Category: ASP.NET Interview Questions

Introduction

ASP.NET

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

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

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

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

What’s the difference between Response.Write() andResponse.Output.Write()?The latter one allows you to write formattedoutput.

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.

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

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

What’s the difference between Codebehind=”MyCode.aspx.cs” and Src=”MyCode.aspx.cs”?CodeBehind is relevant to Visual Studio.NET only.

What’s a bubbled event?
When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button,row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of its constituents.
Suppose you want a certain ASP.NET function executed on MouseOver over a certain button.

Where do you add an event handler?It’s the Attributesproperty, the Add function inside that property.            
e.g. btnSubmit.Attributes.Add(“onMouseOver”,”someClientCode();”)

What data type does the RangeValidator control support?Integer,String and Date.

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

Data Caching: Caches the objects programmatically. For     data caching asp.net provides a cache object for eg: cache[“States”] = dsStates;

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

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

How do I debug an ASP.NET application that wasn’t written with Visual Studio.NET and that doesn’t use code-behind?Start the DbgClr debugger that comes with the .NET Framework SDK, open the file containing      the code you want to debug, and set your breakpoints. Start the ASP.NET application. Go back to DbgClr, choose Debug Processes from the Tools menu, and select  aspnet_wp.exe from  the list of processes. (If aspnet_wp.exe doesn’t appear in the list,check the “Show system      processes” box.) Click the Attach button to attach to aspnet_wp.exe and begin debugging.
Be sure to enable debugging in the ASPX file before debugging it with DbgClr. You can   enable tell ASP.NET to build debug executables by placing a
   statement at the top of an ASPX file or a   statement in a Web.config file.

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

What’s the difference between Page.RegisterClientScriptBlock and Page.RegisterStartupScript?RegisterClientScriptBlock is for returning blocks of client-side script containing functions. RegisterStartupScript is for returning blocks of client-script not   packaged in functions-in other words, code that’s to execute when the page is loaded. The latter positions script blocks near the end of the document so elements on the page that the script interacts are loaded before the script runs.

Is it necessary to lock application state before accessing it?Only if you’re performing a multistep update and want the update to be treated as an atomic     operation. Here’s an example:

Application.Lock ();
                Application["ItemsSold"] = (int) Application["ItemsSold"] + 1;
                Application["ItemsLeft"] = (int) Application["ItemsLeft"] - 1;
                Application.UnLock ();

By locking application state before updating it and unlocking it afterwards, you ensure  that another request being processed on another thread doesn’t read application state   at exactly the wrong time and see an inconsistent view of it. If I update session state, should I lock it, too? Are concurrent accesses by multiple requests executing on multiple threads a concern with session state?
Concurrent accesses aren’t an issue with session state, for two reasons. One, it’s unlikely that two requests from the same user will overlap. Two, if they do overlap, ASP.NET locks down session state during request processing so that two threads can’t touch it at once. Session state is locked down when the HttpApplication instance that’s processing the request fires an AcquireRequestState event and unlocked when it fires a ReleaseRequestState event.

MailMessage message = new MailMessage ();
        message.From = ;
        message.To = ;
        message.Subject = "Scheduled Power Outage";
        message.Body = "Our servers will be down tonight.";
        SmtpMail.SmtpServer = "localhost";
        SmtpMail.Send (message);

<?xml version="1.0" ?>
<dynamicDiscovery
xmlns="urn:schemas-dynamicdiscovery:disco.2000-03-17">
<exclude path="_vti_cnf" />
<exclude path="_vti_pvt" />
<exclude path="_vti_log" />
<exclude path="_vti_script" />
<exclude path="_vti_txt" />
</dynamicDiscovery>

<%@ Page Language="C#" %>
<html>
<body>
<%
              Response.Cache.SetNoStore ();
              Response.Write (DateTime.Now.ToLongTimeString ());
%>
</body>
</html>

<%@ Page AspCompat="true" %>

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

Should validation (did the user enter a real date) occur server-side or client-side? Why?Client-side validation because there is no need to request a server side date when you  could obtain a date from the client machine.

