Asp.NET Importent Interview Questions


   1. What do I need to create and run an ASP.NET application?

    * Windows 2000, Windows Server 2003 or Windows XP.
    * ASP.NET, which can be either the redistributable (included in the .NET SDK) or Visual Studio .NET.

   1. Where can I download the .NET SDK?

      .NET SDK can be obtained here.

      (You have to install the Microsoft .NET Framework Version 1.1 Redistributable Package before installing the .NET SDK.)

   2. Are there any free IDEs for the .NET SDK?
          * Microsoft provides Visual Studio 2005 Express Edition Beta for free. Of particular interest to the ASP.NET developers would be the Visual Web Developer 2005 Express Edition Beta 2 available as a free download.
          * The ASP.NET Web Matrix Project (supported by Microsoft) is a free IDE for developing ASP.NET applications and is available here.
          * There is also a free open-source UNIX version of the Microsoft .NET development platform called Mono available for download here.
          * Another increasingly popular Open Source Development Environment for .NET is the #develop (short for SharpDevelop) available for download here.

   3. When was ASP.NET released?

      ASP.NET is a part of the .NET framework which was released as a software platform in 2002
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   4. Is a new version coming up?

      ASP.NET 2.0, Visual Studio 2005 (Whidbey), Visual Web Developer 2005 Express Edition are the next releases of Microsoft's Web platform and tools. They have already been released as Beta versions. They are scheduled to be released in the week of November 7, 2005.

   5. Explain Namespace.

      Namespaces are logical groupings of names used within a program. There may be multiple namespaces in a single application code, grouped based on the identifiers’ use. The name of any given identifier must appear only once in its namespace.

   6. List the types of Authentication supported by ASP.NET.

          * Windows (default)
          * Forms
          * Passport
          * None (Security disabled)

   7. What is CLR?

      Common Language Runtime (CLR) is a run-time environment that manages the execution of .NET code and provides services like memory management, debugging, security, etc. The CLR is also known as Virtual Execution System (VES).
   8. What is CLI?

      The CLI is a set of specifications for a runtime environment, including a common type system, base class library, and a machine-independent intermediate code known as the Common Intermediate Language (CIL). (Source: Wikipedia.)

   9. List the various stages of Page-Load lifecycle.
          * Init()
          * Load()
          * PreRender()
          * Unload()

  10. Explain Assembly and Manifest.

      An assembly is a collection of one or more files and one of them (DLL or EXE) contains a special metadata called Assembly Manifest. The manifest is stored as binary data and contains details like versioning requirements for the assembly, the author, security permissions, and list of files forming the assembly. An assembly is created whenever a DLL is built. The manifest can be viewed programmatically by making use of classes from the System.Reflection namespace. The tool Intermediate Language Disassembler (ILDASM) can be used for this purpose. It can be launched from the command prompt or via Start> Run.

  11. What is Shadow Copy?

      In order to replace a COM component on a live dedicated server, it was necessary to stop the entire website, copy the new files and then restart the website. This is not feasible for the web servers that need to be always running. .NET components are different. They can be overwritten at any time using a mechanism called Shadow Copy. It prevents the Portable Executable (PE) files like DLLs and EXEs from being locked. Whenever new versions of the PEs are released, they are automatically detected by the CLR and the changed components will be automatically loaded. They will be used to process all new requests not currently executing, while the older version still runs the currently executing requests. By bleeding out the older version, the update is completed.

  12. What is DLL Hell?

      DLL hell is the problem that occurs when an installation of a newer application might break or hinder other applications as newer DLLs are copied into the system and the older applications do not support or are not compatible with them. .NET overcomes this problem by supporting multiple versions of an assembly at any given time. This is also called side-by-side component versioning.

  13. Explain Web Services.

      Web services are programmable business logic components that provide access to functionality through the Internet. Standard protocols like HTTP can be used to access them. Web services are based on the Simple Object Access Protocol (SOAP), which is an application of XML. Web services are given the .asmx extension.

  14. Explain Windows Forms.

      Windows Forms is employed for developing Windows GUI applications. It is a class library that gives developers access to Windows Common Controls with rich functionality. It is a common GUI library for all the languages supported by the .NET Framework.

  15. What is Postback?

      When an action occurs (like button click), the page containing all the controls within the <FORM... > tag performs an HTTP POST, while having itself as the target URL. This is called Postback.

  16. 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. 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. Since the code is included in the HTML page, anyone can see the code by viewing the page source. It also poses as a possible security hazard for the client computer.

  17. Enumerate the types of Directives.
          * @ Page directive
          * @ Import directive
          * @ Implements directive
          * @ Register directive
          * @ Assembly directive
          * @ OutputCache directive
          * @ Reference directive

  18. What is Code-Behind?

      Code-Behind is a concept where the contents of a page are in one file and the server-side code is in another. This allows different people to work on the same page at the same time and also allows either part of the page to be easily redesigned, with no changes required in the other. An Inherits attribute is added to the @ Page directive to specify the location of the Code-Behind file to the ASP.NET page.
  19. Describe the difference between inline and code behind.

      Inline code is written along side the HTML in a page. There is no separate distinction between design code and logic code. Code-behind is code written in a separate file and referenced by the .aspx page.
  20. List the ASP.NET validation controls?
          * RequiredFieldValidator
          * RangeValidator
          * CompareValidator
          * RegularExpressionValidator
          * CustomValidator
          * ValidationSummary

  21. What is Data Binding?

      Data binding is a way used to connect values from a collection of data (e.g. DataSet) to the controls on a web form. The values from the dataset are automatically displayed in the controls without having to write separate code to display them.

  22. Describe Paging in ASP.NET.

      The DataGrid control in ASP.NET enables easy paging of the data. The AllowPaging property of the DataGrid can be set to True to perform paging. ASP.NET automatically performs paging and provides the hyperlinks to the other pages in different styles, based on the property that has been set for PagerStyle.Mode.
  23. Should user input data validation occur server-side or client-side? Why?

      All user input data validation should occur on the server and minimally on the client-side, though it is a good way to reduce server load and network traffic because we can ensure that only data of the appropriate type is submitted from the form. It is totally insecure. The user can view the code used for validation and create a workaround for it. Secondly, the URL of the page that handles the data is freely visible in the original form page. This will allow unscrupulous users to send data from their own forms to your application. Client-side validation can sometimes be performed where deemed appropriate and feasible to provide a richer, more responsive experience for the user.

  24. What is the difference between Server.Transfer and Response.Redirect?
          * Response.Redirect: This tells the browser that the requested page can be found at a new location. The browser then initiates another request to the new page loading its contents in the browser. This results in two requests by the browser.
          * Server.Transfer: It transfers execution from the first page to the second page on the server. As far as the browser client is concerned, it made one request and the initial page is the one responding with content. The benefit of this approach is one less round trip to the server from the client browser. Also, any posted form variables and query string parameters are available to the second page as well.


  26. What is an interface and what is an abstract class?

      In an interface, all methods must be abstract (must not be defined). In an abstract class, some methods can be defined. In an interface, no accessibility modifiers are allowed, whereas it is allowed in abstract classes.

