Dotnet FAQS
1. What is .NET Framework?
The .NET Framework has two main components: the common language runtime and
the .NET Framework class library.
You can think of the runtime as an agent that manages code at execution time,
providing core services such as memory management, thread management, and
remoting, while also enforcing strict type safety and other forms of code accuracy that ensure security and robustness.
The class library, is a comprehensive, object-oriented collection of reusable types that you can use to develop applications ranging from traditional command-line or
graphical user interface (GUI) applications to applications based on the latest
innovations provided by ASP.NET, such as Web Forms and XML Web services.
2. What is CLR?
The CLS is simply a specification that defines the rules to support language integration
in such a way that programs written in any language, yet can interoperate with one
another, taking full advantage of inheritance, polymorphism, exceptions, and other
features. These rules and the specification are documented in the ECMA proposed
standard document, "Partition I Architecture", available here.
3. Is .NET a runtime service or a development platform?
Ans: It's both and actually a lot more. Microsoft .NET includes a new way of delivering software and services to businesses and consumers. A part of Microsoft.NET is the .NET Frameworks. The .NET frameworks SDK consists of two parts: the .NET common language runtime and the .NET class library. In addition, the SDK also includes command-line compilers for C#, C++, JScript, and VB. You use these compilers to build applications and components. These components require the runtime to execute so this is a development platform.
4. What are the new features of Framework 1.1 ?
1. Native Support for Developing Mobile Web Applications
2. Enable Execution of Windows Forms Assemblies Originating from the Internet
Assemblies originating from the Internet zone—for example, Microsoft Windows® Forms controls embedded in an Internet-based Web page or Windows Forms assemblies hosted on an Internet Web server and loaded either through the Web browser or programmatically using the System.Reflection.Assembly.LoadFrom() method—now receive sufficient permission to execute in a semi-trusted manner. Default security policy has been changed so that assemblies assigned by the common language runtime (CLR) to the Internet zone code group now receive the constrained permissions associated with the Internet permission set. In the .NET
Framework 1.0 Service Pack 1 and Service Pack 2, such applications received the permissions associated with the Nothing permission set and could not execute.
3. Enable Code Access Security for ASP.NET Applications
Systems administrators can now use code access security to further lock down
the permissions granted to ASP.NET Web applications and Web services.
Although the operating system account under which an application runs imposes security restrictions on the application, the code access security system of the CLR can enforce additional restrictions on selected application resources based on policies specified by systems administrators. You can use this feature in a shared server environment (such as an Internet service provider (ISP) hosting multiple Web applications on one server) to isolate separate applications from one another, as well as with stand-alone servers where you want applications to run with the minimum necessary privileges.
4. Native Support for Communicating with ODBC and Oracle Databases
5. Unified Programming Model for Smart Client Application Development The Microsoft .NET Compact Framework brings the CLR, Windows Forms controls, and other .NET Framework features to small devices. The .NET Compact Framework supports a large subset of the .NET Framework class library optimized for small devices.
6. Support for IPv6
The .NET Framework 1.1 supports the emerging update to the Internet Protocol, commonly referred to as IP version 6, or simply IPv6. This protocol is designed to significantly increase the address space used to identify communication endpoints in the Internet to accommodate its ongoing growth.
http://msdn.microsoft.com/netframework/technologyinfo/Overview/whatsnew.aspx
5. What is Code Access Security (CAS)?
CAS is the part of the .NET security model that determines whether or not a piece of
code is allowed to run, and what resources it can use when it is running. For example,
it is CAS that will prevent a .NET web applet from formatting your hard disk.
How does CAS work?
The CAS security policy revolves around two key concepts - code groups and
permissions. Each .NET assembly is a member of a particular code group, and each
code group is granted the permissions specified in a named permission set.
For example, using the default security policy, a control downloaded from a web site
belongs to the 'Zone - Internet' code group, which adheres to the permissions defined
by the 'Internet' named permission set. (Naturally the 'Internet' named permission set
represents a very restrictive range of permissions.)
Who defines the CAS code groups?
Microsoft defines some default ones, but you can modify these and even create your
own. To see the code groups defined on your system, run 'caspol -lg' from the
command-line. On my ssystem it looks like this:
6. Level = Machine
7. Code Groups:
8.
9. 1. All code: Nothing
10. 1.1. Zone - MyComputer: FullTrust
11. 1.1.1. Honor SkipVerification requests: SkipVerification
12. 1.2. Zone - Intranet: LocalIntranet
13. 1.3. Zone - Internet: Internet
14. 1.4. Zone - Untrusted: Nothing
15. 1.5. Zone - Trusted: Internet
16. 1.6. StrongName -
0024000004800000940000000602000000240000525341310004000003
17. 000000CFCB3291AA715FE99D40D49040336F9056D7886FED46775BC7BB5430BA44
44FEF8348EBD06
18. F962F39776AE4DC3B7B04A7FE6F49F25F740423EBF2C0B89698D8D08AC48D69CED
0FC8F83B465E08
19. 07AC11EC1DCC7D054E807A43336DDE408A5393A48556123272CEEEE72F1660B71
927D38561AABF5C
AC1DF1734633C602F8F2D5: Everything
Note the hierarchy of code groups - the top of the hierarchy is the most general ('All
code'), which is then sub-divided into several groups, each of which in turn can be
sub-divided. Also note that (somewhat counter-intuitively) a sub-group can be
associated with a more permissive permission set than its parent.
How do I define my own code group?
Use caspol. For example, suppose you trust code from www.mydomain.com and you
want it have full access to your system, but you want to keep the default restrictions
for all other internet sites. To achieve this, you would add a new code group as a subgroup of the 'Zone - Internet' group, like this:
caspol -ag 1.3 -site www.mydomain.com FullTrust
Now if you run caspol -lg you will see that the new group has been added as group
1.3.1:
...
1.3. Zone - Internet: Internet
1.3.1. Site - www.mydomain.com: FullTrust
...
Note that the numeric label (1.3.1) is just a caspol invention to make the code groups easy to manipulate from the command-line. The underlying runtime never sees it.
How do I change the permission set for a code group?
Use caspol. If you are the machine administrator, you can operate at the 'machine'
level - which means not only that the changes you make become the default for the
machine, but also that users cannot change the permissions to be more permissive. If you are a normal (non-admin) user you can still modify the permissions, but only to make them more restrictive. For example, to allow intranet code to do what it likes
you might do this:
caspol -cg 1.2 FullTrust
Note that because this is more permissive than the default policy (on a standard
system), you should only do this at the machine level - doing it at the user level will
have no effect.
Can I create my own permission set?
Yes. Use caspol -ap, specifying an XML file containing the permissions in the
permission set. To save you some time, here is a sample file corresponding to the
'Everything' permission set - just edit to suit your needs. When you have edited the
sample, add it to the range of available permission sets like this:
caspol -ap samplepermset.xml
Then, to apply the permission set to a code group, do something like this:
caspol -cg 1.3 SamplePermSet (By default, 1.3 is the 'Internet' code group)
I'm having some trouble with CAS. How can I diagnose my problem?
Caspol has a couple of options that might help. First, you can ask caspol to tell you
what code group an assembly belongs to, using caspol -rsg. Similarly, you can ask
what permissions are being applied to a particular assembly using caspol -rsp.
I can't be bothered with all this CAS stuff. Can I turn it off?
Yes, as long as you are an administrator. Just run:
caspol -s off
20. What is MSIL, IL?
When compiling to managed code, the compiler translates your source code into
Microsoft intermediate language (MSIL), which is a CPU-independent set of
instructions that can be efficiently converted to native code. MSIL includes instructions for loading, storing, initializing, and calling methods on objects, as well as instructions for arithmetic and logical operations, control flow, direct memory access, exception handling, and other operations. Microsoft intermediate language (MSIL) is a language used as the output of a number of compilers and as the input to a just-in-time (JIT) compiler. The common language runtime includes a JIT compiler for converting MSIL to native code.
21. Can I write IL programs directly?
Yes. Peter Drayton posted this simple example to the DOTNET mailing list:
.assembly MyAssembly {}
.class MyApp {
.method static void Main() {
.entrypoint
ldstr "Hello, IL!"
call void System.Console::WriteLine(class System.Object)
ret
}
}
Just put this into a file called hello.il, and then run ilasm hello.il. An exe assembly will be generated.
Can I do things in IL that I can't do in C#?
Yes. A couple of simple examples are that you can throw exceptions that are not
derived from System.Exception, and you can have non-zero-based arrays.
22. What is CTS?
The common type system defines how types are declared, used, and managed in the runtime, and is also an important part of the runtime's support for cross-language integration.
The common type system supports two general categories of types, each of which is further divided into subcategories:
• Value types
Value types directly contain their data, and instances of value types are either allocated on the stack or allocated inline in a structure. Value types can be built-in (implemented by the runtime), user-defined, or enumerations.
• Reference types
Reference types store a reference to the value's memory address, and are allocated on the heap. Reference types can be self-describing types, pointer types, or interface types. The type of a reference type can be determined from values of self-describing types. Self-describing types are further split into arrays and class types. The class types are user-defined classes, boxed value types, and delegates.
23. What is JIT (just in time)? how it works?
Before Microsoft intermediate language (MSIL) can be executed, it must be converted by a .NET Framework just-in-time (JIT) compiler to native code, which is CPU-specific code that runs on the same computer architecture as the JIT compiler.
Rather than using time and memory to convert all the MSIL in a portable executable (PE) file to native code, it converts the MSIL as it is needed during execution and stores the resulting native code so that it is accessible for subsequent calls.
The runtime supplies another mode of compilation called install-time code generation.
The install-time code generation mode converts MSIL to native code just as the regular JIT compiler does, but it converts larger units of code at a time, storing the resulting native code for use when the assembly is subsequently loaded and executed.
As part of compiling MSIL to native code, code must pass a verification process unless an administrator has established a security policy that allows code to bypass verification. Verification examines MSIL and metadata to find out whether the code can be determined to be type safe, which means that it is known to access only the
memory locations it is authorized to access.
24. What is strong name?
A name that consists of an assembly's identity—its simple text name, version number,
and culture information (if provided)—strengthened by a public key and a digital
signature generated over the assembly.
25. What is portable executable (PE)?
The file format defining the structure that all executable files (EXE) and Dynamic Link Libraries (DLL) must use to allow them to be loaded and executed by Windows. PE is derived from the Microsoft Common Object File Format (COFF). The EXE and DLL files created using the .NET Framework obey the PE/COFF formats and also add additional header and data sections to the files that are only used by the CLR. The specification
for the PE/COFF file formats is available at
http://www.microsoft.com/whdc/hwdev/hardware/pecoffdown.mspx
26. Which namespace is the base class for .net Class library?
Ans: system.object
27. What is Event - Delegate? clear syntax for writing a event delegate
The event keyword lets you specify a delegate that will be called upon the occurrence of some "event" in your code. The delegate can have one or more associated methods that will be called when your code indicates that the event has occurred. An event in one program can be made available to other programs that target the .NET Framework
Common Language Runtime.
// keyword_delegate.cs
// delegate declaration
delegate void MyDelegate(int i);
28. class Program
29. {
30. public static void Main()
31. {
32. TakesADelegate(new MyDelegate(DelegateFunction));
33. }
34. public static void TakesADelegate(MyDelegate SomeFunction)
35. {
36. SomeFunction(21);
37. }
38. public static void DelegateFunction(int i)
39. {
40. System.Console.WriteLine("Called by delegate with number: {0}.", i);
41. }
}
42. What are object pooling and connection pooling and difference? Where do we set the Min and Max Pool size for connection pooling?
Object pooling is a COM+ service that enables you to reduce the overhead of creating each object from scratch. When an object is activated, it is pulled from the pool. When the object is deactivated, it is placed back into the pool to await the next request. You can configure object pooling by applying the ObjectPoolingAttribute attribute to a class that derives from the System.EnterpriseServices.ServicedComponent class.
Object pooling lets you control the number of connections you use, as opposed to
connection pooling, where you control the maximum number reached. Following are important differences between object pooling and connection pooling:
• Creation. When using connection pooling, creation is on the same thread, so if there is nothing in the pool, a connection is created on your behalf. With object pooling, the pool might decide to create a new object. However, if you have already reached your maximum, it instead gives you the next available object. This is crucial behavior when it takes a long time to create an object, but you do not use it for very long.
• Enforcement of minimums and maximums. This is not done in connection pooling. The maximum value in object pooling is very important when trying to scale your application. You might need to multiplex thousands of requests to just a few objects. (TPC/C benchmarks rely on this.)
COM+ object pooling is identical to what is used in .NET Framework managed SQL Client connection pooling. For example, creation is on a different thread and minimums and maximums are enforced.
43. What is Application Domain?
The primary purpose of the AppDomain is to isolate an application from other applications. Win32 processes provide isolation by having distinct memory address spaces. This is effective, but it is expensive and doesn't scale well. The .NET runtime enforces AppDomain isolation by keeping control over the use of memory - all memory in the AppDomain is managed by the .NET runtime, so the runtime can ensure that AppDomains do not access each other's memory. Objects in different application domains communicate either by transporting copies of objects across application domain boundaries, or by using a proxy to exchange messages.
MarshalByRefObject is the base class for objects that communicate across
application domain boundaries by exchanging messages using a proxy. Objects that do not inherit from MarshalByRefObject are implicitly marshal by value. When a remote application references a marshal by value object, a copy of the object is passed across application domain boundaries.