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

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

What event handlers can I include in Global.asax?

<SESSIONSTATE
StateConnectionString="tcpip=127.0.0.1:42424"
sqlConnectionString="data source=127.0.0.1; user id=sa; password="
cookieless="false"
timeout="30"
/>

How do you create a permanent cookie? Permanent cookies are available until a specified expiration date, and are stored on the hard disk.So Set the ‘Expires’ property any value greater than DataTime.MinValue with respect to the current datetime. If u want the cookie which never expires set its Expires property equal to DateTime.maxValue.
Which method do you use to redirect the user to another page without performing a round trip to the client?
Server.Transfer and Server.Execute

Should validation (did the user enter a real date) occur server-side or client-side? Why? It should occur both at client-side and Server side.By using expression validator control with the specified expression ie.. the regular expression provides the facility of only validatating the date specified is in the correct format or not. But for checking the date where it is the real data or not should be done at the server side, by getting the system date ranges and checking the date whether it is in between that range or not.

What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other? 
Server.Transfer() : client is shown as it is on the requesting page only, but the all the content is of the requested page. Data can be persist accros the pages using Context.Item collection, which is one of the best way to transfer data from one page to another keeping the page state alive.

Can you give an example of when it would be appropriate to use a web service as opposed to a non-serviced .NET component? 

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

What are the advantages and  disadvantages of viewstate?The primary advantages of the ViewState feature in ASP.NET are:

1. Simplicity. There is no need to write possibly complex code to store form data between page submissions.
2. Flexibility. It is possible to enable, configure, and disable ViewState on a control-by-control basis, choosing to persist the values of some fields but not others.

1. Does not track across pages. ViewState information does not automatically transfer from page to page. With the session approach, values can be stored in the session and accessed from other pages. This is not possible with ViewState, so storing data into the session must be done explicitly.
2. ViewState is not suitable for transferring data for back-end systems. That is, data still has to be transferred to the back end using some form of data object.

Describe session handling in a webfarm, how does it work and what are the limits? ASP.NET Session supports storing of session data in 3 ways, i] in In-Process ( in the same memory that ASP.NET uses) , ii] out-of-process using Windows NT Service )in separate memory from ASP.NET ) or iii] in SQL Server (persistent storage). Both the Windows Service and SQL Server solution support a webfarm scenario where all the web-servers can be configured to share common session state store.

1. Windows Service :
We can start this service by Start | Control Panel | Administrative Tools | Services | . In that we service names  ASP.NET State Service. We can start or stop service by manually or configure to start automatically. Then we have to configure our web.config file

<CONFIGURATION><configuration>
<system.web>
<SessionState
mode = “StateServer”
stateConnectionString = “tcpip=127.0.0.1:42424”
stateNetworkTimeout = “10”
sqlConnectionString=”data source = 127.0.0.1; uid=sa;pwd=”
cookieless =”Flase”
timeout= “20” />
</system.web>
</configuration> </SYSTEM.WEB>
</CONFIGURATION>

Here ASP.Net Session is directed to use Windows Service for state management on local server (address : 127.0.0.1 is TCP/IP loop-back address). The default port is 42424. we can configure to any port but for that we have to manually edit the registry.
 Follow these simple steps

• In a webfarm make sure you have the same config file in all your web servers.
• Also make sure your objects are serializable.
• For session state to be maintained across different web servers in the webfarm, the application path of the web-site in the IIS Metabase should be identical in all the web-servers in the webfarm.

Which template must you provide, in order to display data in a Repeater control? You have to use the ItemTemplate to Display data. Syntax is as follows,

< ItemTemplate >
< div class =”rItem” >
< img src=”images/<%# Container.DataItem(“ImageURL”)%>”  hspace=”10” />
< b > <% # Container.DataItem(“Title”)%>
< /div >
< ItemTemplate >

What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control?
 Set the DataMember property to the name of the table to bind to. (If this property is not set, by default the first table in the dataset is used.)
DataBind method, use this method to bind data from a source to a server control. This method is commonly used after retrieving a data set through a database query.

