allow you to check for a required field, to test against a specific value or pattern of characters, to verify that a value lies within a range, and so on.
• User controls Controls that you create as Web Forms pages. You can embed Web Forms user controls in other Web Forms pages, which is an easy way to create menus, toolbars, and other reusable elements.
• Note You can also create output for mobile devices. To do so, you use the same ASP.NET page framework, but you create Mobile Web Forms instead of Web Forms pages and use controls specifically designed for mobile devices.

4. What are the validation controls available in ASP.net?

Type of validation Control to use Description

Required entry RequiredFieldValidator Ensures that the user does not skip an entry.
Comparison to a value CompareValidator Compares a user's entry against a constant value, or against a property value of another control, using a comparison operator (less than, equal, greater than, and so on).
Range checking RangeValidator Checks that a user's entry is between specified lower and upper boundaries. You can check ranges within pairs of numbers, alphabetic characters, and dates.
Pattern matching RegularExpressionValidator Checks that the entry matches a pattern defined by a regular expression. This type of validation allows you to check for predictable sequences of characters, such as those in social security numbers, e-mail addresses, telephone numbers, postal codes, and so on.
User-defined CustomValidator Checks the user's entry using validation logic that you write yourself. This type of validation allows you to check for values derived at run time.
Source: MSDN

5. How will you upload a file to IIS in Asp and how will you do the same in ASP.net?

First of all, we need a HTML server control to allow the user to select the file. This is nothing but the same old <input tag, with the type set to File, such as <input type=file id=”myFile” runat=server />. This will give you the textbox and a browse button. Once you have this, the user can select any file from their computer (or even from a network). Then, in the Server side, we need the following line to save the file to the Web Server.

myFile.PostedFile.SaveAs ("DestinationPath")

Note: The Form should have the following ENC Type
<form enctype="multipart/form-data" runat="server">

Source: ASP Alliance
6. What is Attribute Programming? What are attributes? Where are they used?

Attributes are a mechanism for adding metadata, such as compiler instructions and other data about your data, methods, and classes, to the program itself. Attributes are inserted into the metadata and are visible through ILDasm and other metadata-reading tools. Attributes can be used to identify or use the data at runtime execution using .NET Reflection.
Source: OnDotNet.com

7. What is the difference between Data Reader & Dataset?

Data Reader is connected, read only forward only record set.
Dataset is in memory database that can store multiple tables, relations and constraints; moreover dataset is disconnected and is not aware of the data source.

8. What is the difference between server side and client side code?

Server code is executed on the web server where as the client code is executed on the browser machine.

9. Why would you use “EnableViewState” property? What are the disadvantages?

EnableViewState allows me to retain the values of the controls properties across the requests in the same session. It hampers the performance of the application.

10. What is the difference between Server. Transfer and Response. Redirect?

The Transfer method allows you to transfer from inside one ASP page to another ASP page. All of the state information that has been created for the first (calling) ASP page will be transferred to the second (called) ASP page. This transferred information includes all objects and variables that have been given a value in an Application or Session scope, and all items in the Request collections. For example, the second ASP page will have the same SessionID as the first ASP page.

When the second (called) ASP page completes its tasks, you do not return to the first (calling) ASP page. All these happen on the server side browser is not aware of this.
The redirect message issue HTTP 304 to the browser and causes browser to got the specified page. Hence there is round trip between client and server. Unlike transfer, redirect doesn’t pass context information to the called page.

11. What is the difference between Application_start and Session_start?

Application_start gets fired when an application receive the very first request. Session_start gets fired for each of the user session.

12. What is inheritance and when would you use inheritance?

The concept of child class inheriting the behavior of the parent is called inheritance. If there are many classes in an application that have some part of their behavior common among all , inheritance would be used.

13. What is the order of events in a web form?
1. Init
2. Load
3. Cached post back events
4. Prerender
5. Unload

14. Can you edit Data in repeater control?

No

15. Which template you must provide to display data in a repeater control?

Item Template

16. How can you provide an alternating color scheme in a Data Grid?

Use ALTERNATINGITEMSTYLE and ITEMSTYLE, attributes or Templates

17. Is it possible to bind a data to Textbox?

Yes

18. What method I should call to bind data to control?

Bind Data ()

19. How can I kill a user session?

Call session. abandon.

21. Which is the common property among all the validation controls?

ControlToValidate

22. How do you bind a data grid column manually?

Use BoundColumn tag.

23. Web services can only be written in .NET, true or false?

False

24. What does WSDL, UDDI stands for?

Web Service Description Language.
Universal Description Discovery and Integration
25. How can you make a property read only? (C#)

Use key word Read Only

25. Which validation control is used to match values in two controls?

Compare Validation control.

26. To test a Web Service I must create either web application or windows application. True or false?

False

27. How many classes can a single .NET assembly contains?

Any number

28. What are the data types available in JavaScript?

Object is the only data type available.

29. Is it possible to share session information among ASP and ASPX page?

No, it is not possible as both of these are running under different processes.

30. What are the caching techniques available?
Page cahahing.
Fragment Caching
And Data Caching

31. What are the different types of authentication modes available?

1. Window.
2. Form.
3. Passport.
4. None.

32. Explain the steps involved to populate dataset with data?

Open connection
Initialize Adapter passing SQL and connection as parameter
Initialize Dataset
Call Fill method of the adapter passes dataset as the parameter
Close connection.

33. Can I have data from two different sources into a single dataset?

Yes, it is possible.

34. Is it possible load XML into a Data Reader?

No.

35. Is it possible to have tables in the dataset that are not bound to any data source?

Yes, we can create table object in code and add it to the dataset.

36. Why do you deploy an assembly into GAC?

To allow other application to access the shared assembly.

37. How do you uninstall assembly from GAC?

Use Gacutil.exe with U switch.

38. What does Regasm do?

The Assembly Registration tool reads the metadata within an assembly and adds the necessary entries to the registry, which allows COM clients to create .NET Framework classes transparently. Once a class is registered, any COM client can use it as though the class were a COM class. The class is registered only once, when the assembly is installed. Instances of classes within the assembly cannot be created from COM until they are actually registered.

39. What is the difference between Execute Scalar and ExceuteNonQuery?

Execute Scalar returns the value in the first row first column of a query result set.
ExceuteNonQuery return number of rows affected.

40. What is an assembly?
Assembly is a deployment unit of .NET application. In practical terms assembly is an Executable or a class library.

