dot net questions 1

Usually, not a thing—most applications will run safely and will not be exploitable by malicious attacks. By simply using the standard class libraries to access resources (like files) or perform protected operations (such as a reflection on private members of a type), security will be enforced by these libraries. The one simple thing application developers may want to do is include a permission request (a form of declarative security) to limit the permissions their code may receive (to only those it requires). This also ensures that if the code is allowed to run, it will do so with all the permissions it needs.

Only developers writing new base class libraries that expose new kinds of resources need to work directly with the security system. Instead of all code being a potential security risk, code access security constrains this to a very small bit of code that explicitly overrides the security system.

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

Default security policy gives only a restricted set of permissions to code that comes from the local intranet zone. This zone is defined by the Internet Explorer security settings, and should be configured to match the local network within an enterprise. Since files named by UNC or by a mapped drive (such as with the NET USE command) are being sent over this local network, they too are in the local intranet zone.

The default is set for the worst case of an unsecured intranet. If your intranet is more secure you can modify security policy (with the .NET Framework Configuration tool or the CASPol tool) to grant more permissions to the local intranet, or to portions of it (such as specific machine share names).

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

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

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

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

How does evidence-based security work with Windows 2000 security?

Evidence-based security (which authorizes code) works together with Windows 2000 security (which is based on log on identity). For example, to access a file, managed code must have both the code access security file permission and must also be running under a log on identity that has NTFS file access rights. The managed libraries that are included with the .NET Framework also provide classes for role-based security. These allow the application to work with Windows log on identities and user groups.

How big is the datatype int in .NET? 32 bits.
How big is the char? 16 bits (Unicode).
How do you initiate a string without escaping each backslash? Put an @ sign in front of the double-quoted string.
What are valid signatures for the Main function?
- publicstatic void Main()
- publicstatic int Main()
- publicstatic void Main( string[] args )
- publicstatic int Main(string[] args )
How do you initialize a two-dimensional array that you don’t know the dimensions of?
- int [, ] myArray; //declaration
- myArray= new int [5, 8]; //actualinitialization
What’s the access level of the visibility type internal? Current application.
What’s the difference between struct and class in C#?
- Structscannot be inherited.
- Structsare passed by value, not by reference.
- Structis stored on the stack, not the heap.
Explain encapsulation. The implementation is hidden, the interface is exposed.
What data type should you use if you want an 8-bit value that’s signed? sbyte.
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++.
Where are the value-type variables allocated in the computer RAM? Stack.
Where do the reference-type variables go in the RAM? The references go on the stack, while the objects themselves go on the heap.
What is the difference between the value-type variables and reference-type variables in terms of garbage collection? The value-type variables are not garbage-collected, they just fall off the stack when they fall out of scope, the reference-type objects are picked up by GC when their references go null.
How do you convert a string into an integer in .NET? Int32.Parse(string)
How do you box a primitive data type variable? Assign it to the object, pass an object.
Why do you need to box a primitive variable? To pass it by reference.
What’s the difference between Java and .NET garbage collectors? Sun left the implementation of a specific garbage collector up to the JRE developer, so their performance varies widely, depending on whose JRE you’re using. Microsoft standardized on their garbage collection.
How do you enforce garbage collection in .NET? System.GC.Collect();
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? You can initialize readonly variables to some runtime values. Let’s say your program uses current date and time as one of the values that won’t change. This way you declare public readonly string DateT = new DateTime().ToString().
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.
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.
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.
When you inherit a protected class-level variable, who is it available to? Classes in the same namespace.
Are private class-level variables inherited? Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are.
Describe the accessibility modifier protected internal. It’s available to derived classes and classes within the same Assembly (and naturally from the base class it’s declared in).
C# provides a default constructor for me. I write a constructor that takes a string as a parameter, but want to keep the no parameter one. How many constructors should I write? Two. Once you write at least one constructor, C# cancels the freebie constructor, and now you have to write one yourself, even if there’s no implementation in it.
What’s the top .NET class that everything is derived from? System.Object.
How’s method overriding different from overloading? When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.
What does the keyword virtual mean in the method definition? The method can be over-ridden.
Can you declare the override method static while the original method is non-static? No, you can’t, the signature of the virtual method must remain the same, only the keyword virtual is changed to keyword override.
Can you override private virtual methods? No, moreover, you cannot access private methods in inherited classes, have to be protected in the base class to allow any sort of access.
Can you prevent your class from being inherited and becoming a base class for some other classes? Yes, that’s what keyword sealed in the class definition is for. The developer trying to derive from your class will get a message: cannot inherit from Sealed class WhateverBaseClassName. It’s the same concept as final class in Java.
Can you allow class to be inherited, but prevent the method from being over-ridden? Yes, just leave the class public and make the method sealed.
What’s an abstract class? A class that cannot be instantiated. A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden. Essentially, it’s a blueprint for a class without any implementation.
When do you absolutely have to declare a class as abstract (as opposed to free-willed educated choice or decision based on UML diagram)? When at least one of the methods in the class is abstract. When the class itself is inherited from an abstract class, but not all base abstract methods have been over-ridden.
What’s an interface class? It’s an abstract class with public abstract methods all of which must be implemented in the inherited classes.
Why can’t you specify the accessibility modifier for methods inside the interface? They all must be public. Therefore, to prevent you from getting the false impression that you have any freedom of choice, you are not allowed to specify any accessibility, it’s public by default.
Can you inherit multiple interfaces? Yes, why not.
And if they have conflicting method names? It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.
What’s the difference between an interface and abstract class? In the interface all methods must be abstract, in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.
How can you overload a method? Different parameter data types, different number of parameters, different order of parameters.
If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor? Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.
What’s the difference between System.String and System.StringBuilder classes? System.String is immutable, System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.
Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe in the page loading process. inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received (usually a file with .aspx extension),the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.
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 pageis instantiated, Load() - when the page is loaded into server memory,PreRender() - the brief moment before the page is displayed to the user asHTML, 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" andSrc="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 itsconstituents.
Suppose you want a certain ASP.NET function executed on MouseOver overa certain button. Where do you add an event handler? It’s the Attributesproperty, the Add function inside that property. So btnSubmit.Attributes.Add("onMouseOver","someClientCode();")
What data type does the RangeValidator control support? Integer,String and Date.

Unmanaged code is everything you have been programming for years, before .NET Unmanaged, or "native" code, includes VB6, COM, Win32, native C++, and so forth. It is code that predated .NET and therefore, has absolutely no knowledge of .NET and cannot directly make use of any managed facilities. Unmanaged code is one which do not targets the Runtime.

Managed code is code written for the .NET runtime or CLR. More specifically, managed code is "managed" because the code is under the control of the CLR. Managed code is one which targets the Runtime.

To create a permanent Cookie you have to specify a date in the future. The easiest way to do this is with:

"NEVER" in this case is translated automatically into a date in the far future. You can also specify a specific date instead of never, but it must be a real date and it must follow GMT naming. For example:

The virtual path that it applies to. By default this is the Web's root path, but realistically you should scope it to the virtual directory that the request is running in. For example if you run the following url:

where /wconnect is a virtual directory the cookie should be scoped to the /wconnect path.

Optional - Sets an expiration for the cookie. This must be a fully qualified string:

HTML controls represent common HTML elements and are available through the HTML tab of the Visual Studio .NET toolbox.

HTML controls are only of little use in ASP.NET programs because they can't be accessed from the server-side code.

ASP.NET provides two other sets of controls that are much better suited for server-side programming: HTML server controls and Web server controls.

HTML server controls are similar to HTML controls with the added feature of server-side availability. You can convert any HTML control to run as an HTML server control by adding a runat="server" attribute to its declaration. You can accomplish the same task visually by right-clicking an HTML control and selecting Run As Server Control from the shortcut menu.

Web server controls provide a higher level of abstraction than HTML server controls because their "OBJECT MODELs" matches closely with the .NET Framework rather than matching with the requirements of HTML syntax.

1.Web server controls provide a rich object model that closely matches with the rest of the .NET Framework.

2.Some Web server controls provide richer functionality, such as the Calendar control, AdRotator control, and so on, not available with HTML controls.

3.Web server controls have advanced features such as automatic browser detection, automatic postback, and event bubbling.

Some advanced Web server controls, such as Data Grid, can also contain other controls (such as a button). Data Grid controls usually display dynamically generated data, and if each row of the Data Grid contains a button, you might have a variable number of button controls. Writing an individual event handler for each button control in this case is a tedious process. To simplify event handling, controls such as Data Grid support bubbling of events. In bubbling, all events raised at the level of child control are bubbled up to the container control, where the container control can raise a generic event in response to the child events.

This coding style places all the code that is to be executed by the server into separate files for each .aspx page. This allows web designers who specialize in the HTML development of a site, and application developers who specialize in the programming logic of the site to work together in a way that the page designer does not disturb the code in the page.

<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="HelloWorldWACS.WebForm1" %>

The first thing to notice is the @Page directive. It only contains one attribute which is the Language=C#. This allows the web server to know which compiler to invoke on the code being run within the page.

The @Page directive includes the Codebehind= attribute which indicates the class file that will contain the code that would be included within the server script tags on an inline code page. The Inherits= attribute gives the namespace and class that contains the code for the page. The AutoEventWireup= attribute determines if ASP.NET controls events automatically get fired back up to the server or not.

2. Code-behind files that are compiled into a .dll file and then removed from production.
3. Code-behind files that are compiled on the web server as they are needed.

<%@ Page language="c#" Src="WebForm2.aspx.cs" Inherits="HelloWorldWACS.WebForm2"%>

This page still uses a code-behind file but now the file is dynamically compiled “on the fly” when the page is requested. This @Page directive contains a Src= attribute which directs the compiler to the code file to compile. The Inherits= attribute determines the class to use after the file is compiled.

ASP.NET provides a set of Web server controls called validation controls that provide sophisticated validation on both the client side and the server side depending on the validation settings and the browser's capabilities.

ASP.NET ensures that validations are performed on the server side even if they were already performed on the client side. This ensures that validations are not bypassed if a malicious user circumvents client-side validation. If the client-side validation fails, the server-side validation is never performed.

Using the Page.Validate() Method and Page.IsValid Property:

Each validation control maintains an IsValid property that indicates the status of the validation test. The Page control that hosts the Web controls also contains a property called IsValid that indicates the status of the validation for the whole page. When all the validation controls on the Web form set their IsValid properties to true, Page.IsValid also becomes true. If the validation fails on any of the validation controls, Page.IsValid is false.

The Page class maintains a collection of the validation controls on a Web page that can be accessed through its Validators property. The Page class also contains a Validate() method that invokes the Validate() method of all the validation controls in the page. The Page.Validate() method is used to perform validation programmatically on all the validation controls of a Web page.

Validation Web Server Controls:

ASP.NET validation controls derive their basic functionality from the BaseValidator abstract class available in the System.Web.UI.WebControls.

ASP.NET provides the following validation controls that derive their functionality from the BaseValidator class: RequiredFieldValidator, RegularExpressionValidator, RangeValidator, CompareValidator, and CustomValidator.

These validation controls are usually associated with the input server controls on which the validation needs to be performed. For validation to work properly, the validation control and the input server control should be placed in the same container control. The validation controls are usually placed next to the associated input control so that you can display error messages or indicators next to the input control. You can associate any number of validation controls with an input server control.

3.10 Important Members of the BaseValidator Class

The RequiredFieldValidator Control:

The RequiredFieldValidator control can be used to check whether the input control contains an entry. It makes the associated input control a required field in the Web page and ensures that some input data is passed to it. The control also trims whitespace prior to checking for the required field entry.

The RequiredFieldValidator control contains a special property called InitialValue that can be passed the initial value of the associated input control. During validation, if the input control's validation property contains the same initial value or is empty, it sets IsValid to false, indicating that the validation failed.

The RequiredFieldValidator control is the only validation control that ensures that the associated input control is a required field. Other validation controls assume the input control's data to be valid if it is left blank.

The RegularExpressionValidator Control:

The RegularExpressionValidator control checks whether the associated input control's validation property matches a Specified pattern. This pattern is specified by the ValidationExpression property using a regular expression. If you are not familiar with regular expressions, you can find more information in the Microsoft .NET Framework documentation.

The RangeValidator Control:

The RangeValidator control is used to check whether the input control contains a value in the Specified range. You can check the range of values against different data types such as String, Date, and Integer.

Table 3.11 Important Properties of the RangeValidator Class

The CompareValidator Control:

The CompareValidator control is used to compare the input server control's value against another value. The CompareValidator control can compare against a value specified to the validator control or against the value of another input control. The comparison can be made with different comparison operators such as equal, greater than, and so on. A special comparison operation can be used to verify that the associated input control's value is in the specified data type. You can make comparisons against various data types, such as String, Date, Integer, and so on.

Table 3.12 Important Properties of the CompareValidator Class

If both the ControlToCompare and ValueToCompare properties are set for a CompareValidator control, the ControlToCompare property takes precedence.

If the Operator property of a CompareValidator is set to DataTypeCheck, the ControlToCompare and ValueToCompare properties are ignored. The validator control tries to convert the input control value to the data type specified by the Type property and sets the IsValid property with the result.

The CustomValidator Control:

The CustomValidator control allows you to build a validation control for a custom specification. You can perform any custom validation both at the server side and at the client side with the help of this validation control.

This control exposes a property called ClientValidationFunction that specifies the name of the client script function to be executed for validation on the client side. This custom validation function is passed two arguments: The first one is the custom validator control, and the second argument is an object that contains two properties—IsValid and Value. The Value property contains the value that is to be validated, and the IsValid property is used to set the result of the validation.

At the server side, during the validation on the server, the validation control fires a ServerValidate event. An event handler containing the custom validation code is added to this event to perform validation on the server. The event sends a ServerValidateEventArgs object containing event-related data. This object contains two properties: The Value property contains the value of the control that is to be validated, and the IsValid property is used to set the result of the validation.

The ValidationSummary Control

The ValidationSummary control is used to display a summary of all the validation errors of a Web page. It displays the ErrorMessage property of the validation controls in the summary. If the ErrorMessage property is not set, the Text property is displayed as error messages for all the validation controls whose validations fail.

Table 3.13 Important Properties of the ValidationSummary Class

The advantages of Server-Side scripting are many. Because all of the server side code is executed before the HTML is sent to the browser, your code is hidden. Server-side code is also the only choice if you want to access files and directories on the local machine. Server-side code is also browser independent. Because the HTML code returned by the server is simple HTML, you do not have to worry about the version of browser the client is using. The disadvantage to server-side scripting is that the server must use valuable resources to parse each page it sends out. This could slow down your web site.

Client-side scripting can be very useful. The major advantage is that each web browser uses its own resources to execute the code found on the web page. This eases the burden on the server. The disadvantages are that you can not prevent the user from seeing your code and that you can not use client-side code to access local files, directories, or databases.

Sets or retrieves a value indicating whether the server control persists its view state to the requesting client.

You must enable view state for the server control to maintain its state across HTTP requests. A server control's view state, and the view state of any child controls it contains, is the accumulation of all its property values. In order to preserve these values across HTTP requests.

Redirect and Transfer both cause a new page to be processed, but the interaction between the client (web browser) and server (ASP.NET) is different in each situation.

Redirect: A redirect is just a suggestion – it’s like saying to the client “Hey, you might want to look at this”. All you tell the client is the new URL to look at, and if they comply, they do a second request for the new URL.

If you want to pass state from the source page to the new page, you have to pass it either on the URL (such as a database key, or message string), or you can store it in the Session object (caveat: there may be more than one browser window, and they’ll all use the same session object).

e.g. Redirect to the new.aspx page, passing an ID on the query string. "true" stops processing the current page:

Transfer: A transfer happens without the client knowing – it’s the equivalent of a client requesting one page, but being given another. As far as the client knows, they are still visiting the original URL.
Sharing state between pages is much easier using Server.Transfer – you can put values into the Context.Items dictionary, which is similar to Session and Application, except that it lasts only for the current request. (search for HttpContext in MSDN). The page receiving postback can process data, store values in the Context, and then transfer to a page that uses the values.

e.g. Store a message in the context dictionary, and transfer to the default.aspx page (which can then display the message):

· Managed Code is a very important feature of the .NET architectural framework. VB.NET code targets the Common Language Runtime (CLR) by compiling into an intermediate language, which is then executed under strict control (managed). The application also becomes more maintainable because of the managed code.

· Under the .NET framework, VB.NET applications are packaged as self-contained, self-describing, versioned assemblies (collection of classes and meta data). One can deploy, remove and manage N different versions of an application or DLL on the same machine without creating conflicts

· Desktop applications can be much more easily converted to Web Based applications using the WebForms paradigm of .NET made available throughVB.NET.

· XML Web Services creation and integration as facilitated by the .NET platform are readily available through VB.NET.

· .NET applications when developed carefully can be platform independent. Managed code built using .NET will run on platforms that host the .NET framework irrespective of the Operating System or machine type.

· VB.NET uses XML to transfer data between the various layers in the DNA Architecture i.e. data are passed as simple text strings.

· VB.NET is totally object oriented . This is a major addition that VB6 and other earlier releases didn't have.

· Error handling has changed in VB.NET. A new Try-Catch-Finally block has been introduced to handle errors and exceptions as a unit, allowing appropriate action to be taken at the place the error occurred thus discouraging the use of ON ERROR GOTO statement. This again credits to the maintainability of the code.

· Another great feature added to VB.NET is free threading against the VB single-threaded apartment feature.

· CLR takes care of garbage collection i.e. the CLR releases resources as soon as an object is no more in use. This relieves the developer from thinking of ways to manage memory. CLR does this for them.

· The .NET framework comes with ADO.NET , which follows the disconnected paradigm , i.e. once the required records are fetched the connection no longer exists.

MigrationWizard:
Visual Studio.NET provides a Visual Basic Upgrade Wizard (also called as Migration Wizard). This wizard does almost the entire migration barring some modifications that must be made to complete the upgrade process. The wizard produces a report in HTML format with the information of the places where it failed to migrate the application to .NET.

Fresh Design:
Redesign of certain core modules or perhaps the whole application is a possible approach if new features of the .NET architectural framework are considered. Managed code (under CLR) can run in tandem with unmanaged code (e.g. COM components). Therefore it is possible to reuse many existing components as such.

Use of Customized tools to enhance migration:
Porting driven by a wizard and re-design are easier when migrated using customized tools like the “Cal-Migrater” developed internally by CSWL for a health care product migration. This tool makes use of both the wizard and redesign approach to make faster pace through the .NET porting activity.

The Global.asax file contains subroutines that handle application wide events and objects declared with application scope. If you add other modules to your standard application events, additional events are exposed in the Global.asax file.

An application can contain in its root directory a Web.Config file that specifies configuration information for the entire application. Web.Config files, which are standard, human-readable XML files that you can open and modify with any text editor.

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.

The ASP.NET framework uses a pool of application instances to process each request to the server. When a request is made, an application instance is assigned to the request. Immediately after any of these application instances are created, the Init event is raised.

Requesting the first page from the Web site raises both the Application_Start and Init events. The Application_Start event won't be raised again for the lifetime of the application. The Init event, on the other hand, might be raised multiple times.

You can use the Init event to initialize any variables or objects that you'll need to use throughout the lifetime of a particular application instance. If you assign values to local variables, the variables retain their values across multiple requests.

The ASP.NET Web Forms page framework is a scalable common language runtime programming model that can be used on the server to dynamically generate Web pages. Web Forms enable developers to easily create cross-platform, cross-browser programmable Web applications, using the same techniques employed to build "forms-based" desktop applications. Supported in Visual Studio with powerful rapid application development (RAD) tools for designing and programming your forms.

Assemblies are building blocks of programming in the .Net Framework. An Assembly contains the MSIL code, which the CLR executes, and type Meta Data. An Assembly also contains the Assembly manifest which contains information about the assembly version, its security identity, the resources required by the assembly, and the scope of the assembly.

A delegate is nothing but a object which encapsulates a reference to a method. In C++ they were referred to as function pointers.

When you write a multilingual or multi-cultural application in .NET, and want to distribute the core application separately from the localized modules, the localized assemblies that modify the core application are called satellite assemblies.

CorDBG – command-line debugger, and DbgCLR – graphic debugger. Visual Studio .NET uses the DbgCLR. To use CorDbg, you must compile the original C# file using the /debug switch.

An Error is an Event which happens during the exceptions of the code and disrupts the flow of the program and creates the exceptions object.

When an error interrupts the flow, the program tries to find an exception handler — a block of code that tells it how to react — that will help it resume the flow.

In other words, an error is the event; an exception is the object that the event creates.

If you do not put the Overrides keyword on the function in the derived class, the function is assumed to shadow the original function. A shadowed function is a function in the derived class that has the same name as a function in the base class but is not intended to override the base class function.

Tip: To minimize complexity and simplify maintenance, limit your inheritance hierarchies to no more than about four levels.

Building Constructors and Destructors:

Visual Basic .NET introduces true constructors that are executed whenever a new instance of the class is created. These constructors are defined with a subroutine named New.

You can pass data to a constructor for more flexibility and power in initializing the object. Constructors with parameters are called parameterized constructors.

Both of these constructors can be define for one class. Actually, any number of constructors can be defined for a class as long as they each have different parameters. This feature is called overloading. The appropriate constructor is called based on the data passed to the constructor. You do not have to define a constructor. If you don't create one, a default constructor is used.

Instead of a Terminate event, Visual Basic .NET provides a Finalize destructor. This destructor is called when the .NET garbage collector determines that the object is not longer needed. There may be a delay between the time an object is terminated and the time the garbage collector actually destroys the object.

Tip: You should not normally use a Finalize destructor because of this delay and the additional processing required by the system to manage objects with a Finalize destructor. Use the Dispose destructor instead. In order to better manage the resources used by your class, implement the IDisposable interface and the Dispose destructor.

The Inherits keyword defines the parent or base class. All of the public properties and methods of the base class are accessible to this derived class.

The Overrides keyword on the second function denotes that this is overriding the function defined within the base class. This allows a derived class to provide its own implementation of a particular function.

Overriding an inherited event handler is the same as overriding any other kind of inherited method, with one important difference: When you override an inherited event handler, you have to remove the Handles clause.

A DataSet uses a DiffGram to store and preserve all versions of data that it contains. A DiffGram is in XML forma. We can use Diffgrams to differentiate between the current and original versions of data. When we create a DataSet with DiffGram, it is populated with all the information that we require to recreate the contents of the DataSet.

Boxing and Unboxing is a essential concept in C#’s type system. With Boxing and Unboxing one can link between value-types and reference-types by allowing any value of a value-type to be converted to and from type object. Boxing and Unboxing enables a unified view of the type system wherein a value of any type can ultimately be treated as an object.

Converting a value type to reference type is called Boxing. Unboxing is an explicit operation.

An int value can be converted to object and back again to int. This example shows both Boxing and Unboxing. We can only UnBox a variable that has been previously Boxed.

URIs are simple text strings that refer to Internet resources. URIs may refer to documents, resources, to people, and indirectly to anything.

URL A URL is a Uniform Resource Locator. Think of it as a networked extension of the standard filename concept: not only can you point to a file in a directory, but that file and that directory can exist on any machine on the network, can be served via any of several different methods, and might not even be something as simple as a file: URLs can also point to queries, documents stored deep within databases, the results of a finger or archie command, or whatever.

Services and components that can be used on the Internet. Web services provide new added value services by combining various Web services without the need for manual input. Web services use XML-related technologies such as SOAP as the communication protocol, WSDL as the interface description language, and UDDI for registering and searching services. Sometimes called XML Web services.

Web Services represent black-box functionality that can be used and reused without regard to how the service is implemented.

The common language runtime provides built-in support for creating and exposing Web Services. The resulting model is both scalable and extensible, and embraces open Internet standards (HTTP, XML, SOAP, WSDL) so that it can be accessed and consumed from any client or Internet-enabled device.

ASP.NET provides support for Web Services with the .asmx file. An .asmx file is a text file that is similar to an .aspx file. These files can be part of an ASP.NET application that includes .aspx files. These files are then URI-addressable, just as .aspx files are.

To make this service available, We might name the file HelloWorld.asmx and place it on a server called GotDotNet.com inside a virtual directory called someFolder. Using a Web browser, you could then enter the URL http://apps.gotdotnet.com/QuickStart/HelloWorld/HelloWorld.asmx, and the resulting page would show the public methods for this Web Service (those marked with the WebMethod attribute), as well as which protocols (such as SOAP, or HTTP GET) you can use to invoke these methods.

Entering the address: http://apps.gotdotnet.com/QuickStart/HelloWorld/HelloWorld.asmx?WSDL into the browser returns a Web Service Description Language (WSDL) document. This WSDL document is very important, and is used by clients that will access the service.

In addition to the ASP.NET server side technology that allows developers to create Web Services, the .NET Framework provides a sophisticated set of tools and code to consume Web Services. Because Web Services are based on open protocols such as the Simple Object Access Protocol (SOAP), this client technology can also be used to consume non-ASP.NET Web Services.

Within the SDK, there is a tool called the Web Services Description Language tool (WSDL.exe). This command-line tool is used to create proxy classes from WSDL. For example, you could enter:

This class would look very similar to the class created in the previous section. It would contain a method called SayHelloWorld that returns a string. Compiling this proxy class into an application and then calling this proxy class's method results in the proxy class packaging a SOAP request across HTTP and receiving the SOAP-encoded response, which is then marshaled as a string.

WSDL.exe accepts a variety of command-line options, however to create a proxy only one option is required: the URI to the WSDL. In this example, we are passing a few extra options that specify the preferred language, namespace, and output location for the proxy. We are also compiling against a previously saved WSDL file instead of the URI to the service itself:

Once the proxy class exists, you can create objects based on it. Each method call made with the object then goes out to the URI of the XML Web service (usually as a SOAP request).

The Repeater control is used to display a repeated list of items that are bound to the control. The Repeater control may be bound to a database table, an XML file, or another list of items.

By default, an ArrayList object contains 16 entries. An ArrayList can be sized to its final size with the TrimToSize() method.

An ArrayList can also be sorted alphabetically or numerically with the Sort() method.

To sort in reverse order, apply the Reverse() method after the Sort() method

To bind data to a RadioButtonList control, first create a RadioButtonList control (without any asp:ListItem elements) in an .aspx page:

Then add the script that builds the list and binds the values in the list to the RadioButtonList control.

The DataSource property of the List control is set to the ArrayList and it defines the data source of the List control. The DataBind() method of the List control binds the data source with the List control

The Hashtable object contains items in key/value pairs. The keys are used as indexes, and very quick searches can be made for values by searching through their keys.

rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()

The SortedList object contains items in key/value pairs. A SortedList object automatically sort the items in alphabetic or numeric order.

Items are added to the SortedList with the Add() method. A SortedList can be sized to its final size with the TrimToSize() method.

The following code creates a SortedList named mycountries and four elements are added:

rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()

The DataList control is, like the Repeater control, used to display a repeated list of items that are bound to the control. However, the DataList control adds a table around the data items by default. The DataList control may be bound to a database table, an XML file, or another list of items.

Positive test cases (correct data, correct output), negative test cases (broken or missing data, proper handling), exception test cases (exceptions are thrown and caught properly).

What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET?

SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. OLE-DB.NET is universal for accessing other sources, like Oracle, DB2, Microsoft Access and Informix, but it’s a .NET layer on top of OLE layer, so not the fastest thing in the world. ODBC.NET is a deprecated layer provided for backward compatibility to ODBC engines.

Transaction must be Atomic (it is one unit of work and does not dependent on previous and following transactions), Consistent (data is either committed or roll back, no “in-between” case where something has been updated and something hasn’t), Isolated (no transaction sees the intermediate results of the current transaction), Durable (the values persist if the data had been committed even if the system crashes right after).

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

When a datum is passed "by value" to a function, a copy of the datum is passed to the function; if the function modifies that value, the change affects only the function's copy of the datum--it does not affect the original datum.

When a datum is passed to a function "by reference:" a reference to the value is passed to the function, and the function can use that reference to modify the value itself; any such modifications will be visible outside the function.

The Common Language Runtime allocates memory for objects in two places: on the stack and in the heap. The stack is an orderly first-in last-out memory structure, and is used for storing value-type objects. When a method is invoked, the CLR bookmarks the top of the stack, and then allocates memory on top of this for any value type objects (including local variables) that are created. When the method completes, the stack is 'popped' back to the bookmark and all the value-type objects created - and their associated memory - are released.

The heap, on the other hand, can be pictured as a disorderly jumble of objects, suitable for objects managed by reference. When a reference-type object is created, the CLR allocates a block of heap memory, creates the object, then gives us a reference to it. While the object itself will always be created on the heap, its reference may either exist on the heap or stack - depending on whether it’s part of another heap-object, or is a local variable.

· Enables datacentric applications to connect to various data sources and retrieve, manipulate, and update data.

· Disconnected Architecture. Using Disconnected Architecture, appln connect to database only for retrieving or updating of data. Hence reducing the No. of open connections to various database servers.

· Dataset is a cache of records that we retrieve from data source such as XML or database file.

· A Dataset contains data from one or more tables. In addition, a dataset contains information regarding the relationships between tables. Enables u to remain disconnected from the database. Another adv is that components can exchange datasets.

· A .NET dataprovider enables u to connect to a datasource and execute commands to retrieve results and manipulate data.

· The Classes of ADO.NET are defined in the System.Data namespace. This namespace define classes, such as dataset and Datatable, which constitute the ADO.NET architecture.

- To fetch the next record, the Datareader reconnects to the datasource and retrieves the data.

· DataAdapter- This object enables a database and dataset to communicate with each other. We can use Dataadapter object to transfer data between a data source and a dataset. In addition, the dataadapter object can transfer data between a dataset and some other applns, such Microsoft Exchange Server.

· The structure of dataset, including table definitions, columns, datatypes, and constraints , is defined by using an XML schema.

· We can serialize the dataset as XML an we can serialize the structure of dataset as XML schema.

1. Richer data type: COM marshalling can only convert data types that are defined by the COM standard. In XML- based data transfer, restrictions on datatypes do not exists. We can use XML –based data transfer to transfer any data that is serializable.

2. By Passing Firewalls: A Firewall does not allow system-level requests, such as COM marshalling. Therefore, a recordset cannot bypass a firewall. However, Firewall allow HTML text to pass and we can use ADO.NET dataset through Firewall.

Though we can use OLEDB .NET data provider to access data from SQL server, we should use SQL server .Net data provider to access data from SQL server(Version 7.0 or Later).

The SQL server .Net Data provider makes Native calls to SQL server and therefore it is more efficient than the OLEDB .NET data provider.

We do not need to provide the “Provider” attribute in the Connection string property for SQL connection class in the SQL server .NET data Provider.

The ExecuteScalar method executes a SQL statement against a specified datasource and returns a single value. The single value represents value in the first row and first column. The rest of the values are ignored.

The ExecuteReader Method executes a SQL statement or a stored procedure against a available data source and returns an OledbdataReader Object.

The ExecuteNonQuery method is used to execute INSERT, UPDATE, or DELETE statements. The ExecuteNonQuery method executes these commands and returns the no. of rows affected.

– Reduces the system overhead at any time because only one row of data exists in Memory.

– To fetch the next record, the Datareader reconnects to the datasource and retrieves the data.

– After reading the Datareader using Read(), we’ve to close the Datareader.

– After closing, we can call the Isclosed() method and RecordsAffected property

Note: When we create a Relationship betn a table, a unique constraint is added to the parent table, and the foreign key constraint is added to the child table by default.

· Check primary keys – if primary keys do not match, Exception is thrown and the dataset raises the Mergefailed Event.

· Preserve changes – to specify whether to preserve the changes in the existing dataset. If True, the existing values in the table receiving data are not overwritten with the Incoming values. If False, the existing values in the table receiving data are not overwritten with the Incoming values in the current version of the existing row.

· Apply constraints – Constraints are not checked when Merge method is executed. After we add the data, constraints are enforced. Therefore we need to ensure that we can handle the exceptions in our code

Sometimes we might need to work with data without affecting the original data in the dataset. In such cases, we can create a copy of an existing dataset present in a dataset.

· Create a exact copy of dataset including schema, data, row state information, and row version.

· Create a Dataset that contains the schema of an existing dataset containing only modified rows.

· Copy only the schema or relational structure of a dataset but nt any rows from the original dataset.

Like a Database, a Dataset allows us to create a view. However Unlike database view, we cannot

· Exclude or append columns that are present , and not present in the source table respectively.

Dim EmployeeDV as dataview = new dataview(EmployeeDS.tables(“Employees”), “Country=’

USA

’ “, “City”, Dataviewrowstate.currentrows)

ADO.NET supports event-driven programming, which enables us to capture the changes and react to them properly.

Mergefailed event: ( Has two property namely Conflict Property and Table property)

Addhandler EmployeeDS.Mergefailed, New MergefailedEventHandler(Addressof DataSetMergeFailed)

Private shared sub DataSetMergeFailed(sender as object, args as MergedFailedEventArgs)

For a programming language to be a true OOP language, the language must meet the following criteria:

Abstraction—Abstraction manages the complexities of a business problem by allowing you to identify a set of objects involved with that business problem.

Encapsulation—Encapsulation hides the internal implementation of an abstraction within the particular object.

Polymorphism—Polymorphism provides for multiple implementations of the same method. For example, different objects can have a Save method, each of which perform different processing.

Inheritance—The excitement of Visual Basic .NET lies in inheritance. Visual Basic 5 introduced the concept of interface inheritance, which allows you to reuse the interface of a class, but not its implementation. Visual Basic .NET provides for true implementation inheritance whereby you can reuse the implementation of a class.

A. False. .NET Framework is one of the technologies that could be used create webservices.

2.) What property do you have to set to tell the grid which page to go to when using the Pager object?

A. CurrentPageIndex. You need to set this one with the DataGridPageChangedEventArgs' NewPageIndex.

3.) What tags do you need to add within the <asp:datagrid> tags to bind columns manually.

4.) 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?

A. If it has only get accessor.

ex:
public class abc
{
private string stringIt="This is the string";
public string StringIt
{
get
{
return stringIt;
}
}
}

But you could set an attribute prior to the property name with [ReadOnly="true"],
if that property defined an attribute

6.) Where on the Internet would you look for Web services?
Somebody told me it is UDDI server. what actually is UDDI?

A. UDDI is Universal Description, Discovery and Integration of Web Services.
The UDDI servers serves as yellow pages to WebServices (visit http://www.uddi.org)

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

A. Use CompareValidator

8.) True or False: To test a Web service you must create a windows application or Web application to consume this service?

A. No need, the webservice comes with a test page and it provides HTTP-GET method to test.
And if the web service turned off HTTP-GET for security purposes then you need to create
a web application or windows app as a client to this to test.

9.) How many classes can a single .NET DLL contain?
(a) One and only one
(b) Not more than 2
(c) Many

A. (c). many is correct. Yes an assembly can contain one or more classes and an assembly can
be contained in one dll or could spread across multiple dlls. too. Take System.dll, it is
collections of so many classes.

10.) What is the transport protocol you use to call a Web service? Is it SOAP or HTTP-Get or HTTP-Post???

A. You could use all the three, but SOAP is the preferred and secured method of consuming the Service.

11.) What is WSDL?

A. WSDL is web services description language, which is used to define the webservice.

Conceptual Questions

What is the .NET Framework?

Runtime Technical Questions

Terminology

What is the common language runtime (CLR)?

What is the common type system (CTS)?

What is the Common Language Specification (CLS)?

What is the Microsoft Intermediate Language (MSIL)?

What is managed code and managed data?

Assemblies

What is an assembly?

What are private assemblies and shared assemblies?

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

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

Application Deployment and Isolation

What options are available to deploy my .NET applications?

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

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

What is an application domain?

Garbage Collection

What is garbage collection?

How does non-deterministic garbage collection affect my code?

Can I avoid using the garbage collected heap?

Remoting

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

Interoperability

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

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

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

Security

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