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

Which two properties are on every validation control? We have two common properties for every validation controls

1. Control to Validate,
2. Error Message.

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

Response.Cookies ("Name") = "Nigel"
Response.Cookies ("Name"). Expires = DateAdd ("m", 1, Now ())

What tag do you use to add a hyperlink column to the DataGrid?

< asp:HyperLinkColumn > </ asp:HyperLinkColumn>

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

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

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

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

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

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

What is the sequence of operation takes place when a page is loaded?BeginTranaction  – only if the request is transacted
Init    – every time a page is processed
LoadViewState  – Only on postback
ProcessPostData1  – Only on postback
Load    – every time
ProcessData2   – Only on Postback
RaiseChangedEvent  – Only on Postback
RaisePostBackEvent  – Only on Postback
PreRender   – everytime
BuildTraceTree  – only if tracing is enabled
SaveViewState  – every time
Render   – Everytime
End Transaction  – only if the request is transacted
Trace.EndRequest  – only when tracing is enabled
UnloadRecursive  – Every request

Name the validation control available in asp.net?.RequiredField, RangeValidator,RegularExpression,Custom validator,compare Validator

What are the various ways of securing a web site that could prevent from hacking etc .. ?

1. Authentication/Authorization
2. Encryption/Decryption
3. Maintaining web servers outside the corporate firewall. etc.,

What is ViewState? How is it encoded? Is it encrypted? Who uses ViewState? ViewState is the mechanism ASP.NET uses to keep track of server control state values that don’t otherwise post back as part of the HTTP form. ViewState Maintains the UI State of a Page
  ViewState is base64-encoded. 
 It is not encrypted but it can be encrypted by setting EnableViewStatMAC=”true” & setting the machineKey validation type to 3DES.  If you want to NOT maintain the ViewState, include the directive at the top of an .aspx page or add the attribute EnableViewState=”false” to any control.\

1. In-process session-state mode
   Limitations:
   * When using the in-process session-state mode, session-state data is lost if aspnet_wp.exe or the application domain restarts.
   * If you enable Web garden mode in the element of the application’s Web.config file, do not use in-process session-state mode. Otherwise, random data loss can occur.
   Advantage:
   * in-process session state is by far the fastest solution. If you are storing only small amounts of volatile data in session state, it is recommended that you use the in-process provider.
2. The State Server simply stores session state in memory when in out-of-proc mode. In this mode the worker process talks directly to the State Server
3. SQL mode, session states are stored in a SQL Server database and the worker process talks directly to SQL. The ASP.NET worker processes are then able to take advantage of this simple storage service by serializing and saving (using .NET serialization services) all objects within a client’s Session collection at the end of each Web request
   Both these out-of-process solutions are useful primarily if you scale your application across multiple processors or multiple computers, or where data cannot be lost if a server or process is restarted.

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

Private
Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)
Handles MyBase.Load
'Put user code to initialize the
page here
Dim str As System.Text.StringBuilder
str.Append("hi") ' Error Line as str is not instantiated
Response.Write(str.ToString)
End Sub

< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >
< error statusCode="404" redirect="Notfound.aspx" / >
< /customErrors >
'This will take the user to NotFound.aspx defined in IIS.

1. Using DataAdapter.fill method give the value of ‘Maxrecords’ parameter
   (Note: – Don’t use it because query will return all records but fill the dataset based on value of ‘maxrecords’ parameter).
2. For SQL server database, combines a WHERE clause and a ORDER BY clause with TOP predicate.
3. If Data does not change often just cache records locally in DataSet and just take some records from the DataSet to display.