41. What is CLR?
The common language runtime is the execution engine for .NET Framework applications. It provides a number of services, including the following:
• Code management (loading and execution) Application memory isolation
• Verification of type safety
• Conversion of IL to native code
• Access to metadata (enhanced type information)
• Managing memory for managed objects
• Enforcement of code access security
• Exception handling, including cross-language exceptions
• Interoperation between managed code, COM objects, and pre-existing DLLs (unmanaged code and data)
• Automation of object layout
• Support for developer services (profiling, debugging, and so on)

42. What is the common type system (CTS)?

The common type system is a rich type system, built into the common language runtime that supports the types and operations found in most programming languages. The common type system supports the complete implementation of a wide range of programming languages.

43. What is the Common Language Specification (CLS)?

The Common Language Specification is a set of constructs and constraints that serves as a guide for library writers and compiler writers. It allows libraries to be fully usable from any language supporting the CLS, and for those languages to integrate with each other. The Common Language Specification is a subset of the common type system. The Common Language Specification is also important to application developers who are writing code that will be used by other developers. When developers design publicly accessible APIs following the rules of the CLS, those APIs are easily used from all other programming languages that target the common language runtime.

44. What is the Microsoft Intermediate Language (MSIL)?

MSIL is the CPU-independent instruction set into which .NET Framework programs are compiled. It contains instructions for loading, storing, initializing, and calling methods on objects.
Combined with metadata and the common type system, MSIL allows for true cross-language integration.
Prior to execution, MSIL is converted to machine code. It is not interpreted.

45. What is managed code and managed data?

Managed code is code that is written to target the services of the common language runtime (see what is the Common Language Runtime?). In order to target these services, the code must provide a minimum level of information (metadata) to the runtime. All C#, Visual Basic .NET, and JScript .NET code is managed by default. Visual Studio .NET C++ code is not managed by default, but the compiler can produce managed code by specifying a command-line switch (/CLR).
Closely related to managed code is managed data—data that is allocated and de-allocated by the common language runtime's garbage collector. C#, Visual Basic, and JScript .NET data is managed by default. C# data can, however, be marked as unmanaged through the use of special keywords. Visual Studio .NET C++ data is unmanaged by default (even when using the /CLR switch), but when using Managed Extensions for C++, a class can be marked as managed by using the __gc keyword. As the name suggests, this means that the memory for instances of the class is managed by the garbage collector. In addition, the class becomes a full participating member of the .NET Framework community, with the benefits and restrictions that brings. An example of a benefit is proper interoperability with classes written in other languages (for example, a managed C++ class can inherit from a Visual Basic class). An example of a restriction is that a managed class can only inherit from one base class.

46. What is an assembly?

An assembly is the primary building block of a .NET Framework application. It is a collection of functionality that is built, versioned, and deployed as a single implementation unit (as one or more files). All managed types and resources are marked either as accessible only within their implementation unit or as accessible by code outside that unit.

Assemblies are self-describing by means of their manifest, which is an integral part of every assembly.

The manifest: Establishes the assembly identity (in the form of a text name), version, culture, and digital signature (if the assembly is to be shared across applications).
Defines what files (by name and file hash) make up the assembly implementation.
Specifies the types and resources that make up the assembly, including which are exported from the assembly.
Itemizes the compile-time dependencies on other assemblies.
Specifies the set of permissions required for the assembly to run properly.

This information is used at run time to resolve references, enforce version binding policy, and validate the integrity of loaded assemblies. The runtime can determine and locate the assembly for any running object, since every type is loaded in the context of an assembly. Assemblies are also the unit at which code access security permissions are applied. The identity evidence for each assembly is considered separately when determining what permissions to grant the code it contains.
The self-describing nature of assemblies also helps makes zero-impact install and XCOPY deployment feasible.

47. What are private assemblies and shared assemblies?

A private assembly is used only by a single application, and is stored in that application's install directory (or a subdirectory therein). A shared assembly is one that can be referenced by more than one application. In order to share an assembly, the assembly must be explicitly built for this purpose by giving it a cryptographically strong name (referred to as a strong name). By contrast, a private assembly name need only be unique within the application that uses it.
By making a distinction between private and shared assemblies, we introduce the notion of sharing as an explicit decision. Simply by deploying private assemblies to an application directory, you can guarantee that that application will run only with the bits it was built and deployed with. References to private assemblies will only be resolved locally to the private application directory.
There are several reasons you may elect to build and use shared assemblies, such as the ability to express version policy. The fact that shared assemblies have a cryptographically strong name means that only the author of the assembly has the key to produce a new version of that assembly. Thus, if you make a policy statement that says you want to accept a new version of an assembly, you can have some confidence that version updates will be controlled and verified by the author. Otherwise, you don't have to accept them.
For locally installed applications, a shared assembly is typically explicitly installed into the global assembly cache (a local cache of assemblies maintained by the .NET Framework). Key to the version management features of the .NET Framework is that downloaded code does not affect the execution of locally installed applications. Downloaded code is put in a special download cache and is not globally available on the machine even if some of the downloaded components are built as shared assemblies.
The classes that ship with the .NET Framework are all built as shared assemblies.

48. If I want to build a shared assembly, does that require the overhead of signing and managing key pairs?

Building a shared assembly does involve working with cryptographic keys. Only the public key is strictly needed when the assembly is being built. Compilers targeting the .NET Framework provide command line options (or use custom attributes) for supplying the public key when building the assembly. It is common to keep a copy of a common public key in a source database and point build scripts to this key. Before the assembly is shipped, the assembly must be fully signed with the corresponding private key. This is done using an SDK tool called SN.exe (Strong Name).
Strong name signing does not involve certificates like Authenticode does. There are no third party organizations involved, no fees to pay, and no certificate chains. In addition, the overhead for verifying a strong name is much less than it is for Authenticode. However, strong names do not make any statements about trusting a particular publisher. Strong names allow you to ensure that the contents of a given assembly haven't been tampered with, and that the assembly loaded on your behalf at run time comes from the same publisher as the one you developed against. But it makes no statement about whether you can trust the identity of that publisher.