How does an AppDomain get created?
AppDomains are usually created by hosts. Examples of hosts are the Windows Shell,
ASP.NET and IE. When you run a .NET application from the command-line, the host is the Shell. The Shell creates a new AppDomain for every application.
AppDomains can also be explicitly created by .NET applications. Here is a C# sample
which creates an AppDomain, creates an instance of an object inside it, and then executes one of the object's methods. Note that you must name the executable
'appdomaintest.exe' for this code to work as-is.
using System;
using System.Runtime.Remoting;
public class CAppDomainInfo : MarshalByRefObject
{
public string GetAppDomainInfo()
{
return "AppDomain = " + AppDomain.CurrentDomain.FriendlyName;
}
}
public class App
{
public static int Main()
{
AppDomain ad = AppDomain.CreateDomain( "Andy's new domain", null,
null );
ObjectHandle oh = ad.CreateInstance( "appdomaintest",
"CAppDomainInfo" );
CAppDomainInfo adInfo = (CAppDomainInfo)(oh.Unwrap());
string info = adInfo.GetAppDomainInfo();
Console.WriteLine( "AppDomain info: " + info );
return 0;
}
}
44. What is serialization in .NET? What are the ways to control serialization?
Serialization is the process of converting an object into a stream of bytes. Deserialization is the opposite process of creating an object from a stream of bytes.
Serialization/Deserialization is mostly used to transport objects (e.g. during remoting), or to persist objects (e.g. to a file or database).Serialization can be defined as the process of storing the state of an object to a storage medium. During this process, the public and private fields of the object and the name of the class, including the assembly containing the class, are converted to a stream of bytes, which is then written to a data stream. When the object is subsequently deserialized, an exact clone of the original object is created.
• Binary serialization preserves type fidelity, which is useful for preserving the state of an object between different invocations of an application. For example, you can share an object between different applications by serializing it to the clipboard. You can serialize an object to a stream, disk, memory, over the network, and so forth. Remoting uses serialization to pass objects "by value" from one computer or application domain to another.
• XML serialization serializes only public properties and fields and does not preserve type fidelity. This is useful when you want to provide or consume data without restricting the application that uses the data. Because XML is an open standard, it is an attractive choice for sharing data across the Web. SOAP is an open standard, which makes it an attractive choice. There are two separate mechanisms provided by the .NET class library – XmlSerializer and SoapFormatter/BinaryFormatter. Microsoft uses XmlSerializer for Web Services, and uses SoapFormatter/BinaryFormatter for remoting. Both are available for use in your own code.
Why do I get errors when I try to serialize a Hashtable?
XmlSerializer will refuse to serialize instances of any class that implements IDictionary, e.g. Hashtable. SoapFormatter and BinaryFormatter do not have this
restriction.
45. What is the use of trace utility?
**
46. What are server controls?
ASP.NET server controls are components that run on the server and encapsulate userinterface
and other related functionality. They are used in ASP.NET pages and in
ASP.NET code-behind classes.
47. What is the difference between Web User Control and Web Custom Control? Custom Controls
Web custom controls are compiled components that run on the server and that encapsulate user-interface and other related functionality into reusable packages. They can include all the design-time features of standard ASP.NET server controls, including full support for Visual Studio design features such as the Properties window, the visual designer, and the Toolbox.
There are several ways that you can create Web custom controls:
• You can compile a control that combines the functionality of two or more existing controls. For example, if you need a control that encapsulates a button and a text box, you can create it by compiling the existing controls together.
• If an existing server control almost meets your requirements but lacks some required features, you can customize the control by deriving from it and overriding its properties, methods, and events.
• If none of the existing Web server controls (or their combinations) meet your requirements, you can create a custom control by deriving from one of the base control classes. These classes provide all the basic functionality of Web server controls, so you can focus on programming the features you need.
If none of the existing ASP.NET server controls meet the specific requirements of your applications, you can create either a Web user control or a Web custom control that encapsulates the functionality you need. The main difference between the two controls lies in ease of creation vs. ease of use at design time.
Web user controls are easy to make, but they can be less convenient to use in
advanced scenarios. You develop Web user controls almost exactly the same way that you develop Web Forms pages. Like Web Forms, user controls can be created in the visual designer, they can be written with code separated from the HTML, and they can handle execution events. However, because Web user controls are compiled
dynamically at run time they cannot be added to the Toolbox, and they are represented by a simple placeholder glyph when added to a page. This makes Web
user controls harder to use if you are accustomed to full Visual Studio .NET designtime support, including the Properties window and Design view previews. Also, the only way to share the user control between applications is to put a separate copy in each application, which takes more maintenance if you make changes to the control.
Web custom controls are compiled code, which makes them easier to use but more difficult to create; Web custom controls must be authored in code. Once you have created the control, however, you can add it to the Toolbox and display it in a visual
designer with full Properties window support and all the other design-time features of
ASP.NET server controls. In addition, you can install a single copy of the Web custom
control in the global assembly cache and share it between applications, which makes
maintenance easier.
48. What is exception handling?
When an exception occurs, the system searches for the nearest catch clause that can
handle the exception, as determined by the run-time type of the exception. First, the
current method is searched for a lexically enclosing try statement, and the associated catch clauses of the try statement are considered in order. If that fails, the method that called the current method is searched for a lexically enclosing try statement that encloses the point of the call to the current method. This search continues until a catch clause is found that can handle the current exception, by naming an exception class that is of the same class, or a base class, of the run-time type of the exception being thrown. A catch clause that doesn't name an exception class can handle any exception.
Once a matching catch clause is found, the system prepares to transfer control to the first statement of the catch clause. Before execution of the catch clause begins, the system first executes, in order, any finally clauses that were associated with try statements more nested that than the one that caught the exception.
Exceptions that occur during destructor execution are worth special mention. If an
exception occurs during destructor execution, and that exception is not caught, then
the execution of that destructor is terminated and the destructor of the base class (if
any) is called. If there is no base class (as in the case of the object type) or if there is no base class destructor, then the exception is discarded.
49. What is Assembly?
Assemblies are the building blocks of .NET Framework applications; they form the fundamental unit of deployment, version control, reuse, activation scoping, and security permissions. An assembly is a collection of types and resources that are built to work together and form a logical unit of functionality. An assembly provides the common language runtime with the information it needs to be aware of type implementations. To the runtime, a type does not exist outside the context of an assembly.
Assemblies are a fundamental part of programming with the .NET Framework. An assembly performs the following functions:
• It contains code that the common language runtime executes. Microsoft intermediate language (MSIL) code in a portable executable (PE) file will not be executed if it does not have an associated assembly manifest. Note that each assembly can have only one entry point (that is, DllMain, WinMain, or Main).
• It forms a security boundary. An assembly is the unit at which permissions are requested and granted.
• It forms a type boundary. Every type's identity includes the name of the assembly in which it resides. A type called MyType loaded in the scope of one assembly is not the same as a type called MyType loaded in the scope of another assembly.
• It forms a reference scope boundary. The assembly's manifest contains assembly metadata that is used for resolving types and satisfying resource requests. It specifies the types and resources that are exposed outside the
assembly. The manifest also enumerates other assemblies on which it depends.
• It forms a version boundary. The assembly is the smallest versionable unit in the common language runtime; all types and resources in the same assembly are versioned as a unit. The assembly's manifest describes the version dependencies you specify for any dependent assemblies.
• It forms a deployment unit. When an application starts, only the assemblies that the application initially calls must be present. Other assemblies, such as localization resources or assemblies containing utility classes, can be retrieved on demand. This allows applications to be kept simple and thin when first downloaded.
• It is the unit at which side-by-side execution is supported.
Assemblies can be static or dynamic. Static assemblies can include .NET Framework types (interfaces and classes), as well as resources for the assembly (bitmaps, JPEG files, resource files, and so on). Static assemblies are stored on disk in PE files. You can also use the .NET Framework to create dynamic assemblies, which are run directly from memory and are not saved to disk before execution. You can save dynamic
assemblies to disk after they have executed. There are several ways to create assemblies. You can use development tools, such as Visual Studio .NET, that you have used in the past to create .dll or .exe files. You can use tools provided in the .NET Framework SDK to create assemblies with modules created in other development environments. You can also use common language runtime APIs, such as Reflection.Emit, to create dynamic assemblies.
50. What are the contents of assembly?
In general, a static assembly can consist of four elements:
• The assembly manifest, which contains assembly metadata.
• Type metadata.
• Microsoft intermediate language (MSIL) code that implements the types.
• A set of resources.
51. What are the different types of assemblies?
Private, Public/Shared, Satellite
52. What is the difference between a private assembly and a shared assembly?
0. Location and visibility: A private assembly is normally used by a single application, and is stored in the application's directory, or a sub-directory beneath. A shared assembly is normally stored in the global assembly cache, which is a repository of assemblies maintained by the .NET runtime. Shared assemblies are usually libraries of code which many applications will find useful, e.g. the .NET framework classes.
1. Versioning: The runtime enforces versioning constraints only on shared
assemblies, not on private assemblies.
53. What are Satellite Assemblies? How you will create this? How will you get the different language strings?
Satellite assemblies are often used to deploy language-specific resources for an application. These language-specific assemblies work in side-by-side execution because the application has a separate product ID for each language and installs satellite assemblies in a language-specific subdirectory for each language. When
uninstalling, the application removes only the satellite assemblies associated with a given language and .NET Framework version. No core .NET Framework files are removed unless the last language for that .NET Framework version is being removed. (For example, English and Japanese editions of the .NET Framework version 1.1 share the same core files. The Japanese .NET Framework version 1.1 adds satellite
assemblies with localized resources in a \ja subdirectory. An application that supports the .NET Framework version 1.1, regardless of its language, always uses the same core runtime files.)
http://www.ondotnet.com/lpt/a/2637
**
54. How will u load dynamic assembly? How will create assemblies at run time?
**
55. What is Assembly manifest? what all details the assembly manifest will
contain?
Every assembly, whether static or dynamic, contains a collection of data that describes how the elements in the assembly relate to each other. The assembly manifest contains this assembly metadata. An assembly manifest contains all the metadata needed to specify the assembly's version requirements and security identity, and all metadata needed to define the scope of the assembly and resolve references to resources and classes. The assembly manifest can be stored in either a PE file (an .exe or .dll) with Microsoft intermediate language (MSIL) code or in a standalone PE file that contains only assembly manifest information.
It contains Assembly name, Version number, Culture, Strong name information, List of all files in the assembly, Type reference information, Information on referenced
assemblies.
56. Difference between assembly manifest & metadata?
assembly manifest - An integral part of every assembly that renders the assembly
self-describing. The assembly manifest contains the assembly's metadata. The
manifest establishes the assembly identity, specifies the files that make up the
assembly implementation, specifies the types and resources that make up the
assembly, itemizes the compile-time dependencies on other assemblies, and specifies the set of permissions required for the assembly to run properly. This information is used at run time to resolve references, enforce version binding policy, and validate the integrity of loaded assemblies. The self-describing nature of assemblies also helps makes zero-impact install and XCOPY deployment feasible.
metadata - Information that describes every element managed by the common
language runtime: an assembly, loadable file, type, method, and so on. This can
include information required for debugging and garbage collection, as well as security
attributes, marshaling data, extended class and member definitions, version binding,
and other information required by the runtime.
57. What is Global Assembly Cache (GAC) and what is the purpose of it? (How to make an assembly to public? Steps) How more than one version of an assembly can keep in same place?
Each computer where the common language runtime is installed has a machine-wide
code cache called the global assembly cache. The global assembly cache stores
assemblies specifically designated to be shared by several applications on the
computer. You should share assemblies by installing them into the global assembly
cache only when you need to.
Steps
- Create a strong name using sn.exe tool
eg: sn -k keyPair.snk
- with in AssemblyInfo.cs add the generated file name
eg: [assembly: AssemblyKeyFile("abc.snk")]
- recompile project, then install it to GAC by either
drag & drop it to assembly folder (C:\WINDOWS\assembly OR C:\WINNT\assembly)
(shfusion.dll tool)
or
gacutil -i abc.dll
58. If I have more than one version of one assemblies, then how'll I use old
version (how/where to specify version number?)in my application?
**
59. How to find methods of a assembly file (not using ILDASM)
Reflection
60. What is Garbage Collection in .Net? Garbage collection process?
The process of transitively tracing through all pointers to actively used objects in order to locate all objects that can be referenced, and then arranging to reuse any heap memory that was not found during this trace. The common language runtime garbage collector also compacts the memory that is in use to reduce the working space needed for the heap.
61. Readonly vs. const?
A const field can only be initialized at the declaration of the field. A readonly field can be initialized either at the declaration or in a constructor. Therefore, readonly fields can have different values depending on the constructor used. Also, while a const field is a compile-time constant, the readonly field can be used for runtime constants, as in the following example:
public static readonly uint l1 = (uint) DateTime.Now.Ticks;
62. What is Reflection in .NET? Namespace? How will you load an assembly
which is not referenced by current assembly?
All .NET compilers produce metadata about the types defined in the modules they produce. This metadata is packaged along with the module (modules in turn are packaged together in assemblies), and can be accessed by a mechanism called reflection. The System.Reflection namespace contains classes that can be used to
interrogate the types for a module/assembly.
Using reflection to access .NET metadata is very similar to using ITypeLib/ITypeInfo to access type library data in COM, and it is used for similar purposes - e.g. determining data type sizes for marshaling data across context/process/machine boundaries. Reflection can also be used to dynamically invoke methods (see System.Type.InvokeMember), or even create types dynamically at run-time (see
System.Reflection.Emit.TypeBuilder).
63. What is Custom attribute? How to create? If I'm having custom attribute in an assembly, how to say that name in the code?
A: The primary steps to properly design custom attribute classes are as follows:
. Applying the AttributeUsageAttribute ([AttributeUsage(AttributeTargets.All,
Inherited = false, AllowMultiple = true)])
a. Declaring the attribute. (class public class MyAttribute : System.Attribute { // .
. . })
b. Declaring constructors (public MyAttribute(bool myvalue) { this.myvalue =
myvalue; })
c. Declaring properties
d. public bool MyProperty
e. {
f. get {return this.myvalue;}
g. set {this.myvalue = value;}
h. }
64. The following example demonstrates the basic way of using reflection to get access
to custom attributes.
65. class MainClass
66. {
67. public static void Main()
68. {
69. System.Reflection.MemberInfo info = typeof(MyClass);
70. object[] attributes = info.GetCustomAttributes();
71. for (int i = 0; i < attributes.Length; i ++)
72. {
73. System.Console.WriteLine(attributes[i]);
74. }
75. }
}
76. What is the managed and unmanaged code in .net?
The .NET Framework provides a run-time environment called the Common Language Runtime, which manages the execution of code and provides services that make the development process easier. Compilers and tools expose the runtime's functionality and enable you to write code that benefits from this managed execution environment. Code that you develop with a language compiler that targets the runtime is called managed code; it benefits from features such as cross-language integration, crosslanguage exception handling, enhanced security, versioning and deployment support, a simplified model for component interaction, and debugging and profiling services.
77. How do you create threading in .NET? What is the namespace for that?
**
System.Threading.Thread
78. Serialize and MarshalByRef?
79. using directive vs using statement
You create an instance in a using statement to ensure that Dispose is called on the object when the using statement is exited. A using statement can be exited either when the end of the using statement is reached or if, for example, an exception is thrown and control leaves the statement block before the end of the statement.
The using directive has two uses:
• Create an alias for a namespace (a using alias).
• Permit the use of types in a namespace, such that, you do not have to qualify
the use of a type in that namespace (a using directive).
80. Describe the Managed Execution Process?
The managed execution process includes the following steps:
0. Choosing a compiler.
To obtain the benefits provided by the common language runtime, you must use one or more language compilers that target the runtime.
1. Compiling your code to Microsoft intermediate language (MSIL).
Compiling translates your source code into MSIL and generates the required metadata.
2. Compiling MSIL to native code.
At execution time, a just-in-time (JIT) compiler translates the MSIL into native
code. During this compilation, code must pass a verification process that examines the MSIL and metadata to find out whether the code can be determined to be type safe.
3. Executing your code.
The common language runtime provides the infrastructure that enables execution to take place as well as a variety of services that can be used during execution.
81. What is Active Directory? What is the namespace used to access the Microsoft Active Directories? What are ADSI Directories?
Active Directory Service Interfaces (ADSI) is a programmatic interface for Microsoft
Windows Active Directory. It enables your applications to interact with diverse directories on a network, using a single interface. Visual Studio .NET and the .NET
Framework make it easy to add ADSI functionality with the DirectoryEntry and
DirectorySearcher components.
Using ADSI, you can create applications that perform common administrative tasks,
such as backing up databases, accessing printers, and administering user accounts.
ADSI makes it possible for you to:
• Log on once to work with diverse directories. The DirectoryEntry component class provides username and password properties that can be entered at runtime and communicated to the Active Directory object you are binding to.
• Use a single application programming interface (API) to perform tasks on multiple directory systems by offering the user a variety of protocols to use. The DirectoryServices namespace provides the classes to perform most administrative functions.
• Perform "rich querying" on directory systems. ADSI technology allows for searching for an object by specifying two query dialects: SQL and LDAP.
• Access and use a single, hierarchical structure for administering and maintaining diverse and complicated network configurations by accessing an Active Directory tree.
• Integrate directory information with databases such as SQL Server. The DirectoryEntry path may be used as an ADO.NET connection string provided that it is using the LDAP provider. using System.DirectoryServices;
82. How Garbage Collector (GC) Works?
The methods in this class influence when an object is garbage collected and when resources allocated by an object are released. Properties in this class provide information about the total amount of memory available in the system and the age
category, or generation, of memory allocated to an object. Periodically, the garbage
collector performs garbage collection to reclaim memory allocated to objects for which there are no valid references. Garbage collection happens automatically when a request for memory cannot be satisfied using available free memory. Alternatively, an application can force garbage collection using the Collect method.
Garbage collection consists of the following steps:
0. The garbage collector searches for managed objects that are referenced in
managed code.
1. The garbage collector attempts to finalize objects that are not referenced.
2. The garbage collector frees objects that are not referenced and reclaims their
memory.
83. Why do we need to call CG.SupressFinalize?
Requests that the system not call the finalizer method for the specified object.
public static void SuppressFinalize(
object obj
);
The method removes obj from the set of objects that require finalization. The obj
parameter is required to be the caller of this method. Objects that implement the IDisposable interface can call this method from the IDisposable.Dispose method to prevent the garbage collector from calling Object.Finalize on an object that does not require it.
84. What is nmake tool?
The Nmake tool (Nmake.exe) is a 32-bit tool that you use to build projects based on
commands contained in a .mak file.
usage : nmake -a all
85. What are Namespaces?
The namespace keyword is used to declare a scope. This namespace scope lets you
organize code and gives you a way to create globally-unique types. Even if you do not
explicitly declare one, a default namespace is created. This unnamed namespace,
sometimes called the global namespace, is present in every file. Any identifier in the
global namespace is available for use in a named namespace. Namespaces implicitly
have public access and this is not modifiable.
86. C++ & C# differences
**
87. If you want to write your own dot net language, what steps you will u take
care?
88. What is custom events? How to create it?
89. how dot net compiled code will become platform independent?
90. without modifying source code if we compile again, will it be generated MSIL
again?
91. Describe the difference between inline and code behind - which is best in a
loosely coupled solution?
92. What is the difference between CONST and READONLY?
93. What is the difference between ref & out parameters?
What is the difference between arrays and Arraylist?
94. What are indexers?
95. How to create events for a control?
96. Explain about SOAP
97. Practical Example of Passing an Events to delegates
98. How can you read 3rd line from a text file?
99. What is Asynchronous call and how it can be implemented using delegates?
100. What is the difference between Array and LinkedList?
101. What is Jagged Arrays?
A jagged array is an array whose elements are arrays. The elements of a jagged array can be of different dimensions and sizes. A jagged array is sometimes called an
"array-of-arrays." (COM)
102. Interop Services?
The common language runtime provides two mechanisms for interoperating with
unmanaged code:
• Platform invoke, which enables managed code to call functions exported from
an unmanaged library.
• COM interop, which enables managed code to interact with COM objects
through interfaces.
Both platform invoke and COM interop use interop marshaling to accurately move
method arguments between caller and callee and back, if required.
103. How does u handle this COM components developed in other
programming languages in .NET?
104. What is RCW (Runtime Callable Wrappers)?
The common language runtime exposes COM objects through a proxy called the runtime callable wrapper (RCW). Although the RCW appears to be an ordinary object
to .NET clients, its primary function is to marshal calls between a .NET client and a
COM object.
105. What is CCW (COM Callable Wrapper)
A proxy object generated by the common language runtime so that existing COM applications can use managed classes, including .NET Framework classes, transparently.
106. How CCW and RCW is working?
**
107. How will you register com+ services?
The .NET Framework SDK provides the .NET Framework Services Installation Tool
(Regsvcs.exe - a command-line tool) to manually register an assembly containing
serviced components. You can also access these registration features programmatically with the System.EnterpriseServicesRegistrationHelper class by
creating an instance of class RegistrationHelper and using the method InstallAssembly
108. What is use of ContextUtil class?
ContextUtil is the preferred class to use for obtaining COM+ context information.
109. What is the new three features of COM+ services, which are not there
in COM (MTS)?
**
110. Is the COM architecture same as .Net architecture? What is the
difference between them?
**
111. Can we copy a COM dll to GAC folder?
**
112. What is Pinvoke?
Platform invoke is a service that enables managed code to call unmanaged functions
implemented in dynamic-link libraries (DLLs), such as those in the Win32 API. It
locates and invokes an exported function and marshals its arguments (integers,
strings, arrays, structures, and so on) across the interoperation boundary as needed.
113. Is it true that COM objects no longer need to be registered on the
server?
Answer: Yes and No. Legacy COM objects still need to be registered on the server
before they can be used. COM developed using the new .NET Framework will not need
to be registered. Developers will be able to auto-register these objects just by placing
them in the 'bin' folder of the application.
114. Can .NET Framework components use the features of Component
Services?
Answer: Yes, you can use the features and functions of Component Services from a
.NET Framework component.
http://msdn.microsoft.com/library/techart/Pahlcompserv.htm
(OOPS)
115. What are the OOPS concepts?
1) Encapsulation: It is the mechanism that binds together code and data in
manipulates, and keeps both safe from outside interference and misuse. In short it
isolates a particular code and data from all other codes and data. A well-defined
interface controls the access to that particular code and data.
2) Inheritance: It is the process by which one object acquires the properties of
another object. This supports the hierarchical classification. Without the use of
hierarchies, each object would need to define all its characteristics explicitly. However, by use of inheritance, an object need only define those qualities that make it unique within its class. It can inherit its general attributes from its parent. A new sub-class inherits all of the attributes of all of its ancestors.
3) Polymorphism: It is a feature that allows one interface to be used for general class of actions. The specific action is determined by the exact nature of the situation. In general polymorphism means "one interface, multiple methods", This means that it is possible to design a generic interface to a group of related activities. This helps reduce complexity by allowing the same interface to be used to specify a general class of action. It is the compiler's job to select the specific action (that is, method) as it applies to each situation.
116. What is the difference between a Struct and a Class?
• The struct type is suitable for representing lightweight objects such as Point, Rectangle, and Color. Although it is possible to represent a point as a class, a struct is more efficient in some scenarios. For example, if you declare an array of 1000 Point objects, you will allocate additional memory for referencing each object. In this case, the struct is less expensive.
• When you create a struct object using the new operator, it gets created and the appropriate constructor is called. Unlike classes, structs can be instantiated without using the new operator. If you do not use new, the fields will remain unassigned and the object cannot be used until all of the fields are initialized.
• It is an error to declare a default (parameterless) constructor for a struct. A default constructor is always provided to initialize the struct members to their default values.
• It is an error to initialize an instance field in a struct.
• There is no inheritance for structs as there is for classes. A struct cannot inherit from another struct or class, and it cannot be the base of a class. Structs, however, inherit from the base class Object. A struct can implement interfaces, and it does that exactly as classes do.
• A struct is a value type, while a class is a reference type.
117. Value type & reference types difference? Example from .NET. Integer
& struct are value types or reference types in .NET?
Most programming languages provide built-in data types, such as integers and
floating-point numbers, that are copied when they are passed as arguments (that is,
they are passed by value). In the .NET Framework, these are called value types. The
runtime supports two kinds of value types:
• Built-in value types
The .NET Framework defines built-in value types, such as System.Int32 and System.Boolean, which correspond and are identical to primitive data types used by programming languages.
• User-defined value types
Your language will provide ways to define your own value types, which derive from System.ValueType. If you want to define a type representing a value that is small, such as a complex number (using two floating-point numbers), you might choose to define it as a value type because you can pass the value type efficiently by value. If the type you are defining would be more efficiently passed by reference, you should define it as a class instead. Variables of reference types, referred to as objects, store references to the actual data. This following are the reference types:
• class
• interface
• delegate
This following are the built-in reference types:
• object
• string
118. What is Inheritance, Multiple Inheritance, Shared and Repeatable
Inheritance?
**
119. What is Method overloading?
Method overloading occurs when a class contains two methods with the same name,
but different signatures.
120. What is Method Overriding? How to override a function in C#?
Use the override modifier to modify a method, a property, an indexer, or an event. An override method provides a new implementation of a member inherited from a base class. The method overridden by an override declaration is known as the overridden base method. The overridden base method must have the same signature as the override method. You cannot override a non-virtual or static method. The overridden base method must be virtual, abstract, or override.
121. Can we call a base class method without creating instance?
Its possible If its a static method.
Its possible by inheriting from that class also.
Its possible from derived classes using base keyword.
122. You have one base class virtual function how will call that function
from derived class?
Ans:
123. class a
124. {
125. public virtual int m()
126. {
127. return 1;
128. }
129. }
130. class b:a
131. {
132. public int j()
133. {
134. return m();
135. }
}
136. In which cases you use override and new base?
Use the new modifier to explicitly hide a member inherited from a base class. To hide
an inherited member, declare it in the derived class using the same name, and modify it with the new modifier.