1. Public static AppDomain CreateDomain(String friendlyName)
2. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo)
3. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, AppDomainSetup info)
4. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, String appBasePath, String appRelativeSearchPath, bool shadowCopyFiles)

1. Authentication Modes
2. IP Address and Domain Name Restriction
3. DNS Lookups DNS Lookups
4. The Network ID and Subnet Mask
5. SSL

< asp:datagrid EnableViewState="false" ... / >

< %@ Page EnableViewState="False" ... % >

< Pages EnableViewState="false" ... / >

.NET FrameWork FAQ’s

What is the CTS?

What is the CLS?

What is IL?

What does ‘managed’ mean in the .NET context?

What is reflection?

Changes to which portion of version number indicates an incompatible change?Major or minor. Changes to the major or minor portion of the version number indicate an incompatible change. Under this convention then, version 2.0.0.0 would be considered incompatible with version 1.0.0.0. Examples of an incompatible change would be a change to the types of some method parameters or the removal of a type or method altogether. Build. The Build number is typically used to distinguish between daily builds or smaller compatible releases. Revision. Changes to the revision number are typically reserved for an incremental build needed to fix a particular bug. You’ll sometimes hear this referred to as the “emergency bug fix” number in that the revision is what is often changed when a fix to a specific bug is shipped to a customer.

Why string are called Immutable data Type ?

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

Where is the output of TextWriterTraceListener redirected?

How does assembly versioning work?

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

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

What is serialization?

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

Can I customise the serialization process?

Why is XmlSerializer so slow?

Why do I get errors when I try to serialize a Hashtable?

What are attributes?

How does CAS work?The CAS security policy revolves around two key concepts – code groups and permissions. Each .NET assembly is a member of a particular code group, and each code group is granted the permissions specified in a named permission set.
For example, using the default security policy, a control downloaded from a web site belongs to the ‘Zone – Internet’ code group, which adheres to the permissions defined by the ‘Internet’ named permission set. (Naturally the ‘Internet’ named permission set represents a very restrictive range of permissions.)

Who defines the CAS code groups?Microsoft defines some default ones, but you can modify these and even create your own. To see the code groups defined on your system, run ‘caspol -lg’ from the command-line. On my system it looks like this:
Level = Machine

How do I define my own code group?

I can’t be bothered with all this CAS stuff. Can I turn it off?

Can source code be reverse-engineered from IL?

Can I redirect tracing to a file?

What are the contents of assembly?

What is GC (Garbage Collection) and how it works

What is Reference type and value type ?

What is JIT and how is works ?

What is portable executable (PE) ?

What is difference between constants, readonly and, static ?Constants: The value can’t be changed

What is namespace used for loading assemblies at run time and name the methods?System.Reflection

1. Form authentication
2. Windows authentication
3. Passport

What is the difference between a Struct and a Class ?

How big is the datatype int in .NET?

How big is the char?

How do you initiate a string without escaping each backslash?

What’s the access level of the visibility type internal?

Explain encapsulation ?

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

Speaking of Boolean data types, what’s different between C# and C/C++?

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

Where do the reference-type variables go in the RAM?

What is the difference between the value-type variables and reference-type variables in terms of garbage collection?

How do you convert a string into an integer in .NET?

How do you box a primitive data type variable?

Why do you need to box a primitive variable?

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

How do you enforce garbage collection in .NET?

What’s different about namespace declaration when comparing that to package declaration in Java? No semicolon.

What’s the difference between const and readonly?

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

What’s the advantage of using System.Text.StringBuilder over System.String?

Can you store multiple data types in System.Array?

What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?

How can you sort the elements of the array in descending order?

What’s the .NET datatype that allows the retrieval of data by a unique key?

What’s class SortedList underneath?

Will finally block get executed if the exception had not occurred?

Can multiple catch blocks be executed?

Why is it a bad idea to throw your own exceptions?

What’s a delegate?

What’s a multicast delegate?

How’s the DLL Hell problem solved in .NET?

What are the ways to deploy an assembly?

What’s a satellite assembly?

What namespaces are necessary to create a localized application?

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

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

Where is the output of TextWriterTraceListener redirected?

What namespaces are necessary to create a localized application?

Can you change the value of a variable while debugging a C# application?

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

How do you inherit from a class in C#?