  27. Session state vs. View state:

      In some cases, using view state is not feasible. The alternative for view state is session state. Session state is employed under the following situations:
          * Large amounts of data - View state tends to increase the size of both the HTML page sent to the browser and the size of form posted back. Hence session state is used.
          * Secure data - Though the view state data is encoded and may be encrypted, it is better and secure if no sensitive data is sent to the client. Thus, session state is a more secure option.
          * Problems in serializing of objects into view state - View state is efficient for a small set of data. Other types like DataSet are slower and can generate a very large view state.

  28. Can two different programming languages be mixed in a single ASPX file?

      ASP.NET’s built-in parsers are used to remove code from ASPX files and create temporary files. Each parser understands only one language. Therefore mixing of languages in a single ASPX file is not possible.

  29. Is it possible to see the code that ASP.NET generates from an ASPX file?

      By enabling debugging using a <%@ Page Debug="true" %> directive in the ASPX file or a <compilation debug="true"> statement in Web.config, the generated code can be viewed. The code is stored in a CS or VB file (usually in the \%SystemRoot%\Microsoft.NET\Framework\v1.0.nnnn\Temporary ASP.NET Files).

  30. Can a custom .NET data type be used in a Web form?

      This can be achieved by placing the DLL containing the custom data type in the application root's bin directory and ASP.NET will automatically load the DLL when the type is referenced.

  31. List the event handlers that can be included in Global.asax?
          * Application start and end event handlers
          * Session start and end event handlers
          * Per-request event handlers
          * Non-deterministic event handlers

  32. Can the view state be protected from tampering?

      This can be achieved by including an @ Page directive with an EnableViewStateMac="true" attribute in each ASPX file that has to be protected. Another way is to include the <pages enableViewStateMac="true" /> statement in the Web.config file.

  33. Can the view state be encrypted?

      The view state can be encrypted by setting EnableViewStateMac to true and either modifying the <machineKey> element in Machine.config to <machineKey validation="3DES” /> or by adding the above statement to Web.config.

  34. When during the page processing cycle is ViewState available?

      The view state is available after the Init() and before the Render() methods are called during Page load.

  35. Do Web controls support Cascading Style Sheets?

      All Web controls inherit a property named CssClass from the base class System.Web.UI.WebControls.WebControl which can be used to control the properties of the web control.

  36. What namespaces are imported by default in ASPX files?

      The following namespaces are imported by default. Other namespaces must be imported manually using @ Import directives.
          * System
          * System.Collections
          * System.Collections.Specialized
          * System.Configuration
          * System.Text
          * System.Text.RegularExpressions
          * System.Web
          * System.Web.Caching
          * System.Web.Security
          * System.Web.SessionState
          * System.Web.UI
          * System.Web.UI.HtmlControls
          * System.Web.UI.WebControls

  37. What classes are needed to send e-mail from an ASP.NET application?

      The classes MailMessage and SmtpMail have to be used to send email from an ASP.NET application. MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's System.Web.Mail namespace.
  38. Why do some web service classes derive from System.Web.WebServices while others do not?

      Those Web Service classes which employ objects like Application, Session, Context, Server, and User have to derive from System.Web.WebServices. If it does not use these objects, it is not necessary to be derived from it.

  39. What are VSDISCO files?

      VSDISCO files are DISCO files that enable dynamic discovery of Web Services. ASP.NET links the VSDISCO to a HTTP handler that scans the host directory and subdirectories for ASMX and DISCO files and returns a dynamically generated DISCO document. A client who requests a VSDISCO file gets back what appears to be a static DISCO document.

  40. How can files be uploaded to Web pages in ASP.NET?

      This can be done by using the HtmlInputFile class to declare an instance of an <input type="file" runat="server"/> tag. Then, a byte[] can be declared to read in the data from the input file. This can then be sent to the server.

  41. How do I create an ASPX page that periodically refreshes itself?

      The following META tag can be used as a trigger to automatically refresh the page every n seconds:

      <meta http-equiv="Refresh" content="nn">

  42. How do I initialize a TextBox whose TextMode is "password", with a password?

      The TextBox’s Text property cannot be used to assign a value to a password field. Instead, its Value field can be used for that purpose.

      <asp:TextBox Value="imbatman" TextMode="Password"
                            ID="Password" RunAt="server" />

  43. Why does the control's PostedFile property always show null when using HtmlInputFile control to upload files to a Web server?

      This occurs when an enctype="multipart/form-data" attribute is missing in the <form> tag.

  44. How can the focus be set to a specific control when a Web form loads?

      This can be achieved by using client-side script:

      document.forms[0].TextBox1.focus ()

      The above code will set the focus to a TextBox named TextBox1 when the page loads.

  45. How does System.Web.UI.Page's IsPostBack property work?

      IsPostBack checks to see whether the HTTP request is accompanied by postback data containing a __VIEWSTATE or __EVENTTARGET parameter. If there are none, then it is not a postback.

  46. What is WSDL?

      WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint. Related concrete endpoints are combined into abstract endpoints (services). (Source: www.w3.org)

  47. What is UDDI?

      UDDI stands for Universal Description, Discovery, and Integration. It is like an "Yellow Pages" for Web Services. It is maintained by Microsoft, IBM, and Ariba, and is designed to provide detailed information regarding registered Web Services for all vendors. The UDDI can be queried for specific Web Services.

  48. Is it possible to generate the source code for an ASP.NET Web service from a WSDL?

      The Wsdl.exe tool (.NET Framework SDK) can be used to generate source code for an ASP.NET web service with its WSDL link.

      Example: wsdl /server http://api.google.com/GoogleSearch.wsdl.

  49. Why do uploads fail while using an ASP.NET file upload control to upload large files?

      ASP.NET limits the size of file uploads for security purposes. The default size is 4 MB. This can be changed by modifying the maxRequestLength attribute of Machine.config's <httpRuntime> element.

  50. Describe the difference between inline and code behind.

      Inline code is written along side the HTML in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

What's New in the .NET Framework 4 ?

This topic contains information about key features and improvements in the .NET Framework version 4. This topic does not provide comprehensive information about all new features and is subject to change.

The .NET Framework 4 introduces an improved security model. For more information, see Security Changes in the .NET Framework 4.

Other new features and improvements in the .NET Framework 4 are described in the following sections:

    *      Application Compatibility and Deployment
  

     *  Core New Features and Improvements
   

    *   Managed Extensibility Framework
  

      *  Parallel Computing
  

    *   Networking
  

     *  Web
   

     *  Client
   

     *  Data
   

     *  Windows Communication Foundation
 

       *  Windows Workflow Foundation

See New Types and Members in the .NET Framework 4 for lists of new namespaces, new types, and new members added to existing types.
Application Compatibility and Deployment

The .NET Framework 4 is highly compatible with applications that are built with earlier .NET Framework versions, except for some changes that were made to improve security, standards compliance, correctness, reliability, and performance.

The .NET Framework 4 does not automatically use its version of the common language runtime to run applications that are built with earlier versions of the .NET Framework. To run older applications with .NET Framework 4, you must compile your application with the target .NET Framework version specified in the properties for your project in Visual Studio, or you can specify the supported runtime with the <supportedRuntime> Element in an application configuration file.

If your application or component does not work after .NET Framework 4 is installed, please submit a bug on the Microsoft Connect Web site. You can test compatibility as described in the .NET Framework 4 Application Compatibility topic and learn about new features by using the Visual Studio 2010 and .NET Framework 4 Walkthroughs.