49. What is the difference between a namespace and an assembly name?

A namespace is a logical naming scheme for types in which a simple type name, such as MyType, is preceded with a dot-separated hierarchical name. Such a naming scheme is completely under the control of the developer. For example, types MyCompany.FileAccess.A and MyCompany.FileAccess.B might be logically expected to have functionality related to file access. The .NET Framework uses a hierarchical naming scheme for grouping types into logical categories of related functionality, such as the Microsoft® ASP.NET application framework, or remoting functionality. Design tools can make use of namespaces to make it easier for developers to browse and reference types in their code. The concept of a namespace is not related to that of an assembly. A single assembly may contain types whose hierarchical names have different namespace roots, and a logical namespace root may span multiple assemblies. In the .NET Framework, a namespace is a logical design-time naming convenience, whereas an assembly establishes the name scope for types at run time.

50. What options are available to deploy my .NET applications?

The .NET Framework simplifies deployment by making zero-impact install and XCOPY deployment of applications feasible. Because all requests are resolved first to the private application directory, simply copying an application's directory files to disk is all that is needed to run the application. No registration is required.
This scenario is particularly compelling for Web applications, Web Services, and self-contained desktop applications. However, there are scenarios where XCOPY is not sufficient as a distribution mechanism. An example is when the application has little private code and relies on the availability of shared assemblies, or when the application is not locally installed (but rather downloaded on demand). For these cases, the .NET Framework provides extensive code download services and integration with the Windows Installer. The code download support provided by the .NET Framework offers several advantages over current platforms, including incremental download, code access security (no more Authenticode dialogs), and application isolation (code downloaded on behalf of one application doesn't affect other applications). The Windows Installer is another powerful deployment mechanism available to .NET applications. All of the features of Windows Installer, including publishing, advertisement, and application repair will be available to .NET applications in Windows Installer 2.0.

51. I've written an assembly that I want to use in more than one application. Where do I deploy it?

Assemblies that are to be used by multiple applications (for example, shared assemblies) are deployed to the global assembly cache. In the prerelease and Beta builds, use the /i option to the GACUtil SDK tool to install an assembly into the cache:
gacutil /i myDll.dll
Windows Installer 2.0, which ships with Windows XP and Visual Studio .NET will be able to install assemblies into the global assembly cache.

52. How can I see what assemblies are installed in the global assembly cache?

The .NET Framework ships with a Windows shell extension for viewing the assembly cache. Navigating to % windir%\assembly with the Windows Explorer activates the viewer.

53. What is an application domain?

An application domain (often AppDomain) is a virtual process that serves to isolate an application. All objects created within the same application scope (in other words, anywhere along the sequence of object activations beginning with the application entry point) are created within the same application domain. Multiple application domains can exist in a single operating system process, making them a lightweight means of application isolation.

An OS process provides isolation by having a distinct memory address space. While this is effective, it is also expensive, and does not scale to the numbers required for large web servers. The Common Language Runtime, on the other hand, enforces application isolation by managing the memory use of code running within the application domain. This ensures that it does not access memory outside the boundaries of the domain. It is important to note that only type-safe code can be managed in this way (the runtime cannot guarantee isolation when unsafe code is loaded in an application domain).

54. What is garbage collection?

Garbage collection is a mechanism that allows the computer to detect when an object can no longer be accessed. It then automatically releases the memory used by that object (as well as calling a clean-up routine, called a "finalizer," which is written by the user). Some garbage collectors, like the one used by .NET, compact memory and therefore decrease your program's working set.

55. How does non-deterministic garbage collection affect my code?

For most programmers, having a garbage collector (and using garbage collected objects) means that you never have to worry about deallocating memory, or reference counting objects, even if you use sophisticated data structures. It does require some changes in coding style, however, if you typically deallocate system resources (file handles, locks, and so forth) in the same block of code that releases the memory for an object. With a garbage collected object you should provide a method that releases the system resources deterministically (that is, under your program control) and let the garbage collector release the memory when it compacts the working set.

56. Can I avoid using the garbage collected heap?

All languages that target the runtime allow you to allocate class objects from the garbage-collected heap. This brings benefits in terms of fast allocation, and avoids the need for programmers to work out when they should explicitly 'free' each object.
The CLR also provides what are called ValueTypes—these are like classes, except that ValueType objects are allocated on the runtime stack (rather than the heap), and therefore reclaimed automatically when your code exits the procedure in which they are defined. This is how "structs" in C# operate.
Managed Extensions to C++ lets you choose where class objects are allocated. If declared as managed Classes, with the __gc keyword, then they are allocated from the garbage-collected heap. If they don't include the __gc keyword, they behave like regular C++ objects, allocated from the C++ heap, and freed explicitly with the "free" method.

57. How do in-process and cross-process communication work in the Common Language Runtime?

There are two aspects to in-process communication: between contexts within a single application domain, or across application domains. Between contexts in the same application domain, proxies are used as an interception mechanism. No marshaling/serialization is involved. When crossing application domains, we do marshaling/serialization using the runtime binary protocol.
Cross-process communication uses a pluggable channel and formatter protocol, each suited to a specific purpose.
If the developer specifies an endpoint using the tool soapsuds.exe to generate a metadata proxy, HTTP channel with SOAP formatter is the default.
If a developer is doing explicit remoting in the managed world, it is necessary to be explicit about what channel and formatter to use. This may be expressed administratively, through configuration files, or with API calls to load specific channels. Options are:
HTTP channel w/ SOAP formatter (HTTP works well on the Internet, or anytime traffic must travel through firewalls)
TCP channel w/ binary formatter (TCP is a higher performance option for local-area networks (LANs))
When making transitions between managed and unmanaged code, the COM infrastructure (specifically, DCOM) is used for remoting. In interim releases of the CLR, this applies also to serviced components (components that use COM+ services). Upon final release, it should be possible to configure any remotable component.
Distributed garbage collection of objects is managed by a system called "leased based lifetime." Each object has a lease time, and when that time expires, the object is disconnected from the remoting infrastructure of the CLR. Objects have a default renew time-the lease is renewed when a successful call is made from the client to the object. The client can also explicitly renew the lease.

58. Can I use COM objects from a .NET Framework program?

Yes. Any COM component you have deployed today can be used from managed code, and in common cases the adaptation is totally automatic.
Specifically, COM components are accessed from the .NET Framework by use of a runtime callable wrapper (RCW). This wrapper turns the COM interfaces exposed by the COM component into .NET Framework-compatible interfaces. For OLE automation interfaces, the RCW can be generated automatically from a type library. For non-OLE automation interfaces, a developer may write a custom RCW and manually map the types exposed by the COM interface to .NET Framework-compatible types.