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

How’s method overriding different from overloading?

Can you declare the override method static while the original method is non-static?

Can you override private virtual methods?

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

Why can’t you specify the accessibility modifier for methods inside the interface?

And if they have conflicting method names?

What’s the difference between an interface and abstract class?

How can you overload a method?

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?

What’s the difference between System.String and System.StringBuilder classes?

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

Describe the accessibility modifier “protected internal”.

What’s the advantage of using System.Text.StringBuilder over System.String?

What’s the .NET class that allows the retrieval of a data element using a unique key?

Will the finally block get executed if an exception has not occurred?

What’s an abstract class?A class that cannot be instantiated.  An abstract class is a class that must be inherited and have the methods overridden. An abstract class is essentially a blueprint for a class without any implementation.

1. When at least one of the methods in the class is abstract.
2. When the class itself is inherited from an abstract class, but not all base abstract methods have been overridden.

Why can’t you specify the accessibility modifier for methods inside the interface?

What’s the difference between an interface and abstract class?

How is method overriding different from method overloading?

Can you declare an override method to be static if the original method is non-static?

Can you override private virtual methods?

What is a formatter?  

.NET platform systems

Framework Support

Language

Portability

Client device independence

Conclusion

•  Security
•  Type Identity
•  Reference Scope
• Versioning
•  Deployment

1. Those that are directly supported by .NET (Pocket PCs, i-Mode phones, and WAP devices)
2. Those that are not (Palm OS and J2ME-powered devices).

Describe the difference between inline and code behind – which is best in a loosely coupled solution

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

What is manifest?

What are the types of assemblies?

• Public  – Access is not restricted.
• Protected  – Access is limited to the containing class or types derived from the containing class.
• Internal – Access is limited to the current assembly.
• Protected inertnal – Access is limited to the current assembly or types derived · from the containing class.
• Private – Access is limited to the containing type.

What Is Boxing And Unboxing?Boxing :- Boxing is an implicit conversion of a value type to the type object type

int i = 123;
object o = (object) i;
Boxing Conversion

• Stuct Type
• Enumeration Type

• Class
• Interface
• Delegate

• object
• string

public enum Grade
{
   A,
   B,
   C
}

• An Assembly is a  logical unit of code
• Assembly physically exist as DLLs or EXEs
• One assembly can contain one or more files
• The constituent files can include any file types like image files, text files etc. along with DLLs or EXEs
• When you compile your source code by default the exe/dll generated is actually an assembly
• Unless your code is bundled as assembly it can not be used in any other application
• When you talk about version of a component you are actually talking about version of the assembly to which the component belongs.
• Every assembly file contains information about itself. This information is called as Assembly Manifest.

• Create your DLL/EXE source code
• Generate unique assembly name using SN utility
• Sign your DLL/EXE with the private key by modifying AssemblyInfo file
• Compile your DLL/EXE
• Place the resultant DLL/EXE in global assembly cache using AL utility

• Use an installer designed to work with the global assembly cache. This is the preferred option for installing assemblies into the global assembly cache.
• Use a developer tool called the Global Assembly Cache tool (Gacutil.exe), provided by the .NET Framework SDK.
• Use Windows Explorer to drag assemblies into the cache.

What is tracing?Where it used.Explain few methods available

How to set the debug mode?Debug Mode for ASP.NET applications – To set ASP.NET appplication in debugging mode, edit the application’s web.config and assign the “debug” attribute in section to “true” as show below:

< configuration >
< system.web >
< compilation defaultLanguage="vb" debug="true" / >
....
...
..
< / configuration >

1. XmlReader provides a fast, forward-only, read-only cursor for processing an XML document stream.
2. XmlWriter provides an interface for producing XML document streams that conform to the W3C’s XML standards.