For guidance about migrating to the .NET Framework 4, see Migration Guide to the .NET Framework 4 and Version Compatibility in the .NET Framework

The following sections describe deployment improvements.
Client Profile

The .NET Framework 4 Client Profile supports more platforms than in previous versions and provides a fast deployment experience for your applications. Several new project templates now target the Client Profile by default. For more information, see .NET Framework Client Profile.
In-Process Side-by-Side Execution

This feature enables an application to load and start multiple versions of the .NET Framework in the same process. For example, you can run applications that load add-ins (or components) that are based on the .NET Framework 2.0 SP1 and add-ins that are based on the .NET Framework 4 in the same process. Older components continue to use the older .NET Framework version, and new components use the new .NET Framework version. For more information, see In-Process Side-by-Side Execution.


Core New Features and Improvements

The following sections describe new features and improvements provided by the common language runtime and the base class libraries.
Diagnostics and Performance

Earlier versions of the .NET Framework provided no way to determine whether a particular application domain was affecting other application domains, because the operating system APIs and tools, such as the Windows Task Manager, were precise only to the process level. Starting with the .NET Framework 4, you can get processor usage and memory usage estimates per application domain.

You can monitor CPU and memory usage of individual application domains. Application domain resource monitoring is available through the managed and native hosting APIs and event tracing for Windows (ETW). When this feature has been enabled, it collects statistics on all application domains in the process for the life of the process. See the new AppDomain.MonitoringIsEnabled property.

You can now access the ETW events for diagnostic purposes to improve performance. For more information, see CLR ETW Events and Controlling .NET Framework Logging. Also see Performance Counters and In-Process Side-By-Side Applications.

The System.Runtime.ExceptionServices.HandleProcessCorruptedStateExceptionsAttribute attribute enables managed code to handle exceptions that indicate corrupted process state.
Globalization

The .NET Framework 4 provides new neutral and specific cultures, updated property values, improvements in string handling, and other improvements. For more information, see What's New in Globalization and Localization.
Garbage Collection

The .NET Framework 4 provides background garbage collection. This feature replaces concurrent garbage collection in previous versions and provides better performance. For more information, see Fundamentals of Garbage Collection.
Code Contracts

Code contracts let you specify contractual information that is not represented by a method's or type's signature alone. The new System.Diagnostics.Contracts namespace contains classes that provide a language-neutral way to express coding assumptions in the form of preconditions, postconditions, and object invariants. The contracts improve testing with run-time checking, enable static contract verification, and support documentation generation. For more information, see Code Contracts.
Design-Time-Only Interop Assemblies

You no longer have to ship primary interop assemblies (PIAs) to deploy applications that interoperate with COM objects. In the .NET Framework 4, compilers can embed type information from interop assemblies, selecting only the types that an application (for example, an add-in) actually uses. Type safety is ensured by the common language runtime. See Using COM Types in Managed Code and Walkthrough: Embedding Type Information from Microsoft Office Assemblies (C# and Visual Basic).
Dynamic Language Runtime

The dynamic language runtime (DLR) is a new runtime environment that adds a set of services for dynamic languages to the CLR. The DLR makes it easier to develop dynamic languages to run on the .NET Framework and to add dynamic features to statically typed languages. To support the DLR, the new System.Dynamic namespace is added to the .NET Framework.

The expression trees are extended with new types that represent control flow, for example, System.Linq.Expressions.LoopExpression and System.Linq.Expressions.TryExpression. These new types are used by the dynamic language runtime (DLR) and not used by LINQ.

In addition, several new classes that support the .NET Framework infrastructure are added to the System.Runtime.CompilerServices namespace. For more information, see Dynamic Language Runtime Overview.
Covariance and Contravariance

Several generic interfaces and delegates now support covariance and contravariance. For more information, see Covariance and Contravariance in Generics.
BigInteger and Complex Numbers

The new System.Numerics.BigInteger structure is an arbitrary-precision integer data type that supports all the standard integer operations, including bit manipulation. It can be used from any .NET Framework language. In addition, some of the new .NET Framework languages (such as F# and IronPython) have built-in support for this structure.

The new System.Numerics.Complex structure represents a complex number that supports arithmetic and trigonometric operations with complex numbers.
Tuples

The .NET Framework 4 provides the System.Tuple class for creating tuple objects that contain structured data. It also provides generic tuple classes to support tuples that have from one to eight components (that is, singletons through octuples). To support tuple objects that have nine or more components, there is a generic tuple class with seven type parameters and an eighth parameter of any tuple type.
File System Enumeration Improvements

New file enumeration methods improve the performance of applications that access large file directories or that iterate through the lines in large files. For more information, see How to: Enumerate Directories and Files.
Memory-Mapped Files

The .NET Framework now supports memory-mapped files. You can use memory-mapped files to edit very large files and to create shared memory for interprocess communication.
64-Bit Operating Systems and Processes

You can identify 64-bit operating systems and processes with the Environment.Is64BitOperatingSystem and Environment.Is64BitProcess properties.

You can specify a 32-bit or 64-bit view of the registry with the Microsoft.Win32.RegistryView enumeration when you open base keys.
Other New Features

The following list describes additional new capabilities, improvements, and conveniences. Several of these are based on customer suggestions.

    *

      To support culture-sensitive formatting, the System.TimeSpan structure includes new overloads of the ToString, Parse, and TryParse methods, as well as new ParseExact and TryParseExact methods.
    *

      The new String.IsNullOrWhiteSpace method indicates whether a string is null, empty, or consists only of white-space characters. New overloads have been added to the String.Concat and String.Join methods that concatenate members of System.Collections.Generic.IEnumerable(Of T) collections.
    *

      The String.Concat method lets you concatenate each element in an enumerable collection without first converting the elements to strings.
    *

      Two new convenience methods are available: StringBuilder.Clear and Stopwatch.Restart.
    *

      The new Enum.HasFlag method determines whether one or more bit fields or flags are set in an enumeration value. The Enum.TryParse method returns a Boolean value that indicates whether a string or integer value could be successfully parsed.
    *

      The System.Environment.SpecialFolder enumeration contains several new folders.
    *

      You can now easily copy one stream into another with the CopyTo method in classes that inherit from the System.IO.Stream class.
    *

      New Path.Combine method overloads enable you to combine file paths.
    *

      The new System.IObservable(Of T) and System.IObserver(Of T) interfaces provide a generalized mechanism for push-based notifications.
    *

      The System.IntPtr and System.UIntPtr classes now include support for the addition and subtraction operators.
    *

      You can now enable lazy initialization for any custom type by wrapping the type inside a System.Lazy(Of T) class.
    *

      The new System.Collections.Generic.SortedSet(Of T) class provides a self-balancing tree that maintains data in sorted order after insertions, deletions, and searches. This class implements the new System.Collections.Generic.ISet(Of T) interface.
    *

      The compression algorithms for the System.IO.Compression.DeflateStream and System.IO.Compression.GZipStream classes have improved so that data that is already compressed is no longer inflated. Also, the 4-gigabyte size restriction for compressing streams has been removed.
    *

      The new Monitor.Enter(Object, Boolean) method overload takes a Boolean reference and atomically sets it to true only if the monitor is successfully entered.
    *

      You can use the Thread.Yield method to have the calling thread yield execution to another thread that is ready to run on the current processor.
    *

      The System.Guid structure now contains the TryParse and TryParseExact methods.
    *

      The new Microsoft.Win32.RegistryOptions enumeration lets you specify a volatile registry key that does not persist after the computer restarts.
    *

      Registry keys are no longer restricted to a maximum length of 255 characters.


Managed Extensibility Framework

The Managed Extensibility Framework (MEF) is a new library in the .NET Framework 4 that helps you build extensible and composable applications. MEF enables you to specify points where an application can be extended, to expose services to offer to other extensible applications and to create parts for consumption by extensible applications. It also enables easy discoverability of available parts based on metadata, without the need to load the assemblies for the parts. For more information, see Managed Extensibility Framework Overview and Managed Extensibility Framework. For a list of the MEF types, see the System.ComponentModel.Composition namespace.

Parallel Computing

The .NET Framework 4 introduces a new programming model for writing multithreaded and asynchronous code that greatly simplifies the work of application and library developers. The new model enables developers to write efficient, fine-grained, and scalable parallel code in a natural idiom without having to work directly with threads or the thread pool. The new System.Threading.Tasks namespace and other related types support this new model. Parallel LINQ (PLINQ), which is a parallel implementation of LINQ to Objects, enables similar functionality through declarative syntax. For more information, see Parallel Programming in the .NET Framework.

Networking

Networking improvements include the following:

    *

      Security improvements for Windows authentication in several classes, including System.Net.HttpWebRequest, System.Net.HttpListener, System.Net.Mail.SmtpClient, System.Net.Security.SslStream, and System.Net.Security.NegotiateStream. Extended protection is available for applications on Windows 7 and Windows Server 2008 R2. For more information, see Integrated Windows Authentication with Extended Protection.
    *

      Support for Network Address Translation (NAT) traversal using IPv6 and Teredo. For more information, see NAT Traversal using IPv6 and Teredo.
    *

      New networking performance counters that provide information about HttpWebRequest objects. For more information, see Networking Performance Counters.
    *

      In the System.Net.HttpWebRequest class, support for using large byte range headers (64-bit ranges) with new overloads for the AddRange method. New properties on the System.Net.HttpWebRequest class allow an application to set many HTTP headers. You can use the Host property to set the Host header value in an HTTP request that is independent from the request URI.
    *

      Secure Sockets Layer (SSL) support for the System.Net.Mail.SmtpClient and related classes.
    *

      Improved support for mail headers in the System.Net.Mail.MailMessage class.
    *

      Support for a null cipher for use in encryption. You can specify the encryption policy by using the System.Net.ServicePointManager class and the EncryptionPolicy property. Constructors for the System.Net.Security.SslStream class now take a System.Net.Security.EncryptionPolicy class as a parameter.
    *

      Credentials for password-based authentication schemes such as basic, digest, NTLM, and Kerberos authentication in the System.Net.NetworkCredential class. To improve security, passwords may now be treated as System.Security.SecureString instances rather than System.String instances.
    *

      Ability to specify how a URI with percent-encoded values is converted and normalized in the System.Uri and System.Net.HttpListener classes. For more information, see the System.Net.Configuration.HttpListenerElement, System.Configuration.SchemeSettingElement, System.Configuration.SchemeSettingElementCollection, and System.Configuration.UriSection classes.

Web

ASP.NET version 4 introduces new features in the following areas:

    *

      Core services, including a new API that lets you extend caching, support for compression for session-state data, and a new application preload manager (autostart feature).
    *

      Web Forms, including more integrated support for ASP.NET routing, enhanced support for Web standards, updated browser support, new features for data controls, and new features for view state management.
    *

      Web Forms controls, including a new Chart control.
    *

      MVC, including new helper methods for views, support for partitioned MVC applications, and asynchronous controllers.
    *

      Dynamic Data, including support for existing Web applications, support for many-to-many relationships and inheritance, new field templates and attributes, and enhanced data filtering.
    *

      Microsoft Ajax, including additional support for client-based Ajax applications in the Microsoft Ajax Library.
    *

      Visual Web Developer, including improved IntelliSense for JScript, new auto-complete snippets for HTML and ASP.NET markup, and enhanced CSS compatibility.
    *

      Deployment, including new tools for automating typical deployment tasks.
    *

      Multi-targeting, including better filtering for features that are not available in the target version of the .NET Framework.

For more information about these features, see What's New in ASP.NET 4 and Visual Web Developer.


Client

Windows Presentation Foundation (WPF) version 4 contains changes and improvements in the following areas:

    *

      New controls, including Calendar, DataGrid, and DatePicker.
    *

      VisualStateManager supports changing states of controls.
    *

      Touch and Manipulation enables you to create applications that receive input from multiple touches simultaneously on Windows 7.
    *

      Graphics and animation supports layout rounding, Pixel Shader version 3.0, cached composition, and easing functions.
    *

      Text has improved text rendering and supports customizing the caret color and selection color in text boxes.
    *

      Binding is supported on the Command property of an InputBinding, dynamic objects, and the Text property.
    *

      XAML browser applications (XBAPs) support communication with the Web page and support full-trust deployment.
    *

      New types in the System.Windows.Shell namespace enable you to communicate with the Windows 7 taskbar and pass data to the Windows shell.
    *

      The WPF and Silverlight Designer in Visual Studio 2010 has various designer improvements to help create WPF or Silverlight applications.

For more information, see What's New in WPF Version 4.

Data
ADO.NET

ADO.NET provides new features for the Entity Framework, including persistence-ignorant objects, functions in LINQ queries, and customized object layer code generation. For more information, see What's New in ADO.NET.
Dynamic Data

For ASP.NET 4, Dynamic Data has been enhanced to give you even more power for quickly building data-driven Web sites. This includes the following:

    *

      Automatic validation that is based on constraints that are defined in the data model.
    *

      The ability to easily change the markup that is generated for fields in the GridView and DetailsView controls by using field templates that are part of a Dynamic Data project.

For more information, see What's New in ASP.NET 4 and Visual Web Developer.
WCF Data Services

ADO.NET Data Service has been renamed to WCF Data Services, and has the following new features

    *

      Data binding.
    *

      Counting entities in an entity set.
    *

      Server-driven paging.
    *

      Query projections.
    *

      Custom data service providers.
    *

      Streaming of binary resources.

For more information, see What's New in WCF Data Services.


Windows Communication Foundation

Windows Communication Foundation (WCF) provides the following improvements:

    *

      Configuration-based activation: Removes the requirement for having an .svc file.
    *

      System.Web.Routing integration: Gives you more control over your service's URL by allowing the use of extensionless URLs.
    *

      Multiple IIS site bindings support: Allows you to have multiple base addresses with the same protocol on the same Web site.
    *

      Routing Service: Allows you to route messages based on content.
    *

      Support for WS-Discovery: Allows you to create and search for discoverable services.
    *

      Standard endpoints: Predefined endpoints that allow you to specify only certain properties.
    *

      Workflow services: Integrates WCF and WF by providing activities to send and receive messages, the ability to correlate messages based on content, and a workflow service host.
    *

      WCF REST features:
          o

            Web HTTP caching: Allows caching of Web HTTP service responses.
          o

            Web HTTP formats support: Allows you to dynamically determine the best format for a service operation to respond in.
          o

            Web HTTP services help page: Provides an automatic help page for Web HTTP services, similar to the WCF service help page.
          o

            Web HTTP error handling: Allows Web HTTP Services to return error information in the same format as the operation.
          o

            Web HTTP cross-domain JavaScript support: Allows use of JSON Padding (JSONP).
    *

      Simplified configuration: Reduces the amount of configuration a service requires

For more information, see What's New in Windows Communication Foundation.


Windows Workflow Foundation

Windows Workflow Foundation (WF) provides improvements in the following areas:

    *

      Improved workflow activity model: The Activity class provides the base abstraction of workflow behavior.
    *

      Rich composite activity options: Workflows benefit from new flow-control activities that model traditional flow-control structures, such as Flowchart, TryCatch, and Switch(Of T).
    *

      Expanded built-in activity library: New features of the activity library include new flow-control activities, activities for manipulating member data, and activities for controlling transactions.
    *

      Explicit activity data model: New options for storing or moving data include variable and directional arguments.
    *

      Enhanced hosting, persistence, and tracking options: Hosting enhancements include more options for running workflows, explicit persistence using the Persistactivity, persisting without unloading, preventing persistence by using no-persist zones, using ambient transactions from the host, recording tracking information to the event log, and resuming pending workflows by using a Bookmark object.
    *

      Easier ability to extend the WF Designer: The new WF Designer is built on Windows Presentation Foundation (WPF) and provides an easier model to use when rehosting the WF Designer outside of Visual Studio.

For more information, see What's New in Windows Workflow Foundation.

Asp.net Important Topics.

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, likeDataGrid, 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","someClient Code();")


· 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
CachingOutput Caching: Caches the dynamic output generated by a
request. Some times it is useful to cache the output of a website even
for a minute, which will result in a better performance. For caching
the whole page the page should have OutputCache directive.<%@
OutputCache Duration="60" VaryByParam="state" %>
Fragment Caching: Caches the portion of the page generated by the
request. Some times it is not practical to cache the entire page, in
such cases we can cache a portion of page<%@ OutputCache Duration="120"
VaryByParam="CategoryID;SelectedID"%>
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 <%@ Page
AspCompat="TRUE" language="C#" %>
@Control:Defines control-specific attributes used by the ASP.NET page
parser and compiler. Can be included only in .ascx files. <%@
Control Language="VB" EnableViewState="false" %>
@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. <% @ Import Namespace="System.web" %>
@Implements: Indicates that the current page or user control implements
the specified .NET framework interface.<%@ Implements
Interface="System.Web.UI.IPostBackEventHandler" %>
@Register: Associates aliases with namespaces and class names for
concise notation in custom server control syntax.<%@ Register
Tagprefix="Acme" Tagname="AdRotator" Src="AdRotator.ascx" %>
@Assembly: Links an assembly to the current page during compilation,
making all the assembly's classes and interfaces available
for use on the page. <%@ Assembly Name="MyAssembly" %><%@ Assembly
Src="MySource.vb" %>
@OutputCache: Declaratively controls the output caching policies of an
ASP.NET page or a user control contained in a page<%@
OutputCache Duration="#ofseconds" Location="Any | Client | Downstream |
Server | None" Shared="True | False" VaryByControl="controlname"
VaryByCustom="browser | customstring" VaryByHeader="headers"
VaryByParam="parametername" %>
@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
<%@ Page Debug="true" % statement at the top of an ASPX file or a
<COMPILATION debug="true" />statement in a Web.config file.

· Can a user browsing my Web site read my Web.config or Global.asax
files?
No. The <HTTPHANDLERS>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.<%@ Reference
Control="MyControl.ascx" %>
· 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.
Do ASP.NET forms authentication cookies provide any protection against
replay attacks? Do they, for example, include the client's IP address
or anything else that would distinguish the real client from an
attacker?

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

MailMessage message = new MailMessage ();
message.From = <email>;
message.To = <email>;
message.Subject = "Scheduled Power Outage";
message.Body = "Our servers will be down tonight.";
SmtpMail.SmtpServer = "localhost";
SmtpMail.Send (message);
MailMessage and SmtpMail are classes defined in the .NET Framework
Class Library's System.Web.Mail namespace. Due to a security change
made to ASP.NET just before it shipped, you need to set SmtpMail's
SmtpServer property to "localhost" even though "localhost" is the
default. In addition, you must use the IIS configuration applet to
enable localhost (127.0.0.1) to relay messages through the local SMTP
service.
· What are VSDISCO files?
VSDISCO files are DISCO files that support dynamic discovery of Web
services. If you place the following VSDISCO file in a directory on
your Web server, for example, it returns references to all ASMX and
DISCO files in the host directory and any subdirectories not
noted in <excludeelements:
<?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>
· How does dynamic discovery work?

ASP.NET maps the file name extension VSDISCO to an HTTP handler that
scans the host directory and subdirectories for ASMX and DISCO files
and returns a dynamically generated DISCO document. A client who
requests a VSDISCO file gets back what appears to be a static DISCO
document.
Note that VSDISCO files are disabled in the release version of ASP.NET.
You can reenable them by uncommenting the line in the <httpHandlers>
section of Machine.config that maps *.vsdisco to
System.Web.Services.Discovery.DiscoveryRequestHand ler and granting the
ASPNET user account permission to read the IIS metabase. However,
Microsoft is actively discouraging the use of VSDISCO files because
they could represent a threat to Web server security.


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

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

<%@ Page Language="C#" %>
<html>
<body>
<%
Response.Cache.SetNoStore ();
Response.Write (DateTime.Now.ToLongTimeString ());
%>
</body>
</html>
SetNoStore works by returning a Cache-Control: private, no-store header
in the HTTP response. In this example, it prevents caching of a Web
page that shows the current time.
· What does AspCompat="true" mean and when should I use it?
AspCompat is an aid in migrating ASP pages to ASPX pages. It defaults
to false but should be set to true in any ASPX file that creates
apartment-threaded COM objects--that is, COM objects registered
ThreadingModel=Apartment. That includes all COM objects written with
Visual Basic 6.0. AspCompat should also be set to true (regardless of
threading model) if the page creates COM objects that access
intrinsic ASP objects such as Request and Response. The following
directive sets AspCompat to true:
<%@ Page AspCompat="true" %>
Setting AspCompat to true does two things. First, it makes intrinsic
ASP objects available to the COM components by placing unmanaged
wrappers around the equivalent ASP.NET objects. Second, it improves the
performance of calls that the page places to apartment- threaded COM
objects by ensuring that the page (actually, the thread that processes
the request for the page) and the COM objects it creates share an
apartment. AspCompat="true" forces ASP.NET request threads into
single-threaded apartments (STAs). If those threads create COM objects
marked ThreadingModel=Apartment, then the objects are created in the
same STAs as the threads that created them. Without AspCompat="true,"
request threads run in a multithreaded apartment (MTA) and each call to
an STA-based COM object incurs a performance hit when it's marshaled
across apartment boundaries.
Do not set AspCompat to true if your page uses no COM objects or if it
uses COM objects that don't access ASP intrinsic objects and that are
registered ThreadingModel=Free or ThreadingModel=Both.
· Explain the differences between Server-side and Client-side code?
Server side scripting means that all the script will be executed by
the server and interpreted as needed. ASP doesn't have some of the
functionality like sockets, uploading, 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.

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

· 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.

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

In earlier versions of IIS, if we wanted to send a user to a new Web
page, the only option we had was Response.Redirect. While this method
does accomplish our goal, it has several important drawbacks. The
biggest problem is that this method causes each page to be treated as a
separate transaction. Besides making it difficult to maintain your
transactional integrity, Response.Redirect introduces some additional
headaches. First, it prevents good encapsulation of code. Second, you
lose access to all of the properties in the Request object. Sure,
there are workarounds, but they're difficult. Finally,
Response.Redirect necessitates a round trip to the client, which, on
high-volume sites, causes scalability problems.
As you might suspect, Server.Transfer fixes all of these problems. It
does this by performing the transfer on the server without requiring a
roundtrip to the client.

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

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

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

ItemTemplate

· What event handlers can I include in Global.asax?
Application_Start,Application_End, Application_AcquireRequestState,
Application_AuthenticateRequest, Application_AuthorizeRequest,
Application_BeginRequest, Application_Disposed,
Application_EndRequest, Application_Error,
Application_PostRequestHandlerExecute,
Application_PreRequestHandlerExecute,
Application_PreSendRequestContent, Application_PreSendRequestHeaders,
Application_ReleaseRequestState, Application_ResolveRequestCache,
Application_UpdateRequestCache, Session_Start,Session_End
You can optionally include "On" in any of method names. For example,
you can name a BeginRequest event handler.Application_BeginRequest or
Application_OnBeginRequest.You can also include event handlers in
Global.asax for events fired by custom HTTP modules.Note that not all
of the event handlers make sense for Web Services (they're designed for
ASP.NET applications in general, whereas .NET XML Web Services are
specialized instances of an ASP.NET app). For example, the
Application_AuthenticateRequest and Application_AuthorizeRequest events
are designed to be used with ASP.NET Forms authentication.

· What is different b/w webconfig.xml & Machineconfig.xml
Web.config & machine.config both are configuration files.Web.config
contains settings specific to an application where as machine.config
contains settings to a computer. The Configuration system first
searches settings in machine.config file & then looks in application
configuration files.Web.config, can appear in multiple directories on
an ASP.NET Web application server. Each Web.config file applies
configuration settings to its own directory and all child directories
below it. There is only Machine.config file on a web server.
If I'm developing an application that must accomodate multiple security
levels though secure login and my ASP.NET web appplication is spanned
across three web-servers (using round-robbin load balancing) what would
be the best approach to maintain login-in state for the users?
Use the state server or store the state in the database. This can be
easily done through simple setting change in the web.config.
<SESSIONSTATE
StateConnectionString="tcpip=127.0.0.1:42424"
sqlConnectionString="data source=127.0.0.1; user id=sa; password="
cookieless="false"
timeout="30"
/>
You can specify mode as "stateserver" or "sqlserver".
Where would you use an iHTTPModule, and what are the limitations of any
approach you might take in implementing one
"One of ASP.NET's most useful features is the extensibility of the HTTP
pipeline, the path that data takes between client and server. You can
use them to extend your ASP.NET applications by adding pre- and
post-processing to each HTTP request coming into your application. For
example, if you wanted custom authentication facilities for your
application, the best technique would be to intercept the request when
it comes in and process the request in a custom HTTP module.
· How do you turn off cookies for one page in your site?
Since no Page Level directive is present, I am afraid that cant be
done.

· How do you create a permanent cookie?
Permanent cookies are available until a specified expiration date, and
are stored on the hard disk.So Set the 'Expires' property 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

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

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

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

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

Server.Transfer() : 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.
Response.Dedirect() :client know the physical location (page name and
query string as well). Context.Items loses the persisitance when
nevigate to destination page. In earlier versions of IIS, if we wanted
to send a user to a new Web page, the only option we had was
Response.Redirect. While this method does accomplish our goal, it has
several important drawbacks. The biggest problem is that this method
causes each page to be treated as a separate transaction. Besides
making it difficult to maintain your transactional integrity,
Response.Redirect introduces some additional headaches. First, it
prevents good encapsulation of code. Second, you lose access to all of
the properties in the Request object. Sure, there are workarounds, but
they're difficult. Finally, Response.Redirect necessitates a round trip
to the client, which, on high-volume sites, causes scalability
problems. As you might suspect, Server.Transfer fixes all of these
problems. It does this by performing the transfer on the server without
requiring a roundtrip to the client.
· 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
· Can you give an example of what might be best suited to place in
the Application_Start and Session_Start subroutines?
The Application_Start event is guaranteed to occur only once throughout
the lifetime of the application. It's a good place to initialize global
variables. For example, you might want to retrieve a list of products
from a database table and place the list in application state or the
Cache object. SessionStateModule exposes both Session_Start and
Session_End events.

· What are the advantages and disadvantages of viewstate?
The primary advantages of the ViewState feature in ASP.NET are:
1. Simplicity. There is no need to write possibly complex code to store
form data between page submissions.
2. Flexibility. It is possible to enable, configure, and disable
ViewState on a control-by-control basis, choosing to persist the values
of some fields but not others.
There are, however a few disadvantages that are worth pointing out:
1. Does not track across pages. ViewState information does not
automatically transfer from page to page. With the 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 >

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

Using the AlternatintItemTemplate

· What property must you set, and what method must you call in your
code, 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.
ASP.NET automatically deletes a user's Session object, dumping its
contents, after it has been idle for a configurable timeout interval.
This interval, in minutes, is set in the <SESSIONSTATE>section of the
web.config file. The default is 20 minutes.
· How do you turn off cookies for one page in your site?
Use Cookie.Discard property, Gets or sets the discard flag set by the
server. When true, this property instructs the client application not
to save the Cookie on the user's hard disk when a session ends.

· Which two properties are on every validation control?
We have two common properties for every validation controls
1. Control to Validate,
2. Error Message.

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

< asp:DataGrid id="dgCart" AutoGenerateColumns="False" CellPadding="4"
Width="448px" runat="server" >
< Columns >
< asp:ButtonColumn HeaderText="SELECT" Text="SELECT"
CommandName="select" >< /asp:ButtonColumn >
< asp:BoundColumn DataField="ProductId" HeaderText="Product ID" ><
/asp:BoundColumn >
< asp:BoundColumn DataField="ProductName" HeaderText="Product Name" ><
/asp:BoundColumn >
< asp:BoundColumn DataField="UnitPrice" HeaderText="UnitPrice" ><
/asp:BoundColumn >
< /Columns >
< /asp:DataGrid >
· How do you create a permanent cookie?
Permanent cookies are the ones that are most useful. Permanent cookies
are available until a specified expiration date, and are stored on the
hard disk. The location of cookies differs with each browser, but this
doesn't matter, as this is all handled by your browser and the
server. If you want to create a permanent cookie called Name with a
value of Nigel, which expires in one month, you'd use the following
code
Response.Cookies ("Name") = "Nigel"
Response.Cookies ("Name"). Expires = DateAdd ("m", 1, Now ())

· What tag do you use to add a hyperlink column to the DataGrid?
< asp:HyperLinkColumn </ asp:HyperLinkColumn>

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

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

· Explain role based security ?
Role Based Security lets you identify groups of users to allow or deny
based on their role in the organization.In Windows NT and Windows XP,
roles map to names used to identify user groups. Windows defines
several built-in groups, including Administrators, Users, and Guests.To
allow or deny access to certain groups of users, add the <ROLES>element
to the authorization list in your Web application's Web.config
file.e.g.
<AUTHORIZATION>< authorization >
< allow roles="Domain Name\Administrators" / < !-- Allow
Administrators in domain. -- >
< deny users="*" / < !-- Deny anyone
else. -- >
< /authorization >

· How do you register JavaScript for webcontrols ?
You can register javascript for controls using <CONTROL
-name>Attribtues.Add(scriptname,scripttext) method.

· When do you set "<IDENTITY impersonate="true" />" ?
Identity is a webconfig declaration under System.web, which helps to
control the application Identity of the web applicaton. Which can be at
any level(Machine,Site,application,subdirectory,or page), attribute
impersonate with "true" as value specifies that client impersonation is
used.

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

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

· What is ViewState ? and how it is managed ?

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

· What is web.config file ?
Web.config file is the configuration file for the Asp.net web
application. There is one web.config file for one asp.net application
which configures
the particular application. Web.config file is written in XML with
specific tags having specific meanings.It includes databa which
includes
connections,Session States,Error Handling,Security etc.
For example :
< configuration >
< appSettings >
< add key="ConnectionString"
value="server=localhost;uid=sa;pwd=;database=MyDB" / >
< /appSettings >
< /configuration >
· What is advantage of viewstate and what are benefits?
When a form is submitted in classic ASP, all form values are cleared.
Suppose you have submitted a form with a lot of information and the
server comes back with an error. You will have to go back to the form
and correct the information. You click the back button, and what
happens.......ALL form values are CLEARED, and you will have to start
all over again! The site did not maintain your ViewState.With ASP
..NET, the form reappears in the browser window together with all form
values.This is because ASP .NET maintains your ViewState. The ViewState
indicates the status of the page when submitted to the server.

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

Set AutoGenerateColumns Property to false on the datagrid tag and then
use Column tag and an ASP:databound tag
< 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 property on a Combo Box do you set with a column name, prior
to setting the DataSource, to display data in the combo box?
DataTextField and DataValueField

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

CompareValidator is used to ensure that two fields are identical.

· What is validationsummary server control?where it is used?.
The ValidationSummary control allows you to summarize the error
messages from all validation controls on a Web page in a single
location. The summary can be displayed as a list, a bulleted list, or a
single paragraph, based on the value of the DisplayMode property. The
error message displayed in the ValidationSummary control for each
validation control on the page is specified by the ErrorMessage
property of each validation control. If the ErrorMessage property of
the validation control is not set, no error message is displayed in the
ValidationSummary control for that validation control. You can also
specify a custom title in the heading section of the ValidationSummary
control by setting the HeaderText property.
You can control whether the ValidationSummary control is displayed or
hidden by setting the ShowSummary property. The summary can also be
displayed in a message box by setting the ShowMessageBox property to
true.

· What is the sequence of 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

· Difference between asp and asp.net?.

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

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

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

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

· What is the difference between in-proc and out-of-proc?
An inproc is one which runs in the same process area as that of the
client giving tha advantage of speed but the disadvantage of stability
becoz if it crashes it takes the client application also with
it.Outproc is one which works outside the clients memory thus giving
stability to the client, but we have to compromise a bit on speed.
· When you're running a component within ASP.NET, what process is
it running within on Windows XP? Windows 2000? Windows 2003?
On Windows 2003 (IIS 6.0) running in native mode, the component is
running within the w3wp.exe process associated with the application
pool which has been configured for the web application containing the
component.
On Windows 2003 in IIS 5.0 emulation mode, 2000, or XP, it's running
within the IIS helper process whose name I do not remember, it being
quite a while since I last used IIS 5.0.
· What does aspnet_regiis -i do ?
Aspnet_regiis.exe is The ASP.NET IIS Registration tool allows an
administrator or installation program to easily update the script maps
for an ASP.NET application to point to the ASP.NET ISAPI version
associated with the tool. The tool can also be used to display the
status of all installed versions of ASP. NET, register the ASP.NET
version coupled with the tool, create client-script directories, and
perform other configuration operations.

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

The tool can be launched with a set of optional parameters. Option "i"
Installs the version of ASP.NET associated with Aspnet_regiis.exe and
updates the script maps at the IIS metabase root and below. Note that
only applications that are currently mapped to an earlier version of
ASP.NET are affected
· What is a PostBack?
The process in which a Web page sends data back to the same page on the
server.
· What is ViewState? How is it encoded? Is it encrypted? Who uses
ViewState?

ViewState is the mechanism ASP.NET uses to 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
< %@ Page EnableViewState="false" % at the top of an .aspx page or
add the attribute EnableViewState="false" to any control.
· What is the < machinekey element and what two ASP.NET
technologies is it used for?

Configures keys to use for encryption and decryption of forms
authentication cookie data and view state data, and for verification of
out-of-process session state identification.There fore 2 ASP.Net
technique in which it is used are Encryption/Decryption & Verification
· What three Session State providers are available in ASP.NET 1.1?
What are the pros and cons of each?

ASP.NET provides three distinct ways to store session data for your
application: in-process session state, out-of-process session state as
a Windows service, and out-of-process session state in a SQL Server
database. Each has it advantages.
1.In-process session-state mode
Limitations:
* When using the in-process session-state mode, session-state data is
lost if aspnet_wp.exe or the application domain restarts.
* If you enable Web garden mode in the < processModel element of the
application's Web.config file, do not use in-process session-state
mode. Otherwise, random data loss can occur.
Advantage:
* in-process session state is by far the fastest solution. If you are
storing only small amounts of volatile data in session state, it is
recommended that you use the in-process provider.
2. The State Server simply stores session state in memory when in
out-of-proc mode. In this mode the worker process talks directly to the
State Server
3. SQL mode, session states are stored in a SQL Server database and the
worker process talks directly to SQL. The ASP.NET worker processes are
then able to take advantage of this simple storage service by
serializing and saving (using .NET serialization services) all objects
within a client's Session collection at the end of each Web request
Both these out-of-process solutions are useful primarily if you scale
your application across multiple processors or multiple computers, or
where data cannot be lost if a server or process is restarted.
· What is the difference between HTTP-Post and HTTP-Get?
As their names imply, both HTTP GET and HTTP POST use HTTP as their
underlying protocol. Both of these methods encode request parameters as
name/value pairs in the HTTP request.
The GET method creates a query string and appends it to the script's
URL on the server that handles the request.
The POST method creates a name/value pairs that are passed in the body
of the HTTP request message.
· Name and describe some HTTP Status Codes and what they express to
the requesting client.
When users try to access content on a server that is running Internet
Information Services (IIS) through HTTP or File Transfer Protocol
(FTP), IIS returns a numeric code that indicates the status of the
request. This status code is recorded in the IIS log, and it may also
be displayed in the Web browser or FTP client. The status code can
indicate whether a particular request is successful or unsuccessful and
can also reveal the exact reason why a request is unsuccessful. There
are 5 groups ranging from 1xx - 5xx of http status codes exists.
101 - Switching protocols.
200 - OK. The client request has succeeded
302 - Object moved.
400 - Bad request.
500.13 - Web server is too busy.
· Explain < @OutputCache% and the usage of VaryByParam,
VaryByHeader.
OutputCache is used to control the caching policies of an ASP.NET page
or user control. To cache a page @OutputCache directive should be
defined as follows < %@ OutputCache Duration="100" VaryByParam="none" %
>
VaryByParam: A semicolon-separated list of strings used to vary the
output cache. By default, these strings correspond to a query string
value sent with GET method attributes, or a parameter sent using the
POST method. When this attribute is set to multiple parameters, the
output cache contains a different version of the requested document for
each specified parameter. Possible values include none, *, and any
valid query string or POST parameter name.
VaryByHeader: A semicolon-separated list of HTTP headers used to vary
the output cache. When this attribute is set to multiple headers, the
output cache contains a different version of the requested document for
each specified header.
· What is the difference between repeater over datalist and datagrid?
The Repeater class is not derived from the WebControl class, like the
DataGrid and DataList. Therefore, the Repeater lacks the stylistic
properties common to both the DataGrid and DataList. What this boils
down to is that if you want to format the data displayed in the
Repeater, you must do so in the HTML markup.
The Repeater control provides the maximum amount of flexibility over
the HTML produced. Whereas the DataGrid wraps the DataSource contents
in an HTML < table >, and the DataList wraps the contents in either an
HTML < table or < span tags (depending on the DataList's
RepeatLayout property), the Repeater adds absolutely no HTML content
other than what you explicitly specify in the templates.
While using Repeater control, If we wanted to display the employee
names in a bold font we'd have to alter the "ItemTemplate" to include
an HTML bold tag, Whereas with the DataGrid or DataList, we could have
made the text appear in a bold font by setting the control's
ItemStyle-Font-Bold property to True.
The Repeater's lack of stylistic properties can drastically add to the
development time metric. For example, imagine that you decide to use
the Repeater to display data that needs to be bold, centered, and
displayed in a particular font-face with a particular background color.
While all this can be specified using a few HTML tags, these tags will
quickly clutter the Repeater's templates. Such clutter makes it much
harder to change the look at a later date. Along with its increased
development time, the Repeater also lacks any built-in functionality to
assist in supporting paging, editing, or editing of data. Due to this
lack of feature-support, the Repeater scores poorly on the usability
scale.
However, The Repeater's performance is slightly better than that of the
DataList's, and is more noticeably better than that of the DataGrid's.
Following figure shows the number of requests per second the Repeater
could handle versus the DataGrid and DataList
· Can we handle the error and redirect to some pages using
web.config?

Yes, we can do this, but to handle errors, we must know the error
codes; only then we can take the user to a proper error message page,
else it may confuse the user.
CustomErrors Configuration section in web.config file:
The default configuration is:
< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >
< error statusCode="404" redirect="Notfound.aspx" / >
< /customErrors >
If mode is set to Off, custom error messages will be disabled. Users
will receive detailed exception error messages.
If mode is set to On, custom error messages will be enabled.
If mode is set to RemoteOnly, then users will receive custom errors,
but users accessing the site locally will receive detailed error
messages.
Add an < error tag for each error you want to handle. The error tag
will redirect the user to the Notfound.aspx page when the site returns
the 404 (Page not found) error.

[Example]
There is a page MainForm.aspx
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
Dim str As System.Text.StringBuilder
str.Append("hi") ' Error Line as str is not instantiated
Response.Write(str.ToString)
End Sub
[Web.Config]
< customErrors mode="On" defaultRedirect="Error.aspx"/ >
' a simple redirect will take the user to Error.aspx [user defined]
error file.
< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >
< error statusCode="404" redirect="Notfound.aspx" / >
< /customErrors >
'This will take the user to NotFound.aspx defined in IIS.
· How do you implement Paging in .Net?
The DataGrid provides the means to display a group of records from the
data source (for example, the first 10), and then navigate to the
"page" containing the next 10 records, and so on through the data.
Using Ado.Net we can explicit control over the number of records
returned from the data source, as well as how much data is to be cached
locally in the DataSet.
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.
· What is the difference between Server.Transfer and
Response.Redirect?

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

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

The various security methods which IIS provides are
a) Authentication Modes
b) IP Address and Domain Name Restriction
c) DNS Lookups DNS Lookups
d) The Network ID and Subnet Mask
e) SSL
· What is Web Gardening? How would using it affect a design?
The Web Garden Model
The Web garden model is configurable through the section of the
machine.config file. Notice that the section is the only configuration
section that cannot be placed in an application-specific web.config
file. This means that the Web garden mode applies to all applications
running on the machine. However, by using the node in the
machine.config source, you can adapt machine-wide settings on a
per-application basis.
Two attributes in the section affect the Web garden model. They are
webGarden and cpuMask. The webGarden attribute takes a Boolean value
that indicates whether or not multiple worker processes (one per each
affinitized CPU) have to be used. The attribute is set to false by
default. The cpuMask attribute stores a DWORD value whose binary
representation provides a bit mask for the CPUs that are eligible to
run the ASP.NET worker process. The default value is -1 (0xFFFFFF),
which means that all available CPUs can be used. The contents of the
cpuMask attribute is ignored when the webGarden attribute is false. The
cpuMask attribute also sets an upper bound to the number of copies of
aspnet_wp.exe that are running.
Web gardening enables multiple worker processes to run at the same
time. However, you should note that all processes will have their own
copy of application state, in-process session state, ASP.NET cache,
static data, and all that is needed to run applications. When the Web
garden mode is enabled, the ASP.NET ISAPI launches as many worker
processes as there are CPUs, each a full clone of the next (and each
affinitized with the corresponding CPU). To balance the workload,
incoming requests are partitioned among running processes in a
round-robin manner. Worker processes get recycled as in the single
processor case. Note that ASP.NET inherits any CPU usage restriction
from the operating system and doesn't include any custom semantics for
doing this.
All in all, the Web garden model is not necessarily a big win for all
applications. The more stateful applications are, the more they risk to
pay in terms of real performance. Working data is stored in blocks of
shared memory so that any changes entered by a process are immediately
visible to others. However, for the time it takes to service a request,
working data is copied in the context of the process. Each worker
process, therefore, will handle its own copy of working data, and the
more stateful the application, the higher the cost in performance. In
this context, careful and savvy application benchmarking is an absolute
must.
Changes made to the section of the configuration file are effective
only after IIS is restarted. In IIS 6, Web gardening parameters are
stored in the IIS metabase; the webGarden and cpuMask attributes are
ignored.
· What is view state?.where it stored?.can we disable it?
The web is state-less protocol, so the page gets instantiated,
executed, rendered and then disposed on every round trip to the server.
The developers code to add "statefulness" to the page by using
Server-side storage for the state or posting the page to itself. When
require to persist and read the data in control on webform, developer
had to read the values and store them in hidden variable (in the form),
which were then used to restore the values. With advent of .NET
framework, ASP.NET came up with ViewState mechanism, which tracks the
data values of server controls on ASP.NET webform. In effect,ViewState
can be viewed as "hidden variable managed by ASP.NET framework!". When
ASP.NET page is executed, data values from all server controls on page
are collected and encoded as single string, which then assigned to
page's hidden atrribute "< input type=hidden >", that is part of page
sent to the client.
ViewState value is temporarily saved in the client's browser.ViewState
can be disabled for a single control, for an entire page orfor an
entire web application. The syntax is:
Disable ViewState for control (Datagrid in this example)
< asp:datagrid EnableViewState="false" ... / >
Disable ViewState for a page, using Page directive
< %@ Page EnableViewState="False" ... % >
Disable ViewState for application through entry in web.config
< Pages EnableViewState="false" ... / >