C# Language features
137. What are Sealed Classes in C#?
The sealed modifier is used to prevent derivation from a class. A compile-time error
occurs if a sealed class is specified as the base class of another class. (A sealed class
cannot also be an abstract class)
138. What is Polymorphism? How does VB.NET/C# achieve polymorphism?
**
139. class Token
140. {
141. public string Display()
142. {
143. //Implementation goes here
144. return "base";
145. }
146. }
147. class IdentifierToken:Token
148. {
149. public new string Display() //What is the use of new keyword
150. {
151. //Implementation goes here
152. return "derive";
153. }
154. }
155. static void Method(Token t)
156. {
157. Console.Write(t.Display());
158. }
159. public static void Main()
160. {
161. IdentifierToken Variable=new IdentifierToken();
162. Method(Variable); //Which Class Method is called here
163. Console.ReadLine();
164. }
165. For the above code What is the "new" keyword and Which Class Method is
166. called here
A: it will call base class Display method
167. class Token
168. {
169. public virtual string Display()
170. {
171. //Implementation goes here
172. return "base";
173. }
174. }
175. class IdentifierToken:Token
176. {
177. public override string Display() //What is the use of new keyword
178. {
179. //Implementation goes here
180. return "derive";
181. }
182. }
183. static void Method(Token t)
184. {
185. Console.Write(t.Display());
186. }
187. public static void Main()
188. {
189. IdentifierToken Variable=new IdentifierToken();
190. Method(Variable); //Which Class Method is called here
191. Console.ReadLine();
192. }
193. A: Derive
194. In which Scenario you will go for Interface or Abstract Class?
Interfaces, like classes, define a set of properties, methods, and events. But unlike
classes, interfaces do not provide implementation. They are implemented by classes,
and defined as separate entities from classes. Even though class inheritance allows
your classes to inherit implementation from a base class, it also forces you to make
most of your design decisions when the class is first published.
Abstract classes are useful when creating components because they allow you specify
an invariant level of functionality in some methods, but leave the implementation of
other methods until a specific implementation of that class is needed. They also
version well, because if additional functionality is needed in derived classes, it can be
added to the base class without breaking code.
195. see the code
196. interface ICommon
197. {
198. int getCommon();
199. }
200. interface ICommonImplements1:ICommon
201. {
202. }
203. interface ICommonImplements2:ICommon
204. {
205. }
206. public class a:ICommonImplements1,ICommonImplements2
207. {
}
How to implement getCommon method in class a? Are you seeing any problem in the
implementation?
Ans:
public class a:ICommonImplements1,ICommonImplements2
{
public int getCommon()
{
return 1;
}
}
208. interface IWeather
209. {
210. void display();
211. }
212. public class A:IWeather
213. {
214. public void display()
215. {
216. MessageBox.Show("A");
217. }
218. }
219. public class B:A
220. {
221. }
222. public class C:B,IWeather
223. {
224. public void display()
225. {
226. MessageBox.Show("C");
227. }
228. }
229. When I instantiate C.display(), will it work?
230. interface IPrint
231. {
232. string Display();
233. }
234. interface IWrite
235. {
236. string Display();
237. }
238. class PrintDoc:IPrint,IWrite
239. {
240. //Here is implementation
241. }
how to implement the Display in the class printDoc (How to resolve the naming
Conflict) A: no naming conflicts
class PrintDoc:IPrint,IWrite
{
public string Display()
{
return "s";
}
}
242. interface IList
243. {
244. int Count { get; set; }
245. }
246. interface ICounter
247. {
248. void Count(int i);
249. }
250. interface IListCounter: IList, ICounter {}
251. class C
252. {
253. void Test(IListCounter x)
254. {
255. x.Count(1); // Error
256. x.Count = 1; // Error
257. ((IList)x).Count = 1; // Ok, invokes IList.Count.set
258. ((ICounter)x).Count(1); // Ok, invokes ICounter.Count
259. }
260. }
Write one code example for compile time binding and one for run time
binding? What is early/late binding?
An object is early bound when it is assigned to a variable declared to be of a specific object type. Early bound objects allow the compiler to allocate memory and perform other optimizations before an application executes.
' Create a variable to hold a new object.
Dim FS As FileStream
' Assign a new object to the variable.
FS = New FileStream("C:\tmp.txt", FileMode.Open)
By contrast, an object is late bound when it is assigned to a variable declared to be of type Object. Objects of this type can hold references to any object, but lack many of the advantages of early-bound objects.
Dim xlApp As Object
xlApp = CreateObject("Excel.Application")
262. Can you explain what inheritance is and an example of when you
might use it?
263. How can you write a class to restrict that only one object of this class
can be created (Singleton class)?
(Access specifiers)
264. What are the access-specifiers available in c#?
Private, Protected, Public, Internal, Protected Internal.
265. Explain about Protected and protected internal, “internal” accessspecifier?
protected - Access is limited to the containing class or types derived from the
containing class.
internal - Access is limited to the current assembly.
protected internal - Access is limited to the current assembly or types derived from the
containing class.
(Constructor / Destructor)
266. Difference between type constructor and instance constructor? What
is static constructor, when it will be fired? And what is its use?
(Class constructor method is also known as type constructor or type initializer)
Instance constructor is executed when a new instance of type is created and the class constructor is executed after the type is loaded and before any one of the type members is accessed. (It will get executed only 1st time, when we call any static methods/fields in the same class.) Class constructors are used for static field initialization. Only one class constructor per type is permitted, and it cannot use the vararg (variable argument) calling convention.
A static constructor is used to initialize a class. It is called automatically to initialize
the class before the first instance is created or any static members are referenced.
267. What is Private Constructor? and it’s use? Can you create instance of a
class which has Private Constructor?
A: When a class declares only private instance constructors, it is not possible for classes outside the program to derive from the class or to directly create instances of
it. (Except Nested classes)
Make a constructor private if:
- You want it to be available only to the class itself. For example, you might have a
special constructor used only in the implementation of your class' Clone method.
- You do not want instances of your component to be created. For example, you may
have a class containing nothing but Shared utility functions, and no instance data.
Creating instances of the class would waste memory.
268. I have 3 overloaded constructors in my class. In order to avoid making
instance of the class do I need to make all constructors to private?
(yes)
269. Overloaded constructor will call default constructor internally?
(no)
270. What are virtual destructors?
271. Destructor and finalize
Generally in C++ the destructor is called when objects gets destroyed. And one can
explicitly call the destructors in C++. And also the objects are destroyed in reverse order that they are created in. So in C++ you have control over the destructors. In C# you can never call them, the reason is one cannot destroy an object. So who has the control over the destructor (in C#)? it's the .Net frameworks Garbage Collector (GC). GC destroys the objects only when necessary. Some situations of necessity are memory is exhausted or user explicitly calls System.GC.Collect() method.
Points to remember:
1. Destructors are invoked automatically, and cannot be invoked explicitly.
2. Destructors cannot be overloaded. Thus, a class can have, at most, one destructor.
3. Destructors are not inherited. Thus, a class has no destructors other than the one,
which may be declared in it.
4. Destructors cannot be used with structs. They are only used with classes.
5. An instance becomes eligible for destruction when it is no longer possible for any
code to use the instance.
6. Execution of the destructor for the instance may occur at any time after the
instance becomes eligible for destruction.
7. When an instance is destructed, the destructors in its inheritance chain are called,
in order, from most derived to least derived.
http://msdn.microsoft.com/library/default.asp?url=/library/enus/
cpguide/html/cpconfinalizemethodscdestructors.asp
272. What is the difference between Finalize and Dispose (Garbage collection)
Class instances often encapsulate control over resources that are not managed by the runtime, such as window handles (HWND), database connections, and so on.
Therefore, you should provide both an explicit and an implicit way to free those resources. Provide implicit control by implementing the protected Finalize Method on an object (destructor syntax in C# and the Managed Extensions for C++). The garbage collector calls this method at some point after there are no longer any valid references to the object.
In some cases, you might want to provide programmers using an object with the ability to explicitly release these external resources before the garbage collector frees the object. If an external resource is scarce or expensive, better performance can be achieved if the programmer explicitly releases resources when they are no longer being used. To provide explicit control, implement the Dispose method provided by the IDisposable Interface. The consumer of the object should call this method when it is done using the object. Dispose can be called even if other references to the object are alive.
Note that even when you provide explicit control by way of Dispose, you should
provide implicit cleanup using the Finalize method. Finalize provides a backup to
prevent resources from permanently leaking if the programmer fails to call Dispose.
273. What is close method? How its different from Finalize & Dispose?
**
274. What is boxing & unboxing?
275. What is check/uncheck?
276. What is the use of base keyword? Tell me a practical example for base
keyword’s usage?
277. What are the different .net tools which u used in projects?
278. try
{
...
}
catch
{
...//exception occurred here. What'll happen?
}
finally
{
..
}
Ans : It will throw exception.
279. What will do to avoid prior case?
Ans:
280. try
. {
try
{
. ...
}
catch
. {
. ...
. //exception occurred here.
}
finally
. {
. ...
294. }
295. }
296. catch
297. {
298. ...
299. }
300. finally
301. {
302. ...
}
303. try
304. {
305. ...
306. }
307. catch
308. {
309. ...
310. }
311. finally
312. {
313. ..
314. }
315. Will it go to finally block if there is no exception happened?
Ans: Yes. The finally block is useful for cleaning up any resources allocated in the try
block. Control is always passed to the finally block regardless of how the try block
exits.
316. Is goto statement supported in C#? How about Java?
Gotos are supported in C#to the fullest. In Java goto is a reserved keyword that
provides absolutely no functionality.
317. What’s different about switch statements in C#?
No fall-throughs allowed. Unlike the C++ switch statement, C# does not support an
explicit fall through from one case label to another. If you want, you can use goto a
switch-case, or goto default.
case 1:
cost += 25;
break;
case 2:
cost += 25;
goto case 1;
(ADO.NET)
318. Advantage of ADO.Net?
• ADO.NET Does Not Depend On Continuously Live Connections
• Database Interactions Are Performed Using Data Commands
• Data Can Be Cached in Datasets
• Datasets Are Independent of Data Sources
• Data Is Persisted as XML
• Schemas Define Data Structures
319. How would u connect to database using .NET?
SqlConnection nwindConn = new SqlConnection("Data Source=localhost; Integrated
Security=SSPI;" +
"Initial Catalog=northwind");
nwindConn.Open();
320. What are relation objects in dataset and how & where to use them?
In a DataSet that contains multiple DataTable objects, you can use DataRelation
objects to relate one table to another, to navigate through the tables, and to return
child or parent rows from a related table. Adding a DataRelation to a DataSet adds, by default, a UniqueConstraint to the parent table and a ForeignKeyConstraint to the child table.
The following code example creates a DataRelation using two DataTable objects in a DataSet. Each DataTable contains a column named CustID, which serves as a link between the two DataTable objects. The example adds a single DataRelation to the Relations collection of the DataSet. The first argument in the example specifies the name of the DataRelation being created. The second argument sets the parent DataColumn and the third argument sets the child DataColumn.
custDS.Relations.Add("CustOrders",
custDS.Tables["Customers"].Columns["CustID"],
custDS.Tables["Orders"].Columns["CustID"]);
OR
private void CreateRelation()
{
// Get the DataColumn objects from two DataTable objects in a DataSet.
DataColumn parentCol;
DataColumn childCol;
// Code to get the DataSet not shown here.
parentCol = DataSet1.Tables["Customers"].Columns["CustID"];
childCol = DataSet1.Tables["Orders"].Columns["CustID"];
// Create DataRelation.
DataRelation relCustOrder;
relCustOrder = new DataRelation("CustomersOrders", parentCol, childCol);
// Add the relation to the DataSet.
DataSet1.Relations.Add(relCustOrder);
}
321. Difference between OLEDB Provider and SqlClient ?
Ans: SQLClient .NET classes are highly optimized for the .net / sqlserver combination
and achieve optimal results. The SqlClient data provider is fast. It's faster than the Oracle provider, and faster than accessing database via the OleDb layer. It's faster because it accesses the native library (which automatically gives you better performance), and it was written with lots of help from the SQL Server team.
322. What are the different namespaces used in the project to connect the
database? What data providers available in .net to connect to database?
• System.Data.OleDb – classes that make up the .NET Framework Data Provider
for OLE DB-compatible data sources. These classes allow you to connect to an
OLE DB data source, execute commands against the source, and read the
results.
• System.Data.SqlClient – classes that make up the .NET Framework Data Provider for SQL Server, which allows you to connect to SQL Server 7.0, execute commands, and read results. The System.Data.SqlClient namespace is similar to the System.Data.OleDb namespace, but is optimized for access to SQL Server 7.0 and later.
• System.Data.Odbc - classes that make up the .NET Framework Data Provider
for ODBC. These classes allow you to access ODBC data source in the managed space.
• System.Data.OracleClient - classes that make up the .NET Framework Data Provider for Oracle. These classes allow you to access an Oracle data source in the managed space.
323. Difference between DataReader and DataAdapter / DataSet and
DataAdapter?
You can use the ADO.NET DataReader to retrieve a read-only, forward-only stream of data from a database. Using the DataReader can increase application performance and reduce system overhead because only one row at a time is ever in memory. After creating an instance of the Command object, you create a DataReader by calling Command.ExecuteReader to retrieve rows from a data source, as shown in the following example.
SqlDataReader myReader = myCommand.ExecuteReader();
You use the Read method of the DataReader object to obtain a row from the results of the query.
while (myReader.Read())
Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));
myReader.Close();
The DataSet is a memory-resident representation of data that provides a consistent
relational programming model regardless of the data source. It can be used with multiple and differing data sources, used with XML data, or used to manage data ocal to the application. The DataSet represents a complete set of data including related tables, constraints, and relationships among the tables. The methods and objects in a DataSet are consistent with those in the relational database model. The DataSet can also persist and reload its contents as XML and its schema as XML Schema definition language (XSD) schema.
The DataAdapter serves as a bridge between a DataSet and a data source for retrieving and saving data. The DataAdapter provides this bridge by mapping Fill, which changes the data in the DataSet to match the data in the data source, and Update, which changes the data in the data source to match the data in the DataSet. If you are connecting to a Microsoft SQL Server database, you can increase overall performance by using the SqlDataAdapter along with its associated SqlCommand and SqlConnection. For other OLE DB-supported databases, use the DataAdapter with its associated OleDbCommand and OleDbConnection objects.
324. Which method do you invoke on the DataAdapter control to load your
generated dataset with data?
Fill()
325. Explain different methods and Properties of DataReader which you
have used in your project?
Read
GetString
GetInt32
while (myReader.Read())
Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));
myReader.Close();
326. What happens when we issue Dataset.ReadXml command?
Reads XML schema and data into the DataSet.
327. In how many ways we can retrieve table records count? How to find
the count of records in a dataset?
foreach(DataTable thisTable in myDataSet.Tables){
// For each row, print the values of each column.
foreach(DataRow myRow in thisTable.Rows){
328. How to check if a datareader is closed or opened?
IsClosed()
329. What happens when u try to update data in a dataset in .NET while the
record is already deleted in SQL SERVER as backend?
OR What is concurrency? How will you avoid concurrency when dealing with
dataset? (One user deleted one row after that another user through his
dataset was trying to update same row. What will happen? How will you
avoid the problem?)
**
330. How do you merge 2 datasets into the third dataset in a simple
manner? OR If you are executing these statements in commandObject.
"Select * from Table1;Select * from Table2” how you will deal result set?
**
331. How do you sort a dataset?
**
332. If a dataset contains 100 rows, how to fetch rows between 5 and 15
only?
**
333. Differences between dataset.clone and dataset.copy?
Clone - Copies the structure of the DataSet, including all DataTable schemas,
relations, and constraints. Does not copy any data.
Copy - Copies both the structure and data for this DataSet.
334. What is the use of parameter object?
**
335. How to generate XML from a dataset and vice versa?
**
336. What is method to get XML and schema from Dataset?
ans: getXML () and get Schema ()
337. How do u implement locking concept for dataset?
**
(ASP.NET)
338. Asp.net and asp – differences?
339. How ASP and ASP.NET page works? Explain about asp.net page life
cycle?
**
340. Order of events in an asp.net page? Control Execution Lifecycle?
Phase What a control needs to do Method or event to override
341. Note To override an EventName event, override the OnEventName method
(and call base. OnEventName).
(Session/State)
342. Application and Session Events
The ASP.NET page framework provides ways for you to work with events that can be
raised when your application starts or stops or when an individual user's session starts
or stops:
• Application events are raised for all requests to an application. For example,
Application_BeginRequest is raised when any Web Forms page or XML Web
service in your application is requested. This event allows you to initialize
resources that will be used for each request to the application. A
corresponding event, Application_EndRequest, provides you with an
opportunity to close or otherwise dispose of resources used for the request.
• Session events are similar to application events (there is a Session_OnStart
and a Session_OnEnd event), but are raised with each unique session within
the application. A session begins when a user requests a page for the first time
from your application and ends either when your application explicitly closes
the session or when the session times out.
You can create handlers for these types of events in the Global.asax file.
343. Difference between ASP Session and ASP.NET Session?
asp.net session supports cookie less session & it can span across multiple servers.
344. What is cookie less session? How it works?
By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. If cookies are not available, a session can be tracked by adding a session identifier to the URL. This can be enabled by setting the following:
http://samples.gotdotnet.com/quickstart/aspplus/doc/stateoverview.aspx
345. How you will handle session when deploying application in more than
a server? Describe session handling in a webfarm, how does it work and what are the limits?
By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. Additionally, ASP.NET can store session data in an external process, which can even reside on another machine. To enable this feature:
• Start the ASP.NET state service, either using the Services snap-in or by
executing "net start aspnet_state" on the command line. The state service will
by default listen on port 42424. To change the port, modify the registry key
for the service:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Par
ameters\Port
• Set the mode attribute of the
• Configure the stateConnectionString attribute with the values of the
machine on which you started aspnet_state.
The following sample assumes that the state service is running on the same machine
as the Web server ("localhost") and uses the default port (42424):
stateConnectionString="tcpip=localhost:42424"
/>
Note that if you try the sample above with this setting, you can reset the Web server
(enter iisreset on the command line) and the session state value will persist. **
346. What method do you use to explicitly kill a users session?
Abandon()
347. What are the different ways you would consider sending data across
pages in ASP (i.e between 1.asp to 2.asp)?
Session
public properties
348. What is State Management in .Net and how many ways are there to
maintain a state in .Net? What is view state?
Web pages are recreated each time the page is posted to the server. In traditional
Web programming, this would ordinarily mean that all information associated with the page and the controls on the page would be lost with each round trip. To overcome this inherent limitation of traditional Web programming, the ASP.NET page framework includes various options to help you preserve changes — that is, for managing state. The page framework includes a facility called view state that automatically preserves property values of the page and all the controls on it between round trips.
However, you will probably also have application-specific values that you want to preserve. To do so, you can use one of the state management options. Client-Based State Management Options:
View State
Hidden Form Fields
Cookies
Query Strings
Server-Based State Management Options
Application State
Session State
Database Support
349. What are the disadvantages of view state / what are the benefits?
Automatic view-state management is a feature of server controls that enables them to repopulate their property values on a round trip (without you having to write any code). This feature does impact performance, however, since a server control's view state is passed to and from the server in a hidden form field. You should be aware of
when view state helps you and when it hinders your page's performance.
350. When maintaining session through Sql server, what is the impact of
Read and Write operation on Session objects? will performance degrade?
Maintaining state using database technology is a common practice when storing userspecific information where the information store is large. Database storage is particularly useful for maintaining long-term state or state that must be preserved even if the server must be restarted.
**
351. What are the contents of cookie?
**
352. How do you create a permanent cookie?
**
353. What is ViewState? What does the "EnableViewState" property do?
Why would I want it on or off?
**
354. Explain the differences between Server-side and Client-side code?
Server side code will process at server side & it will send the result to client. Client
side code (javascript) will execute only at client side.
355. Can you give an example of what might be best suited to place in the
Application_Start and Session_Start subroutines?
**
356. Which ASP.NET configuration options are supported in the ASP.NET
implementation on the shared web hosting platform?
A: Many of the ASP.NET configuration options are not configurable at the site,
application or subdirectory level on the shared hosting platform. Certain options can
affect the security, performance and stability of the server and, therefore cannot be
changed. The following settings are the only ones that can be changed in your site’s
web.config file (s):
browserCaps
clientTarget
pages
customErrors
globalization
authorization
authentication
webControls
webServices
http://msdn.microsoft.com/library/default.asp?url=/library/enus/
cpguide/html/cpconaspnetconfiguration.asp
357. Briefly describe the role of global.asax?
358. How can u debug your .net application?
359. How do u deploy your asp.net application?
360. Where do we store our connection string in asp.net application?
361. Various steps taken to optimize a web based application (caching,
stored procedure etc.)
362. How does ASP.NET framework maps client side events to Server side
events.
(Security)
363. Security types in ASP/ASP.NET? Different Authentication modes?
364. How .Net has implemented security for web applications?
365. How to do Forms authentication in asp.net?
366. Explain authentication levels in .net ?
367. Explain autherization levels in .net ?
368. What is Role-Based security?
A role is a named set of principals that have the same privileges with respect to
security (such as a teller or a manager). A principal can be a member of one or more
roles. Therefore, applications can use role membership to determine whether a
principal is authorized to perform a requested action.
**
369. How will you do windows authentication and what is the namespace?
If a user is logged under integrated windows authentication mode, but he is
still not able to logon, what might be the possible cause for this? In ASP.Net
application how do you find the name of the logged in person under windows
authentication?
370. What are the different authentication modes in the .NET environment?
371.
372.
374. protection="All|None|Encryption|Validation"
375. timeout="30" path="/" >
376. requireSSL="true|false"
377. slidingExpiration="true|false">
378.
379.
380.
381.
382.
Attribute Option Description
mode Controls the default authentication mode for an application.
Windows Specifies Windows authentication as the default authentication
mode. Use this mode when using any form of Microsoft Internet
Information Services (IIS) authentication: Basic, Digest,
Integrated Windows authentication (NTLM/Kerberos), or
certificates.
Forms Specifies ASP.NET forms-based authentication as the default
authentication mode.
Passport Specifies Microsoft Passport authentication as the default
authentication mode.
None Specifies no authentication. Only anonymous users are expected
or applications can handle events to provide their own
authentication.
383. How do you specify whether your data should be passed as Query
string and Forms (Mainly about POST and GET)
Through attribute tag of form tag.
384. What is the other method, other than GET and POST, in ASP.NET?
385. What are validator? Name the Validation controls in asp.net? How do u
disable them? Will the asp.net validators run in server side or client side?
How do you do Client-side validation in .Net? How to disable validator control
by client side JavaScript?
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 ("EnableClientScript"
property set to true/false) using client script.
The following validation controls are available in asp.net:
RequiredFieldValidator Control, CompareValidator Control, RangeValidator Control,
RegularExpressionValidator Control, CustomValidator Control, ValidationSummary
Control.
386. Which two properties are there on every validation control?
ControlToValidate, ErrorMessage
387. How do you use css in asp.net?
Within the section of an HTML document that will use these styles, add a link
to this external CSS style sheet that
follows this form:
MyStyles.css is the name of your external CSS style sheet.
388. How do you implement postback with a text box? What is postback
and usestate?
Make AutoPostBack property to true
389. How can you debug an ASP page, without touching the code?
390. What is SQL injection?
An SQL injection attack "injects" or manipulates SQL code by adding unexpected SQL
to a query.
Many web pages take parameters from web user, and make SQL query to the
database. Take for instance when a user login, web page that user name and
password and make SQL query to the database to check if a user has valid name and
password.
Username: ' or 1=1 ---
Password: [Empty]
This would execute the following query against the users table:
select count(*) from users where userName='' or 1=1 --' and userPass=''
391. How can u handle Exceptions in Asp.Net?
392. How can u handle Un Managed Code Exceptions in ASP.Net?
393. Asp.net - How to find last error which occurred?
A: Server.GetLastError();
[C#]
Exception LastError;
String ErrMessage;
LastError = Server.GetLastError();
if (LastError != null)
ErrMessage = LastError.Message;
else
ErrMessage = "No Errors";
Response.Write("Last Error = " + ErrMessage);
394. How to do Caching in ASP?
A: <%@ OutputCache Duration="60" VaryByParam="None" %>
VaryByParam
value
Description
none One version of page cached (only raw GET)
*
n versions of page cached based on query string and/or
POST body
v1
n versions of page cached based on value of v1 variable
in query string or POST body
v1;v2
n versions of page cached based on value of v1 and v2
variables in query string or POST body
395. <%@ OutputCache Duration="60" VaryByParam="none" %>
<%@ OutputCache Duration="60" VaryByParam="*" %>
<%@ OutputCache Duration="60" VaryByParam="name;age" %>
The OutputCache directive supports several other cache varying options
• VaryByHeader - maintain separate cache entry for header string changes
(UserAgent, UserLanguage, etc.)
• VaryByControl - for user controls, maintain separate cache entry for
properties of a user control
• VaryByCustom - can specify separate cache entries for browser types and
version or provide a custom GetVaryByCustomString method in
HttpApplicationderived class
396. What is the Global ASA(X) File?
397. Any alternative to avoid name collisions other then Namespaces.
A scenario that two namespaces named N1 and N2 are there both having the same
class say A. now in another class i ve written
using N1;using N2;
and i am instantiating class A in this class. Then how will u avoid name collisions?
Ans: using alias
Eg: using MyAlias = MyCompany.Proj.Nested;
398. Which is the namespace used to write error message in event Log
File?
399. What are the page level transaction and class level transaction?
400. What are different transaction options?
401. What is the namespace for encryption?
402. What is the difference between application and cache variables?
403. What is the difference between control and component?
404. You ve defined one page_load event in aspx page and same page_load
event in code behind how will prog run?
405. Where would you use an IHttpModule, and what are the limitations of
any approach you might take in implementing one?
406. Can you edit data in the Repeater control? Which template must you provide,
in order to display data in a Repeater control? How can you provide an alternating
color scheme in a Repeater control? 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?
407. What is the use of web.config? Difference between machine.config and
Web.config?
ASP.NET configuration files are XML-based text files--each named web.config--that can appear in any directory on an ASP.NET Web application server. Each web.config file applies configuration settings to the directory it is located in and to all virtual child directories beneath it. Settings in child directories can optionally override or modify settings specified in parent directories.
The root configuration file--
WinNT\Microsoft.NET\Framework\
default configuration settings for the entire machine. ASP.NET configures IIS to
prevent direct browser access to web.config files to ensure that their values cannot become public (attempts to access them will cause ASP.NET to return 403: Access
Forbidden).
At run time ASP.NET uses these web.config configuration files to hierarchically
compute a unique collection of settings for each incoming URL target request (these settings are calculated only once and then cached across subsequent requests; ASP.NET automatically watches for file changes and will invalidate the cache if any of the configuration files change).
http://samples.gotdotnet.com/quickstart/aspplus/doc/configformat.aspx
408. What is the use of sessionstate tag in the web.config file?
Configuring session state: Session state features can be configured via the
409. What are the different modes for the sessionstates in the web.config
file?
Off Indicates that session state is not enabled.
Inproc Indicates that session state is stored locally.
StateServer Indicates that session state is stored on a remote server.
SQLServer Indicates that session state is stored on the SQL Server.
410. What is smart navigation?
When a page is requested by an Internet Explorer 5 browser, or later, smart
navigation enhances the user's experience of the page by performing the following:
• eliminating the flash caused by navigation.
• persisting the scroll position when moving from page to page.
• persisting element focus between navigations.
• retaining only the last page state in the browser's history.
Smart navigation is best used with ASP.NET pages that require frequent postbacks but with visual content that does not change dramatically on return. Consider this carefully when deciding whether to set this property to true.
Set the SmartNavigation attribute to true in the @ Page directive in the .aspx file.
When the page is requested, the dynamically generated class sets this property.
411. In what order do the events of an ASPX page execute. As a developer
is it important to undertsand these events?
412. How would you get ASP.NET running in Apache web servers - why
would you even do this?
413. What tags do you need to add within the asp:datagrid tags to bind
columns manually
414. What base class do all Web Forms inherit from?
System.Web.UI.Page
415. How can we create pie chart in asp.net?
416. Is it possible for me to change my aspx file extension to some other
name?
Yes.
Open IIS->Default Website -> Properties
Select HomeDirectory tab
Click on configuration button
Click on add. Enter aspnet_isapi details
(C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\aspnet_isapi.dll |
GET,HEAD,POST,DEBUG)
Open machine.config(C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\CONFIG) &
add new extension under
417. What is AutoEventWireup attribute for ?
(WEBSERVICE & REMOTING)
418. What is a WebService and what is the underlying protocol used in it?
Namespace?
Web Services are applications delivered as a service on the Web. Web services allow
for programmatic access of business logic over the Web. Web services typically rely on XML-based protocols, messages, and interface descriptions for communication and access. Web services are designed to be used by other programs or applications rather than directly by end user. Programs invoking a Web service are called clients. SOAP over HTTP is the most commonly used protocol for invoking Web services.
419. Why Web Services?
By exposing data and functionality using standard protocols, Web services make it
easy to build sophisticated applications that integrate many features and content.
There are three main uses of Web services. Application integration Web services within an intranet are commonly used to integrate business applications running on disparate platforms. For example, a .NET client running on Windows 2000 can easily invoke a Java Web service running on a mainframe or Unix machine to retrieve data from a legacy application. Business integration Web services allow trading partners to engage in e-business leveraging the existing Internet infrastructure. Organizations can send electronic purchase orders to suppliers and receive electronic invoices. Doing ebusiness with Web services means a low barrier to entry because Web services can be added to existing applications running on any platform without changing legacy code.
Commercial Web services focus on selling content and business services to clients over the Internet similar to familiar Web pages. Unlike Web pages, commercial Web
services target applications not humans as their direct users. Continental Airlines
exposes flight schedules and status Web services for travel Web sites and agencies to use in their applications. Like Web pages, commercial Web services are valuable only if they expose a valuable service or content. It would be very difficult to get customers to pay you for using a Web service that creates business charts with the customers? data. Customers would rather buy a charting component (e.g. COM or .NET component) and install it on the same machine as their application. On the other hand, it makes sense to sell real-time weather information or stock quotes as a Web service. Technology can help you add value to your services and explore new markets, but ultimately customers pay for contents and/or business services, not for technology
420. In a Webservice, need to display 10 rows from a table. So DataReader
or DataSet is best choice?
A: WebService will support only DataSet.
421. Are Web Services a replacement for other distributed computing
platforms?
No. Web Services is just a new way of looking at existing implementation platforms.
422. What is SOAP, WSDL, UDDI and the concept behind Web Services?
What are various components of WSDL? What is the use of WSDL.exe utility?
SOAP is an XML-based messaging framework specifically designed for exchanging
formatted data across the Internet, for example using request and reply messages or
sending entire documents. SOAP is simple, easy to use, and completely neutral with
respect to operating system, programming language, or distributed computing
platform.
After SOAP became available as a mechanism for exchanging XML messages among
enterprises (or among disparate applications within the same enterprise), a better way was needed to describe the messages and how they are exchanged. The Web Services Description Language (WSDL) is a particular form of an XML Schema, developed by Microsoft and IBM for the purpose of defining the XML message, operation, and protocol mapping of a web service accessed using SOAP or other XML protocol. WSDL defines web services in terms of "endpoints" that operate on XML messages. The WSDL syntax allows both the messages and the operations on the messages to be defined abstractly, so they can be mapped to multiple physical implementations. The current WSDL spec describes how to map messages and operations to SOAP 1.1, HTTP GET/POST, and MIME. WSDL creates web service definitions by mapping a group of endpoints into a logical sequence of operations on XML messages. The same XML message can be mapped to multiple operations (or services) and bound to one or more communications protocols (using "ports").
The Universal Description, Discovery, and Integration (UDDI) framework defines a
data model (in XML) and SOAP APIs for registration and searches on business information, including the web services a business exposes to the Internet. UDDI is an independent consortium of vendors, founded by Microsoft, IBM, and Ariba, for the
purpose of developing an Internet standard for web service description registration and discovery. Microsoft, IBM, and Ariba also are hosting the initial deployment of a UDDI service, which is conceptually patterned after DNS (the Internet service that translates URLs into TCP addresses). UDDI uses a private agreement profile of SOAP
(i.e. UDDI doesn't use the SOAP serialization format because it's not well suited to
passing complete XML documents (it's aimed at RPC style interactions). The main idea is that businesses use the SOAP APIs to register themselves with UDDI, and other businesses search UDDI when they want to discover a trading partner, for example someone from whom they wish to procure sheet metal, bolts, or transistors. The information in UDDI is categorized according to industry type and geographical
location, allowing UDDI consumers to search through lists of potentially matching businesses to find the specific one they want to contact. Once a specific business is chosen, another call to UDDI is made to obtain the specific contact information for that business. The contact information includes a pointer to the target business's WSDL or other XML schema file describing the web service that the target business publishes.
423. How to generate proxy class other than .net app and wsdl tool?
To access an XML Web service from a client application, you first add a Web reference, which is a reference to an XML Web service. When you create a Web reference, Visual Studio creates an XML Web service proxy class automatically and adds it to your project. This proxy class exposes the methods of the XML Web service and handles the marshalling of appropriate arguments back and forth between the XML Web service and your application. Visual Studio uses the Web Services Description Language (WSDL) to create the proxy. To generate an XML Web service proxy class:
• From a command prompt, use Wsdl.exe to create a proxy class, specifying (at
a minimum) the URL to an XML Web service or a service description, or the
path to a saved service description.
Wsdl /language:language /protocol:protocol /namespace:myNameSpace
/out:filename
/username:username /password:password /domain:domain
424. asynchronous web service means?
425. What are the events fired when web service called?
426. How does SOAP transport happen and what is the role of HTTP in it?
How you can access a webservice using soap?
427. How will do transaction in Web Services?
428. What are the different formatters can be used in both? Why?..
binary/soap
429. What is a proxy in web service? How do I use a proxy server when
invoking a Web service?
If you are using the SOAP Toolkit, you need to set some connector properties to use a
proxy server: Dim soap As SoapClient Set soap=New SoapClient
soap.ConnectorProperty("ProxyServer") = ?proxyservername?
soap.ConnectorProperty("ProxyPort") = ?8080? soap.ConnectorProperty("UseProxy")
= True While with .NET , you just need to create a System.Net.WebProxy object and
use it to set the Proxy property Dim webs As localhost.MyService() webs.Proxy=New
System.Net.WebProxy(?http://proxyserver:8080?)
430. How you will protect / secure a web service?
For the most part, things that you do to secure a Web site can be used to secure a
Web Service. If you need to encrypt the data exchange, you use Secure Sockets Layer (SSL) or a Virtual Private Network to keep the bits secure. For authentication, use HTTP Basic or Digest authentication with Microsoft® Windows® integration to figure out who the caller is. these items cannot:
• Parse a SOAP request for valid values
• Authenticate access at the Web Method level (they can authenticate at the
Web Service level)
• Stop reading a request as soon as it is recognized as invalid
http://msdn.microsoft.com/library/default.asp?url=/library/enus/
cpguide/html/cpcontransactionsupportinaspnetwebservices.asp
431. How will you expose/publish a webservice?
432. What’s the attribute for webservice method? What is the namespace
for creating webservice?
433. What is disco file?
434. What is Remoting?
The process of communication between different operating system processes,
regardless of whether they are on the same computer. The .NET remoting system is
an architecture designed to simplify communication between objects living in different application domains, whether on the same computer or not, and between different contexts, whether in the same application domain or not.
435. Difference between web services & remoting?
Though both the .NET Remoting infrastructure and ASP.NET Web services can
enable cross-process communication, each is designed to benefit a different target
audience. ASP.NET Web services provide a simple programming model and a wide
reach. .NET Remoting provides a more complex programming model and has a much
narrower reach.
As explained before, the clear performance advantage provided by TCPChannelremoting should make you think about using this channel whenever you can afford to do so. If you can create direct TCP connections from your clients to your server and if you need to support only the .NET platform, you should go for this channel. If you are going to go cross-platform or you have the requirement of supporting SOAP via HTTP, you should definitely go for ASP.NET Web services.
Both the .NET remoting and ASP.NET Web services are powerful technologies that
provide a suitable framework for developing distributed applications. It is important to understand how both technologies work and then choose the one that is right for your application. For applications that require interoperability and must function over public networks, Web services are probably the best bet. For those that require
communications with other .NET components and where performance is a key priority, .NET Remoting is the best choice. In short, use Web services when you need to send and receive data from different computing platforms, use .NET Remoting when sending and receiving data between .NET applications. In some architectural scenarios, you might also be able to use.NET Remoting in conjunction with ASP.NET Web services and take advantage of the best of both worlds.
The Key difference between ASP.NET webservices and .NET Remoting is how they serialize data into messages and the format they choose for metadata. ASP.NET uses XML serializer for serializing or Marshalling. And XSD is used for Metadata. .NET Remoting relies on System.Runtime.Serialization.Formatter.Binary and System.Runtime.Serialization.SOAPFormatter and relies on .NET CLR Runtime assemblies for metadata.
437. Can you pass SOAP messages through remoting?
438. CAO and SAO.
Client Activated objects are those remote objects whose Lifetime is directly Controlled by the client. This is in direct contrast to SAO. Where the server, not the client has complete control over the lifetime of the objects.
Client activated objects are instantiated on the server as soon as the client request the object to be created. Unlike as SAO a CAO doesn’t delay the object creation until the first method is called on the object. (In SAO the object is instantiated when the client calls the method on the object)
439. singleton and singlecall.
Singleton types never have more than one instance at any one time. If an instance
exists, all client requests are serviced by that instance.
Single Call types always have one instance per client request. The next method
invocation will be serviced by a different server instance, even if the previous instance has not yet been recycled by the system.
440. What is Asynchronous Web Services?
441. How to generate WebService proxy?
442. Web Client class and its methods?
443. Flow of remoting?
(XML)
444. Explain the concept of data island?
445. How to use XML DOM model on client side using JavaScript.
446. What are the ways to create a tree view control using XML, XSL &
JavaScript?
447. Questions on XPathNavigator, and the other classes in System.XML
Namespace?
448. What is Use of Template in XSL?
449. What is “Well Formed XML” and “Valid XML”
450. How you will do SubString in XSL
451. Can we do sorting in XSL ? how do you deal sorting columns
dynamically in XML.
452. What is “Async” property of XML Means ?
453. What is XPath Query ?
454. Difference Between Element and Node.
455. What is CDATA Section.
456. DOM & SAX parsers explanation and difference
457. What is GetElementbyname method will do?
458. What is selectnode method will give?
459. What is valid xml document? What a well formed xml document?
460. What is the Difference between XmlDocument and XmlDataDocument?
461. Explain what a DiffGram is, and a good use for one?
A DiffGram is an XML format that is used to identify current and original versions of
data elements. When sending and retrieving a DataSet from an XML Web service, the DiffGram format is implicitly used.
The DataSet uses the DiffGram format to load and persist its contents, and to
serialize its contents for transport across a network connection. When a DataSet is
written as a DiffGram, it populates the DiffGram with all the necessary information to
accurately recreate the contents, though not the schema, of the DataSet, including
column values from both the Original and Current row versions, row error
information, and row order.
DiffGram Format
The DiffGram format is divided into three sections: the current data, the original (or
"before") data, and an errors section, as shown in the following example.
462.
463.
465. xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgramv1"
466. xmlns:xsd="http://www.w3.org/2001/XMLSchema">
467.
468.
469.
470.
471.
472.
473.
474.
475.
The DiffGram format consists of the following blocks of data:
The name of this element, DataInstance, is used for explanation purposes in this
documentation. A DataInstance element represents a DataSet or a row of a
DataTable. Instead of DataInstance, the element would contain the name of the
DataSet or DataTable. This block of the DiffGram format contains the current data,
whether it has been modified or not. An element, or row, that has been modified is
identified with the diffgr:hasChanges annotation.
This block of the DiffGram format contains the original version of a row. Elements in
this block are matched to elements in the DataInstance block using the diffgr:id
annotation.
This block of the DiffGram format contains error information for a particular row in the
DataInstance block. Elements in this block are matched to elements in the
DataInstance block using the diffgr:id annotation.
476. If I replace my Sqlserver with XML files and how about handling the
same?
477. Write syntax to serialize class using XML Serializer?
(IIS)
478. In which process does IIS runs (was asking about the EXE file)
inetinfo.exe is the Microsoft IIS server running, handling ASP.NET requests among
other things. When an ASP.NET request is received (usually a file with .aspx
extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request to
the actual worker process aspnet_wp.exe.
479. Where are the IIS log files stored?
C:\WINDOWS\system32\Logfiles\W3SVC1
OR
c:\winnt\system32\LogFiles\W3SVC1
480. What are the different IIS authentication modes in IIS 5.0 and
Explain? Difference between basic and digest authentication modes?
IIS provides a variety of authentication schemes:
• Anonymous (enabled by default)
• Basic
• Digest
• Integrated Windows authentication (enabled by default)
• Client Certificate Mapping
Anonymous
Anonymous authentication gives users access to the public areas of your Web site without prompting them for a user name or password. Although listed as an authentication scheme, it is not technically performing any client authentication because the client is not required to supply any credentials. Instead, IIS provides stored credentials to Windows using a special user account, IUSR_machinename. By default, IIS controls the password for this account. Whether or not IIS controls the password affects the permissions the anonymous user has. When IIS controls the password, a sub authentication DLL (iissuba.dll) authenticates the user using a network logon. The function of this DLL is to validate the password supplied by IIS and to inform Windows that the password is valid, thereby authenticating the client. However, it does not actually provide a password to Windows. When IIS does not
control the password, IIS calls the LogonUser() API in Windows and provides the account name, password and domain name to log on the user using a local logon. After the logon, IIS caches the security token and impersonates the account. A local logon makes it possible for the anonymous user to access network resources, whereas a network logon does not.
Basic Authentication
IIS Basic authentication as an implementation of the basic authentication scheme
found in section 11 of the HTTP 1.0 specification.
As the specification makes clear, this method is, in and of itself, non-secure. The
reason is that Basic authentication assumes a trusted connection between client and
server. Thus, the username and password are transmitted in clear text. More
specifically, they are transmitted using Base64 encoding, which is trivially easy to
decode. This makes Basic authentication the wrong choice to use over a public
network on its own.
Basic Authentication is a long-standing standard supported by nearly all browsers. It
also imposes no special requirements on the server side -- users can authenticate
against any NT domain, or even against accounts on the local machine. With SSL to
shelter the security credentials while they are in transmission, you have an
authentication solution that is both highly secure and quite flexible.
Digest Authentication
The Digest authentication option was added in Windows 2000 and IIS 5.0. Like Basic
authentication, this is an implementation of a technique suggested by Web standards, namely RFC 2069 (superceded by RFC 2617).
Digest authentication also uses a challenge/response model, but it is much more
secure than Basic authentication (when used without SSL). It achieves this greater
security not by encrypting the secret (the password) before sending it, but rather by
following a different design pattern -- one that does not require the client to transmit
the password over the wire at all.
Instead of sending the password itself, the client transmits a one-way message digest (a checksum) of the user's password, using (by default) the MD5 algorithm. The server then fetches the password for that user from a Windows 2000 Domain
Controller, reruns the checksum algorithm on it, and compares the two digests. If they match, the server knows that the client knows the correct password, even though the password itself was never sent. (If you have ever wondered what the default ISAPI filter "md5filt" that is installed with IIS 5.0 is used for, now you know.
Integrated Windows Authentication
Integrated Windows authentication (formerly known as NTLM authentication and
Windows NT Challenge/Response authentication) can use either NTLM or Kerberos V5
authentication and only works with Internet Explorer 2.0 and later.
When Internet Explorer attempts to access a protected resource, IIS sends two WWWAuthenticate headers, Negotiate and NTLM.
• If Internet Explorer recognizes the Negotiate header, it will choose it because
it is listed first. When using Negotiate, the browser will return information for
both NTLM and Kerberos. At the server, IIS will use Kerberos if both the client
(Internet Explorer 5.0 and later) and server (IIS 5.0 and later) are running
Windows 2000 and later, and both are members of the same domain or
trusted domains. Otherwise, the server will default to using NTLM.
• If Internet Explorer does not understand Negotiate, it will use NTLM.
So, which mechanism is used depends upon a negotiation between Internet Explorer
and IIS. When used in conjunction with Kerberos v5 authentication, IIS can delegate security credentials among computers running Windows 2000 and later that are trusted and configured for delegation. Delegation enables remote access of resources on behalf of the delegated user.
Integrated Windows authentication is the best authentication scheme in an intranet
environment where users have Windows domain accounts, especially when using
Kerberos. Integrated Windows authentication, like digest authentication, does not pass the user's password across the network. Instead, a hashed value is exchanged.
Client Certificate Mapping
A certificate is a digitally signed statement that contains information about an entity
and the entity's public key, thus binding these two pieces of information together. A
trusted organization (or entity) called a Certification Authority (CA) issues a certificate
after the CA verifies that the entity is who it says it is. Certificates can contain
different types of data. For example, an X.509 certificate includes the format of the
certificate, the serial number of the certificate, the algorithm used to sign the
certificate, the name of the CA that issued the certificate, the name and public key of
the entity requesting the certificate, and the CA's signature. X.509 client certificates
simplify authentication for larger user bases because they do not rely on a centralized account database. You can verify a certificate simply by examining the certificate.
http://msdn.microsoft.com/library/default.asp?url=/library/enus/
vsent7/html/vxconIISAuthentication.asp
481. How to configure the sites in Web server (IIS)?
482. Advantages in IIS 6.0?
http://www.microsoft.com/windowsserver2003/iis/evaluation/features/default.mspx
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/win
dowsserver2003/proddocs/datacenter/gs_whatschanged.asp
483. IIS Isolation Levels?
Internet Information Server introduced the notion "Isolation Level", which is also
present in IIS4 under a different name. IIS5 supports three isolation levels, that you
can set from the Home Directory tab of the site's Properties dialog:
• Low (IIS Process): ASP pages run in INetInfo.Exe, the main IIS process,
therefore they are executed in-process. This is the fastest setting, and is the
default under IIS4. The problem is that if ASP crashes, IIS crashes as well and
must be restarted (IIS5 has a reliable restart feature that automatically
restarts a server when a fatal error occurs).
• Medium (Pooled): In this case ASP runs in a different process, which makes
this setting more reliable: if ASP crashes IIS won't. All the ASP applications at
the Medium isolation level share the same process, so you can have a web site
running with just two processes (IIS and ASP process). IIS5 is the first
Internet Information Server version that supports this setting, which is also
the default setting when you create an IIS5 application. Note that an ASP
application that runs at this level is run under COM+, so it's hosted in
DLLHOST.EXE (and you can see this executable in the Task Manager).
• High (Isolated): Each ASP application runs out-process in its own process
space, therefore if an ASP application crashes, neither IIS nor any other ASP
application will be affected. The downside is that you consume more memory
and resources if the server hosts many ASP applications. Both IIS4 and IIS5
supports this setting: under IIS4 this process runs inside MTS.EXE, while
under IIS5 it runs inside DLLHOST.EXE.
When selecting an isolation level for your ASP application, keep in mind that outprocess
settings - that is, Medium and High - are less efficient than in-process (Low).
However, out-process communication has been vastly improved under IIS5, and in
fact IIS5's Medium isolation level often deliver better results than IIS4's Low isolation.
In practice, you shouldn't set the Low isolation level for an IIS5 application unless you
really need to serve hundreds pages per second.
Controls
484. How will you do Redo and Undo in a TextControl?
485. How to implement DataGrid in .NET? How would u make a combo-box
appear in one column of a DataGrid? What are the ways to show data grid
inside a data grid for a master details type of tables? If we write any code for
DataGrid methods, what is the access specifier used for that methods in the
code behind file and why?
486. How can we create Tree control in asp.net?
Programming
487. Write a program in C# for checking a given number is PRIME or not.
488. Write a program to find the angle between the hours and minutes in a
clock
489. Write a C# program to find the Factorial of n
490. How do I upload a file from my ASP.NET page?
A: In order to perform file upload in your ASP.NET page, you will need to use two
classes: the System.Web.UI.HtmlControls.HtmlInputFile class and the
System.Web.HttpPostedFile class. The HtmlInputFile class represents and HTML input
control that the user will use on the client side to select a file to upload. The
HttpPostedFile class represents the uploaded file and is obtained from the PostedFile
property of the HtmlInputFile class. In order to use the HtmlInputFile control, you
need to add the enctype attribute to your form tag as follows:
491. How do I send an email message from my ASP.NET page?
A: You can use the System.Web.Mail.MailMessage and the System.Web.Mail.SmtpMail
class to send email in your ASPX pages. Below is a simple example of using this class
to send mail in C# and VB.NET. In order to send mail through our mail server, you
would want to make sure to set the static SmtpServer property of the SmtpMail class
to mail-fwd.
C#
<%@ Import Namespace="System" %>
<%@ Import Namespace="System.Web" %>
<%@ Import Namespace="System.Web.Mail" %>
492. Write a program to create a user control with name and surname as
data members and login as method and also the code to call it. (Hint use
event delegates)
ASP.NET
What is view state and use of it?
The current property settings of an ASP.NET page and those of any ASP.NET server controls contained within the page. ASP.NET can detect when a form is requested for the first time versus when the form is posted (sent to the server), which allows you to program accordingly.
What are user controls and custom controls?
Custom controls:
A control authored by a user or a third-party software vendor that does not belong to the .NET Framework class library. This is a generic term that includes user controls. A custom server control is used in Web Forms (ASP.NET pages). A custom client control is used in Windows Forms applications.
User Controls:
In ASP.NET: A user-authored server control that enables an ASP.NET page to be re-used as a server control. An ASP.NET user control is authored declaratively and persisted as a text file with an .ascx extension. The ASP.NET page framework compiles a user control on the fly to a class that derives from the System.Web.UI.UserControl class.
What are the validation controls?
A set of server controls included with ASP.NET that test user input in HTML and Web server controls for programmer-defined requirements. Validation controls perform input checking in server code. If the user is working with a browser that supports DHTML, the validation controls can also perform validation using client script.
What's the difference between Response.Write() andResponse.Output.Write()?
The latter one allows you to write formattedoutput.
What methods are fired during the page load? Init()
When the page is instantiated, Load() - when the page is loaded into server memory,PreRender () - the brief moment before the page is displayed to the user as
HTML, Unload() - when page finishes loading.
Where does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page
Where do you store the information about the user's locale?
System.Web.UI.Page.Culture
What's the difference between Codebehind="MyCode.aspx.cs" and
Src="MyCode.aspx.cs"?
CodeBehind is relevant to Visual Studio.NET only.
What's a bubbled event?
When you have a complex control, 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","someClientCode();")
What data type does the RangeValidator control support?
Integer,String and Date.
What are the different types of caching?
Caching is a technique widely used in computing to increase performance by keeping frequently accessed or expensive data in memory. In context of web application, caching is used to retain the pages or data across HTTP requests and reuse them without the expense of recreating them.ASP.NET has 3 kinds of caching strategiesOutput CachingFragment CachingData
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
Can a user browsing my Web site read my Web.config or Global.asax files?
No. The
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
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 =
message.To =
message.Subject = "Scheduled Power Outage";
message.Body = "Our servers will be down tonight.";
SmtpMail.SmtpServer = "localhost";
SmtpMail.Send (message);
MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's
System.Web.Mail namespace. Due to a security change made to ASP.NET just before it shipped, you need to set SmtpMail's SmtpServer property to "localhost" even though "localhost" is the default. In addition, you must use the IIS configuration applet to enable localhost (127.0.0.1) to relay messages through the local SMTP service.
What are VSDISCO files?
VSDISCO files are DISCO files that support dynamic discovery of Web services. If you place the following VSDISCO file in a directory on your Web server, for example, it returns references to all ASMX and DISCO files in the host directory and any subdirectories not noted in
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
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#" %>
<%
Response.Cache.SetNoStore ();
Response.Write (DateTime.Now.ToLongTimeString ());
%>
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 foll owing 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.
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 HTTPmodule.
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 ataTime.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
stateConnectionString = “tcpip=127.0.0.1:42424”
stateNetworkTimeout = “10”
sqlConnectionString=”data source = 127.0.0.1; uid=sa;pwd=”
cookieless =”Flase”
timeout= “20” />
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
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 >
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 dministrators, Users, and Guests.To allow or deny access to certain groups of users, add the
< 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
When do you set "
Identity is a webconfig declaration under System.web, which helps to control the application Identity of the web applicaton. Which can be at any level(Machine,Site,application,subdirectory,or page), 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 >
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 clientscript 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 theSystem.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 hiddenatrribute
"< 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" ... / >
Explain the differences between Server-side and Client-side code?
Server side code executes on the server.For this to occur page has to be submitted or posted back.Events fired by the controls are executed on the server.Client side code executes in the browser of the client without submitting the page.
e.g. In ASP.NET for webcontrols like asp:button the click event of the button is executed on the server hence the event handler for the same in a part of the code-behind (server-side code). Along the server-side code events one can also attach client side events which are executed in the clients browser i.e. javascript events.
How does VB.NET/C# achieve polymorphism?
Polymorphism is also achieved through interfaces. Like abstract classes, interfaces also describe the methods that a class needs to implement. The difference between abstract classes and interfaces is that abstract classes always act as a base class of the related classes in the class hierarchy. For example, consider a hierarchy-car and truck classes derived from four-wheeler class; the classes two-wheeler and four-wheeler derived from an abstract class vehicle. So, the class 'vehicle' is the base class in the class hierarchy. On the other hand dissimilar classes can implement one interface. For example, there is an interface that compares two objects. This interface can be implemented by the classes like box, person and string, which are unrelated to each other.
C# allows multiple interface inheritance. It means that a class can implement more than one interface. The methods declared in an interface are implicitly abstract. If a class implements an interface, it becomes mandatory for the class to override all the methods declared in the interface, otherwise the derived class would become abstract. Can you explain what inheritance is and an example of when you might use it? The savingaccount class has two data members-accno that stores account number, and trans that keeps track of the number of transactions. We can create an object of savingaccount class as shown below.
savingaccount s = new savingaccount ( "Amar", 5600.00f ) ;
From the constructor of savingaccount class we have called the two-argument constructor of the account class using the base keyword and passed the name and balance to this constructor using which the data member's name and balance are initialised. We can write our own definition of a method that already exists in a base class. This is called method overriding. We have overridden the deposit( ) and withdraw( ) methods in the savingaccount class so that we can make sure that each account maintains a minimum balance of Rs. 500 and the total number of transactions do not exceed 10. From these methods we have called the base class's methods to update the balance using the base keyword. We have also overridden the display( ) method to display additional information, i.e. account number.
Working of currentaccount class is more or less similar to that of savingaccount class. Using the derived class's object, if we call a method that is not overridden in the derived class, the base class method gets executed. Using derived class's object we can call base class's methods, but the reverse is not allowed.
Unlike C++, C# does not support multiple inheritance. So, in C# every class has exactly one base class.
Now, suppose we declare reference to the base class and store in it the address of instance of derived class as shown below.
account a1 = new savingaccount ( "Amar", 5600.00f ) ;
account a2 = new currentaccount ( "MyCompany Pvt. Ltd.", 126000.00f) ;
Such a situation arises when we have to decide at run-time a method of which class in a class hierarchy should get called. Using a1 and a2, suppose we call the method display( ), ideally the method of derived class should get called. But it is the method of base class that gets called. This is because the compiler considers the type of reference (account in this case) and resolves the method call. So, to call the proper method we must make a small change in our program. We must use the virtual keyword while defining the methods in base class as shown below.
public virtual void display( ) { }
We must declare the methods as virtual if they are going to be overridden in derived class. To override a virtual method in derived classes we must use the override keyword as given below.
public override void display( ) { }
Now it is ensured that when we call the methods using upcasted reference, it is the derived class's method that would get called. Actually, when we declare a virtual method, while calling it, the compiler considers the contents of the reference rather than its type. If we don't want to override base class's virtual method, we can declare it with new modifier in derived class. The new modifier indicates that the method is new to this class and is not an override of a base class method.
How would you implement inheritance using VB.NET/C#?
When we set out to implement a class using inheritance, we must first start with an existing class from which we will derive our new subclass. This existing class, or base class, may be part of the .NET system class library framework, it may be part of some other application or .NET assembly, or we may create it as part of our existing application. Once we have a base class, we can then implement one or more subclasses based on that base class. Each of our subclasses will automatically have all of the methods, properties, and events of that base class ? including the implementation behind each method, property, and event. Our subclass can add new methods, properties, and events of its own - extending the original interface with new functionality. Additionally, a subclass can replace the methods and properties of the base class with its own new implementation - effectively overriding the original behavior and replacing it with new behaviors. Essentially inheritance is a way of merging functionality from an existing class into our new subclass. Inheritance also defines rules for how these methods, properties, and events can be merged. In VB.NET we can use implements keyword for inheritance, while in C# we can use the sign ( : ) between subclass and baseclass.
How is a property designated as read-only?
In VB.NET:
Private mPropertyName as DataType
Public ReadOnly Property PropertyName() As DataType
Get Return mPropertyName
End Get
End Property
In C#
Private DataType mPropertyName;
public returntype PropertyName
{
get{
//property implementation goes here
return mPropertyName;
}
// Do not write the set implementation
}
What is hiding in CSharp ?
Hiding is also called as Shadowing. This is the concept of Overriding the methods. It is a concept used in the Object Oriented Programming.
E.g.
public class ClassA {
public virtual void MethodA() {
Trace.WriteLine("ClassA Method");
}
}
public class ClassB : ClassA {
public new void MethodA() {
Trace.WriteLine("SubClass ClassB Method");
}
}
public class TopLevel {
static void Main(string[] args) {
TextWriter tw = Console.Out;
Trace.Listeners.Add(new TextWriterTraceListener(tw));
ClassA obj = new ClassB();
obj.MethodA(); // Outputs “Class A Method"
ClassB obj1 = new ClassB();
obj.MethodA(); // Outputs “SubClass ClassB Method”
}
}
What is the difference between an XML "Fragment" and an XML "Document."
An XML fragment is an XML document with no single top-level root element. To put it simple it is a part (fragment) of a well-formed xml document. (node) Where as a well-formed xml document must have only one root element.
What does it meant to say “the canonical” form of XML?
"The purpose of Canonical XML is to define a standard format for an XML document. Canonical XML is a very strict XML syntax, which lets documents in canonical XML be compared directly.
Using this strict syntax makes it easier to see whether two XML documents are the same. For example, a section of text in one document might read Black & White, whereas the same section of text might read Black & White in another document, and even in another. If you compare those three documents byte by byte, they'll be different. But if you write them all in canonical XML,
which specifies every aspect of the syntax you can use, these three documents would all have the same version of this text (which would be Black & White) and could be compared without problem.
This Comparison is especially critical when xml documents are digitally signed. The digital signal may be interpreted in different way and the document may be rejected.
Why is the XML InfoSet specification different from the Xml DOM? What does the InfoSet
attempt to solve?
"The XML Information Set (Infoset) defines a data model for XML. The Infoset describes the abstract representation of an XML Document. Infoset is the generalized representation of the XML Document, which is primarily meant to act as a set of definitions used by XML technologies to formally describe what parts of an XML document they operate upon. The Document Object Model (DOM) is one technology for representing an XML Document in memory and to programmatically read, modify and manipulate a xml document. Infoset helps defining generalized standards on how to use XML that is not dependent or tied to a particular XML specification or API. The Infoset tells us what part of XML Document should be considered as significant information.
Contrast DTDs versus XSDs. What are their similarities and differences? Which is preferred and why?
Document Type Definition (DTD) describes a model or set of rules for an XML document. XML Schema Definition (XSD) also describes the structure of an XML document but XSDs are much more powerful.
The disadvantage with the Document Type Definition is it doesn’t support data types beyond the basic 10 primitive types. It cannot properly define the type of data contained by the tag. An Xml Schema provides an Object Oriented approach to defining the format of an xml document. The Xml schema support most basic programming types like integer, byte, string, float etc., We can also define complex types of our own which can be used to define a xml document.
Xml Schemas are always preferred over DTDs as a document can be more precisely defined using the XML Schemas because of its rich support for data representation.
Speaking of Boolean data types, what's different between C# and C/C++?
There's no conversion between 0 and false, as well as any other number and true, like in C/C++.
How do you convert a string into an integer in .NET?
Int32.Parse(string)
Can you declare a C++ type destructor in C# like ~MyClass()?
Yes, but what's the point, since it will call Finalize(), and Finalize() has no guarantees when the memory will be cleaned up, plus, it introduces additional load on the garbage collector.
What's different about namespace declaration when comparing that to package declaration in Java?
No semicolon.
What's the difference between const and readonly?
The readonly keyword is different from the const keyword. A const field can only be initialized at the declaration of the field. A readonly field can be initialized either at the declaration or in a constructor. Therefore, readonly fields can have different values depending on the constructor used. Also, while a const field is a compile-time constant, the readonly field can be used for runtime constants as in the following example: public static readonly uint l1 = (uint) DateTime.Now.Ticks;
What does \a character do?
On most systems, produces a rather annoying beep.
Can you create enumerated data types in C#?
Yes.
What's different about switch statements in C#?
No fall-throughs allowed.
What happens when you encounter a continue statement inside the for loop?
The code for the rest of the loop is ignored, the control is transferred back to the beginning of the loop.
How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods.
Will finally block get executed if the exception had not occurred?
Yes.
What's the C# equivalent of C++ catch (…), which was a catch-all statement for any possible exception?
A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.
Can multiple catch blocks be executed?
No, once the proper catch code fires off, the control is transferred to the finally block (if there are any), and then whatever follows the finally block.
Why is it a bad idea to throw your own exceptions?
Well, if at that point you know that an error has occurred, then why not write the proper code to handle that error instead of passing a new Exception object to the catch block? Throwing your own exceptions signifies some design flaws in the project.
What's the difference between // comments, /* */ comments and /// comments?
Single-line, multi-line and XML documentation comments.
How do you generate documentation from the C# file commented properly with a command-line compiler?
Compile it with a /doc switch.
Can you change the value of a variable while debugging a C# application?
Yes, if you are debugging via Visual Studio.NET, just go to Immediate window.
What's the implicit name of the parameter that gets passed into the class' set method?
Value, and it's datatype depends on whatever variable we're changing.
How do you inherit from a class in C#?
Place a colon and then the name of the base class. Notice that it's double colon in C++.
Does C# support multiple inheritance?
No, use interfaces instead.
So how do you retrieve the customized properties of a .NET application from XML .config file? Can you automate this process?
Initialize an instance of AppSettingsReader class. Call the GetValue method of
AppSettingsReader class, passing in the name of the property and the type expected. Assign the result to the appropriate variable. In Visual Studio yes, use Dynamic Properties for automatic .config creation, storage and retrieval.
Why is it not a good idea to insert code into InitializeComponent method when working with Visual Studio?
The designer will likely through it away, most of the code inside InitializeComponent is autogenerated.
Where do you add an event handler?
It's the Attributesproperty, the Add function inside that property.
e.g. btnSubmit.Attributes.Add(""onMouseOver"",""someClientCode();"")
What are jagged array?
First lets us answer the question that what an array is? The dictionary meaning of array is an orderly arrangement or sequential arrangement of elements.
In computer science term:
An array is a data structure that contains a number of variables, which are accessed through computed indices. The variables contained in an array, also called the elements of the array, are all of the same type, and this type is called the element type of the array.
An array has a rank that determines the number of indices associated with each array element. The rank of an array is also referred to as the dimensions of the array. An array with a rank of one is called a single-dimensional array. An array with a rank greater than one is called a multidimensional array. Specific sized multidimensional arrays are often referred to as twodimensional arrays, three-dimensional arrays, and so on.
Now let us answer What are jagged arrays?
A jagged array is an array whose elements are arrays. The elements of jagged array can be of different dimensions and sizes. A jagged array is sometimes called as “array-of-arrays”. It is called jagged because each of its rows is of different size so the final or graphical representation is not a square.
When you create a jagged array you declare the number of rows in your array. Each row will hold an array that will be on any length. Before filling the values in the inner arrays you must declare them.
Jagged array declaration in C#:
For e.g. : int [] [] myJaggedArray = new int [3][];
Declaration of inner arrays:
myJaggedArray[0] = new int[5] ; // First inner array will be of length 5.
myJaggedArray[1] = new int[4] ; // Second inner array will be of length 4.
myJaggedArray[2] = new int[3] ; // Third inner array will be of length 3.
Now to access third element of second row we write:
int value = myJaggedArray[1][2];
Note that while declaring the array the second dimension is not supplied because this you will declare later on in the code.
Jagged array are created out of single dimensional arrays so be careful while using them. Don’t confuse it with multi-dimensional arrays because unlike them jagged arrays are not rectangular arrays.
For more information on arrays:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csref/html/vclrfarrayspg.asp
What is a delegate, why should you use it and how do you call it ?
A delegate is a reference type that refers to a Shared method of a type or to an instance method of an object. Delegate is like a function pointer in C and C++. Pointers are used to store the address of a thing. Delegate lets some other code call your function without needing to know where your function is actually located. All events in .NET actually use delegates in the background to wire up events. Events are really just a modified form of a delegate. It should give you an idea of some different areas in which delegates may be appropriate:
• They enable callback functionality in multi-tier applications as demonstrated in the
examples above.
• The CacheItemRemoveCallback delegate can be used in ASP.NET to keep cached
information up to date. When the cached information is removed for any reason, the
associated callback is exercised and could contain a reload of the cached information.
• Use delegates to facilitate asynchronous processing for methods that do not offer
asynchronous behavior.
• Events use delegates so clients can give the application events to call when the event is fired. Exposing custom events within your applications requires the use of delegates.
How does the XmlSerializer work?
XmlSerializer in the .NET Framework is a great tool to convert Xml into runtime objects and vice versa
If you define integer variable and a object variable and a structure then how those will be plotted in memory.
Integer , structure – System.ValueType -- Allocated memory on stack , infact integer is primitive type recognized and allocated memory by compiler itself .
Infact , System.Int32 definition is as follows :
[C#]
[Serializable]
public struct Int32 : IComparable, IFormattable, IConvertible
So , it’s a struct by definition , which is the same case with various other value types .
Object – Base class , that is by default reference type , so at runtime JIT compiler allocates memory on the “Heap” Data structure .
Reference types are defined as class , derived directly or indirectly by System.ReferenceType
posted by Satya @ 9:14 AM
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