1. Detect and redirect
2. Run-time adjustment
3. Using Satellite assemblies.

public sealed class Planet
 {
//code goes here
 }

class Moon:Planet
{
//Not allowed as base class is sealed
}

What are multicast delegates ? give me an example ?

namespace SampleMultiCastDelegate
{
class MultiCast
  {
public delegate string strMultiCast(string s);
  }
}

using System;

namespace SampleMultiCastDelegate
{

public class MainClass
{
public MainClass()
{
}

public static string Jump(string s)
{
Console.WriteLine(“Jump”);
return String.Empty;
}

public static string Run(string s)
{
Console.WriteLine(“Run”);
return String.Empty;
}

public static string Walk(string s)
{
Console.WriteLine(“Walk”);
return String.Empty;
}
}
}

using System;
using System.Threading;
namespace SampleMultiCastDelegate
{

public class MainMultiCastDelegate
{
public static void Main()
{
MultiCast.strMultiCast Run,Walk,Jump;

MultiCast.strMultiCast myDelegate;

///here mydelegate used the Combine method of System.MulticastDelegate
///and the delegates combine
myDelegate=(MultiCast.strMultiCast)System.Delegate.Combine(Run,Walk);

}
}
}

Difference between int and int32 ?

• Use an installer designed to work with the global assembly cache. This is the preferred option for installing assemblies into the global assembly cache.
• Use a developer tool called the Global Assembly Cache tool (Gacutil.exe), provided by the .NET Framework SDK.
• Use Windows Explorer to drag assemblies into the cache.

interface Identifier {
  InterfaceBody
}

• Interface should not have any implementation.
• Interface can not create any instance.
• Interface should provide high level abstraction from the implementation.
• Interface can have multiple inheritances.
• Default access level of the interface is public.

How is a strongly-named assembly different from one that isn’t strongly-named? Strong names are used to enable the stricter naming requirements associated with shared assemblies. These strong names are created by a .NET utility – sn.exe

• Name uniqueness. Shared assemblies must have names that are globally unique.
• Prevent name spoofing. Developers don’t want someone else releasing a subsequent version of one of your assemblies and falsely claim it came from you, either by accident or intentionally.
• Provide identity on reference. When resolving a reference to an assembly, strong names are used to guarantee the assembly that is loaded came from the expected publisher.

How does the generational garbage collector in the .NET CLR manage object lifetime? What is non-deterministic finalization?

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

Explain the use of virtual, sealed, override, and abstract.

{
int a
public virtual void Display()
  {
   Console.WriteLine("Shape");
  }
 }

class Rectangle:Shape
{
public override void Display()
{
Console.WriteLine(“Derived”);
}
}

public class MyBaseClass: Object {
}

public class MyDerivedClass: MyBaseClass {
}

public class Test {

public static void Main() {
MyBaseClass myBase = new MyBaseClass();
MyDerivedClass myDerived = new MyDerivedClass();
object o = myDerived;
MyBaseClass b = myDerived;

Console.WriteLine(“mybase: Type is {0}”, myBase.GetType());
Console.WriteLine(“myDerived: Type is {0}”, myDerived.GetType());
Console.WriteLine(“object o = myDerived: Type is {0}”, o.GetType());
Console.WriteLine(“MyBaseClass b = myDerived: Type is {0}”, b.GetType());
}
}

/*

This code produces the following output.

mybase: Type is MyBaseClass
myDerived: Type is MyDerivedClass
object o = myDerived: Type is MyDerivedClass
MyBaseClass b = myDerived: Type is MyDerivedClass

*/

< Department >
< Name >DVS1< /Name >
< addr:Address xmlns:addr="http://www.tu-darmstadt.de/ito/addresses" >
< addr:Street >Wilhelminenstr. 7< /addr:Street >
< addr:City >Darmstadt< /addr:City >
< addr:State >Hessen< /addr:State >
< addr:Country >Germany< /addr:Country >
< addr:PostalCode >D-64285< /addr:PostalCode >
< /addr:Address >
< serv:Server xmlns:serv="http://www.tu-darmstadt.de/ito/servers" >
< serv:Name >OurWebServer< /serv:Name >
< serv:Address >123.45.67.8< /serv:Address >
< /serv:Server >
< /Department >

What is Boxing and unboxing? Does it occure automaatically or u need to write code to box and unbox?

