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(FAQ) VB.Net FAQ With Answers (Part # 2 of 2)

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Hello

The second part of .Net questions is as follows. Enu

118. What is Inheritance, Multiple Inheritance, Shared and Repeatable Inheritance?

**

119. What is Method overloading?

Method overloading occurs when a class contains two methods with the same name, but different signatures.

120. What is Method Overriding? How to override a function in C#?

Use the override modifier to modify a method, a property, an indexer, or an event. An override method provides a new implementation of a member inherited from a base class. The method overridden by an override declaration is known as the overridden base method. The overridden base method must have the same signature as the override method.

You cannot override a non-virtual or static method. The overridden base method must be virtual, abstract, or override.

121. Can we call a base class method without creating instance?

Its possible If its a static method.

Its possible by inheriting from that class also.

Its possible from derived classes using base keyword.

122. You have one base class virtual function how will call that function from derived class?

Ans:

123. class a

124. {

125. public virtual int m()

126. {

127. return 1;

128. }

129. }

130. class b:a

131. {

132. public int j()

133. {

134. return m();

135. }

}

136. In which cases you use override and new base?

Use the new modifier to explicitly hide a member inherited from a base class. To hide an inherited member, declare it in the derived class using the same name, and modify it with the new modifier.

C# Language features

137. What are Sealed Classes in C#?

The sealed modifier is used to prevent derivation from a class. A compile-time error occurs if a sealed class is specified as the base class of another class. (A sealed class cannot also be an abstract class)

138. What is Polymorphism? How does VB.NET/C# achieve polymorphism?

**

139. class Token

140. {

141. public string Display()

142. {

143. //Implementation goes here

144. return "base";

145. }

146. }

147. class IdentifierToken:Token

148. {

149. public new string Display() //What is the use of new keyword

150. {

151. //Implementation goes here

152. return "derive";

153. }

154. }

155. static void Method(Token t)

156. {

157. Console.Write(t.Display());

158. }

159. public static void Main()

160. {

161. IdentifierToken Variable=new IdentifierToken();

162. Method(Variable); //Which Class Method is called here

163. Console.ReadLine();

164. }

165. For the above code What is the "new" keyword and Which Class Method is

166. called here

A: it will call base class Display method

167. class Token

168. {

169. public virtual string Display()

170. {

171. //Implementation goes here

172. return "base";

173. }

174. }

175. class IdentifierToken:Token

176. {

177. public override string Display() //What is the use of new keyword

178. {

179. //Implementation goes here

180. return "derive";

181. }

182. }

183. static void Method(Token t)

184. {

185. Console.Write(t.Display());

186. }

187. public static void Main()

188. {

189. IdentifierToken Variable=new IdentifierToken();

190. Method(Variable); //Which Class Method is called here

191. Console.ReadLine();

192. }

193. A: Derive

194. In which Scenario you will go for Interface or Abstract Class?

Interfaces, like classes, define a set of properties, methods, and events. But unlike classes, interfaces do not provide implementation. They are implemented by classes, and defined as separate entities from classes. Even though class inheritance allows your classes to inherit implementation from a base class, it also forces you to make most of your design decisions when the class is first published.

Abstract classes are useful when creating components because they allow you specify an invariant level of functionality in some methods, but leave the implementation of other methods until a specific implementation of that class is needed. They also version well, because if additional functionality is needed in derived classes, it can be added to the base class without breaking code.

Interfaces vs. Abstract Classes

Feature Interface Abstract class

Multiple inheritance A class may implement several interfaces. A class may extend only one abstract class.

Default implementation An interface cannot provide any code at all, much less default code. An abstract class can provide complete code, default code, and/or just stubs that have to be overridden.

Constants Static final constants only, can use them without qualification in classes that implement the interface. On the other paw, these unqualified names pollute the namespace. You can use them and it is not obvious where they are coming from since the qualification is optional. Both instance and static constants are possible. Both static and instance intialiser code are also possible to compute the constants.

Third party convenience An interface implementation may be added to any existing third party class. A third party class must be rewritten to extend only from the abstract class.

is-a vs -able or can-do Interfaces are often used to describe the peripheral abilities of a class, not its central identity, e.g. an Automobile class might implement the Recyclable interface, which could apply to many otherwise totally unrelated objects. An abstract class defines the core identity of its descendants. If you defined a Dog abstract class then Damamation descendants are Dogs, they are not merely dogable. Implemented interfaces enumerate the general things a class can do, not the things a class is.

Plug-in You can write a new replacement module for an interface that contains not one stick of code in common with the existing implementations. When you implement the interface, you start from scratch without any default implementation. You have to obtain your tools from other classes; nothing comes with the interface other than a few constants. This gives you freedom to implement a radically different internal design. You must use the abstract class as-is for the code base, with all its attendant baggage, good or bad. The abstract class author has imposed structure on you. Depending on the cleverness of the author of the abstract class, this may be good or bad. Another issue that's important is what I call "heterogeneous vs. homogeneous." If implementors/subclasses are homogeneous, tend towards an abstract base class. If they are heterogeneous, use an interface. (Now all I have to do is come up with a good definition of hetero/homogeneous in this context.) If the various objects are all of-a-kind, and share a common state and behavior, then tend towards a common base class. If all they share is a set of method signatures, then tend towards an interface.

Homogeneity If all the various implementations share is the method signatures, then an interface works best. If the various implementations are all of a kind and share a common status and behavior, usually an abstract class works best.

Maintenance If your client code talks only in terms of an interface, you can easily change the concrete implementation behind it, using a factory method. Just like an interface, if your client code talks only in terms of an abstract class, you can easily change the concrete implementation behind it, using a factory method.

Speed Slow, requires extra indirection to find the corresponding method in the actual class. Modern JVMs are discovering ways to reduce this speed penalty. Fast

Terseness The constant declarations in an interface are all presumed public static final, so you may leave that part out. You can't call any methods to compute the initial values of your constants. You need not declare individual methods of an interface abstract. They are all presumed so. You can put shared code into an abstract class, where you cannot into an interface. If interfaces want to share code, you will have to write other bubblegum to arrange that. You may use methods to compute the initial values of your constants and variables, both instance and static. You must declare all the individual methods of an abstract class abstract.

Adding functionality If you add a new method to an interface, you must track down all implementations of that interface in the universe and provide them with a concrete implementation of that method. If you add a new method to an abstract class, you have the option of providing a default implementation of it. Then all existing code will continue to work without change.

195. see the code

196. interface ICommon

197. {

198. int getCommon();

199. }

200. interface ICommonImplements1:ICommon

201. {

202. }

203. interface ICommonImplements2:ICommon

204. {

205. }

206. public class a:ICommonImplements1,ICommonImplements2

207. {

}

How to implement getCommon method in class a? Are you seeing any problem in the implementation?

Ans:

public class a:ICommonImplements1,ICommonImplements2

{

public int getCommon()

{

return 1;

}

}

208. interface IWeather

209. {

210. void display();

211. }

212. public class A:IWeather

213. {

214. public void display()

215. {

216. MessageBox.Show("A");

217. }

218. }

219. public class B:A

220. {

221. }

222. public class C:B,IWeather

223. {

224. public void display()

225. {

226. MessageBox.Show("C");

227. }

228. }

229. When I instantiate C.display(), will it work?

230. interface IPrint

231. {

232. string Display();

233. }

234. interface IWrite

235. {

236. string Display();

237. }

238. class PrintDoc:IPrint,IWrite

239. {

240. //Here is implementation

241. }

how to implement the Display in the class printDoc (How to resolve the naming Conflict) A: no naming conflicts

class PrintDoc:IPrint,IWrite

{

public string Display()

{

return "s";

}

}

242. interface IList

243. {

244. int Count { get; set; }

245. }

246. interface ICounter

247. {

248. void Count(int i);

249. }

250. interface IListCounter: IList, ICounter {}

251. class C

252. {

253. void Test(IListCounter x)

254. {

255. x.Count(1); // Error

256. x.Count = 1; // Error

257. ((IList)x).Count = 1; // Ok, invokes IList.Count.set

258. ((ICounter)x).Count(1); // Ok, invokes ICounter.Count

259. }

260. }

261. Write one code example for compile time binding and one for run time binding? What is early/late binding?

An object is early bound when it is assigned to a variable declared to be of a specific object type. Early bound objects allow the compiler to allocate memory and perform other optimizations before an application executes.

' Create a variable to hold a new object.

Dim FS As FileStream

' Assign a new object to the variable.

FS = New FileStream("C:\tmp.txt", FileMode.Open)

By contrast, an object is late bound when it is assigned to a variable declared to be of type Object. Objects of this type can hold references to any object, but lack many of the advantages of early-bound objects.

Dim xlApp As Object

xlApp = CreateObject("Excel.Application")

262. Can you explain what inheritance is and an example of when you might use it?

263. How can you write a class to restrict that only one object of this class can be created (Singleton class)?

(Access specifiers)

264. What are the access-specifiers available in c#?

Private, Protected, Public, Internal, Protected Internal.

265. Explain about Protected and protected internal, “internal†access-specifier?

protected - Access is limited to the containing class or types derived from the containing class.

internal - Access is limited to the current assembly.

protected internal - Access is limited to the current assembly or types derived from the containing class.

(Constructor / Destructor)

266. Difference between type constructor and instance constructor? What is static constructor, when it will be fired? And what is its use?

(Class constructor method is also known as type constructor or type initializer)

Instance constructor is executed when a new instance of type is created and the class constructor is executed after the type is loaded and before any one of the type members is accessed. (It will get executed only 1st time, when we call any static methods/fields in the same class.) Class constructors are used for static field initialization. Only one class constructor per type is permitted, and it cannot use the vararg (variable argument) calling convention.

A static constructor is used to initialize a class. It is called automatically to initialize the class before the first instance is created or any static members are referenced.

267. What is Private Constructor? and it’s use? Can you create instance of a class which has Private Constructor?

A: When a class declares only private instance constructors, it is not possible for classes outside the program to derive from the class or to directly create instances of it. (Except Nested classes)

Make a constructor private if:

- You want it to be available only to the class itself. For example, you might have a special constructor used only in the implementation of your class' Clone method.

- You do not want instances of your component to be created. For example, you may have a class containing nothing but Shared utility functions, and no instance data. Creating instances of the class would waste memory.

268. I have 3 overloaded constructors in my class. In order to avoid making instance of the class do I need to make all constructors to private?

(yes)

269. Overloaded constructor will call default constructor internally?

(no)

270. What are virtual destructors?

271. Destructor and finalize

Generally in C++ the destructor is called when objects gets destroyed. And one can explicitly call the destructors in C++. And also the objects are destroyed in reverse order that they are created in. So in C++ you have control over the destructors.

In C# you can never call them, the reason is one cannot destroy an object. So who has the control over the destructor (in C#)? it's the .Net frameworks Garbage Collector (GC). GC destroys the objects only when necessary. Some situations of necessity are memory is exhausted or user explicitly calls System.GC.Collect() method.

Points to remember:

1. Destructors are invoked automatically, and cannot be invoked explicitly.

2. Destructors cannot be overloaded. Thus, a class can have, at most, one destructor.

3. Destructors are not inherited. Thus, a class has no destructors other than the one, which may be declared in it.

4. Destructors cannot be used with structs. They are only used with classes.

5. An instance becomes eligible for destruction when it is no longer possible for any code to use the instance.

6. Execution of the destructor for the instance may occur at any time after the instance becomes eligible for destruction.

7. When an instance is destructed, the destructors in its inheritance chain are called, in order, from most derived to least derived.

http://msdn.microsoft.com/library/default....destructors.asp

272. What is the difference between Finalize and Dispose (Garbage collection)

Class instances often encapsulate control over resources that are not managed by the runtime, such as window handles (HWND), database connections, and so on. Therefore, you should provide both an explicit and an implicit way to free those resources. Provide implicit control by implementing the protected Finalize Method on an object (destructor syntax in C# and the Managed Extensions for C++). The garbage collector calls this method at some point after there are no longer any valid references to the object.

In some cases, you might want to provide programmers using an object with the ability to explicitly release these external resources before the garbage collector frees the object. If an external resource is scarce or expensive, better performance can be achieved if the programmer explicitly releases resources when they are no longer being used. To provide explicit control, implement the Dispose method provided by the IDisposable Interface. The consumer of the object should call this method when it is done using the object. Dispose can be called even if other references to the object are alive.

Note that even when you provide explicit control by way of Dispose, you should provide implicit cleanup using the Finalize method. Finalize provides a backup to prevent resources from permanently leaking if the programmer fails to call Dispose.

273. What is close method? How its different from Finalize & Dispose?

**

274. What is boxing & unboxing?

275. What is check/uncheck?

276. What is the use of base keyword? Tell me a practical example for base keyword’s usage?

277. What are the different .net tools which u used in projects?

278. try

{

...

}

catch

{

...//exception occurred here. What'll happen?

}

finally

{

..

}

Ans : It will throw exception.

279. What will do to avoid prior case?

Ans:

280. try

281. {

282. try

283. {

284. ...

285. }

286. catch

287. {

288. ...

289. //exception occurred here.

290. }

291. finally

292. {

293. ...

294. }

295. }

296. catch

297. {

298. ...

299. }

300. finally

301. {

302. ...

}

303. try

304. {

305. ...

306. }

307. catch

308. {

309. ...

310. }

311. finally

312. {

313. ..

314. }

315. Will it go to finally block if there is no exception happened?

Ans: Yes. The finally block is useful for cleaning up any resources allocated in the try block. Control is always passed to the finally block regardless of how the try block exits.

316. Is goto statement supported in C#? How about Java?

Gotos are supported in C#to the fullest. In Java goto is a reserved keyword that provides absolutely no functionality.

317. What’s different about switch statements in C#?

No fall-throughs allowed. Unlike the C++ switch statement, C# does not support an explicit fall through from one case label to another. If you want, you can use goto a switch-case, or goto default.

case 1:

cost += 25;

break;

case 2:

cost += 25;

goto case 1;

(ADO.NET)

318. Advantage of ADO.Net?

• ADO.NET Does Not Depend On Continuously Live Connections

• Database Interactions Are Performed Using Data Commands

• Data Can Be Cached in Datasets

• Datasets Are Independent of Data Sources

• Data Is Persisted as XML

• Schemas Define Data Structures

319. How would u connect to database using .NET?

SqlConnection nwindConn = new SqlConnection("Data Source=localhost; Integrated Security=SSPI;" +

"Initial Catalog=northwind");

nwindConn.Open();

320. What are relation objects in dataset and how & where to use them?

In a DataSet that contains multiple DataTable objects, you can use DataRelation objects to relate one table to another, to navigate through the tables, and to return child or parent rows from a related table. Adding a DataRelation to a DataSet adds, by default, a UniqueConstraint to the parent table and a ForeignKeyConstraint to the child table.

The following code example creates a DataRelation using two DataTable objects in a DataSet. Each DataTable contains a column named CustID, which serves as a link between the two DataTable objects. The example adds a single DataRelation to the Relations collection of the DataSet. The first argument in the example specifies the name of the DataRelation being created. The second argument sets the parent DataColumn and the third argument sets the child DataColumn.

custDS.Relations.Add("CustOrders",

custDS.Tables["Customers&quot].Columns["CustID&quot],

custDS.Tables["Orders&quot].Columns["CustID&quot]);

OR

private void CreateRelation()

{

// Get the DataColumn objects from two DataTable objects in a DataSet.

DataColumn parentCol;

DataColumn childCol;

// Code to get the DataSet not shown here.

parentCol = DataSet1.Tables["Customers&quot].Columns["CustID&quot];

childCol = DataSet1.Tables["Orders&quot].Columns["CustID&quot];

// Create DataRelation.

DataRelation relCustOrder;

relCustOrder = new DataRelation("CustomersOrders", parentCol, childCol);

// Add the relation to the DataSet.

DataSet1.Relations.Add(relCustOrder);

}

321. Difference between OLEDB Provider and SqlClient ?

Ans: SQLClient .NET classes are highly optimized for the .net / sqlserver combination and achieve optimal results. The SqlClient data provider is fast. It's faster than the Oracle provider, and faster than accessing database via the OleDb layer. It's faster because it accesses the native library (which automatically gives you better performance), and it was written with lots of help from the SQL Server team.

322. What are the different namespaces used in the project to connect the database? What data providers available in .net to connect to database?

• System.Data.OleDb – classes that make up the .NET Framework Data Provider for OLE DB-compatible data sources. These classes allow you to connect to an OLE DB data source, execute commands against the source, and read the results.

• System.Data.SqlClient – classes that make up the .NET Framework Data Provider for SQL Server, which allows you to connect to SQL Server 7.0, execute commands, and read results. The System.Data.SqlClient namespace is similar to the System.Data.OleDb namespace, but is optimized for access to SQL Server 7.0 and later.

• System.Data.Odbc - classes that make up the .NET Framework Data Provider for ODBC. These classes allow you to access ODBC data source in the managed space.

• System.Data.OracleClient - classes that make up the .NET Framework Data Provider for Oracle. These classes allow you to access an Oracle data source in the managed space.

323. Difference between DataReader and DataAdapter / DataSet and DataAdapter?

You can use the ADO.NET DataReader to retrieve a read-only, forward-only stream of data from a database. Using the DataReader can increase application performance and reduce system overhead because only one row at a time is ever in memory.

After creating an instance of the Command object, you create a DataReader by calling Command.ExecuteReader to retrieve rows from a data source, as shown in the following example.

SqlDataReader myReader = myCommand.ExecuteReader();

You use the Read method of the DataReader object to obtain a row from the results of the query.

while (myReader.Read())

Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));

myReader.Close();

The DataSet is a memory-resident representation of data that provides a consistent relational programming model regardless of the data source. It can be used with multiple and differing data sources, used with XML data, or used to manage data local to the application. The DataSet represents a complete set of data including related tables, constraints, and relationships among the tables. The methods and objects in a DataSet are consistent with those in the relational database model. The DataSet can also persist and reload its contents as XML and its schema as XML Schema definition language (XSD) schema.

The DataAdapter serves as a bridge between a DataSet and a data source for retrieving and saving data. The DataAdapter provides this bridge by mapping Fill, which changes the data in the DataSet to match the data in the data source, and Update, which changes the data in the data source to match the data in the DataSet. If you are connecting to a Microsoft SQL Server database, you can increase overall performance by using the SqlDataAdapter along with its associated SqlCommand and SqlConnection. For other OLE DB-supported databases, use the DataAdapter with its associated OleDbCommand and OleDbConnection objects.

324. Which method do you invoke on the DataAdapter control to load your generated dataset with data?

Fill()

325. Explain different methods and Properties of DataReader which you have used in your project?

Read

GetString

GetInt32

while (myReader.Read())

Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));

myReader.Close();

326. What happens when we issue Dataset.ReadXml command?

Reads XML schema and data into the DataSet.

327. In how many ways we can retrieve table records count? How to find the count of records in a dataset?

foreach(DataTable thisTable in myDataSet.Tables){

// For each row, print the values of each column.

foreach(DataRow myRow in thisTable.Rows){

328. How to check if a datareader is closed or opened?

IsClosed()

329. What happens when u try to update data in a dataset in .NET while the record is already deleted in SQL SERVER as backend?

OR What is concurrency? How will you avoid concurrency when dealing with dataset? (One user deleted one row after that another user through his dataset was trying to update same row. What will happen? How will you avoid the problem?)

**

330. How do you merge 2 datasets into the third dataset in a simple manner? OR If you are executing these statements in commandObject. "Select * from Table1;Select * from Table2†how you will deal result set?

**

331. How do you sort a dataset?

**

332. If a dataset contains 100 rows, how to fetch rows between 5 and 15 only?

**

333. Differences between dataset.clone and dataset.copy?

Clone - Copies the structure of the DataSet, including all DataTable schemas, relations, and constraints. Does not copy any data.

Copy - Copies both the structure and data for this DataSet.

334. What is the use of parameter object?

**

335. How to generate XML from a dataset and vice versa?

**

336. What is method to get XML and schema from Dataset?

ans: getXML () and get Schema ()

337. How do u implement locking concept for dataset?

**

(ASP.NET)

338. Asp.net and asp – differences?

Code Render Block Code Declaration Block

Compiled

Request/Response Event Driven

Object Oriented - Constructors/Destructors, Inheritance, overloading..

Exception Handling - Try, Catch, Finally

Down-level Support

Cultures

User Controls

In-built client side validation

Session - weren't transferable across servers It can span across servers, It can survive server crashes, can work with browsers that don't support cookies

built on top of the window & IIS, it was always a separate entity & its functionality was limited. its an integral part of OS under the .net framework. It shares many of the same objects that traditional applications would use, and all .net objects are available for asp.net's consumption.

Garbage Collection

Declare variable with datatype

In built graphics support

Cultures

339. How ASP and ASP.NET page works? Explain about asp.net page life cycle?

**

340. Order of events in an asp.net page? Control Execution Lifecycle?

Phase What a control needs to do Method or event to override

Initialize Initialize settings needed during the lifetime of the incoming Web request. Init event (OnInit method)

Load view state At the end of this phase, the ViewState property of a control is automatically populated as described in Maintaining State in a Control. A control can override the default implementation of the LoadViewState method to customize state restoration. LoadViewState method

Process postback data Process incoming form data and update properties accordingly. LoadPostData method (if IPostBackDataHandler is implemented)

Load Perform actions common to all requests, such as setting up a database query. At this point, server controls in the tree are created and initialized, the state is restored, and form controls reflect client-side data. Load event

(OnLoad method)

Send postback change notifications Raise change events in response to state changes between the current and previous postbacks. RaisePostDataChangedEvent method (if IPostBackDataHandler is implemented)

Handle postback events Handle the client-side event that caused the postback and raise appropriate events on the server. RaisePostBackEvent method(if IPostBackEventHandler is implemented)

Prerender Perform any updates before the output is rendered. Any changes made to the state of the control in the prerender phase can be saved, while changes made in the rendering phase are lost. PreRender event

(OnPreRender method)

Save state The ViewState property of a control is automatically persisted to a string object after this stage. This string object is sent to the client and back as a hidden variable. For improving efficiency, a control can override the SaveViewState method to modify the ViewState property. SaveViewState method

Render Generate output to be rendered to the client. Render method

Dispose Perform any final cleanup before the control is torn down. References to expensive resources such as database connections must be released in this phase. Dispose method

Unload Perform any final cleanup before the control is torn down. Control authors generally perform cleanup in Dispose and do not handle this event. UnLoad event (On UnLoad method)

341. Note To override an EventName event, override the OnEventName method (and call base. OnEventName).

(Session/State)

342. Application and Session Events

The ASP.NET page framework provides ways for you to work with events that can be raised when your application starts or stops or when an individual user's session starts or stops:

• Application events are raised for all requests to an application. For example, Application_BeginRequest is raised when any Web Forms page or XML Web service in your application is requested. This event allows you to initialize resources that will be used for each request to the application. A corresponding event, Application_EndRequest, provides you with an opportunity to close or otherwise dispose of resources used for the request.

• Session events are similar to application events (there is a Session_OnStart and a Session_OnEnd event), but are raised with each unique session within the application. A session begins when a user requests a page for the first time from your application and ends either when your application explicitly closes the session or when the session times out.

You can create handlers for these types of events in the Global.asax file.

343. Difference between ASP Session and ASP.NET Session?

asp.net session supports cookie less session & it can span across multiple servers.

344. What is cookie less session? How it works?

By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. If cookies are not available, a session can be tracked by adding a session identifier to the URL. This can be enabled by setting the following:

<sessionState cookieless="true" />

345. How you will handle session when deploying application in more than a server? Describe session handling in a webfarm, how does it work and what are the limits?

By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. Additionally, ASP.NET can store session data in an external process, which can even reside on another machine. To enable this feature:

• Start the ASP.NET state service, either using the Services snap-in or by executing "net start aspnet_state" on the command line. The state service will by default listen on port 42424. To change the port, modify the registry key for the service: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\Port

• Set the mode attribute of the <sessionState> section to "StateServer".

• Configure the stateConnectionString attribute with the values of the machine on which you started aspnet_state.

The following sample assumes that the state service is running on the same machine as the Web server ("localhost") and uses the default port (42424):

<sessionState

mode="StateServer"

stateConnectionString="tcpip=localhost:42424"

/>

Note that if you try the sample above with this setting, you can reset the Web server (enter iisreset on the command line) and the session state value will persist. **

346. What method do you use to explicitly kill a users session?

Abandon()

347. What are the different ways you would consider sending data across pages in ASP (i.e between 1.asp to 2.asp)?

Session

public properties

348. What is State Management in .Net and how many ways are there to maintain a state in .Net? What is view state?

Web pages are recreated each time the page is posted to the server. In traditional Web programming, this would ordinarily mean that all information associated with the page and the controls on the page would be lost with each round trip.

To overcome this inherent limitation of traditional Web programming, the ASP.NET page framework includes various options to help you preserve changes — that is, for managing state. The page framework includes a facility called view state that automatically preserves property values of the page and all the controls on it between round trips.

However, you will probably also have application-specific values that you want to preserve. To do so, you can use one of the state management options.

Client-Based State Management Options:

View State

Hidden Form Fields

Cookies

Query Strings

Server-Based State Management Options

Application State

Session State

Database Support

349. What are the disadvantages of view state / what are the benefits?

Automatic view-state management is a feature of server controls that enables them to repopulate their property values on a round trip (without you having to write any code). This feature does impact performance, however, since a server control's view state is passed to and from the server in a hidden form field. You should be aware of when view state helps you and when it hinders your page's performance.

350. When maintaining session through Sql server, what is the impact of Read and Write operation on Session objects? will performance degrade?

Maintaining state using database technology is a common practice when storing user-specific information where the information store is large. Database storage is particularly useful for maintaining long-term state or state that must be preserved even if the server must be restarted.

**

351. What are the contents of cookie?

**

352. How do you create a permanent cookie?

**

353. What is ViewState? What does the "EnableViewState" property do? Why would I want it on or off?

**

354. Explain the differences between Server-side and Client-side code?

Server side code will process at server side & it will send the result to client. Client side code (javascript) will execute only at client side.

355. Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines?

**

356. Which ASP.NET configuration options are supported in the ASP.NET implementation on the shared web hosting platform?

A: Many of the ASP.NET configuration options are not configurable at the site, application or subdirectory level on the shared hosting platform. Certain options can affect the security, performance and stability of the server and, therefore cannot be changed. The following settings are the only ones that can be changed in your site’s web.config file (s):

browserCaps

clientTarget

pages

customErrors

globalization

authorization

authentication

webControls

webServices

http://msdn.microsoft.com/library/default....nfiguration.asp

357. Briefly describe the role of global.asax?

358. How can u debug your .net application?

359. How do u deploy your asp.net application?

360. Where do we store our connection string in asp.net application?

361. Various steps taken to optimize a web based application (caching, stored procedure etc.)

362. How does ASP.NET framework maps client side events to Server side events.

(Security)

363. Security types in ASP/ASP.NET? Different Authentication modes?

364. How .Net has implemented security for web applications?

365. How to do Forms authentication in asp.net?

366. Explain authentication levels in .net ?

367. Explain autherization levels in .net ?

368. What is Role-Based security?

A role is a named set of principals that have the same privileges with respect to security (such as a teller or a manager). A principal can be a member of one or more roles. Therefore, applications can use role membership to determine whether a principal is authorized to perform a requested action.

**

369. How will you do windows authentication and what is the namespace? If a user is logged under integrated windows authentication mode, but he is still not able to logon, what might be the possible cause for this? In ASP.Net application how do you find the name of the logged in person under windows authentication?

370. What are the different authentication modes in the .NET environment?

371. <authentication mode="Windows|Forms|Passport|None">

372. <forms name="name"

373. loginUrl="url"

374. protection="All|None|Encryption|Validation"

375. timeout="30" path="/" >

376. requireSSL="true|false"

377. slidingExpiration="true|false">

378. <credentials passwordFormat="Clear|SHA1|MD5">

379. <user name="username" password="password"/>

380. </credentials>

381. </forms>

382. <passport redirectUrl="internal"/>

</authentication>

Attribute Option Description

mode Controls the default authentication mode for an application.

Windows Specifies Windows authentication as the default authentication mode. Use this mode when using any form of Microsoft Internet Information Services (IIS) authentication: Basic, Digest, Integrated Windows authentication (NTLM/Kerberos), or certificates.

Forms Specifies ASP.NET forms-based authentication as the default authentication mode.

Passport Specifies Microsoft Passport authentication as the default authentication mode.

None Specifies no authentication. Only anonymous users are expected or applications can handle events to provide their own authentication.

383. How do you specify whether your data should be passed as Query string and Forms (Mainly about POST and GET)

Through attribute tag of form tag.

384. What is the other method, other than GET and POST, in ASP.NET?

385. What are validator? Name the Validation controls in asp.net? How do u disable them? Will the asp.net validators run in server side or client side? How do you do Client-side validation in .Net? How to disable validator control by client side JavaScript?

A set of server controls included with ASP.NET that test user input in HTML and Web server controls for programmer-defined requirements. Validation controls perform input checking in server code. If the user is working with a browser that supports DHTML, the validation controls can also perform validation ("EnableClientScript" property set to true/false) using client script.

The following validation controls are available in asp.net:

RequiredFieldValidator Control, CompareValidator Control, RangeValidator Control, RegularExpressionValidator Control, CustomValidator Control, ValidationSummary Control.

386. Which two properties are there on every validation control?

ControlToValidate, ErrorMessage

387. How do you use css in asp.net?

Within the <HEAD> section of an HTML document that will use these styles, add a link to this external CSS style sheet that

follows this form:

<LINK REL="STYLESHEET" TYPE="text/css" HREF="MyStyles.css">

MyStyles.css is the name of your external CSS style sheet.

388. How do you implement postback with a text box? What is postback and usestate?

Make AutoPostBack property to true

389. How can you debug an ASP page, without touching the code?

390. What is SQL injection?

An SQL injection attack "injects" or manipulates SQL code by adding unexpected SQL to a query.

Many web pages take parameters from web user, and make SQL query to the database. Take for instance when a user login, web page that user name and password and make SQL query to the database to check if a user has valid name and password.

Username: ' or 1=1 ---

Password: [Empty]

This would execute the following query against the users table:

select count(*) from users where userName='' or 1=1 --' and userPass=''

391. How can u handle Exceptions in Asp.Net?

392. How can u handle Un Managed Code Exceptions in ASP.Net?

393. Asp.net - How to find last error which occurred?

A: Server.GetLastError();

[C#]

Exception LastError;

String ErrMessage;

LastError = Server.GetLastError();

if (LastError != null)

ErrMessage = LastError.Message;

else

ErrMessage = "No Errors";

Response.Write("Last Error = " + ErrMessage);

394. How to do Caching in ASP?

A: <%@ OutputCache Duration="60" VaryByParam="None" %>

VaryByParam value Description

none One version of page cached (only raw GET)

* n versions of page cached based on query string and/or POST body

v1 n versions of page cached based on value of v1 variable in query string or POST body

v1;v2 n versions of page cached based on value of v1 and v2 variables in query string or POST body

395. <%@ OutputCache Duration="60" VaryByParam="none" %>

<%@ OutputCache Duration="60" VaryByParam="*" %>

<%@ OutputCache Duration="60" VaryByParam="name;age" %>

The OutputCache directive supports several other cache varying options

• VaryByHeader - maintain separate cache entry for header string changes (UserAgent, UserLanguage, etc.)

• VaryByControl - for user controls, maintain separate cache entry for properties of a user control

• VaryByCustom - can specify separate cache entries for browser types and version or provide a custom GetVaryByCustomString method in HttpApplicationderived class

396. What is the Global ASA(X) File?

397. Any alternative to avoid name collisions other then Namespaces.

A scenario that two namespaces named N1 and N2 are there both having the same class say A. now in another class i ve written

using N1;using N2;

and i am instantiating class A in this class. Then how will u avoid name collisions?

Ans: using alias

Eg: using MyAlias = MyCompany.Proj.Nested;

398. Which is the namespace used to write error message in event Log File?

399. What are the page level transaction and class level transaction?

400. What are different transaction options?

401. What is the namespace for encryption?

402. What is the difference between application and cache variables?

403. What is the difference between control and component?

404. You ve defined one page_load event in aspx page and same page_load event in code behind how will prog run?

405. Where would you use an IHttpModule, and what are the limitations of any approach you might take in implementing one?

406. Can you edit data in the Repeater control? Which template must you provide, in order to display data in a Repeater control? How can you provide an alternating color scheme in a Repeater control? What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control?

407. What is the use of web.config? Difference between machine.config and Web.config?

ASP.NET configuration files are XML-based text files--each named web.config--that can appear in any directory on an ASP.NET

Web application server. Each web.config file applies configuration settings to the directory it is located in and to all

virtual child directories beneath it. Settings in child directories can optionally override or modify settings specified in

parent directories. The root configuration file--WinNT\Microsoft.NET\Framework\<version>\config\machine.config--provides

default configuration settings for the entire machine. ASP.NET configures IIS to prevent direct browser access to web.config

files to ensure that their values cannot become public (attempts to access them will cause ASP.NET to return 403: Access

Forbidden).

At run time ASP.NET uses these web.config configuration files to hierarchically compute a unique collection of settings for

each incoming URL target request (these settings are calculated only once and then cached across subsequent requests; ASP.NET

automatically watches for file changes and will invalidate the cache if any of the configuration files change).

408. What is the use of sessionstate tag in the web.config file?

Configuring session state: Session state features can be configured via the <sessionState> section in a web.config file. To double the default timeout of 20 minutes, you can add the following to the web.config file of an application:

<sessionState

timeout="40"

/>

409. What are the different modes for the sessionstates in the web.config file?

Off Indicates that session state is not enabled.

Inproc Indicates that session state is stored locally.

StateServer Indicates that session state is stored on a remote server.

SQLServer Indicates that session state is stored on the SQL Server.

410. What is smart navigation?

When a page is requested by an Internet Explorer 5 browser, or later, smart navigation enhances the user's experience of the page by performing the following:

• eliminating the flash caused by navigation.

• persisting the scroll position when moving from page to page.

• persisting element focus between navigations.

• retaining only the last page state in the browser's history.

Smart navigation is best used with ASP.NET pages that require frequent postbacks but with visual content that does not change dramatically on return. Consider this carefully when deciding whether to set this property to true.

Set the SmartNavigation attribute to true in the @ Page directive in the .aspx file. When the page is requested, the dynamically generated class sets this property.

411. In what order do the events of an ASPX page execute. As a developer is it important to undertsand these events?

412. How would you get ASP.NET running in Apache web servers - why would you even do this?

413. What tags do you need to add within the asp:datagrid tags to bind columns manually

414. What base class do all Web Forms inherit from?

System.Web.UI.Page

415. How can we create pie chart in asp.net?

416. Is it possible for me to change my aspx file extension to some other name?

Yes.

Open IIS->Default Website -> Properties

Select HomeDirectory tab

Click on configuration button

Click on add. Enter aspnet_isapi details (C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\aspnet_isapi.dll | GET,HEAD,POST,DEBUG)

Open machine.config(C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\CONFIG) & add new extension under <httpHandlers> tag

<add verb="*" path="*.santhosh" type="System.Web.UI.PageHandlerFactory"/>

417. What is AutoEventWireup attribute for ?

(WEBSERVICE & REMOTING)

418. What is a WebService and what is the underlying protocol used in it? Namespace?

Web Services are applications delivered as a service on the Web. Web services allow for programmatic access of business logic over the Web. Web services typically rely on XML-based protocols, messages, and interface descriptions for communication and access. Web services are designed to be used by other programs or applications rather than directly by end user. Programs invoking a Web service are called clients. SOAP over HTTP is the most commonly used protocol for invoking Web services.

419. Why Web Services?

By exposing data and functionality using standard protocols, Web services make it easy to build sophisticated applications that integrate many features and content. There are three main uses of Web services. Application integration Web services within an intranet are commonly used to integrate business applications running on disparate platforms. For example, a .NET client running on Windows 2000 can easily invoke a Java Web service running on a mainframe or Unix machine to retrieve data from a legacy application. Business integration Web services allow trading partners to engage in e-business leveraging the existing Internet infrastructure. Organizations can send electronic purchase orders to suppliers and receive electronic invoices. Doing e-business with Web services means a low barrier to entry because Web services can be added to existing applications running on any platform without changing legacy code. Commercial Web services focus on selling content and business services to clients over the Internet similar to familiar Web pages. Unlike Web pages, commercial Web services target applications not humans as their direct users. Continental Airlines exposes flight schedules and status Web services for travel Web sites and agencies to use in their applications. Like Web pages, commercial Web services are valuable only if they expose a valuable service or content. It would be very difficult to get customers to pay you for using a Web service that creates business charts with the customers? data. Customers would rather buy a charting component (e.g. COM or .NET component) and install it on the same machine as their application. On the other hand, it makes sense to sell real-time weather information or stock quotes as a Web service. Technology can help you add value to your services and explore new markets, but ultimately customers pay for contents and/or business services, not for technology

420. In a Webservice, need to display 10 rows from a table. So DataReader or DataSet is best choice?

A: WebService will support only DataSet.

421. Are Web Services a replacement for other distributed computing platforms?

No. Web Services is just a new way of looking at existing implementation platforms.

422. What is SOAP, WSDL, UDDI and the concept behind Web Services? What are various components of WSDL? What is the use of WSDL.exe utility?

SOAP is an XML-based messaging framework specifically designed for exchanging formatted data across the Internet, for example using request and reply messages or sending entire documents. SOAP is simple, easy to use, and completely neutral with respect to operating system, programming language, or distributed computing platform.

After SOAP became available as a mechanism for exchanging XML messages among enterprises (or among disparate applications within the same enterprise), a better way was needed to describe the messages and how they are exchanged. The Web Services Description Language (WSDL) is a particular form of an XML Schema, developed by Microsoft and IBM for the purpose of defining the XML message, operation, and protocol mapping of a web service accessed using SOAP or other XML protocol. WSDL defines web services in terms of "endpoints" that operate on XML messages. The WSDL syntax allows both the messages and the operations on the messages to be defined abstractly, so they can be mapped to multiple physical implementations. The current WSDL spec describes how to map messages and operations to SOAP 1.1, HTTP GET/POST, and MIME. WSDL creates web service definitions by mapping a group of endpoints into a logical sequence of operations on XML messages. The same XML message can be mapped to multiple operations (or services) and bound to one or more communications protocols (using "ports").

The Universal Description, Discovery, and Integration (UDDI) framework defines a data model (in XML) and SOAP APIs for registration and searches on business information, including the web services a business exposes to the Internet. UDDI is an independent consortium of vendors, founded by Microsoft, IBM, and Ariba, for the purpose of developing an Internet standard for web service description registration and discovery. Microsoft, IBM, and Ariba also are hosting the initial deployment of a UDDI service, which is conceptually patterned after DNS (the Internet service that translates URLs into TCP addresses). UDDI uses a private agreement profile of SOAP (i.e. UDDI doesn't use the SOAP serialization format because it's not well suited to passing complete XML documents (it's aimed at RPC style interactions). The main idea is that businesses use the SOAP APIs to register themselves with UDDI, and other businesses search UDDI when they want to discover a trading partner, for example someone from whom they wish to procure sheet metal, bolts, or transistors. The information in UDDI is categorized according to industry type and geographical location, allowing UDDI consumers to search through lists of potentially matching businesses to find the specific one they want to contact. Once a specific business is chosen, another call to UDDI is made to obtain the specific contact information for that business. The contact information includes a pointer to the target business's WSDL or other XML schema file describing the web service that the target business publishes.

423. How to generate proxy class other than .net app and wsdl tool?

To access an XML Web service from a client application, you first add a Web reference, which is a reference to an XML Web service. When you create a Web reference, Visual Studio creates an XML Web service proxy class automatically and adds it to your project. This proxy class exposes the methods of the XML Web service and handles the marshalling of appropriate arguments back and forth between the XML Web service and your application. Visual Studio uses the Web Services Description Language (WSDL) to create the proxy.

To generate an XML Web service proxy class:

• From a command prompt, use Wsdl.exe to create a proxy class, specifying (at a minimum) the URL to an XML Web service or a service description, or the path to a saved service description.

Wsdl /language:language /protocol:protocol /namespace:myNameSpace /out:filename

/username:username /password:password /domain:domain <url or path>

424. asynchronous web service means?

425. What are the events fired when web service called?

426. How does SOAP transport happen and what is the role of HTTP in it? How you can access a webservice using soap?

427. How will do transaction in Web Services?

428. What are the different formatters can be used in both? Why?.. binary/soap

429. What is a proxy in web service? How do I use a proxy server when invoking a Web service?

If you are using the SOAP Toolkit, you need to set some connector properties to use a proxy server: Dim soap As SoapClient Set soap=New SoapClient soap.ConnectorProperty("ProxyServer") = ?proxyservername? soap.ConnectorProperty("ProxyPort") = ?8080? soap.ConnectorProperty("UseProxy") = True While with .NET , you just need to create a System.Net.WebProxy object and use it to set the Proxy property Dim webs As localhost.MyService() webs.Proxy=New System.Net.WebProxy(?http://proxyserver:8080?)

430. How you will protect / secure a web service?

For the most part, things that you do to secure a Web site can be used to secure a Web Service. If you need to encrypt the data exchange, you use Secure Sockets Layer (SSL) or a Virtual Private Network to keep the bits secure. For authentication, use HTTP Basic or Digest authentication with Microsoft® Windows® integration to figure out who the caller is.

these items cannot:

• Parse a SOAP request for valid values

• Authenticate access at the Web Method level (they can authenticate at the Web Service level)

• Stop reading a request as soon as it is recognized as invalid

431. How will you expose/publish a webservice?

432. What’s the attribute for webservice method? What is the namespace for creating webservice?

433. What is disco file?

434. What is Remoting?

The process of communication between different operating system processes, regardless of whether they are on the same computer. The .NET remoting system is an architecture designed to simplify communication between objects living in different application domains, whether on the same computer or not, and between different contexts, whether in the same application domain or not.

435. Difference between web services & remoting?

ASP.NET Web Services .NET Remoting

Protocol Can be accessed only over HTTP Can be accessed over any protocol (including TCP, HTTP, SMTP and so on)

State Management Web services work in a stateless environment Provide support for both stateful and stateless environments through Singleton and SingleCall objects

Type System Web services support only the datatypes defined in the XSD type system, limiting the number of objects that can be serialized. Using binary communication, .NET Remoting can provide support for rich type system

Interoperability Web services support interoperability across platforms, and are ideal for heterogeneous environments. .NET remoting requires the client be built using .NET, enforcing homogenous environment.

Reliability Highly reliable due to the fact that Web services are always hosted in IIS Can also take advantage of IIS for fault isolation. If IIS is not used, application needs to provide plumbing for ensuring the reliability of the application.

Extensibility Provides extensibility by allowing us to intercept the SOAP messages during the serialization and deserialization stages. Very extensible by allowing us to customize the different components of the .NET remoting framework.

Ease-of-Programming Easy-to-create and deploy. Complex to program.

436. Though both the .NET Remoting infrastructure and ASP.NET Web services can enable cross-process communication, each is designed to benefit a different target audience. ASP.NET Web services provide a simple programming model and a wide reach. .NET Remoting provides a more complex programming model and has a much narrower reach.

As explained before, the clear performance advantage provided by TCPChannel-remoting should make you think about using this channel whenever you can afford to do so. If you can create direct TCP connections from your clients to your server and if you need to support only the .NET platform, you should go for this channel. If you are going to go cross-platform or you have the requirement of supporting SOAP via HTTP, you should definitely go for ASP.NET Web services.

Both the .NET remoting and ASP.NET Web services are powerful technologies that provide a suitable framework for developing distributed applications. It is important to understand how both technologies work and then choose the one that is right for your application. For applications that require interoperability and must function over public networks, Web services are probably the best bet. For those that require communications with other .NET components and where performance is a key priority, .NET Remoting is the

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Thanx it is very use full

HelloThe second part of .Net questions is as follows. Enu118. What is Inheritance, Multiple Inheritance, Shared and Repeatable Inheritance?** 119. What is Method overloading?Method overloading occurs when a class contains two methods with the same name, but different signatures. 120. What is Method Overriding? How to override a function in C#?Use the override modifier to modify a method, a property, an indexer, or an event. An override method provides a new implementation of a member inherited from a base class. The method overridden by an override declaration is known as the overridden base method. The overridden base method must have the same signature as the override method.You cannot override a non-virtual or static method. The overridden base method must be virtual, abstract, or override. 121. Can we call a base class method without creating instance?Its possible If its a static method.Its possible by inheriting from that class also.Its possible from derived classes using base keyword. 122. You have one base class virtual function how will call that function from derived class?Ans:123. class a124. {125. public virtual int m()126. {127. return 1;128. }129. }130. class b:a131. {132. public int j()133. {134. return m();135. } }136. In which cases you use override and new base?Use the new modifier to explicitly hide a member inherited from a base class. To hide an inherited member, declare it in the derived class using the same name, and modify it with the new modifier. C# Language features 137. What are Sealed Classes in C#?The sealed modifier is used to prevent derivation from a class. A compile-time error occurs if a sealed class is specified as the base class of another class. (A sealed class cannot also be an abstract class) 138. What is Polymorphism? How does VB.NET/C# achieve polymorphism?** 139. class Token140. {141. public string Display()142. {143. //Implementation goes here144. return "base";145. }146. }147. class IdentifierToken:Token148. {149. public new string Display() //What is the use of new keyword150. {151. //Implementation goes here152. return "derive";153. }154. }155. static void Method(Token t)156. {157. Console.Write(t.Display());158. }159. public static void Main()160. {161. IdentifierToken Variable=new IdentifierToken();162. Method(Variable); //Which Class Method is called here163. Console.ReadLine();164. }165. For the above code What is the "new" keyword and Which Class Method is166. called hereA: it will call base class Display method 167. class Token168. {169. public virtual string Display()170. {171. //Implementation goes here172. return "base";173. }174. }175. class IdentifierToken:Token176. {177. public override string Display() //What is the use of new keyword178. {179. //Implementation goes here180. return "derive";181. }182. }183. static void Method(Token t)184. {185. Console.Write(t.Display());186. }187. public static void Main()188. {189. IdentifierToken Variable=new IdentifierToken();190. Method(Variable); //Which Class Method is called here191. Console.ReadLine();192. }193. A: Derive 194. In which Scenario you will go for Interface or Abstract Class?Interfaces, like classes, define a set of properties, methods, and events. But unlike classes, interfaces do not provide implementation. They are implemented by classes, and defined as separate entities from classes. Even though class inheritance allows your classes to inherit implementation from a base class, it also forces you to make most of your design decisions when the class is first published.Abstract classes are useful when creating components because they allow you specify an invariant level of functionality in some methods, but leave the implementation of other methods until a specific implementation of that class is needed. They also version well, because if additional functionality is needed in derived classes, it can be added to the base class without breaking code. Interfaces vs. Abstract ClassesFeature Interface Abstract classMultiple inheritance A class may implement several interfaces. A class may extend only one abstract class. Default implementation An interface cannot provide any code at all, much less default code. An abstract class can provide complete code, default code, and/or just stubs that have to be overridden.Constants Static final constants only, can use them without qualification in classes that implement the interface. On the other paw, these unqualified names pollute the namespace. You can use them and it is not obvious where they are coming from since the qualification is optional. Both instance and static constants are possible. Both static and instance intialiser code are also possible to compute the constants.Third party convenience An interface implementation may be added to any existing third party class. A third party class must be rewritten to extend only from the abstract class.is-a vs -able or can-do Interfaces are often used to describe the peripheral abilities of a class, not its central identity, e.g. an Automobile class might implement the Recyclable interface, which could apply to many otherwise totally unrelated objects. An abstract class defines the core identity of its descendants. If you defined a Dog abstract class then Damamation descendants are Dogs, they are not merely dogable. Implemented interfaces enumerate the general things a class can do, not the things a class is. Plug-in You can write a new replacement module for an interface that contains not one stick of code in common with the existing implementations. When you implement the interface, you start from scratch without any default implementation. You have to obtain your tools from other classes; nothing comes with the interface other than a few constants. This gives you freedom to implement a radically different internal design. You must use the abstract class as-is for the code base, with all its attendant baggage, good or bad. The abstract class author has imposed structure on you. Depending on the cleverness of the author of the abstract class, this may be good or bad. Another issue that's important is what I call "heterogeneous vs. homogeneous." If implementors/subclasses are homogeneous, tend towards an abstract base class. If they are heterogeneous, use an interface. (Now all I have to do is come up with a good definition of hetero/homogeneous in this context.) If the various objects are all of-a-kind, and share a common state and behavior, then tend towards a common base class. If all they share is a set of method signatures, then tend towards an interface.Homogeneity If all the various implementations share is the method signatures, then an interface works best. If the various implementations are all of a kind and share a common status and behavior, usually an abstract class works best.Maintenance If your client code talks only in terms of an interface, you can easily change the concrete implementation behind it, using a factory method. Just like an interface, if your client code talks only in terms of an abstract class, you can easily change the concrete implementation behind it, using a factory method.Speed Slow, requires extra indirection to find the corresponding method in the actual class. Modern JVMs are discovering ways to reduce this speed penalty. FastTerseness The constant declarations in an interface are all presumed public static final, so you may leave that part out. You can't call any methods to compute the initial values of your constants. You need not declare individual methods of an interface abstract. They are all presumed so. You can put shared code into an abstract class, where you cannot into an interface. If interfaces want to share code, you will have to write other bubblegum to arrange that. You may use methods to compute the initial values of your constants and variables, both instance and static. You must declare all the individual methods of an abstract class abstract.Adding functionality If you add a new method to an interface, you must track down all implementations of that interface in the universe and provide them with a concrete implementation of that method. If you add a new method to an abstract class, you have the option of providing a default implementation of it. Then all existing code will continue to work without change.195. see the code196. interface ICommon197. {198. int getCommon();199. }200. interface ICommonImplements1:ICommon201. {202. }203. interface ICommonImplements2:ICommon204. {205. }206. public class a:ICommonImplements1,ICommonImplements2207. { }How to implement getCommon method in class a? Are you seeing any problem in the implementation?Ans: public class a:ICommonImplements1,ICommonImplements2 { public int getCommon() { return 1; } }208. interface IWeather209. {210. void display();211. }212. public class A:IWeather213. {214. public void display()215. {216. MessageBox.Show("A");217. }218. }219. public class B:A220. {221. }222. public class C:B,IWeather223. {224. public void display()225. {226. MessageBox.Show("C");227. }228. }229. When I instantiate C.display(), will it work? 230. interface IPrint231. {232. string Display();233. }234. interface IWrite235. {236. string Display();237. }238. class PrintDoc:IPrint,IWrite239. {240. //Here is implementation241. }how to implement the Display in the class printDoc (How to resolve the naming Conflict) A: no naming conflictsclass PrintDoc:IPrint,IWrite { public string Display() { return "s"; } }242. interface IList243. {244. int Count { get; set; }245. }246. interface ICounter247. {248. void Count(int i);249. }250. interface IListCounter: IList, ICounter {}251. class C252. {253. void Test(IListCounter x)254. {255. x.Count(1); // Error256. x.Count = 1; // Error257. ((IList)x).Count = 1; // Ok, invokes IList.Count.set258. ((ICounter)x).Count(1); // Ok, invokes ICounter.Count259. }260. }261. Write one code example for compile time binding and one for run time binding? What is early/late binding?An object is early bound when it is assigned to a variable declared to be of a specific object type. Early bound objects allow the compiler to allocate memory and perform other optimizations before an application executes.' Create a variable to hold a new object.Dim FS As FileStream' Assign a new object to the variable.FS = New FileStream("C:\tmp.txt", FileMode.Open)By contrast, an object is late bound when it is assigned to a variable declared to be of type Object. Objects of this type can hold references to any object, but lack many of the advantages of early-bound objects.Dim xlApp As ObjectxlApp = CreateObject("Excel.Application") 262. Can you explain what inheritance is and an example of when you might use it? 263. How can you write a class to restrict that only one object of this class can be created (Singleton class)? (Access specifiers) 264. What are the access-specifiers available in c#?Private, Protected, Public, Internal, Protected Internal. 265. Explain about Protected and protected internal, “internal†access-specifier?protected - Access is limited to the containing class or types derived from the containing class. internal - Access is limited to the current assembly.protected internal - Access is limited to the current assembly or types derived from the containing class.(Constructor / Destructor) 266. Difference between type constructor and instance constructor? What is static constructor, when it will be fired? And what is its use?(Class constructor method is also known as type constructor or type initializer)Instance constructor is executed when a new instance of type is created and the class constructor is executed after the type is loaded and before any one of the type members is accessed. (It will get executed only 1st time, when we call any static methods/fields in the same class.) Class constructors are used for static field initialization. Only one class constructor per type is permitted, and it cannot use the vararg (variable argument) calling convention.A static constructor is used to initialize a class. It is called automatically to initialize the class before the first instance is created or any static members are referenced. 267. What is Private Constructor? and it’s use? Can you create instance of a class which has Private Constructor?A: When a class declares only private instance constructors, it is not possible for classes outside the program to derive from the class or to directly create instances of it. (Except Nested classes)Make a constructor private if:- You want it to be available only to the class itself. For example, you might have a special constructor used only in the implementation of your class' Clone method.- You do not want instances of your component to be created. For example, you may have a class containing nothing but Shared utility functions, and no instance data. Creating instances of the class would waste memory. 268. I have 3 overloaded constructors in my class. In order to avoid making instance of the class do I need to make all constructors to private?(yes) 269. Overloaded constructor will call default constructor internally?(no) 270. What are virtual destructors? 271. Destructor and finalizeGenerally in C++ the destructor is called when objects gets destroyed. And one can explicitly call the destructors in C++. And also the objects are destroyed in reverse order that they are created in. So in C++ you have control over the destructors.In C# you can never call them, the reason is one cannot destroy an object. So who has the control over the destructor (in C#)? it's the .Net frameworks Garbage Collector (GC). GC destroys the objects only when necessary. Some situations of necessity are memory is exhausted or user explicitly calls System.GC.Collect() method.Points to remember:1. Destructors are invoked automatically, and cannot be invoked explicitly.2. Destructors cannot be overloaded. Thus, a class can have, at most, one destructor.3. Destructors are not inherited. Thus, a class has no destructors other than the one, which may be declared in it.4. Destructors cannot be used with structs. They are only used with classes.5. An instance becomes eligible for destruction when it is no longer possible for any code to use the instance. 6. Execution of the destructor for the instance may occur at any time after the instance becomes eligible for destruction.7. When an instance is destructed, the destructors in its inheritance chain are called, in order, from most derived to least derived.http://msdn.microsoft.com/library/default....destructors.asp 272. What is the difference between Finalize and Dispose (Garbage collection)Class instances often encapsulate control over resources that are not managed by the runtime, such as window handles (HWND), database connections, and so on. Therefore, you should provide both an explicit and an implicit way to free those resources. Provide implicit control by implementing the protected Finalize Method on an object (destructor syntax in C# and the Managed Extensions for C++). The garbage collector calls this method at some point after there are no longer any valid references to the object.In some cases, you might want to provide programmers using an object with the ability to explicitly release these external resources before the garbage collector frees the object. If an external resource is scarce or expensive, better performance can be achieved if the programmer explicitly releases resources when they are no longer being used. To provide explicit control, implement the Dispose method provided by the IDisposable Interface. The consumer of the object should call this method when it is done using the object. Dispose can be called even if other references to the object are alive.Note that even when you provide explicit control by way of Dispose, you should provide implicit cleanup using the Finalize method. Finalize provides a backup to prevent resources from permanently leaking if the programmer fails to call Dispose. 273. What is close method? How its different from Finalize & Dispose?** 274. What is boxing & unboxing? 275. What is check/uncheck? 276. What is the use of base keyword? Tell me a practical example for base keyword’s usage? 277. What are the different .net tools which u used in projects? 278. try{...}catch{...//exception occurred here. What'll happen?}finally{..}Ans : It will throw exception. 279. What will do to avoid prior case?Ans:280. try281. {282. try283. {284. ...285. }286. catch287. {288. ...289. //exception occurred here.290. }291. finally292. {293. ...294. }295. }296. catch297. {298. ...299. }300. finally301. {302. ...}303. try304. {305. ...306. }307. catch308. {309. ...310. }311. finally312. {313. ..314. }315. Will it go to finally block if there is no exception happened?Ans: Yes. The finally block is useful for cleaning up any resources allocated in the try block. Control is always passed to the finally block regardless of how the try block exits. 316. Is goto statement supported in C#? How about Java?Gotos are supported in C#to the fullest. In Java goto is a reserved keyword that provides absolutely no functionality. 317. What’s different about switch statements in C#? No fall-throughs allowed. Unlike the C++ switch statement, C# does not support an explicit fall through from one case label to another. If you want, you can use goto a switch-case, or goto default.case 1:cost += 25;break;case 2:cost += 25;goto case 1;(ADO.NET) 318. Advantage of ADO.Net? • ADO.NET Does Not Depend On Continuously Live Connections • Database Interactions Are Performed Using Data Commands • Data Can Be Cached in Datasets • Datasets Are Independent of Data Sources • Data Is Persisted as XML • Schemas Define Data Structures 319. How would u connect to database using .NET?SqlConnection nwindConn = new SqlConnection("Data Source=localhost; Integrated Security=SSPI;" + "Initial Catalog=northwind");nwindConn.Open(); 320. What are relation objects in dataset and how & where to use them?In a DataSet that contains multiple DataTable objects, you can use DataRelation objects to relate one table to another, to navigate through the tables, and to return child or parent rows from a related table. Adding a DataRelation to a DataSet adds, by default, a UniqueConstraint to the parent table and a ForeignKeyConstraint to the child table.The following code example creates a DataRelation using two DataTable objects in a DataSet. Each DataTable contains a column named CustID, which serves as a link between the two DataTable objects. The example adds a single DataRelation to the Relations collection of the DataSet. The first argument in the example specifies the name of the DataRelation being created. The second argument sets the parent DataColumn and the third argument sets the child DataColumn.custDS.Relations.Add("CustOrders",custDS.Tables["Customers&quot].Columns["CustID&quot],custDS.Tables["Orders&quot].Columns["CustID&quot]);ORprivate void CreateRelation(){// Get the DataColumn objects from two DataTable objects in a DataSet.DataColumn parentCol;DataColumn childCol;// Code to get the DataSet not shown here.parentCol = DataSet1.Tables["Customers&quot].Columns["CustID&quot];childCol = DataSet1.Tables["Orders&quot].Columns["CustID&quot];// Create DataRelation.DataRelation relCustOrder;relCustOrder = new DataRelation("CustomersOrders", parentCol, childCol);// Add the relation to the DataSet.DataSet1.Relations.Add(relCustOrder);} 321. Difference between OLEDB Provider and SqlClient ?Ans: SQLClient .NET classes are highly optimized for the .net / sqlserver combination and achieve optimal results. The SqlClient data provider is fast. It's faster than the Oracle provider, and faster than accessing database via the OleDb layer. It's faster because it accesses the native library (which automatically gives you better performance), and it was written with lots of help from the SQL Server team. 322. What are the different namespaces used in the project to connect the database? What data providers available in .net to connect to database? • System.Data.OleDb – classes that make up the .NET Framework Data Provider for OLE DB-compatible data sources. These classes allow you to connect to an OLE DB data source, execute commands against the source, and read the results. • System.Data.SqlClient – classes that make up the .NET Framework Data Provider for SQL Server, which allows you to connect to SQL Server 7.0, execute commands, and read results. The System.Data.SqlClient namespace is similar to the System.Data.OleDb namespace, but is optimized for access to SQL Server 7.0 and later. • System.Data.Odbc - classes that make up the .NET Framework Data Provider for ODBC. These classes allow you to access ODBC data source in the managed space. • System.Data.OracleClient - classes that make up the .NET Framework Data Provider for Oracle. These classes allow you to access an Oracle data source in the managed space. 323. Difference between DataReader and DataAdapter / DataSet and DataAdapter?You can use the ADO.NET DataReader to retrieve a read-only, forward-only stream of data from a database. Using the DataReader can increase application performance and reduce system overhead because only one row at a time is ever in memory.After creating an instance of the Command object, you create a DataReader by calling Command.ExecuteReader to retrieve rows from a data source, as shown in the following example.SqlDataReader myReader = myCommand.ExecuteReader();You use the Read method of the DataReader object to obtain a row from the results of the query.while (myReader.Read()) Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));myReader.Close();The DataSet is a memory-resident representation of data that provides a consistent relational programming model regardless of the data source. It can be used with multiple and differing data sources, used with XML data, or used to manage data local to the application. The DataSet represents a complete set of data including related tables, constraints, and relationships among the tables. The methods and objects in a DataSet are consistent with those in the relational database model. The DataSet can also persist and reload its contents as XML and its schema as XML Schema definition language (XSD) schema.The DataAdapter serves as a bridge between a DataSet and a data source for retrieving and saving data. The DataAdapter provides this bridge by mapping Fill, which changes the data in the DataSet to match the data in the data source, and Update, which changes the data in the data source to match the data in the DataSet. If you are connecting to a Microsoft SQL Server database, you can increase overall performance by using the SqlDataAdapter along with its associated SqlCommand and SqlConnection. For other OLE DB-supported databases, use the DataAdapter with its associated OleDbCommand and OleDbConnection objects. 324. Which method do you invoke on the DataAdapter control to load your generated dataset with data?Fill() 325. Explain different methods and Properties of DataReader which you have used in your project?ReadGetStringGetInt32while (myReader.Read()) Console.WriteLine("\t{0}\t{1}", myReader.GetInt32(0), myReader.GetString(1));myReader.Close(); 326. What happens when we issue Dataset.ReadXml command?Reads XML schema and data into the DataSet. 327. In how many ways we can retrieve table records count? How to find the count of records in a dataset?foreach(DataTable thisTable in myDataSet.Tables){// For each row, print the values of each column.foreach(DataRow myRow in thisTable.Rows){ 328. How to check if a datareader is closed or opened?IsClosed() 329. What happens when u try to update data in a dataset in .NET while the record is already deleted in SQL SERVER as backend?OR What is concurrency? How will you avoid concurrency when dealing with dataset? (One user deleted one row after that another user through his dataset was trying to update same row. What will happen? How will you avoid the problem?)** 330. How do you merge 2 datasets into the third dataset in a simple manner? OR If you are executing these statements in commandObject. "Select * from Table1;Select * from Table2†how you will deal result set?** 331. How do you sort a dataset?** 332. If a dataset contains 100 rows, how to fetch rows between 5 and 15 only?** 333. Differences between dataset.clone and dataset.copy?Clone - Copies the structure of the DataSet, including all DataTable schemas, relations, and constraints. Does not copy any data. Copy - Copies both the structure and data for this DataSet. 334. What is the use of parameter object?** 335. How to generate XML from a dataset and vice versa?** 336. What is method to get XML and schema from Dataset?ans: getXML () and get Schema () 337. How do u implement locking concept for dataset?**(ASP.NET) 338. Asp.net and asp – differences? Code Render Block Code Declaration Block CompiledRequest/Response Event Driven Object Oriented - Constructors/Destructors, Inheritance, overloading.. Exception Handling - Try, Catch, Finally Down-level Support Cultures User Controls In-built client side validationSession - weren't transferable across servers It can span across servers, It can survive server crashes, can work with browsers that don't support cookiesbuilt on top of the window & IIS, it was always a separate entity & its functionality was limited. its an integral part of OS under the .net framework. It shares many of the same objects that traditional applications would use, and all .net objects are available for asp.net's consumption. Garbage Collection Declare variable with datatype In built graphics support Cultures 339. How ASP and ASP.NET page works? Explain about asp.net page life cycle?** 340. Order of events in an asp.net page? Control Execution Lifecycle? Phase What a control needs to do Method or event to overrideInitialize Initialize settings needed during the lifetime of the incoming Web request. Init event (OnInit method)Load view state At the end of this phase, the ViewState property of a control is automatically populated as described in Maintaining State in a Control. A control can override the default implementation of the LoadViewState method to customize state restoration. LoadViewState methodProcess postback data Process incoming form data and update properties accordingly. LoadPostData method (if IPostBackDataHandler is implemented)Load Perform actions common to all requests, such as setting up a database query. At this point, server controls in the tree are created and initialized, the state is restored, and form controls reflect client-side data. Load event (OnLoad method)Send postback change notifications Raise change events in response to state changes between the current and previous postbacks. RaisePostDataChangedEvent method (if IPostBackDataHandler is implemented)Handle postback events Handle the client-side event that caused the postback and raise appropriate events on the server. RaisePostBackEvent method(if IPostBackEventHandler is implemented)Prerender Perform any updates before the output is rendered. Any changes made to the state of the control in the prerender phase can be saved, while changes made in the rendering phase are lost. PreRender event (OnPreRender method)Save state The ViewState property of a control is automatically persisted to a string object after this stage. This string object is sent to the client and back as a hidden variable. For improving efficiency, a control can override the SaveViewState method to modify the ViewState property. SaveViewState methodRender Generate output to be rendered to the client. Render methodDispose Perform any final cleanup before the control is torn down. References to expensive resources such as database connections must be released in this phase. Dispose methodUnload Perform any final cleanup before the control is torn down. Control authors generally perform cleanup in Dispose and do not handle this event. UnLoad event (On UnLoad method)341. Note To override an EventName event, override the OnEventName method (and call base. OnEventName).(Session/State) 342. Application and Session EventsThe ASP.NET page framework provides ways for you to work with events that can be raised when your application starts or stops or when an individual user's session starts or stops: • Application events are raised for all requests to an application. For example, Application_BeginRequest is raised when any Web Forms page or XML Web service in your application is requested. This event allows you to initialize resources that will be used for each request to the application. A corresponding event, Application_EndRequest, provides you with an opportunity to close or otherwise dispose of resources used for the request. • Session events are similar to application events (there is a Session_OnStart and a Session_OnEnd event), but are raised with each unique session within the application. A session begins when a user requests a page for the first time from your application and ends either when your application explicitly closes the session or when the session times out. You can create handlers for these types of events in the Global.asax file. 343. Difference between ASP Session and ASP.NET Session?asp.net session supports cookie less session & it can span across multiple servers. 344. What is cookie less session? How it works?By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. If cookies are not available, a session can be tracked by adding a session identifier to the URL. This can be enabled by setting the following: <sessionState cookieless="true" />345. How you will handle session when deploying application in more than a server? Describe session handling in a webfarm, how does it work and what are the limits?By default, ASP.NET will store the session state in the same process that processes the request, just as ASP does. Additionally, ASP.NET can store session data in an external process, which can even reside on another machine. To enable this feature: • Start the ASP.NET state service, either using the Services snap-in or by executing "net start aspnet_state" on the command line. The state service will by default listen on port 42424. To change the port, modify the registry key for the service: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\Port • Set the mode attribute of the <sessionState> section to "StateServer". • Configure the stateConnectionString attribute with the values of the machine on which you started aspnet_state. The following sample assumes that the state service is running on the same machine as the Web server ("localhost") and uses the default port (42424): <sessionState mode="StateServer" stateConnectionString="tcpip=localhost:42424" />Note that if you try the sample above with this setting, you can reset the Web server (enter iisreset on the command line) and the session state value will persist. ** 346. What method do you use to explicitly kill a users session?Abandon() 347. What are the different ways you would consider sending data across pages in ASP (i.e between 1.asp to 2.asp)?Sessionpublic properties 348. What is State Management in .Net and how many ways are there to maintain a state in .Net? What is view state?Web pages are recreated each time the page is posted to the server. In traditional Web programming, this would ordinarily mean that all information associated with the page and the controls on the page would be lost with each round trip. To overcome this inherent limitation of traditional Web programming, the ASP.NET page framework includes various options to help you preserve changes — that is, for managing state. The page framework includes a facility called view state that automatically preserves property values of the page and all the controls on it between round trips.However, you will probably also have application-specific values that you want to preserve. To do so, you can use one of the state management options.Client-Based State Management Options:View StateHidden Form FieldsCookiesQuery StringsServer-Based State Management OptionsApplication StateSession StateDatabase Support 349. What are the disadvantages of view state / what are the benefits?Automatic view-state management is a feature of server controls that enables them to repopulate their property values on a round trip (without you having to write any code). This feature does impact performance, however, since a server control's view state is passed to and from the server in a hidden form field. You should be aware of when view state helps you and when it hinders your page's performance. 350. When maintaining session through Sql server, what is the impact of Read and Write operation on Session objects? will performance degrade?Maintaining state using database technology is a common practice when storing user-specific information where the information store is large. Database storage is particularly useful for maintaining long-term state or state that must be preserved even if the server must be restarted.** 351. What are the contents of cookie?** 352. How do you create a permanent cookie?** 353. What is ViewState? What does the "EnableViewState" property do? Why would I want it on or off?** 354. Explain the differences between Server-side and Client-side code?Server side code will process at server side & it will send the result to client. Client side code (javascript) will execute only at client side. 355. Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines?** 356. Which ASP.NET configuration options are supported in the ASP.NET implementation on the shared web hosting platform?A: Many of the ASP.NET configuration options are not configurable at the site, application or subdirectory level on the shared hosting platform. Certain options can affect the security, performance and stability of the server and, therefore cannot be changed. The following settings are the only ones that can be changed in your site’s web.config file (s):browserCapsclientTargetpagescustomErrorsglobalizationauthorizationauthenticationwebControlswebServiceshttp://msdn.microsoft.com/library/default....nfiguration.asp 357. Briefly describe the role of global.asax? 358. How can u debug your .net application? 359. How do u deploy your asp.net application? 360. Where do we store our connection string in asp.net application? 361. Various steps taken to optimize a web based application (caching, stored procedure etc.) 362. How does ASP.NET framework maps client side events to Server side events.(Security) 363. Security types in ASP/ASP.NET? Different Authentication modes? 364. How .Net has implemented security for web applications? 365. How to do Forms authentication in asp.net? 366. Explain authentication levels in .net ? 367. Explain autherization levels in .net ? 368. What is Role-Based security?A role is a named set of principals that have the same privileges with respect to security (such as a teller or a manager). A principal can be a member of one or more roles. Therefore, applications can use role membership to determine whether a principal is authorized to perform a requested action. ** 369. How will you do windows authentication and what is the namespace? If a user is logged under integrated windows authentication mode, but he is still not able to logon, what might be the possible cause for this? In ASP.Net application how do you find the name of the logged in person under windows authentication? 370. What are the different authentication modes in the .NET environment?371. <authentication mode="Windows|Forms|Passport|None">372. <forms name="name"373. loginUrl="url" 374. protection="All|None|Encryption|Validation"375. timeout="30" path="/" >376. requireSSL="true|false"377. slidingExpiration="true|false">378. <credentials passwordFormat="Clear|SHA1|MD5">379. <user name="username" password="password"/>380. </credentials>381. </forms>382. <passport redirectUrl="internal"/></authentication>Attribute Option Descriptionmode Controls the default authentication mode for an application. Windows Specifies Windows authentication as the default authentication mode. Use this mode when using any form of Microsoft Internet Information Services (IIS) authentication: Basic, Digest, Integrated Windows authentication (NTLM/Kerberos), or certificates. Forms Specifies ASP.NET forms-based authentication as the default authentication mode. Passport Specifies Microsoft Passport authentication as the default authentication mode. None Specifies no authentication. Only anonymous users are expected or applications can handle events to provide their own authentication.383. How do you specify whether your data should be passed as Query string and Forms (Mainly about POST and GET)Through attribute tag of form tag. 384. What is the other method, other than GET and POST, in ASP.NET? 385. What are validator? Name the Validation controls in asp.net? How do u disable them? Will the asp.net validators run in server side or client side? How do you do Client-side validation in .Net? How to disable validator control by client side JavaScript?A set of server controls included with ASP.NET that test user input in HTML and Web server controls for programmer-defined requirements. Validation controls perform input checking in server code. If the user is working with a browser that supports DHTML, the validation controls can also perform validation ("EnableClientScript" property set to true/false) using client script.The following validation controls are available in asp.net:RequiredFieldValidator Control, CompareValidator Control, RangeValidator Control, RegularExpressionValidator Control, CustomValidator Control, ValidationSummary Control. 386. Which two properties are there on every validation control?ControlToValidate, ErrorMessage 387. How do you use css in asp.net?Within the <HEAD> section of an HTML document that will use these styles, add a link to this external CSS style sheet that follows this form: <LINK REL="STYLESHEET" TYPE="text/css" HREF="MyStyles.css"> MyStyles.css is the name of your external CSS style sheet. 388. How do you implement postback with a text box? What is postback and usestate?Make AutoPostBack property to true 389. How can you debug an ASP page, without touching the code? 390. What is SQL injection?An SQL injection attack "injects" or manipulates SQL code by adding unexpected SQL to a query.Many web pages take parameters from web user, and make SQL query to the database. Take for instance when a user login, web page that user name and password and make SQL query to the database to check if a user has valid name and password.Username: ' or 1=1 --- Password: [Empty]This would execute the following query against the users table: select count(*) from users where userName='' or 1=1 --' and userPass='' 391. How can u handle Exceptions in Asp.Net? 392. How can u handle Un Managed Code Exceptions in ASP.Net? 393. Asp.net - How to find last error which occurred?A: Server.GetLastError();[C#]Exception LastError;String ErrMessage;LastError = Server.GetLastError();if (LastError != null)ErrMessage = LastError.Message;elseErrMessage = "No Errors";Response.Write("Last Error = " + ErrMessage); 394. How to do Caching in ASP?A: <%@ OutputCache Duration="60" VaryByParam="None" %> VaryByParam value Descriptionnone One version of page cached (only raw GET)* n versions of page cached based on query string and/or POST bodyv1 n versions of page cached based on value of v1 variable in query string or POST bodyv1;v2 n versions of page cached based on value of v1 and v2 variables in query string or POST body395. <%@ OutputCache Duration="60" VaryByParam="none" %><%@ OutputCache Duration="60" VaryByParam="*" %><%@ OutputCache Duration="60" VaryByParam="name;age" %>The OutputCache directive supports several other cache varying options • VaryByHeader - maintain separate cache entry for header string changes (UserAgent, UserLanguage, etc.) • VaryByControl - for user controls, maintain separate cache entry for properties of a user control • VaryByCustom - can specify separate cache entries for browser types and version or provide a custom GetVaryByCustomString method in HttpApplicationderived class 396. What is the Global ASA(X) File? 397. Any alternative to avoid name collisions other then Namespaces.A scenario that two namespaces named N1 and N2 are there both having the same class say A. now in another class i ve written using N1;using N2;and i am instantiating class A in this class. Then how will u avoid name collisions?Ans: using aliasEg: using MyAlias = MyCompany.Proj.Nested; 398. Which is the namespace used to write error message in event Log File? 399. What are the page level transaction and class level transaction? 400. What are different transaction options? 401. What is the namespace for encryption? 402. What is the difference between application and cache variables? 403. What is the difference between control and component? 404. You ve defined one page_load event in aspx page and same page_load event in code behind how will prog run? 405. Where would you use an IHttpModule, and what are the limitations of any approach you might take in implementing one? 406. Can you edit data in the Repeater control? Which template must you provide, in order to display data in a Repeater control? How can you provide an alternating color scheme in a Repeater control? What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control? 407. What is the use of web.config? Difference between machine.config and Web.config?ASP.NET configuration files are XML-based text files--each named web.config--that can appear in any directory on an ASP.NET Web application server. Each web.config file applies configuration settings to the directory it is located in and to all virtual child directories beneath it. Settings in child directories can optionally override or modify settings specified in parent directories. The root configuration file--WinNT\Microsoft.NET\Framework\<version>\config\machine.config--provides default configuration settings for the entire machine. ASP.NET configures IIS to prevent direct browser access to web.config files to ensure that their values cannot become public (attempts to access them will cause ASP.NET to return 403: Access Forbidden). At run time ASP.NET uses these web.config configuration files to hierarchically compute a unique collection of settings for each incoming URL target request (these settings are calculated only once and then cached across subsequent requests; ASP.NET automatically watches for file changes and will invalidate the cache if any of the configuration files change). 408. What is the use of sessionstate tag in the web.config file?Configuring session state: Session state features can be configured via the <sessionState> section in a web.config file. To double the default timeout of 20 minutes, you can add the following to the web.config file of an application: <sessionStatetimeout="40"/> 409. What are the different modes for the sessionstates in the web.config file? Off Indicates that session state is not enabled.Inproc Indicates that session state is stored locally.StateServer Indicates that session state is stored on a remote server.SQLServer Indicates that session state is stored on the SQL Server.410. What is smart navigation?When a page is requested by an Internet Explorer 5 browser, or later, smart navigation enhances the user's experience of the page by performing the following: • eliminating the flash caused by navigation. • persisting the scroll position when moving from page to page. • persisting element focus between navigations. • retaining only the last page state in the browser's history. Smart navigation is best used with ASP.NET pages that require frequent postbacks but with visual content that does not change dramatically on return. Consider this carefully when deciding whether to set this property to true.Set the SmartNavigation attribute to true in the @ Page directive in the .aspx file. When the page is requested, the dynamically generated class sets this property. 411. In what order do the events of an ASPX page execute. As a developer is it important to undertsand these events? 412. How would you get ASP.NET running in Apache web servers - why would you even do this? 413. What tags do you need to add within the asp:datagrid tags to bind columns manually 414. What base class do all Web Forms inherit from?System.Web.UI.Page 415. How can we create pie chart in asp.net? 416. Is it possible for me to change my aspx file extension to some other name?Yes.Open IIS->Default Website -> PropertiesSelect HomeDirectory tabClick on configuration buttonClick on add. Enter aspnet_isapi details (C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\aspnet_isapi.dll | GET,HEAD,POST,DEBUG)Open machine.config(C:\WINDOWS\Microsoft.NET\Framework\v1.0.3705\CONFIG) & add new extension under <httpHandlers> tag<add verb="*" path="*.santhosh" type="System.Web.UI.PageHandlerFactory"/> 417. What is AutoEventWireup attribute for ?(WEBSERVICE & REMOTING) 418. What is a WebService and what is the underlying protocol used in it? Namespace?Web Services are applications delivered as a service on the Web. Web services allow for programmatic access of business logic over the Web. Web services typically rely on XML-based protocols, messages, and interface descriptions for communication and access. Web services are designed to be used by other programs or applications rather than directly by end user. Programs invoking a Web service are called clients. SOAP over HTTP is the most commonly used protocol for invoking Web services. 419. Why Web Services?By exposing data and functionality using standard protocols, Web services make it easy to build sophisticated applications that integrate many features and content. There are three main uses of Web services. Application integration Web services within an intranet are commonly used to integrate business applications running on disparate platforms. For example, a .NET client running on Windows 2000 can easily invoke a Java Web service running on a mainframe or Unix machine to retrieve data from a legacy application. Business integration Web services allow trading partners to engage in e-business leveraging the existing Internet infrastructure. Organizations can send electronic purchase orders to suppliers and receive electronic invoices. Doing e-business with Web services means a low barrier to entry because Web services can be added to existing applications running on any platform without changing legacy code. Commercial Web services focus on selling content and business services to clients over the Internet similar to familiar Web pages. Unlike Web pages, commercial Web services target applications not humans as their direct users. Continental Airlines exposes flight schedules and status Web services for travel Web sites and agencies to use in their applications. Like Web pages, commercial Web services are valuable only if they expose a valuable service or content. It would be very difficult to get customers to pay you for using a Web service that creates business charts with the customers? data. Customers would rather buy a charting component (e.g. COM or .NET component) and install it on the same machine as their application. On the other hand, it makes sense to sell real-time weather information or stock quotes as a Web service. Technology can help you add value to your services and explore new markets, but ultimately customers pay for contents and/or business services, not for technology 420. In a Webservice, need to display 10 rows from a table. So DataReader or DataSet is best choice?A: WebService will support only DataSet. 421. Are Web Services a replacement for other distributed computing platforms?No. Web Services is just a new way of looking at existing implementation platforms. 422. What is SOAP, WSDL, UDDI and the concept behind Web Services? What are various components of WSDL? What is the use of WSDL.exe utility?SOAP is an XML-based messaging framework specifically designed for exchanging formatted data across the Internet, for example using request and reply messages or sending entire documents. SOAP is simple, easy to use, and completely neutral with respect to operating system, programming language, or distributed computing platform.After SOAP became available as a mechanism for exchanging XML messages among enterprises (or among disparate applications within the same enterprise), a better way was needed to describe the messages and how they are exchanged. The Web Services Description Language (WSDL) is a particular form of an XML Schema, developed by Microsoft and IBM for the purpose of defining the XML message, operation, and protocol mapping of a web service accessed using SOAP or other XML protocol. WSDL defines web services in terms of "endpoints" that operate on XML messages. The WSDL syntax allows both the messages and the operations on the messages to be defined abstractly, so they can be mapped to multiple physical implementations. The current WSDL spec describes how to map messages and operations to SOAP 1.1, HTTP GET/POST, and MIME. WSDL creates web service definitions by mapping a group of endpoints into a logical sequence of operations on XML messages. The same XML message can be mapped to multiple operations (or services) and bound to one or more communications protocols (using "ports").The Universal Description, Discovery, and Integration (UDDI) framework defines a data model (in XML) and SOAP APIs for registration and searches on business information, including the web services a business exposes to the Internet. UDDI is an independent consortium of vendors, founded by Microsoft, IBM, and Ariba, for the purpose of developing an Internet standard for web service description registration and discovery. Microsoft, IBM, and Ariba also are hosting the initial deployment of a UDDI service, which is conceptually patterned after DNS (the Internet service that translates URLs into TCP addresses). UDDI uses a private agreement profile of SOAP (i.e. UDDI doesn't use the SOAP serialization format because it's not well suited to passing complete XML documents (it's aimed at RPC style interactions). The main idea is that businesses use the SOAP APIs to register themselves with UDDI, and other businesses search UDDI when they want to discover a trading partner, for example someone from whom they wish to procure sheet metal, bolts, or transistors. The information in UDDI is categorized according to industry type and geographical location, allowing UDDI consumers to search through lists of potentially matching businesses to find the specific one they want to contact. Once a specific business is chosen, another call to UDDI is made to obtain the specific contact information for that business. The contact information includes a pointer to the target business's WSDL or other XML schema file describing the web service that the target business publishes. 423. How to generate proxy class other than .net app and wsdl tool?To access an XML Web service from a client application, you first add a Web reference, which is a reference to an XML Web service. When you create a Web reference, Visual Studio creates an XML Web service proxy class automatically and adds it to your project. This proxy class exposes the methods of the XML Web service and handles the marshalling of appropriate arguments back and forth between the XML Web service and your application. Visual Studio uses the Web Services Description Language (WSDL) to create the proxy.To generate an XML Web service proxy class: • From a command prompt, use Wsdl.exe to create a proxy class, specifying (at a minimum) the URL to an XML Web service or a service description, or the path to a saved service description.Wsdl /language:language /protocol:protocol /namespace:myNameSpace /out:filename/username:username /password:password /domain:domain <url or path> 424. asynchronous web service means? 425. What are the events fired when web service called? 426. How does SOAP transport happen and what is the role of HTTP in it? How you can access a webservice using soap? 427. How will do transaction in Web Services? 428. What are the different formatters can be used in both? Why?.. binary/soap 429. What is a proxy in web service? How do I use a proxy server when invoking a Web service? If you are using the SOAP Toolkit, you need to set some connector properties to use a proxy server: Dim soap As SoapClient Set soap=New SoapClient soap.ConnectorProperty("ProxyServer") = ?proxyservername? soap.ConnectorProperty("ProxyPort") = ?8080? soap.ConnectorProperty("UseProxy") = True While with .NET , you just need to create a System.Net.WebProxy object and use it to set the Proxy property Dim webs As localhost.MyService() webs.Proxy=New System.Net.WebProxy(?http://proxyserver:8080?) 430. How you will protect / secure a web service?For the most part, things that you do to secure a Web site can be used to secure a Web Service. If you need to encrypt the data exchange, you use Secure Sockets Layer (SSL) or a Virtual Private Network to keep the bits secure. For authentication, use HTTP Basic or Digest authentication with Microsoft® Windows® integration to figure out who the caller is.these items cannot: • Parse a SOAP request for valid values • Authenticate access at the Web Method level (they can authenticate at the Web Service level) • Stop reading a request as soon as it is recognized as invalid 431. How will you expose/publish a webservice? 432. What’s the attribute for webservice method? What is the namespace for creating webservice? 433. What is disco file? 434. What is Remoting? The process of communication between different operating system processes, regardless of whether they are on the same computer. The .NET remoting system is an architecture designed to simplify communication between objects living in different application domains, whether on the same computer or not, and between different contexts, whether in the same application domain or not. 435. Difference between web services & remoting? ASP.NET Web Services .NET RemotingProtocol Can be accessed only over HTTP Can be accessed over any protocol (including TCP, HTTP, SMTP and so on)State Management Web services work in a stateless environment Provide support for both stateful and stateless environments through Singleton and SingleCall objectsType System Web services support only the datatypes defined in the XSD type system, limiting the number of objects that can be serialized. Using binary communication, .NET Remoting can provide support for rich type systemInteroperability Web services support interoperability across platforms, and are ideal for heterogeneous environments. .NET remoting requires the client be built using .NET, enforcing homogenous environment. Reliability Highly reliable due to the fact that Web services are always hosted in IIS Can also take advantage of IIS for fault isolation. If IIS is not used, application needs to provide plumbing for ensuring the reliability of the application. Extensibility Provides extensibility by allowing us to intercept the SOAP messages during the serialization and deserialization stages. Very extensible by allowing us to customize the different components of the .NET remoting framework. Ease-of-Programming Easy-to-create and deploy. Complex to program. 436. Though both the .NET Remoting infrastructure and ASP.NET Web services can enable cross-process communication, each is designed to benefit a different target audience. ASP.NET Web services provide a simple programming model and a wide reach. .NET Remoting provides a more complex programming model and has a much narrower reach.As explained before, the clear performance advantage provided by TCPChannel-remoting should make you think about using this channel whenever you can afford to do so. If you can create direct TCP connections from your clients to your server and if you need to support only the .NET platform, you should go for this channel. If you are going to go cross-platform or you have the requirement of supporting SOAP via HTTP, you should definitely go for ASP.NET Web services.Both the .NET remoting and ASP.NET Web services are powerful technologies that provide a suitable framework for developing distributed applications. It is important to understand how both technologies work and then choose the one that is right for your application. For applications that require interoperability and must function over public networks, Web services are probably the best bet. For those that require communications with other .NET components and where performance is a key priority, .NET Remoting is the

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