59. Can .NET Framework components be used from a COM program?

Yes. Managed types you build today can be made accessible from COM, and in the common case the configuration is totally automatic. There are certain new features of the managed development environment that are not accessible from COM. For example, static methods and parameterized constructors cannot be used from COM. In general, it is a good idea to decide in advance who the intended user of a given type will be. If the type is to be used from COM, you may be restricted to using those features that are COM accessible.
Depending on the language used to write the managed type, it may or may not be visible by default.
Specifically, .NET Framework components are accessed from COM by using a COM callable wrapper (CCW). This is similar to an RCW (see previous question), but works in the opposite direction. Again, if the .NET Framework development tools cannot automatically generate the wrapper, or if the automatic behavior is not what you want, a custom CCW can be developed.

60. Can I use the Win32 API from a .NET Framework program?

Yes. Using platform invoke, .NET Framework programs can access native code libraries by means of static DLL entry points.
Here is an example of C# calling the Win32 MessageBox function:
using System;
using System.Runtime.InteropServices;

class MainApp
{
[DllImport("user32.dll", EntryPoint="MessageBox")]
public static extern int MessageBox(int hWnd, String strMessage, String strCaption, uint uiType);

public static void Main()
{
MessageBox( 0, "Hello, this is PInvoke in operation!", ".NET", 0 );
}
}

61. What do I have to do to make my code work with the security system?

Usually, not a thing—most applications will run safely and will not be exploitable by malicious attacks. By simply using the standard class libraries to access resources (like files) or perform protected operations (such as a reflection on private members of a type), security will be enforced by these libraries. The one simple thing application developers may want to do is include a permission request (a form of declarative security) to limit the permissions their code may receive (to only those it requires). This also ensures that if the code is allowed to run, it will do so with all the permissions it needs.
Only developers writing new base class libraries that expose new kinds of resources need to work directly with the security system. Instead of all code being a potential security risk, code access security constrains this to a very small bit of code that explicitly overrides the security system.

62. Why does my code get a security exception when I run it from a network shared drive?

Default security policy gives only a restricted set of permissions to code that comes from the local intranet zone. This zone is defined by the Internet Explorer security settings, and should be configured to match the local network within an enterprise. Since files named by UNC or by a mapped drive (such as with the NET USE command) are being sent over this local network, they too are in the local intranet zone.
The default is set for the worst case of an unsecured intranet. If your intranet is more secure you can modify security policy (with the .NET Framework Configuration tool or the CASPol tool) to grant more permissions to the local intranet, or to portions of it (such as specific machine share names).

63. How do I make it so that code runs when the security system is stopping it?

Security exceptions occur when code attempts to perform actions for which it has not been granted permission. Permissions are granted based on what is known about code; especially its location. For example, code run from the Internet is given fewer permissions than that run from the local machine because experience has proven that it is generally less reliable. So, to allow code to run that is failing due to security exceptions, you must increase the permissions granted to it. One simple way to do so is to move the code to a more trusted location (such as the local file system). But this won't work in all cases (web applications are a good example, and intranet applications on a corporate network are another). So, instead of changing the code's location, you can also change security policy to grant more permissions to that location. This is done using either the .NET Framework Configuration tool or the code access security policy utility (caspol.exe). If you are the code's developer or publisher, you may also digitally sign it and then modify security policy to grant more permissions to code bearing that signature. When taking any of these actions, however, remember that code is given fewer permissions because it is not from an identifiably trustworthy source—before you move code to your local machine or change security policy, you should be sure that you trust the code to not perform malicious or damaging actions.

64. How do I administer security for my machine? For an enterprise?

The .NET Framework includes the .NET Framework Configuration tool, an MMC snap-in (mscorcfg.msc), to configure several aspects of the CLR including security policy. The snap-in not only supports administering security policy on the local machine, but also creates enterprise policy deployment packages compatible with System Management Server and Group Policy. A command line utility, CASPol.exe, can also be used to script policy changes on the computer. In order to run either tool, in a command prompt, change the current directory to the installation directory of the .NET Framework (located in %windir%\Microsoft.Net\Framework\v1.0.2914.16\) and type mscorcfg.msc or caspol.exe.

65. What’s the implicit name and type of the parameter that gets passed into the class’ set method?

Value, and it’s data type depends on whatever variable we’re changing.

66. How do you inherit from a class in C#?

Place a colon and then the name of the base class. Notice that it’s double colon in C++.

67. Does C# support multiple inheritance?

No, use interfaces instead.

68. When you inherit a protected class-level variable, who is it available to?

Classes in the same namespace.

69. Are private class-level variables inherited?

Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are.

69. Describe the accessibility modifier protected internal.

It’s available to derived classes and classes within the same Assembly (and naturally from the base class it’s declared in).

70. C# provides a default constructor for me. I write a constructor that akes a string as a parameter, but want to keep the no parameter one. How many constructors should I write?

Two. Once you write at least one constructor, C# cancels the freebie constructor, and now you have to write one yourself, even if there’s no implementation in it.

71. What’s the top .NET class that everything is derived from?
System.Object .

72. How’s method overriding different from overloading?

When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.

73. What does the keyword virtual mean in the method definition?
The method can be over-ridden.

74. Can you declare the override method static while the original method is non-static?
No, you can’t, the signature of the virtual method must remain the same, only the keyword virtual is changed to keyword override.

75. Can you override private virtual methods?
No, moreover, you cannot access private methods in inherited classes, have to be protected in the base class to allow any sort of access.

76. Can you prevent your class from being inherited and becoming a base class for some other classes?

Yes, that’s what keyword sealed in the class definition is for. The developer trying to derive from your class will get a message: cannot inherit from Sealed class WhateverBaseClassName. It’s the same concept as final class in Java.

77. Can you allow class to be inherited, but prevent the method from being over-ridden?

Yes, just leave the class public and make the method sealed.

78. What’s an abstract class?

A class that cannot be instantiated.A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden. Essentially, it’s a blueprint for a class without any implementation.

79. When do you absolutely have to declare a class as abstract (as opposed to free-willed educated choice or decision based on UML diagram)?
When at least one of the methods in the class is abstract. When the class itself is inherited from an abstract class, but not all base abstract methods have been over-ridden.

80. What’s an interface class?
It’s an abstract class with public abstract methods all of which must be implemented in the inherited classes.

81. Why can’t you specify the accessibility modifier for methods inside the interface?
They all must be public. Therefore, to prevent you from getting the false impression that you have any freedom of choice, you are not allowed to specify any accessibility, it’s public by default.

82. Can you inherit multiple interfaces?
Yes, why not.

83. And if they have conflicting method names?
It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.

84. What’s the difference between an interface and abstract class?
In the interface all methods must be abstract, in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.

85. How can you overload a method?
Different parameter data types, different number of parameters, different order of parameters.

86. If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor?
Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

87. What’s the difference between System. String and System.StringBuilder classes?
System. String is immutable; System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed

88. How big is the data type int in .NET?
32 bits.

89. How big is the char?
16 bits (Unicode).

90. How do you initiate a string without escaping each backslash?
Put an @ sign in front of the double-quoted string.

91. What are valid signatures for the Main function?
public static void Main ()
public static int Main ()
public static void Main ( string[] args )
public static int Main (string[] args )

92. How do you initialize a two-dimensional array that you don’t know the dimensions of?
int [ , ] myArray; //declaration
myArray = new int [5, 8]; //actual initialization

93. What’s the access level of the visibility type internal?
Current application.

94. What’s the difference between struct and class in C#?
Structs cannot be inherited.
Structs are passed by value, not by reference.
Struct is stored on the stack, not the heap.

95. Explain encapsulation.
The implementation is hidden, the interface is exposed.

96. What data type should you use if you want an 8-bit value that’s signed?
sbyte .

97. Speaking of Boolean data types, what’s different between C# and /C++?
There’s no conversion between 0 and false, as well as any other number and true, like in C/C++.

98. Where are the value-type variables allocated in the computer RAM?
Stack.

99. Where do the reference-type variables go in the RAM?
The references go on the stack, while the objects themselves go on the heap.

100. What is the difference between the value-type variables and reference-type variables in terms of garbage collection?
The value-type variables are not garbage-collected, they just fall off the stack when they fall out of scope, the reference-type objects are picked up by GC when their references go null.

101. How do you convert a string into an integer in .NET?
Int32.Parse( string)

102. How do you box a primitive data type variable?
Assign it to the object, pass an object.

103. Why do you need to box a primitive variable?

To pass it by reference.

104. What’s the difference between Java and .NET garbage collectors?

Sun left the implementation of a specific garbage collector up to the JRE developer, so their performance varies widely, depending on whose JRE you’re using. Microsoft standardized on their garbage collection.

105. How do you enforce garbage collection in .NET?

System.GC.Collect ( );

106. Can you declare a C++ type destructor in C# like ~MyClass ()?

Yes, but what’s the point, since it will call Finalize(), and Finalize() has no guarantees when the memory will be cleaned up, plus, it introduces additional load on the garbage collector.

107. What’s different about namespace declaration when comparing that to package declaration in Java?

No semicolon.

108. What’s the difference between const and read only?

You can initialize read only variables to some runtime values. Let’s say your program uses current date and time as one of the values that won’t change. This way you declare public read only string DateT = new DateTime ().ToString ().

109. What does \a character do?

On most systems, produces a rather annoying beep.

110. Can you create enumerated data types in C#?

Yes.

111. What’s different about switch statements in C#?

No fall-throughs allowed.

112. What happens when you encounter a continue statement inside the for loop?

The code for the rest of the loop is ignored; the control is transferred back to the beginning of the loop.

113. Is goto statement supported in C#? How about Java?

Gotos are supported in C# to the fullest. In Java goto is a reserved keyword that provides absolutely no functionality.

114. What is the purpose of XSLT other than displaying XML contents in HTML?

Creating XSLTs to transform XML instances into text, HTML and other XML structures

115. How to refresh a static HTML page?

Using meta tag:

<head>

<META http-equiv="refresh" content="60">

</head>

Using Javascript:

function OnLoad(){

 window.setTimeOut(Refresh, 5000);



}

function Refresh(){

 //do something

}

116. What is the difference between DELETE and TRUNCATE in SQL?

Truncate is ddl (Data Defination Langauge) command. Its faster than delete as it doesnt have go through the rollbacks etc. Truncate being a ddl is auto commit. We can only truncate the whole table (cant use where clause). Once table is truncated we cant rollback the changes.when a table is truncated the memory occupied is released. That id the water mark is adjusted. It can not maintain the Log file to store information.

Delete is a dml (Data Manupulation Langauge) command and can be rolled back is slower than truncate as it is dml has to go through rollback segments etc. We can use where clause with delete when a table is deleted memory occupied is not released ans also the water mark is not adjusted. It maintain the Log file to store the delete information.

117. How to declare the XSLT document?

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

118. What are the data Islands in XML?

An XML data island is an XML document that exists within an HTML page. It allows you to script against the XML document without having to load the XML document through script or through the <OBJECT> tag. Almost anything that can be in a well-formed XML document can be inside a data island.

The <XML> element marks the beginning of the data island, and its ID attribute provides a name that you can use to reference the data island.

The following list shows the methods in which a data island may be created:

· Inline XML

Inline XML is enclosed within the <XML> and </XML> tags, and is inserted in HTML code, as shown in the following example.

<name>Mark Hanson</name>

</customer>

</XML>

· Using the <XML> tag

External XML uses the SRC attribute on the <XML> tag to reference an external file. The SRC attribute can refer to a local file or specify a URL. By using URLs that point to external servers, data can be integrated from several sources. The following code uses the SRC attribute with a local file.

119. Can you read the View State?

The Viewstate of an ASP.NET page is created during the page life cycle, and saved into the rendered HTML using in the “__VIEWSTATE” hidden HTML field. The value stored in the “__VIEWSTATE” hidden field is the result of serialization of two types of data:

Any programmatic change of state of the ASP.NET page and its controls. (Tracking and “Dirty” items come into play here.)

Any data stored by the developer using the Viewstate.

This value is loaded during postbacks, and is used to preserve the state of the web page.

120. What is the difference between encoding and encryption? Which is easy to break?

Encoding is changing the way data is presented
- using a public, generally-understood, and (usually) low-overhead method
- for the purpose of allowing the data to survive intact and easily recoverable after some sort of transfer.

Encryption is changing the way data is presented
- using a method or a key that is restricted and (as it happens) often computationally intensive
- for the purpose of shielding the data from some people while making it available to others.

In short, encoding is for preservation, encryption is for obfuscation.

Encoder is more easy to decode than Encryption.

121. Can we disable the view state application wide?

Yes, can be disable the viewstate of whole application.

122. Can we disable it on page wide?

Yes, can be disable the viewstate of a Page

123. Can we disable it for a control?

Yes, can be disable the viewstate of a Control.

124. What is provider Model?

The provider model is one way to break the rigid implementation problem. With the provider model, the system is flexible enough to be able to use any class that extends a particular base class. Therefore, customers can create their own derived classes that include their custom logic and business rules. This new class can be seamlessly plugged into the system, without disturbing existing code shipped with the application or any new, custom code that has since been created. The provider model is heavily used in ASP.NET 2.0

*Any idea of Data Access Component provided by Microsoft?
*Any idea of Enterprise library?
125. What is web service?

Web services are application components
Web services communicate using open protocols
Web services are self-contained and self-describing
Web services can be discovered using UDDI
Web services can be used by other applications
XML is the basis for Web services

125. Can a web service be only developed in asp. net?

No, it can be developed by any language.

126. Can we use multiple web services from a single application?

Yes.
127. Can we call a web service asynchronously?

Currently there are two methods of performing asynchronous calls:

1. CallBacks

2. WaitHandles

Asynchronous Call using an `AsyncCallback`

In this approach, we create a delegate which can be invoked during runtime when the results from the web service are returned. Here's how it works.

// Button Click event

private void AsyncCallUsingCallBackBtn_Click(object sender, System.EventArgs e)

   string mLangInput = "English";

   // Create an instance of the WebService

   localhost.MyAsyncWebService webServ = new localhost.MyAsyncWebService();

   // Create a delegate to handle the callback

   AsyncCallback asyncCall = new AsyncCallback(CallbackSampleMethod);

   // Make an Asynchronous Call by calling

   // the Begin method of the proxy class

   webServ.BeginMyWebMethod(this.mLangInput, asyncCall, webServ);

   // Do some process while the web

   // service is processing the request

   System.Threading.Thread.Sleep(10000);

// CallBack function

private void CallbackSampleMethod(IAsyncResult asyncResult)

   // Create an instance of the WebService

   localhost.MyAsyncWebService webServ = (localhost.MyAsyncWebService)asyncResult.AsyncState;

   // Get the Result of the WebMethod by calling

   // the end method of the proxy class

   mLangResult = webServ.EndMyWebMethod(asyncResult);

   // Display the results in a label

   Label1.Text = this.mLangResult;

In the Button Click event, the proxy's Begin<WebServiceMethod>(BeginMyWebMethod) web service is called by passing in the following parameters:

WebMethod parameters (this.mLangInput)
AsyncCallback(asyncCall)
An instance of the web service(webServ)

The CallBack function should have an instance of the IAsyncResult instance as a parameter (see the above code). After the web service returns the results, then the Callback function is activated (CallbackSampleMethod). Results of the web service are obtained by calling the proxy'sEnd<WebServiceMethod> (EndMyWebMethod).

Asynchronous Call using `WaitHandle`

This approach utilizes a different technique, in that we have a wait handle object. This object will wait until the web service returns. When the parent thread gets to the function WaitOne (or WaitAll or WaitOne), it waits for the web service to return. After the web service returns the results, then the parent thread process will continue.

string mLangInput = "English";

// Create an instance of the WebService

localhost.MyAsyncWebService webServ =  new localhost.MyAsyncWebService();

// Create an IAsyncResult object to hold results

IAsyncResult asyncResult;

// Make an Asynchronous Call

asyncResult = webServ.BeginMyWebMethod(this.mLangInput, null, null);

// Do something while the WebService is doing its work

str1 = "Doing some work while the WebService is being called.";

// Call WaitHandle to wait for the web service method to return

WaitHandle wtHandle = asyncResult.AsyncWaitHandle;

wtHandle.WaitOne();

// Get the Result of the WebMethod (this occurs when

// WebService finished processing)

mLangResult = webServ.EndMyWebMethod(asyncResult);

// Display the results in a label

Label1.Text = str1 + this.mLangResult;

This process uses the Begin<WebServiceMethod> (BeginMyWebMethod) and assigns the result to the IAsyncResult instance, passing in method parameters and null values for Callback and asyncState (as callback is not used). The WaitOne() method causes the thread to wait for the results from the web service. When the results from the web service are ready, then End<WebServiceMethod>(EndMyWebMethod) is called to retrieve the results.

128. Can a web service be used from a windows application?

Yes.
129. What do we need to deploy a web service?

Web Server
130. What is the significance of web.config?

Web.config file, as it sounds like is a configuration file for the Asp .net web application. An Asp .net application has one web.config file which keeps the configurations required for the corresponding application. Web.config file is written in XML with specific tags having specific meanings.

131. Can we have multiple web.config files in a sigle web project?

Yes, but maintain the hierarchy.
132. Can we have more then one configuration file?

Yes, but maintain the hierarchy.

133. Type of Authentications?

1.Windows-based authentication

Windows authentication is enabled by default in the Machine.Config file. This setting is automatically inherited by all ASP.NET applications running on the same server.

If you have modified the Machine.Config file-for example, you have set the default authentication method to Forms authentication-you can explicitly enable Windows authentication for an application by adding the Web.Config file to the application root directory.

After the Windows authentication is enabled, authorization can be provided to particular users and groups to access particular directories and files by using Web.Config file.

2.Forms-based authentication

Forms-based authentication is an ASP.NET authentication service that enables applications to provide their own logon UI and do their own credential verification. ASP.NET authenticates users, redirects unauthenticated users to the logon page, and performs all the necessary cookie management. This sort of authentication is a popular technique used by many Web sites.

3.Passport-based authentication

Passport authentication is a centralized authentication service provided by Microsoft that offers a single logon and core profile services for member sites. This benefits the user because it is no longer necessary to log on to access new protected resources or sites. If you want your site to be compatible with Passport authentication and authorization, this is the provider you should use. This document provides some introductory material about Microsoft Passport and the ASP.NET support for it.

134. Can we have multiple assemblies in a single web project?

Yes
135. What is GAC?

GAC (Global Assembly Cache) is a repository of shared assemblies maintained by the .NET runtime. The shared assemblies may be used by many applications. To make an assembly a shared assembly, it has to be strongly named.

GAC is located at C:\Windows\Assembly OR C:\Winnt\Assembly

136. What is machine.config?

As web.config file is used to configure one asp.net web application, same way Machine.config file is used to configure the application according to a particular machine. That is, configuration done in machine.config file is affected on any application that runs on a particular machine. Usually, this file is not altered and only web.config is used which configuring applications.

137. What is AJAX?

AJAX (Asynchronous JavaScript and XML) is a web development technique for creating interactive web applications. It allows content on a page to refreshed without refreshing the entire page. This allows one section of page to stay up to date by getting new information regularly at a set frequency with out the need for the website visitor to keep refreshing the entire page.

138. Is AJAX a language?

Ajax is not a technology in itself, but a term that refers to the use of a group of technologies together.

139. What is an AJAX application?

Ajax applications, can send requests to the web server to retrieve only the data that is needed, and may use SOAP or some other XML-based web services dialect. On the client, JavaScript processes the web server's response, and may then modify the document's content through the DOM to show the user that an action has been completed. The result is a more responsive application, since the amount of data interchanged between the web browser and web server is vastly reduced. Web server processing time is also saved, since much of it is done on the client.

140. What is an Assembly?

An Assembly is a fundamental building block of any .NET Framework application. For example, when you build a simple C# application, Visual Studio creates an assembly in the form of a single portable executable (PE) file, specifically an EXE or DLL.

141. Can an assembly contains more then one classes?

Yes.
142. What is strong name?

A name that consists of an assembly's identity—its simple text name, version number, and culture information (if provided)—strengthened by a public key and a digital signature generated over the assembly.

143. What is the difference b/w client and server side?

Server side code get executed on the web server in the response of request for any aspx page
where as client-side code get executed on the client browser (e.g validation of controls etc.)

144. What we need for the deployment of a asp.net web application?

IIS (Internet Information Services)
145. what is the purpose of IIS?

IIS is web server which will accepts the request from client and serve the request ,means it will send the respons of requested web page to the client.
146. Difference between http and https?

Hypertext Transfer Protocol (http) is a system for transmitting and receiving information across the Internet. Http serves as a request and response procedure that all agents on the Internet follow so that information can be rapidly, easily, and accurately disseminated between servers, which hold information, and clients, who are trying to access it. Http is commonly used to access html pages, but other resources can be utilized as well through http. In many cases, clients may be exchanging confidential information with a server, which needs to be secured in order to prevent unauthorized access. For this reason, https, or secure http, was developed by Netscape corporation to allow authorization and secured transactions, that means is that your whatever data that is being transmitted from your browser to the server is encrypted prior transmission and decrypted on the server side.

147. what is purpose of aspnet_wp.exe ?
148. what is an ISAPI filter?

ISAPI filters always run on an IIS server, filtering every request until they find one they need to process. The ability to examine and modify both incoming and outgoing streams of data makes ISAPI filters powerful and flexible.

149. what do you mean by HTTP Handler?
150. What is the purpose of Global.asax?

Global.asax is a file used to declare application-level events and objects. Global.asax is the ASP.NET extension of the ASP Global.asa file. Code to handle application events (such as the start and end of an application) reside in Global.asax. Such event code cannot reside in the ASP.NET page or web service code itself, since during the start or end of the application, its code has not yet been loaded (or unloaded). Global.asax is also used to declare data that is available across different application requests or across different browser sessions. This process is known as application and session state management.

The Global.asax file must reside in the IIS virtual root. Remember that a virtual root can be thought of as the container of a web application. Events and state specified in the global file are then applied to all resources housed within the web application. If, for example, Global.asax defines a state application variable, all .aspx files within the virtual root will be able to access the variable.

Like an ASP.NET page, the Global.asax file is compiled upon the arrival of the first request for any resource in the application. The similarity continues when changes are made to the Global.asax file: ASP.NET automatically notices the changes, recompiles the file, and directs all new requests to the newest compilation.

151. What is the significance of Application_Start/Session_Start/Application_Error?
152. What is the difference between the inline and code behind?

There are a few differences in the processing of code-behind and single-file pages.

Code Behind	Single File
The HTML and controls are in the .aspx file, and the code is in a separate .aspx.vb or.aspx.cs file.	The code is in <script> blocks in the same .aspx file that contains the HTML and controls.
The code for the page is compiled into a separate class from which the .aspx file derives.	The .aspx file derives from the Pageclass.
All project class files (without the .aspx file itself) are compiled into a .dll file, which is deployed to the server without any source code. When a request for the page is received, then an instance of the project .dllfile is created and executed.	When the page is deployed, the source code is deployed along with the Web Forms page, because it is physically in the .aspx file. However, you do not see the code, only the results are rendered when the page runs.

153. what is side by side execution?

Side-by-side execution is the ability to install multiple versions of code so that an application can choose which version of the common language runtime or of a component it uses. Subsequent installations of other versions of the runtime, an application, or a component will not affect applications already installed.

154. Can we have two different versions of dot net frameworks running on the same machine?

YES

158. What is .resx file meant for?

The .resx resource file format consists of XML entries, which specify objects and strings inside XML tags. One advantage of a .resx file is that when opened with a text editor (such as Notepad or Microsoft Word) it can be written to, parsed, and manipulated. When viewing a .resx file, you can actually see the binary form of an embedded object (a picture for example) when this binary information is a part of the resource manifest. Apart from this binary information, a .resx file is completely readable and maintainable.

160. Any idea of ASP NET State Service?

The ASP.NET state service is used to manage session state on a computer. The ASP.NET state service is installed by default when Microsoft® Windows® Server 2003 is installed. The file aspnet_state.exe is installed on the remote server that will store session state information; the default location is systemroot\Microsoft.NET\Framework\version\aspnet_state.exe.

161. Crystal report is only used for read only data and reporting purposes?

YES
162. We can add a crystal report in aspx page using two techniques, what are these?
163. What is the difference between stroed procedure and stored function in SQL?

Stored procedure

A stored procedure is a program (or procedure) which is physically stored within a database. They are usually written in a proprietary database language like PL/SQL for Oracle database or PL/PgSQL for PostgreSQL. The advantage of a stored procedure is that when it is run, in response to a user request, it is run directly by the database engine, which usually runs on a separate database server. As such, it has direct access to the data it needs to manipulate and only needs to send its results back to the user, doing away with the overhead of communicating large amounts of data back and forth.

User-defined function

A user-defined function is a routine that encapsulates useful logic for use in other queries. While views are limited to a single SELECT statement, user-defined functions can have multiple SELECT statements and provide more powerful logic than is possible with views.

In SQL Server 2000

User defined functions have 3 main categories

Scalar-valued function - returns a scalar value such as an integer or a timestamp. Can be used as column name in queries

Inline function - can contain a single SELECT statement.

Table-valued function - can contain any number of statements that populate the table variable to be returned. They become handy when you need to return a set of rows, but you can't enclose the logic for getting this rowset in a single SELECT statement.

Differences between Stored procedure and User defined functions

1. UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be.

2. UDFs that return tables can be treated as another rowset. This can be used in JOINs with other tables.

3. Inline UDF's can be though of as views that take parameters and can be used in JOINs and other Rowset operations.

4. Of course there will be Syntax differences and here is a sample of that

CREATE PROCEDURE dbo.StoredProcedure1
/*
(
@parameter1 datatype = default value,
@parameter2 datatype OUTPUT
)
*/
AS
/* SET NOCOUNT ON */
RETURN

CREATE FUNCTION dbo.Function1
(
/*
@parameter1 datatype = default value,
@parameter2 datatype
*/
)
RETURNS /* datatype */
AS
BEGIN
/* sql statement ... */
RETURN /* value */
END

164. Can we have an updateable view in SQL?

YES
165. What is connection pooling? how can we acheive that in asp.net?

Connection pool and connection string go hand in hand. Every connection pool is associated with a distinct connection string and that too, it is specific to the application. In turn, what it means is – a separate connection pool is maintained for every distinct process, app domain and connection string.

When any database request is made through ADO.NET, ADO.NET searches for the pool associated with the exact match for the connection string, in the same app domain and process. If such a pool is not found, ADO.NET creates a new one for it, however, if it is found, it tries to fetch the usable connection from that pool. If no usable free connection is found in the pool, a new connection is created and added to the pool. This way, new connections keep on adding to the pool tillMax Pool Size is reached, after that when ADO.NET gets request for further connections, it waits for Connection Timeout time and then errors out.

166. What is DataSet?

Dataset is disconnected architecture.dataset persists and load data in xml format.dataset can load data from different datasources.through the dataset we can define relationships among the datadatable.

167. What is the difference between typed and untyped dataset?

A typed dataset is a dataset that is first derived from the base DataSet class and then uses information in an XML Schema file (an .xsd file) to generate a new class. Information from the schema (tables, columns, and so on) is generated and compiled into this new dataset class as a set of first-class objects and properties.

An untyped dataset, in contrast, has no corresponding built-in schema. As in a typed dataset, an untyped dataset contains tables, columns, and so on — but those are exposed only as collections. (However, after manually creating the tables and other data elements in an untyped dataset, you can export the dataset's structure as a schema using the dataset's WriteXmlSchema method.)

An "untyped" dataset is an instance of the DataSet class from the System.Data namespace. It’s called “untyped” because all columns are provided as the base System.Object type (“object” in C# and “Object” in VB.NET) and must be coerced to the appropriate type, e.g.
void Form1_Load(object sender, EventArgs e) {
  DataSet ds = new DataSet();
  sqlDataAdapter1.Fill(ds);
  foreach( DataRow row in ds.Tables[0].Rows ) {
    string fname = (string)row["au_fname"];
    bool contract = (bool)row["contract"];
    string item =
      string.Format("{0} has a contract: {1}", fname, contract);
    listBox1.Items.Add(item);
  }
}
The problem, of course, is that it’s a pain to get the coercion code is tedious to write and easy to get wrong. A type-safe dataset, on the other hand, allows you to write the following code:
void Form1_Load(object sender, EventArgs e) {
  AuthorsDataSet ds = new AuthorsDataSet();
  sqlDataAdapter1.Fill(ds);
  foreach( AuthorsDataSet.authorsRow row in ds.authors.Rows ) {
    string fname = row.au_fname;
    bool contract = row.contract;
    string item =
      string.Format("{0} has a contract: {1}", fname, contract);
    listBox1.Items.Add(item);
  }
}
In this case, notice that we have a new type, AuthorsDataSet. It derives from the DataSet base type and provides type-safe access to each column in each row via the authorsRow nested type and the authors property on the filled AuthorsDataSet. Now we can simply access the columns as if they were fields without any type coercion code.
168.    What is the difference bewteen accessing the data throgh the dataset and datareader?

DataReader
Datareader is like a forward only recordset.It fetches one row at a time so very less Network Cost compare to DataSet(Fetches all the rows at a time). DataReader is readonly so we cannot do any transaction on them. DataReader will be the best choice where we need to show the data to the user which requires no transaction ie reports. Due to DataReader is forward only we cannot fetch the data randomly. .NET Dataproviders optimizes the datareaders to handle the huge amount of data.

DataSet
DataSet is always a bulky object that requires lot of memory space compare to DataReader. We can say the dataset as a small database coz it stores the schema and data in the application memory area. DataSet fetches all data from the datasource at a time to its memory area. So we can traverse through the object to get required data like qureying database.

The dataset maintains the relationships among the datatables insideit. We can manipulate the realational data as XML using dataset.We can do transactions (insert/update/delete) on them and finally the modifications can be updated to the actual database. This provides impressive flexibility to the application but with the cost of memory space. DataSet maintains the original data and the modified data seperately which requires more memory space. If the amount of data in the dataset is huge then it will reduce the applications performance dramatically.

169.    What is a IL?
Twist :- What is MSIL or CIL , What is JIT?
170.    What is a CLR?
171.    What is a CTS?
172.    What is a CLS(Common Language Specification)?
173.    What is a Managed Code?

Managed code is code written in one of over twenty high-level programming languages that are available for use with the Microsoft .NET Framework, including C#, J#, Microsoft Visual Basic .NET, Microsoft JScript .NET, and C++. All of these languages share a unified set of class libraries and can be encoded into an Intermediate Language (IL). A runtime-aware compiler compiles the IL into native executable code within a managed execution environment that ensures type safety, array bound and index checking, exception handling, and garbage collection.

174. What is a Assembly ?

An assembly is a fundamental building block of any .NET Framework application. For example, when you build a simple C# application, Visual Studio creates an assembly in the form of a single portable executable (PE) file, specifically an EXE or DLL.

Assemblies contain metadata that describe their own internal version number and details of all the data and object types they contain.

175. What are different types of Assembly?

An assembly may be Public or Private. A public assembly is also called a Shared Assembly

Posted By: Palash Paul

Sunday, 10 July 2011

Asp.Net Interview Questions

Asynchronous Call using an `AsyncCallback`

Asynchronous Call using `WaitHandle`

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Post a Comment

Sunday, 10 July 2011

Asp.Net Interview Questions

Asynchronous Call using an AsyncCallback

Asynchronous Call using WaitHandle

No comments:

Post a Comment

Asynchronous Call using an `AsyncCallback`

Asynchronous Call using `WaitHandle`