Why only boxed types can be unboxed?

Com +

Can we use com Components in .net?.How ?.can we use .net components in vb?.Explain how ?
COM components have different internal architecture from .NET components hence they are not innately compatible. However .NET  framework supports invocation of unmanaged code from managed code (and vice-versa) through COM/.NET interoperability. .NET application communicates with a COM component through a managed wrapper of the component called Runtime Callable Wrapper (RCW); it acts as managed proxy to the unmanaged COM component. When a method call is made to COM object, it goes onto RCW and not the object itself. RCW manages the lifetime management of the COM component. Implementation Steps –

What are tlbimp and tlbexp tools used for ?

ADO.NET

<?xml version="1.0"?>
<diffgr:diffgram
xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"
xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<DataInstance>
</DataInstance>

<diffgr:before>
</diffgr:before>

<diffgr:errors>
</diffgr:errors>
</diffgr:diffgram>

Can you edit data in the Repeater control? NO.

• Serialized   Data read by a current transaction cannot be changed by another transaction until the current transaction finishes. No new data can be inserted that would affect the current transaction. This is the safest isolation level and is the default.
• Repeatable Read   Data read by a current transaction cannot be changed by another transaction until the current transaction finishes. Any type of new data can be inserted during a transaction.
• Read Committed   A transaction cannot read data that is being modified by another transaction that has not committed. This is the default isolation level in Microsoft® SQL Server.
• Read Uncommitted   A transaction can read any data, even if it is being modified by another transaction. This is the least safe isolation level but allows the highest concurrency.
• Any   Any isolation level is supported. This setting is most commonly used by downstream components to avoid conflicts. This setting is useful because any downstream component must be configured with an isolation level that is equal to or less than the isolation level of its immediate upstream component. Therefore, a downstream component that has its isolation level configured as Any always uses the same isolation level that its immediate upstream component uses. If the root object in a transaction has its isolation level configured to Any, its isolation level becomes Serialized.

How xml files and be read and write using dataset?.DataSet exposes method like ReadXml and WriteXml to read and write xml

Explain acid properties?.The term ACID conveys the role transactions play in mission-critical applications. Coined by transaction processing pioneers, ACID stands for atomicity, consistency, isolation, and durability.

Whate are different types of Commands available with DataAdapter ?The SqlDataAdapter has SelectCommand, InsertCommand, DeleteCommand and UpdateCommand

• Connection: Establishes a connection to a specific data source
• Command: Executes a command against a data source. Exposes Parameters and can execute within the scope of a Transaction from a Connection.
• DataReader: Reads a forward-only, read-only stream of data from a data source.
• DataAdapter: Populates a DataSet and resolves updates with the data source.

How do you handle data concurrency in .NET ?

Is Your Glass Half Full?

Where Did My Changes Go?

Detecting Violations

ALTER
TABLE Employees ADD LastUpdateDateTime DATETIME

Retrieving Row Flags

oUpdCmd.Parameters.Add(new SqlParameter("@NewLastUpdateDateTime",

SqlDbType.DateTime, 8, ParameterDirection.Output,

false, 0, 0, “LastUpdateDateTime”, DataRowVersion.Current, null));

oUpdCmd.UpdatedRowSource = UpdateRowSource.OutputParameters;

Saving Changes

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

{

// Get the employee DataRow (there is only 1 row, otherwise I could

// do a Find)

dsEmployee.EmployeeRow oEmpRow =

(dsEmployee.EmployeeRow)oDsEmployee.Employee.Rows[0];

oEmpRow.LastName = txtLastName.Text;

// Save changes back to Session

Session[“oDsEmployee”] = oDsEmployee;

}

Reporting Violations

string sLastName_Before = oEmpRow["LastName", DataRowVersion.Original];

string sLastName_After = oEmpRow[“LastName”, DataRowVersion.Current];

User’s Choice

Wrapping It Up

Conclusion: