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To create a derived class in C#, the class declaration should be done as: class child: parent To create a derived class in VB.NET, the class declaration should be done as:

Class child Inherits parent End Class Multiple inheritance Multiple inheritance is the possibility that a child class can have multiple parents. Human beings have always two parents, so a child will have characteristics from both parents. In OOP, multiple inheritance might become difficult to handle because it allows ambiguity for the compiler. There are programming languages such as C++ that allow multiple inheritance; however, other programming languages such as Java and the .NET Framework languages do not allow multiple inheritance. Multiple inheritance can be emulated in .NET using Multiple Interface Inheritance, which I will explain in Part 3 of this series. Sealed class A sealed class is a class that does not allow inheritance. Some object model designs need to allow the creation of new instances but not inheritance, if this is the case, the class should be declared as sealed. To create a sealed class in C#, the class declaration should be done as: sealed class Shape To create a sealed class in VB.NET, the class declaration should be done as: NonInheritable Class Shape Abstraction Abstraction is "the process of identifying common patterns that have systematic variations; an abstraction represents the common pattern and provides a means for specifying which variation to use" (Richard Gabriel). An abstract class is a parent class that allows inheritance but can never be instantiated. Abstract classes contain one or more abstract methods that do not have implementation. Abstract classes allow specialization of inherited classes. Figure 2 shows a Shape class, which is an abstract class. In the real world, you never calculate the area or perimeter of a generic shape, you must know what kind of

geometric shape you have because each shape (eg. square, circle, rectangle, etc.) has its own area and perimeter formulas. The parent class shape forces all derived classes to define the behavior for CalculateArea() and CalculatePerimeter(). Another great example is a bank account. People own savings accounts, checking accounts, credit accounts, investment accounts, but not generic bank accounts. In this case, a bank account can be an abstract class and all the other specialized bank accounts inherit from bank account. To create an abstract class in C#, the class declaration should be done as: abstract class Shape To create an abstract class in VB.NET, the class declaration should be done as: MustInherit Class Shape To following code shows a sample implementation of an abstract class: /// C# -------------------------------------------------------------------------------using System; namespace DotNetTreats.OOSE.OOPSamples{ public abstract class Shape{ private float _area; private System.Drawing.Color _color; private float _perimeter; public float Area{ get{ return _area; } set{ _area = value; } } public System.Drawing.Color Color{ get{ return _color; } set{ _color = value; } } public float Perimeter{ get{ return _perimeter; } set{ _perimeter = value; }

} public abstract void CalculateArea(); public abstract void CalculatePerimeter(); } } Listing 1. The Shape abstract class in C#. Polymorphism Polymorphism allows objects to be represented in multiple forms. Even though classes are derived or inherited from the same parent class, each derived class will have its own behavior. Polymorphism is a concept linked to inheritance and assures that derived classes have the same functions even though each derived class performs different operations. Figure 2 shows a Rectangle, a Circle, and Square. All of them are shapes and as shapes their area and perimeter can be calculated; however, each shape calculates its area in a specialized way. Declaring a member as abstract allows polymorphism. The Shape class defines the CalculateArea() and CalculatePerimeter() methods as abstract, this allows each derived class to override the implementation of the parent's methods. To following sample code shows an implementation of a derived class (rectangle). The specific CalculateArea() and CalculatePerimeter() methods for the rectangle class illustrate polymorphism: /// C# -------------------------------------------------------------------------------using System; namespace DotNetTreats.OOSE.OOPSamples{ class Rectangle : Shape{ private float _height; private float _width; public rectangle(float height, float width){ _height = height; _width = width; } public float Height{ get{ return _height; } set{ _height = value; } } public float Width{ get{ return _width;

} set{ _width = value; } } public override void CalculateArea(){ this.Area = _height * _width; } public override void CalculatePerimeter(){ this.Perimeter = (_height * 2) + (_width * 2); } } } Listing 2. Polymorphism represented in the Rectangle's methods. Virtual keyword The virtual keyword allows polymorphism too. A virtual property or method has an implementation in the base class, and can be overriden in the derived classes. To create a virtual member in C#, use the virtual keyword: public virtual void Draw() To create a virtual member in VB.NET, use the Overridable keyword: Public Overridable Function Draw() Override keyword Overriding is the action of modifying or replacing the implementation of the parent class with a new one. Parent classes with virtual or abstract members allow derived classes to override them. To override a member in C#, use the override keyword: public override void CalculateArea() To override a member in VB.NET, use the Overrides keyword: Public Overrides Function CalculateArea() Conclusion Inheritance allows developers to manage a generalization and specialization relationship between objects. OOP concepts such as abstraction and polymorphism help to define better object models where object hierarchies are designed with reusability in mind. In this article, I examined the concept of inheritance, abstraction,

and polymorphism. The third and last part of this series will examine the concepts of interface, multiple interface inheritance, collections, and overloading. ASP.NET Interview Questions This is a list of questions I have gathered and created over a period of time from my experience, many of which I felt where incomplete or simply wrong. I have finally taken the time to go through each question and correct them to the best of my ability. However, please feel free to post feedback to challenge, improve, or suggest new questions. I want to thank those of you that have contributed quality questions and corrections thus far. There are some questions in this list that I do not consider to be good questions for an interview. However, they do exist on other lists available on the Internet so I felt compelled to keep them here for easy access.

1.

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.

2.

What’s the difference between Response.Write() andResponse.Output.Write()? Response.Output.Write() allows you to write formatted output.

3.

What methods are fired during the page load? Init() - when the page is instantiated Load() - when the page is loaded into server memory PreRender() - the brief moment before the page is displayed to the user as HTML Unload() - when page finishes loading.

4.

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

5.

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

6.

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

7.

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

8.

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

9.

Suppose you want a certain ASP.NET function executed on MouseOver for a certain button. Where do you add an event handler? Add an OnMouseOver attribute to the button. Example: btnSubmit.Attributes.Add("onmouseover","someClient CodeHere();");

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

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

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

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

14. What is the difference between Server.Transfer

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

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

15. Can you explain the difference between an

ADO.NET Dataset and an ADO Recordset? Valid answers are: · A DataSet can represent an entire relational database in memory, complete with tables, relations, and views. · A DataSet is designed to work without any continuing connection to the original data source. · Data in a DataSet is bulk-loaded, rather than being loaded on demand. · There's no concept of cursor types in a DataSet. · DataSets have no current record pointer You can use For Each loops to move through the data. · You can store many edits in a DataSet, and write them to the original data source in a single operation. · Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.

16. What is the Global.asax used for?

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

17. What are the Application_Start and

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

18. Can you explain what inheritance is and an

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

19. Whats an assembly?

Assemblies are the building blocks of the .NET framework. Overview of assemblies from MSDN

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

21. Explain what a diffgram is, and a good use for

one? The DiffGram is one of the two XML formats that you

can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.

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

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

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

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

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

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

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

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

30. Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box? DataTextField property.

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

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

Web Service Questions 1.

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

2.

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

3.

What does WSDL stand for? Web Services Description Language.

4.

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

5.

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

State Management Questions 1.

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

2.

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

3.

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

4.

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

ASP.NET Interview Questions 1. 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. 2. What’s the difference between Response.Write() andResponse.Output.Write()? The latter one allows you to write formattedoutput. 3. 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. 4. Where does the Web page belong in the .NET Framework class hierarchy?System.Web.UI.Page 5. Where do you store the information about the user’s locale? System.Web.UI.Page.Culture 6. What’s the difference between Codebehind="MyCode.aspx.cs" andSrc="MyCode.aspx.cs"? CodeBehind is relevant to Visual Studio.NET only. 7. What’s a bubbled event? When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button, row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of its constituents. 8. 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();") 9. What data type does the RangeValidator control support? Integer,String and Date. 10. Explain the differences between Server-side and Client-side code? Server-side code runs on the server. Client-side code runs in the clients’ browser. 11. What type of code (server or client) is found in a Code-Behind class? Server-side code. 12. Should validation (did the user enter a real date) occur server-side or client-side? Why? Client-side. This reduces an additional request to the server to validate the users input.

13. What does the "EnableViewState" property do? Why would I want it on or off? It enables the viewstate on the page. It allows the page to save the users input on a form.

14. What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other? Server.Transfer is used to post a form to another page. Response.Redirect is used to redirect the user to another page or site.

15. Can you explain the difference between an ADO.NET Dataset and an ADO Recordset? · A DataSet can represent an entire relational database in memory, complete with tables, relations, and views. · A DataSet is designed to work without any continuing connection to the original data source. · Data in a DataSet is bulk-loaded, rather than being loaded on demand. · There's no concept of cursor types in a DataSet. · DataSets have no current record pointer You can use For Each loops to move through the data. · You can store many edits in a DataSet, and write them to the original data source in a single operation. · Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources. 16. Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines? This is where you can set the specific variables for the Application and Session objects. 17. If I’m developing an application that must accommodate multiple security levels though secure login and my ASP.NET web application is spanned across three web-servers (using round-robin load balancing) what would be the best approach to maintain login-in state for the users? Maintain the login state security through a database. 18. Can you explain what inheritance is and an example of when you might use it? When you want to inherit (use the functionality of) another class. Base Class Employee. A Manager class could be derived from the Employee base class.

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

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

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

22. Whats MSIL, and why should my developers need an appreciation of it if at all? MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL.

23. Which method do you invoke on the DataAdapter control to load your generated dataset with data? The .Fill() method 24. Can you edit data in the Repeater control? No, it just reads the information from its data source 25. Which template must you provide, in order to display data in a Repeater control? ItemTemplate 26. How can you provide an alternating color scheme in a Repeater control? Use the AlternatingItemTemplate 27. What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control? You must set the DataSource property and call the DataBind method. 28. What base class do all Web Forms inherit from? The Page class. 29. Name two properties common in every validation control? ControlToValidate property and Text property. 30. 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 31. What tag do you use to add a hyperlink column to the DataGrid? 32. What is the transport protocol you use to call a Web service? SOAP is the preferred protocol. 33. True or False: A Web service can only be written in .NET? False 34. What does WSDL stand for? (Web Services Description Language) 35. Where on the Internet would you look for Web services? (http://www.uddi.org) 36. Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box? DataTextField property 37. Which control would you use if you needed to make sure the values in two different controls matched? CompareValidator Control 38. True or False: To test a Web service you must create a windows application or Web application to consume this service? False, the webservice comes with a test page and it provides HTTP-GET method to test. 39. How many classes can a single .NET DLL contain? It can contain many classes. 1) What is CLS (Common Language Specificaiton)? It provides the set of specificaiton which has to be adhered by any new language writer / Compiler writer for .NET Framework. This ensures Interoperability. For example: Within a ASP.NET application written in C#.NET language, we can refer to any DLL written in any other language supported by .NET Framework. As of now .NET Supports around 32 languages. 2) What is CTS (Common Type System)? It defines about how Objects should be declard, defined and used within .NET.

CLS is the subset of CTS. 3) What is Boxing and UnBoxing? Boxing is implicit conversion of ValueTypes to Reference Types (Object) . UnBoxing is explicit conversion of Reference Types (Object) to its equivalent ValueTypes. It requires type-casting. 4) What is the difference between Value Types and Reference Types? Value Types uses Stack to store the data where as the later uses the Heap to store the data. 5) What are the different types of assemblies available and their purpose? Private, Public/shared and Satellite Assemblies. Private Assemblies : Assembly used within an application is known as private assemblies Public/shared Assemblies : Assembly which can be shared across applicaiton is known as shared assemblies. Strong Name has to be created to create a shared assembly. This can be done using SN.EXE. The same has to be registered using GACUtil.exe (Global Assembly Cache). Satellite Assemblies : These assemblies contain resource files pertaining to a locale (Culture+Language). These assemblies are used in deploying an Gloabl applicaiton for different languages. 6) Is String is Value Type or Reference Type in C#? String is an object (Reference Type). 2) 1. Explain the differences between Server-side and Client-side code? Server side code basically gets executed on the server (for example on a webserver) per request/call basis, while client side code gets executed and rendered on the client side (for example web browser as a platform) per response basis. 2. What type of code (server or client) is found in a Code-Behind class? In the Code-behind class the server side code resides, and it generates the responses to the client appropriately while it gets called or requested. 3. Should validation (did the user enter a real date) occur server-side or client-side? Why? That depends. In the up browsers (like IE 5.0 and up and Netscape 6.0) this would help if it gets validated on the client side, because it reduces number of round trips between client and server. But for the down level browsers (IE 4.0 and below and Netscape 5.0 and below) it has to be on server side. Reason being the validation code requires some scripting on client side. 4. What does the "EnableViewState" property do? Why would I want it on or off? EnableViewState stores the current state of the page and the objects in it like text boxes, buttons, tables etc. So this helps not losing the state between the round trips between client and server. But this is a very expensive on browser. It delays rendering on the browser, so you should enable it only for the important fields/objects 5. What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other? Server.Transfer transfers the currnet context of the page to the next page and also avoids double roundtrips. Where as Response.Redirect could only pass

querystring and also requires roundtrip. 6. Can you give an example of when it would be appropriate to use a web service as opposed to a non-serviced .NET component Webservice is one of main component in Service Oriented Architecture. You could use webservices when your clients and servers are running on different networks and also different platforms. This provides a loosely coupled system. And also if the client is behind the firewall it would be easy to use webserivce since it runs on port 80 (by default) instead of having some thing else in SOA apps . 7. Let's say I have an existing application written using Visual Studio 6 (VB 6, InterDev 6) and this application utilizes Windows 2000 COM+ transaction services. How would you approach migrating this application to .NET You have to use System.EnterpriseServices namespace and also COMInterop the existing application 8. Can you explain the difference between an ADO.NET Dataset and an ADO Recordset? ADO.NET DataSet is a mini RDBMS based on XML, where as RecordSet is collection of rows. DataSet is independent of connection and communicates to the database through DataAdapter, so it could be attached to any well defined collections like hashtable, dictionary, tables, arraylists etc. practically. And also it can be bound to DataGrid etc. controls straightaway. RecordSet on the otherhand is tightly coupled to Database System. 9. Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines? In the Application_Start event you could store the data, which is used throughout the life time of an application for example application name, where as Session_Start could be used to store the information, which is required for that session of the application say for example user id or user name. 10. If I'm developing an application that must accomodate multiple security levels though secure login and my ASP.NET web appplication is spanned across three web-servers (using round-robbin load balancing) what would be the best approach to maintain login-in state for the users? Use the state server or store the state in the database. This can be easily done through simple setting change in the web.config. <sessionState mode="InProc" stateConnectionString="tcpip=127.0.0.1:42424" sqlConnectionString="data source=127.0.0.1;user id=sa;password=" cookieless="false" timeout="30" /> in the above one instead of mode="InProc", you specifiy stateserver or sqlserver. 11. What are ASP.NET Web Forms? How is this technology different than what is available though ASP (1.0-3.0)? ASP.NET webforms are analogous to Windows Forms which are available to most VB developers. A webform is essentially a core container in a Page. An empty webform is nothing but a HTML Form tag(control) running at server and posting form to itself by default, but you could change it to post it to something else. This is a container, and you could place the web controls, user

controls and HTML Controls in that one and interact with user on a postback basis. 12. How does VB.NET/C# achieve polymorphism? Polymorphism is achieved through virtual, overloaded, overridden methods in C# and VB.NET 11. Can you explain what inheritance is and an example of when you might use it? . 13. How would you implement inheYou missed the number sequence here). Inheritance is extending the properites, behaviour, methods to child classes from super classes. VB.NET and C# provide single inheritance, means the subclasses can be derived from only one parent unlike C++, where true multiple inheritance is possible. As an alternate to implement multiple inheritance, we could do the same to implement interfaces to the parent classes and implement the same interfaces to derive the child classesritance using VB.NET/C#? 14. Whats an assembly An assembly is the primary building block of .NET. It's a reusable, selfdescribing, versionable deployment unit for types and resources. They are self-describing so to allow the .NET runtime to fully understand the application and enforce dependency and versioning rules 15. Describe the difference between inline and code behind - which is best in a 16. loosely coupled solution 5 and 16. (You missed the sequence again). Inline style is mixing the server side code and client side code (HTML and javascript) on the same page and run it. Where as codebehind is seperating the server side in a different page (enabling developers/coders to work) and leaving the client side code to do the presentation only (so designers would work on it). Inline code would be simplest way of approach because it doesn't require any pre-compilation. But it is not good in many ways, i. You mix the presentation and server side code together so whenever there is a change it would be tough to maintain. ii. The event processing would be a night mare in inline code. iii. Since the codebehind needs to be compile in advance, it would be faster unline inline, which is interpreted per call basis. In a loosely couple situation, code-behind would be the best way to approach. Because it provides better performance 3) 1. What does the keyword static mean when applied to a class member? 1. It means the method can be called through the class without instantiating the class. 2. Declare a method called calculate that takes one integer, adds one and returns the result. Allow this method to be overridden by an inheriting class. 2. Public virtual int calculate(int value) { newValue = value + 1; return newValue; } value++; return value; 3. What is the difference between a class and a struct? 3. The class object is stored in the heap and struct object is stored in the stack. Therefore accessing and removing data from the struct is faster than for

a class. 4. What is the difference between a class and an interface? 4. You can instantiate a class but you cannot instantiate an interace you can only offer the functionality of that interface. 5. What are the .Net web authentication options and which one would generally be used for a secured/public site? 5. None Windows Authentication –Secured side IIS Authentication Forms Authentication – Public Side 6. What are some .Net options for maintaining session state? 6. In process and out of process. (wasn't sure about this one?) I believe the 6th one could be Querystring, Cookies, Session objects (variables) I wasn't sure, but I knew they could either be handled in the memory on the local machine (in process) or through the ASP.NET state service running either locally or remotely (out of process). 7. What is a Singleton? 7. This ensures that a class can only be instantiated once. 4) CTS - The common type system is a rich type system, built into the common language runtime, that supports the types and operations found in most programming languages. The common type system supports the complete implementation of a wide range of programming languages. 3. System.Diagnostics 4. System.Data.Common 5. System.Reflection 6. Protected - Available only to classes that inherit from our class. Friend - Available only to code within the project/component. Protected Friend - Available only to classes that inherit from our class (in any project) or to code within our project/component. This is a combination of Protected and Friend. 7. Abstract classes cannot be instantiated they can only be extended. You call the functionality of the abstract class without having to create an instance of it. 8. a) Interfaces don't have implementation and abstract classes can be partially implemented. From a practical point of view, interfaces can be implemented in any class and more than one interface can be implemented in a class, but abstract classes can only be implemented in the same class hierarchy (subclassing) and only one abstract class can be implemented in a class. b) Basically it's an mixture of non-virtual methods and method hiding. That is, in VB.NET overriding methods never hide while non-overriding methods always do.

c) Overloading a method means that you are providing another version of an existing method that takes different input arguments/parameters. The method will have the same name as an existing method and may or may not have a different return type. It must have a different number and/or type of input parameters. Methods are identified by their name, and number and type of arguments. This is known as the method's signature. The return value of a method is not regarded as part of the signature. Overloading can be done within the same class i.e. you can have several methods defined in one class that have the same name, but different arguments, or it can be done in a class related to another by inheritance i.e. the superclass contains one method, and a subclass provides another version of the method with the same name and different arguments. Overriding a method means that you are replacing the method with your own version. The overriding method must be defined identically to the method being replaced. Overriding can only be done in inherited classes i.e. the superclass provides a method and the subclass redefines the method with one that has exactly the same name and arguments as the superclass version. This will cause the method to behave differently when it is called by an object of the subclass, to when it is called by an object of the superclass. 9. Has application scope...variable only goes out of scope when the application ends. code: public static int Size = 0;

10. The datareader is a forward only, readonly object. It will keep a connection open as long as it is open. It is a fast way to loop through records. The dataset can be used like an in memory representation of the database. You can use DataViews to filter and sort records for presentation. You can also establish relationships with the dataRelation object. You can use the dataset with a data adapter to update the database. These objects can keep track of changes and original values. When updating the database these objects can help to resolve conflicts or concurrency issues. 5) .1 What is serialization? Serialization is the process of converting an object into a stream of bytes. Deserialization is the opposite process, i.e. 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). 6.2 Does the .NET Framework have in-built support for serialization? There are two separate mechanisms provided by the .NET class library XmlSerializer and SoapFormatter/BinaryFormatter. Microsoft uses XmlSerializer for Web Services, and SoapFormatter/BinaryFormatter for remoting. Both are available for use in your own code. 6) Can .Net Components can be used from a COM? Yes, can be used. But There are few restrictions such as COM needs an object to be created. So static methods, parameterized constructor can not be used from COM. These are used by COM using a COM Callable Wrapper (CCW). TlbImp.exe and TlbExp.exe

How does .NET Remoting work? It involves sending messages along channels. Two of the standard channels are HTTP and TCP. TCP is for LANs only and HTTP can be used on LANs or WANs (internet). TCP uses binary serialization and HTTP uses SOAP (.Net Runtime Serialization SOAP Formatter). There are 3 styles of remote access: SingleCall: Each incoming request is handled by new instance. Singleton: All requests are served by single server object. Client-Activated Object: This is old state-full DCOM model. Where client receives reference to the remote object and keep until it finished with it. 7) Object Oriented Programming: It is a Style of programming that represents a program as a system of objects and enables code-reuse. Encapsulation: Binding of attributes and behaviors. Hiding the implementation and exposing the functionality. Abstraction: Hiding the complexity. Defining communication interface for the functionality and hiding rest of the things. In .Net destructor can not be abstract. Can define Either Finalize / Destructor. For Destructor access specifiers can not be assigned. It is Private. Overloading: Adding a new method with the same name in same/derived class but with different number/types of parameters. Implements Polymorphism. Overriding: When we need to provide different implementation than the provide by base class, We define the same method with same signatures in the derived class. Method must be Protected/Protected-Friend/Public for this purpose. (Base class routine can be called by Mybase.Method, base.Method). Shadowing: When the method is defined as Final/sealed in base class and not overridable and we need to provide different implementation for the same. We define method with Shadows/new. Inheritance: Gives you ability to provide is-a relationship. Acquires attributes and behaviors from another. When a class acquires attributes and behaviors from another class. (must not be Final or sealed class in .Net) Abstract Class: Instance can not be created. Optionally can have one or more abstract methods but not necessary. Can provide body to Classes. Interface: What a Class must do, But not how-to. Bridge for the communication when the caller does not know to whom he is calling. Describes externally visible behavior of element. Only Public members which defines the means of the communication with the outer world. Can-be-Used-As Relationship. Can not contain data but can declare property. There can be no implementation. Interface can be derived from another interface.

Polymorphism: Mean by more than one form. Ability to provide different implementation based on different no./type of parameters. A method behaves differently based on the different input parameters. Does not depend on the Return-Type. Pure-Polymorphism: Make an method abstract/virtual in base class. Override it in Derived Class. Declare a variable of type base class and assign an object of derived class to it. Now call the virtual/abstract method. The actual method to be called is decided at runtime. Early-Binding: Calling an non-virtual method decides the method to call at compile time is known as Early-Binding. Late-Binding: Same as pure-polymorphism. Identifiers/Access Specifies and scope: VB.NET: Private, Protected, Friend, Protected Friend, Public. C#: private, protected, internal, protected internal, public. What is a Delegate? A strongly typed function pointer. A delegate object encapsulates a reference to a method. When actual function needs to be called will be decided at runtime. Static Variable and Its Life-Time: VB.NET: Public Shared VAR As Type. C#: public static Type VAR; Life time is till the class is in memory. Constructor: Special Method Always called whenever an instance of the class is created. Destructor/Finalize: Called by GC just before object is being reclaimed by GC. ASP.Net Different Types of Caching? Output Caching: stores the responses from an asp.net page. Fragment Caching: Only caches/stores the portion of page (User Control) Data Caching: is Programmatic way to Cache objects for performance. Authentication and Authorization: Authentication is identifying/validating the user against the credentials (username and password) and Authorization performs after authentication. Authorization allowing access of specific resource to user. Different Types of Directives: Page, Register, Control, OutputCache, Import, Implements, Assembly, Reference Difference between Server-Side and Client-Side: Server-Side code is executed on web-server and does not transmitted to client, while client-side code executed on client(browser) and is rendered to client along with the content. Difference Server.Transfer and Response.Redirect:

Both ends the processing for the current request immediately. Server.Transfer start executing the another resource specified as parameter without acknowledgement to client(browser) while Response.Redirect intimate client that your requested resource is available at this location and then client request for that resource. Different Types of Validators and Validation Controls: RequiredFieldValidator, RangeValidator, RegularExpressionValidator, CompareValidator, CustomValidator, ValidationSummary How to Manage State in ASP.Net? Client based: ViewState, QueryString and Cookies Server based: Session, Application. Difference between User Control and Custom Control: CUSTOM Controls are compiled code (Dlls), easier to use, difficult to create, and can be placed in toolbox. Drag and Drop controls. Attributes can be set visually at design time. Can be used by Multiple Applications (If Shared Dlls), Even if Private can copy to bin directory of webApp add reference and use. Normally designed to provide common functionality independent of consuming Application. 3 Types of Session State Modes? InProc(cookieless, timeout), StateServer (Server, Port stateConnectionString="tcpip=server:port"), SQLServer (sqlconnectionstring) and Off. What is ViewState and How it is managed, Its Advantages/Benefits? ViewState is a special object that ASP.NET uses to maintain the state of page and all webcontrols/ServerControls within it. It is in this object preserves the states of various FORM elements during post-backs. It is rendered to client(browser) as a Hidden variable __VIEWSTATE under

tag. We can also add custom values to it. What is web.config and machine.config: machine.config is default configuration for all applications running under this version, located in %WinDir%\Microsfot.Net\Framework\Version. Settings can be overridden by Web.Config for an specific application Web.Config resides in application’s root/virtual root and exists in sub-sequent folders. Role of Global.asax: Optional file contains the code to handle Application level events raised by ASP.Net or By HttpModule. This file resides in application root directory. Application_Start, _End, _AuthenticateRequest, _Error, Session_Start, _End, BeginRequest, EndRequest. This file is parsed and compiled into dynamically generated class derived from HttpApplication. Page Life Cycle: Init, LoadViewState, LoadPostBackData, Load, RaisePostBackDataChangedEvent, RaisePostBackEvents, Pre-Render, SaveViewState, Render, Unload, (IpostBackDataChangedEventHandler and IpostBackEventHandler) Error, CommitTransaction, AbortTransaction, Abort inetinfo.exe, aspnet_isapi.dll aspnet_wp.exe, HttpModules (OutputCache, Session, Authentication, Authorization, Custom Modules Specified) and Then HttpHandlers PageHandlerFactory for *.aspx Can the action attribute of a server-side tag be set to a value and if not how can you possibly pass data from a form to a subsequent Page? No assigning value will not work because will be overwritten at the time of

rendering. We can assign value to it by register a startup script which will set the action value of form on client-side. Rest are Server.Transfer and Response.Redirect. ASP.Net List Controls and differentiate between them? RadioButtonList, CheckBoxList, DropDownList, Repeater, DataGrid, DataList Type Of Code in Code-Behind class: Server-Side Code. What might be best suited to place in the Application_Start and Session_Start: Application level variables and settings initialization in App_Start User specific variables and settings in Session_Start Difference between inline and code-behind. Which is best? Inline is mixed with html and code-behind is separated. Use code-behind, Because Inline pages are loaded, parsed, compiled and processed at each first request to page and remains in compiled code remains in cache until it expires, If expires it again load, parse and compile While code-behind allows to be pre-compiled and provide better performance. Which Template must provide to display data in Repeater? ItemTemplate. 8) How to Provide Alternating Color Scheme in Repeater? AlternatingItemTemplate What base class all Web Forms inherit from? System.Web.UI.Page What method do you use to explicitly kill a user’s Session? HttpContext.Current.Session.Abandon() How do you turn off cookies in one page of your asp.net application? We will not use it. But can not turn off cookies from server. To allow or not is a client side functionality. Which two properties are on every validation control? ControlToValidate and Text, ErrorMessage How do you create a permanent cookie? Set expires property to Date.MaxValue (HttpCookie.Expires = Date.MaxValue) What is the standard you use to wrap up a call to a Web Service? SOAP Which method do you use to redirect to user to another page without performing a round trip to Client? Server.Transfer(“AnotherPage.aspx”) What is transport protocol you use to call a Web-Service SOAP? HTTP-POST A Web Service can only be written in .NET? FALSE Where on internet would you look for Web services? www.uddi.org

How many classes can a single .NET DLL contain? Unlimited How many namespaces are in .NET version 1.1? 124 What is a bubbled event? When you have a complex control like DataGrid. Writing an event processing routine for each object (cell, button, row etc.). DataGrid handles the events of its constituents and will raise its own defined custom events. Difference between ASP Session State and ASP.Net Session State? ASP: relies on cookies, Serialize all requests from a client, Does not survive process shutdown, Can not maintained across machines in a Web farm/garden. Layouts of ASP.NET Pages: GridLayout and FlowLayout Web User Control: Combines existing Server and HTML controls by using VS.Net. to create functional units that encapsulate some aspects of UI. Resides in Content Files, which must be included in project in which the controls are used. Composite Custom Control: combination of existing HTML and Server Controls. Rendered custom control: create entirely new control by rendering HTML directly rather than using composition. Where do you store the information about user’s Locale? Page.Culture should Validation occur on Client/Server Side for Date Input? Both. Client-side reduces extra round-trip. Server-Side ensures prevention against hacking and failure against automated requests. HTTP GET and HTTP POST: 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. For the POST method, the name/value pairs are passed in the body of the HTTP request message.