Visual Studio .NET - Interview Question

1)what ia http header?

2)What are method in session object?
3)How to get the capacity of an array in C#?

4)How to get the capacity of an array in C#?

5)How to get the capacity of an array in C#?

6)How to get the capacity of an array in C#?

7)How to get the capacity of an array in C#?

8)What is the satellite assembly?
9)What is a Web Service?
10)What is the difference between ADO and ADO.NET?
11)What is connection pooling ?

12)What is the difference between an EXE and a DLL?

13)How do you import Activex component in to .NET?

1)    HttpHeader will useful for the browser protocol. It preserves data between different HTTPRequest such as Get() and Post().

2)   Session.abandon(),  Session.clear(), etc.

3)   Using length property of Array.

8)   If we r using the Globalization in our application. Then we need to create .dll file. It uses resource file. We need to convert that file into .dll file. It uses two files as : resgen.exe and al.exe.

9)   Web Service will run on web server. It is always active on the web service. We can use that system in our application. Web Service use SOAP Protocol. It sends data in XML Format.

11)   If connection pooling is activated then we can use that active connection. So, there is no need to connect again to the database server.

12)   .EXE is the executable file which will run while clicking on it. A .dll is in byte format. Which having code inside it. We can add reference of it and uses it in our application.

 

Hi,

1. HTTP Header

The Headers collection contains the protocol headers associated with the request. The following table lists the HTTP headers that are not stored in the Headers collection but are either set by the system or set by properties or methods.

Header Set by
Accept Set by the Accept property.
Connection Set by the Connection property and KeepAlive property.
Content-Length Set by the ContentLength property.
Content-Type Set by the ContentType property.
Expect Set by the Expect property.
Date Set by the system to the current date.
Host Set by the system to the current host information.
If-Modified-Since Set by the IfModifiedSince property.
Range Set by the AddRange method.
Referer Set by the Referer property.
Transfer-Encoding Set by the TransferEncoding property (the SendChunked property must be true).
User-Agent Set by the UserAgent property.

The Add method throws an ArgumentException if you try to set one of these protected headers.

Changing the Headers property after the request has been started by calling GetRequestStream, BeginGetRequestStream, GetResponse, or BeginGetResponse method will throw an InvalidOperationException.

 

Hi,

2. Session Object

Session Object
When you are working with an application, you open it, do some changes and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are and what you do because the HTTP address doesn't maintain state.

ASP solves this problem by creating a unique cookie for each user. The cookie is sent to the client and it contains information that identifies the user. This interface is called the Session object.

The Session object is used to store information about, or change settings for a user session. Variables stored in the Session object hold information about one single user, and are available to all pages in one application. Common information stored in session variables are name, id, and preferences. The server creates a new Session object for each new user, and destroys the Session object when the session expires.

Methods
Method Description
Abandon Destroys a user session
Contents.Remove Deletes an item from the Contents collection
Contents.RemoveAll() Deletes all items from the Contents collection

Hi,

3,4,5,6,7.

public virtual int Capacity { get; set; }

Property Value

Type: System..::.Int32

The number of elements that the ArrayList can contain.

Exceptions
 
ArgumentOutOfRangeException Capacity is set to a value that is less than Count.
 
OutOfMemoryException There is not enough memory available on the system.
 

Capacity is the number of elements that the ArrayList can store. Count is the number of elements that are actually in the ArrayList.

Capacity is always greater than or equal to Count. If Count exceeds Capacity while adding elements, the capacity is automatically increased by reallocating the internal array before copying the old elements and adding the new elements.

The capacity can be decreased by calling TrimToSize or by setting the Capacity property explicitly. When the value of Capacity is set explicitly, the internal array is also reallocated to accommodate the specified capacity.

Retrieving the value of this property is an O(1) operation; setting the property is an O(n) operation, where n is the new capacity.

 

Hi,

8. satellite Assembly

A definition from MSDN says something like this: "A .NET Framework assembly containing resources specific to a given language. Using satellite assemblies, you can place the resources for different languages in different assemblies, and the correct assembly is loaded into memory only if the user elects to view the application in that language."

This means that you develop your application in a default language and add flexibility to react with change in the locale. Say, for example, you developed your application in an en-US locale. Now, your application has multilingual support. When you deploy your code in, say, India, you want to show labels, messages shown in the national language which is other than English.

Satellite assemblies give this flexibility. You create any simple text file with translated strings, create resources, and put them into the bin\debug folder. That's it. The next time, your code will read the CurrentCulture property of the current thread and accordingly load the appropriate resource.

This is called the hub and spoke model. It requires that you place resources in specific locations so that they can be located and used easily. If you do not compile and name resources as expected, or if you do not place them in the correct locations, the common language runtime will not be able to locate them. As a result, the runtime uses the default resource set.

How do creating a Satellite Assembly ?

1.Create a folder with a specific culture name (for example, en-US) in the application's bin\debug folder.

2.Create a .resx file in that folder. Place all translated strings into it.

3.Create a .resources file by using the following command from the .NET command prompt. (localizationsample is the name of the application namespace. If your application uses a nested namespace structure like MyApp.YourApp.MyName.YourName as the type of namespace, just use the uppermost namespace for creating resources files—MyApp.)

resgen Strings.en-US.resx LocalizationSample.
Strings.en-US.resources
al /embed:LocalizationSample.Strings.en-US.resources
/out:LocalizationSample.resources.dll /c:en-US
The above step will create two files, LocalizationSample.Strings.en-US.resources and LocalizationSample.resources.dll. Here, LocalizationSample is the name space of the application.

4.In the code, find the user's language; for example, en-US. This is culture specific.

5.Give the assembly name as the name of .resx file. In this case, it is Strings.

Hi,

9. Web service

Web services are small units of code
Web services are designed to handle a limited set of tasks
Web services use XML based communicating protocols
Web services are independent of operating systems
Web services are independent of programming languages
Web services connect people, systems and devices

 

Hi,

10. Difference between ADO and ADO.net

Comparison of ADO.NET and ADO
You can understand the features of ADO.NET by comparing them to particular features of ActiveX Data Objects (ADO).

In-memory Representations of Data
In ADO, the in-memory representation of data is the recordset. In ADO.NET, it is the dataset. There are important differences between them.

Number of Tables
A recordset looks like a single table. If a recordset is to contain data from multiple database tables, it must use a JOIN query, which assembles the data from the various database tables into a single result table.

In contrast, a dataset is a collection of one or more tables. The tables within a dataset are called data tables; specifically, they are DataTable objects. If a dataset contains data from multiple database tables, it will typically contain multiple DataTable objects. That is, each DataTable object typically corresponds to a single database table or view. In this way, a dataset can mimic the structure of the underlying database.

A dataset usually also contains relationships. A relationship within a dataset is analogous to a foreign-key relationship in a database —that is, it associates rows of the tables with each other. For example, if a dataset contains a table about investors and another table about each investor's stock purchases, it could also contain a relationship connecting each row of the investor table with the corresponding rows of the purchase table.

Because the dataset can hold multiple, separate tables and maintain information about relationships between them, it can hold much richer data structures than a recordset, including self-relating tables and tables with many-to-many relationships.

Data Navigation and Cursors
In ADO you scan sequentially through the rows of the recordset using the ADO MoveNext method. In ADO.NET, rows are represented as collections, so you can loop through a table as you would through any collection, or access particular rows via ordinal or primary key index. DataRelation objects maintain information about master and detail records and provide a method that allows you to get records related to the one you are working with. For example, starting from the row of the Investor table for "Nate Sun," you can navigate to the set of rows of the Purchase table describing his purchases.

A cursor is a database element that controls record navigation, the ability to update data, and the visibility of changes made to the database by other users. ADO.NET does not have an inherent cursor object, but instead includes data classes that provide the functionality of a traditional cursor. For example, the functionality of a forward-only, read-only cursor is available in the ADO.NET DataReader object. For more information about cursor functionality, see Data Access Technologies.

Minimized Open Connections
In ADO.NET you open connections only long enough to perform a database operation, such as a Select or Update. You can read rows into a dataset and then work with them without staying connected to the data source. In ADO the recordset can provide disconnected access, but ADO is designed primarily for connected access.

There is one significant difference between disconnected processing in ADO and ADO.NET. In ADO you communicate with the database by making calls to an OLE DB provider. In ADO.NET you communicate with the database through a data adapter (an OleDbDataAdapter, SqlDataAdapter, OdbcDataAdapter, or OracleDataAdapter object), which makes calls to an OLE DB provider or the APIs provided by the underlying data source. The important difference is that in ADO.NET the data adapter allows you to control how the changes to the dataset are transmitted to the database — by optimizing for performance, performing data validation checks, or adding any other extra processing.

Note   Data adapters, data connections, data commands, and data readers are the components that make up a .NET Framework data provider. Microsoft and third-party providers can make available other .NET Framework data providers that can be integrated into Visual Studio. For information on the different .NET Data providers, see .NET Data Providers.
Sharing Data Between Applications
Transmitting an ADO.NET dataset between applications is much easier than transmitting an ADO disconnected recordset. To transmit an ADO disconnected recordset from one component to another, you use COM marshalling. To transmit data in ADO.NET, you use a dataset, which can transmit an XML stream.

The transmission of XML files offers the following advantages over COM marshalling:

Richer data types
COM marshalling provides a limited set of data types — those defined by the COM standard. Because the transmission of datasets in ADO.NET is based on an XML format, there is no restriction on data types. Thus, the components sharing the dataset can use whatever rich set of data types they would ordinarily use.

Performance
Transmitting a large ADO recordset or a large ADO.NET dataset can consume network resources; as the amount of data grows, the stress placed on the network also rises. Both ADO and ADO.NET let you minimize which data is transmitted. But ADO.NET offers another performance advantage, in that ADO.NET does not require data-type conversions. ADO, which requires COM marshalling to transmit records sets among components, does require that ADO data types be converted to COM data types.

Penetrating Firewalls
A firewall can interfere with two components trying to transmit disconnected ADO recordsets. Remember, firewalls are typically configured to allow HTML text to pass, but to prevent system-level requests (such as COM marshalling) from passing.

Because components exchange ADO.NET datasets using XML, firewalls can allow datasets to pass.

 

 

Hi,

11. Connection Pooling

Connection pools are actually containers that contain open and reusable connections. Multiple pools can exist in the same application domain at the same point in time, but Connection Pools cannot be shared across application domains. Note that one pool is created per unique connection string. A Connection Pool is created the first time a request for a connection to the database comes in with a unique connection string. Note that if another request comes in with a different connection string for the database, another Connection Pool would be created. Hence, we have one Connection Pool per connection string and not per database. The following code listings below illustrate this.

Listing 1

// A new pool is created.
SqlConnection sqlConnection = new SqlConnection();
sqlConnection.ConnectionString =
"Server=localhost;Database=test;User ID=joydip;Password=joydip;Trusted_Connection=False";
sqlConnection.Open();      Listing 2

// A new pool is created as the connection strings differ.
SqlConnection conn = new SqlConnection();
sqlConnection.ConnectionString =
"Server=localhost;Database=test;User ID=test;Password=test;Trusted_Connection=False";
sqlConnection.Open();   Listing 3

// The connection string is the same as in Listing 1 so no new pool is created.
SqlConnection conn = new SqlConnection();
sqlConnection.ConnectionString =
"Server=localhost;Database=test;User ID=joydip;Password=joydip;Trusted_Connection=False";
sqlConnection.Open();      When a request for a new connection comes in the connection is served from the Connection Pool without creating a new one, i.e., the connections are re-used without creating new ones.  Therefore, it improves the performance and scalability of your applications. When your application closes an open connection, it is returned to the pool where it waits until a reconnect time out period expires. This is the period within which it waits to connect to the same database using the same credentials. If none comes in within this period, the connection to the database is closed and the connection instance is removed from the pool.

When a new Connection Pool is created, the connection objects are placed in the pool and the pool and the connections contained in it are made available for immediate use. The pool can house connections up to the maximum limit as specified in the connection string that was used to connect to the database. Connections are removed from the pool when they remain inactive for a long period of time or have outlived its specified life time or server connectivity.

A Connection Pool is maintained internally by the Connection Pool Manager. When a request for a subsequent connection comes in, the Connection Pool Manager searches the pool for the availability of a free connection and returns it to the application if one is available. The following points elaborate how the Connection Pool Manager works- the operations that it performs when a request for a new connection comes to it.

·         If any unused connection is available, it returns one.

·         If all connections are used up, a new connection is created and added to the pool.

·         If the number of connections reaches the maximum number of connections in the pool, the requests are queued until a connection becomes free for reuse.

Connection Pooling is controlled and the parameters passed to a connection string that basically comprises the following:

·         Connect Timeout

·         Min Pool Size

·         Max Pool Size

·         Pooling

In order to use Connection Pooling efficiently, remember to close the connections once you are done with it so that it returns to the pool.

Hi,

13. Import Activex Component

There are a lot of articles in net for using standard COM components in .NET applications. This article is about importing a particular kind of COM component, a graphical one: the ActiveX control. I’ve tried to import the MSMAPI ActiveX library. Before importing here is a brief introduction to ActiveX and MAPI.

What is an ActiveX control? An ActiveX control is really just another term for “OLE Object” or, more specifically “COM Object”. In another words, it supports IUnknown interface and is also self-registering. With the help of QueryInterface, a container can manage the lifetime of the control, as well as dynamically discover the full extent of a control’s functionality based on the available interfaces. This allows a control to implement as little functionality as it needs to.

MAPI is the Messaging Application Programming Interface, represents a comprehensive set of specifications that link messaging applications on the one hand and the service providers on the other, forming a messaging architecture. Although Microsoft is the prime supplier of MAPI components, it is by no means necessary to have a single Microsoft component to use MAPI (nor it is necessary to use a Windows or Win32 platform, actually). We can have a MAPI-complaint system with third party message store, address guide, and transport providers on a non-Windows operating system. MAPI is a part of WOSA, the Windows Open Services Architecture, which consists of common set of APIs for distributed computing. For more details, read MSDN.

Now, lets see how to import an ActiveX control. There are two ways to use ActiveX controls under .NET. We have an application called AxImp.exe, shipped with .NET SDK. This application does a similar kind of service for ActiveX controls that TlbImp.exe performs for non-graphical COM components. Basically, what it does is, it generates a wrapper component containing a type library that .NET can understand, and this wrapper component is capable of marshalling calls between the .NET runtime and the underlying COM object (the control). This application can from the command line, simply by passing the path and filename of the control.

 
This will create the file as <old_file.ocx> to <old_file.dll> and Ax<old_file.dll>. After creating the wrapper component add a reference to it and start using the control.

The other way is to import directly to the Visual Studio. We can add the controls to the toolbox by simply right clicking one of the tabs and selecting Customize Toolbox from the context menu. To do this select the COM Components tab and select or browse for the controls, you want to add. Here we want MAPI messages control and session control.

 

10)  ADO and ADO.NET are different in several ways:

·         ADO works with connected data. This means that when you access data, such as viewing and updating data, it is real-time, with a connection being used all the time. This is barring, of course, you programming special routines to pull all your data into temporary tables.

ADO.NET uses data in a disconnected fashion. When you access data, ADO.NET makes a copy of the data using XML. ADO.NET only holds the connection open long enough to either pull down the data or to make any requested updates. This makes ADO.NET efficient to use for Web applications. It's also decent for desktop applications.

·         ADO has one main object that is used to reference data, called the Recordset object. This object basically gives you a single table view of your data, although you can join tables to create a new set of records. With ADO.NET, you have various objects that allow you to access data in various ways. The DataSet object will actually allow you to store the relational model of your database. This allows you to pull up customers and their orders, accessing/updating the data in each related table individually.

·         ADO allows you to create client-side cursors only, whereas ADO.NET gives you the choice of either using client-side or server-side cursors. In ADO.NET, classes actually handle the work of cursors. This allows the developer to decide which is best. For Internet development, this is crucial in creating efficient applications.

·         Whereas ADO allows you to persist records in XML format, ADO.NET allows you to manipulate your data using XML as the primary means. This is nice when you are working with other business applications and also helps when you are working with firewalls because data is passed as HTML and XML

 

11)Connection pools are used to enhance the performance of executing commands on a database. Opening and maintaining a database connection for each user, especially requests made to a dynamic database-driven Web application, is costly and wastes resources. In connection pooling, after a connection is created, it is placed in the pool and it is used over again so that a new connection does not have to be established. If all the connections are being used, a new connection is made and is added to the pool. Connection pooling also cuts down on the amount of time a user must wait to establish a connection to the database.

12)  fullname of .exe is Extensible Execute File
fullname of .dll is Dynamic Link Liberary
.exe use by End User like-Client
.Dll can not use by End User.
We can Run the .exe
but we can not Run the .Dll

 

1) HTTP Headers :: http://www.cs.tut.fi/~jkorpela/http.html

2) Session object Methods :: http://www.w3schools.com/asp/asp_ref_session.asp (see Methods part)

8) Satellite Assemblies ::

When you wish to localize the application (make the application customizable for different languages and cultures), it can be written in culture-neutral code (code that uses resources from an assembly rather than hard-coding the resources in the program) and distribute the localized modules in separate assemblies called satellite assemblies.

To create the satellite assemblies, you will use the al.exe utility (Assembly Linker) to link your resource file to an assembly, as shown in this example:

al /t:library /embed:strings.en.resources /culture:en /out:MyApp.resources.dll

The /t option will direct al to build a library,
and the /embed option identifies the file to be linked.

For more details checkout these links

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconcreatingsatelliteassemblies.asp
http://www.ondotnet.com/pub/a/dotnet/2002/10/14/local2.htm
http://www.dotnetspider.com/technology/kbpages/422.aspx

9) Web Services ::

The term Web services describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone. XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available. Used primarily as a means for businesses to communicate with each other and with clients, Web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall.

Unlike traditional client/server models, such as a Web server/Web page system, Web services do not provide the user with a GUI. Web services instead share business logic, data and processes through a programmatic interface across a network. The applications interface, not the users. Developers can then add the Web service to a GUI (such as a Web page or an executable program) to offer specific functionality to users.

Web services allow different applications from different sources to communicate with each other without time-consuming custom coding, and because all communication is in XML, Web services are not tied to any one operating system or programming language. For example, Java can talk with Perl, Windows applications can talk with UNIX applications.

Web services do not require the use of browsers or HTML.

Web services are sometimes called application services.

10) Difference Between ADO and ADO.NET

ADO and ADO.NET are different in several ways:

·         ADO works with connected data. This means that when you access data, such as viewing and updating data, it is real-time, with a connection being used all the time. This is barring, of course, you programming special routines to pull all your data into temporary tables.

ADO.NET uses data in a disconnected fashion. When you access data, ADO.NET makes a copy of the data using XML. ADO.NET only holds the connection open long enough to either pull down the data or to make any requested updates. This makes ADO.NET efficient to use for Web applications. It's also decent for desktop applications.

·         ADO has one main object that is used to reference data, called the Recordset object. This object basically gives you a single table view of your data, although you can join tables to create a new set of records. With ADO.NET, you have various objects that allow you to access data in various ways. The DataSet object will actually allow you to store the relational model of your database. This allows you to pull up customers and their orders, accessing/updating the data in each related table individually.

·         ADO allows you to create client-side cursors only, whereas ADO.NET gives you the choice of either using client-side or server-side cursors. In ADO.NET, classes actually handle the work of cursors. This allows the developer to decide which is best. For Internet development, this is crucial in creating efficient applications.

·         Whereas ADO allows you to persist records in XML format, ADO.NET allows you to manipulate your data using XML as the primary means. This is nice when you are working with other business applications and also helps when you are working with firewalls because data is passed as HTML and XML.

For more details refer thse links

http://msdn.microsoft.com/en-us/library/904fck4k(VS.71).aspx

11) Connection Pooling :: http://www.15seconds.com/issue/040830.htm

Hope this helps.

1)  HttpHeader will useful for the browser protocol. It preserves data between different HTTPRequest such as Get() and Post().
See this link to know more abt it;
http://www.15seconds.com/issue/020417.htm

2)   Session.abandon(),  Session.clear(). The major practical difference is that if you call Session.Abandon(), Session_End will be fired (for InProc mode), and in the next request, Session_Start will be fired. Session.Clear( ) just clears the session data without killing it

3)   You can easily find out the capacity of an array by using length property of Array.
like; MessageBox.Show(arr.length); //This will give you total capacity of an array.

8)   Satellite Assembly

A definition from MSDN says something like this: "A .NET Framework assembly containing resources specific to a given language. Using satellite assemblies, you can place the resources for different languages in different assemblies, and the correct assembly is loaded into memory only if the user elects to view the application in that language."
This means that you develop your application in a default language and add flexibility to react with change in the locale. Say, for example, you developed your application in an en-US locale. Now, your application has multilingual support. When you deploy your code in, say, India, you want to show labels, messages shown in the national language which is other than English.
Satellite assemblies give this flexibility. You create any simple text file with translated strings, create resources, and put them into the bin\debug folder. That's it. The next time, your code will read the CurrentCulture property of the current thread and accordingly load the appropriate resource.
This is called the hub and spoke model. It requires that you place resources in specific locations so that they can be located and used easily. If you do not compile and name resources as expected, or if you do not place them in the correct locations, the common language runtime will not be able to locate them. As a result, the runtime uses the default resource set.
See this link to know more abt, how to create it;
http://www.codeguru.com/csharp/.net/net_general/tipstricks/article.php/c11367/

9)   Web Services
Web Services can convert your applications into Web-applications.
By using Web services, your application can publish its function or message to the rest of the world.
Web Services can be used by other applications.
With Web services your accounting department's Win 2k servers can connect with your IT supplier's UNIX server.
The basic Web Services platform is XML + HTTP.
Web services uses XML to code and decode your data and SOAP to transport it.
Web Service will run on web server. It is always active on the web service. We can use that system in our application. Web Service use SOAP Protocol. It sends data in XML
Format.
http://www.w3schools.com/webservices/default.asp

10) Diff. Betn ADO and ADO.net

ADO..
1.It works with connected area.
2.RecordSet object is there in ADO.This is used to reference data.
3.ADO allows the user to persist records in XML
format.

ADO.NET..
1.It uses data in a disconnection fashion.
2.There are various objects that allow the user to access
data in various ways.
3.It allows the user to manipulate your data using
XML as the primary means.
http://www.dotnetspider.com/forum/ViewForum.aspx?ForumId=33473

11)   Connection pooling
Opening a database connection is a resource intensive and time consuming operation. Connection pooling increases the performance of Web applications by reusing active database connections instead of creating a new connection with every request. Connection pool manager maintains a pool of open database connections. When a new connection requests come in, the pool manager checks if the pool contains any unused connections and returns one if available. If all connections currently in the pool are busy and the maximum pool size has not been reached, the new connection is created and added to the pool. When the pool reaches its maximum size all new connection requests are being queued up until a connection in the pool becomes available or the connection attempt times out.
Connection pooling behavior is controlled by the connection string parameters. The following are four parameters that control most of the connection pooling behavior:

• Connect Timeout - controls the wait period in seconds when a new connection is requested, if this timeout expires, an exception will be thrown. Default is 15 seconds.
• Max Pool Size - specifies the maximum size of your connection pool. Default is 100. Most Web sites do not use more than 40 connections under the heaviest load but it depends on how long your database operations take to complete.
• Min Pool Size - initial number of connections that will be added to the pool upon its creation. Default is zero; however, you may chose to set this to a small number such as 5 if your application needs consistent response times even after it was idle for hours. In this case the first user requests won't have to wait for those database connections to establish.
• Pooling - controls if your connection pooling on or off. Default as you may've guessed is true. Read on to see when you may use Pooling=false setting.

http://www.15seconds.com/issue/040830.htm

12)   In .NET, an assembly may become a DLL or an EXE. Yet, there is a major underlying difference between the two.
An EXE is an executable file, that may run on its own. Its independant. Where as a DLL is a Dynamic Link Library, that binds to an exe, or another DLL at runtime.
A DLL has an exposed interface, through which members of the assembly may be accessed by those objects that require it.
A DLL runs in tandem with the application space in memory, as the application references it. Whereas an EXE is independant, and runs as an independant process.

Best Luck!!!!!!!!!!!!!!!!!!!!
Sujit.