ASP.NET Interview Questions

What is UDDI?

2009-07-14T08:20:00.003-07:00

UDDI is a directory service where companies can register and search for Web services.

UDDI stands for Universal Description, Discovery and Integration
UDDI is a directory for storing information about web services
UDDI is a directory of web service interfaces described by WSDL
UDDI communicates via SOAP
UDDI is built into the Microsoft .NET platform

What is WSDL?

2009-07-14T08:20:00.001-07:00

WSDL is an XML-based language for locating and describing Web services.

WSDL stands for Web Services Description Language
WSDL is based on XML
WSDL is used to describe Web services
WSDL is used to locate Web services
WSDL is a W3C standard

What is SOAP?

2009-07-14T08:19:00.002-07:00

SOAP is an XML-based protocol to let applications exchange information over HTTP.

Or more simple: SOAP is a protocol for accessing a Web Service.

SOAP stands for Simple Object Access Protocol
SOAP is a communication protocol
SOAP is a format for sending messages
SOAP is designed to communicate via Internet
SOAP is platform independent
SOAP is language independent
SOAP is based on XML
SOAP is simple and extensible
SOAP allows you to get around firewalls
SOAP is a W3C standard

Web Services have Two Types of Uses

2009-07-14T08:19:00.001-07:00

Reusable application-components.

There are things applications need very often. So why make these over and over again?

Web services can offer application-components like: currency conversion, weather reports, or even language translation as services.

Connect existing software.

Web services can help to solve the interoperability problem by giving different applications a way to link their data.

With Web services you can exchange data between different applications and different platforms.

How Web Services Work?

2009-07-14T08:18:00.001-07:00

The basic Web services platform is XML + HTTP.

XML provides a language which can be used between different platforms and programming languages and still express complex messages and functions.

The HTTP protocol is the most used Internet protocol.

Web services platform elements:

SOAP (Simple Object Access Protocol)
UDDI (Universal Description, Discovery and Integration)
WSDL (Web Services Description Language)

What is a web service?

2009-07-14T08:16:00.000-07:00

Web services are application components
Web services communicate using open protocols
Web services are self-contained and self-describing
Web services can be discovered using UDDI
Web services can be used by other applications
XML is the basis for Web services
A web service is something you can call over the web from a program. For more background on web services

How is the Google SOAP Search API implemented?

2009-07-14T08:15:00.001-07:00

Google SOAP Search API is implemented as a web service. The service supports several SOAP methods; these are described in an accompanying WSDL file that can be imported into your favorite web services programming environment. Alternately, you can use our custom Java library to call the service.

How do I get access to the Google SOAP Search API service?

2009-07-14T08:14:00.002-07:00

We are no longer issuing new API keys for the SOAP Search API. Depending on your application, the AJAX Search API may be a better choice for you instead. It tends to be better suited for search-based web applications and supports additional features like Video, News, Maps, and Blog search results.

What applications can I create using the Google SOAP Search API?

2009-07-14T08:14:00.001-07:00

The SOAP Search API is limited to applications not for commercial use.

What functionality comes with the Google SOAP Search API?

2009-07-14T08:13:00.003-07:00

Developers can issue search requests to Google's index of billions of web pages and receive results as structured data, access information in the Google cache, and check the spelling of words.

How does the Google SOAP Search API service work?

2009-07-14T08:13:00.001-07:00

Developers write software programs that connect remotely to the Google SOAP Search API service. Communication is performed via SOAP, an XML-based mechanism for exchanging typed information.

What is the Google SOAP Search API?

2009-07-14T08:12:00.000-07:00

This is Best Answer--
The SOAP Search API was created for developers and researchers interested in using Google Search as a resource in their applications. Depending on your application, the AJAX Search API may be a better choice for you instead. It tends to be better suited for search-based web applications and supports additional features like Video, News, Maps, and Blog search results.

What applications can I create using the Google SOAP Search API?

2009-07-14T08:11:00.000-07:00

The SOAP Search API is limited to applications not for commercial use.

Can I develop commercial applications using the Google SOAP Search API?

2009-07-14T08:09:00.000-07:00

No, the API's Terms and Conditions specifically state that you cannot create a commercial service using the Google SOAP Search API service.

Which are the controls don't have Events?

2009-07-09T02:31:00.000-07:00

Two Types are Controls.

What methods are fired during the page load?

2009-07-08T08:07:00.001-07:00

Init() - when the page is instantiated
Load() - when the page is loaded into server memory
PreRender() - the brief moment before the page is displayed to the user as HTML
Unload() - when page finishes loading.

How many classes can a single .NET DLL contain?

2009-07-08T08:06:00.002-07:00

It can contain many classes.

Name two properties common in every validation control?

2009-07-08T08:06:00.001-07:00

ControlToValidate property and Text property.

What base class do all Web Forms inherit from?

2009-07-08T07:35:00.000-07:00

The Page class.

What is delay signing?

2009-07-08T05:58:00.000-07:00

Delay signing allows you to place a shared assembly in the GAC by signing the assembly with just the public key.

What is the Global.asax used for

2009-07-04T05:37:00.001-07:00

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

Download

What data types do the RangeValidator control support?

2009-07-04T05:35:00.003-07:00

Integer,String,and Date.

What's a bubbled event?

2009-07-04T05:35:00.002-07:00

When you have a comlex control,like DataGrid,Writing an event processing routine

for each object(cell,button,row,etc)is quite tedious.The Controls can bubble up their

eventhandlers,allowing the main DataGrid event handler to take care of its constituents.

What namespace does the web page belong in the .Net Framework class hierarchy?

2009-07-04T05:35:00.001-07:00

System.Web.UI.Page

What is the maximum number of cookies that can be allowed to a web site?

2009-07-04T05:34:00.001-07:00

What is the difference between excute query and excute nonquery?

2009-07-04T05:33:00.002-07:00

Execute Query is the method which is used to return the result of the command like select Query,

That is Update Query.

The Execute Non Query is used to return the Query os the statement like Update,Delete,Insert Which returns No Data.

What is the default authentication mode for IIS.?

2009-07-04T05:33:00.001-07:00

Windows

What is ASP.NET 3.5

2009-07-04T00:40:00.001-07:00

This is a very important topic to consider when developing an application. Many elements need to be considered when deciding on the architecture of the application, such as performance, scalability and future development issues. When you are deciding on which architecture to use, first decide on which of the three aforementioned elements you think is most valuable -- as some choices you make will impact on others. For example, some choices that boost performance will impact on the scalability or future development of your design, etc.

Here we will talk generally about what n-Tier architecture is, and then we will have a look at different n-Tier architectures you can use to develop ASP.NET applications and issues that arise relating to performance, scalability and future development issues for each one.
Firstly, what is n-Tier architecture? N-Tier architecture refers to the architecture of an application that has at least 3 "logical" layers -- or parts -- that are separate. Each layer interacts with only the layer directly below, and has specific function that it is responsible for.
Why use n-Tier architecture? Because each layer can be located on physically different servers with only minor code changes, hence they scale out and handle more server load. Also, what each layer does internally is completely hidden to other layers and this makes it possible to change or update one layer without recompiling or modifying other layers.

This is a very powerful feature of n-Tier architecture, as additional features or change to a layer can be done without redeploying the whole application. For example, by separating data access code from the business logic code, when the database servers change you only needs to change the data access code. Because business logic code stays the same, the business logic code does not need to be modified or recompiled.
[Note] tier and layer mean the same thing [End Note]
An n-Tier application usually has three tiers, and they are called the presentation tier, the business tier and the data tier. Let's have a look at what each tier is responsible for.
Presentation Layer
Presentation Layer is the layer responsible for displaying user interface and "driving" that interface using business tier classes and objects. In ASP.NET it includes ASPX pages, user controls, server controls and sometimes security related classes and objects.

Business Tier
Business Tier is the layer responsible for accessing the data tier to retrieve, modify and delete data to and from the data tier and send the results to the presentation tier. This layer is also responsible for processing the data retrieved and sent to the presentation layer.
In ASP.NET it includes using SqlClient or OleDb objects to retrieve, update and delete data from SQL Server or Access databases, and also passing the data retrieved to the presentation layer in a DataReader or DataSet object, or a custom collection object. It might also include the sending of just an integer, but the integer would have been calculated using the data in the data tier such as the number of records a table has.
BLL and DAL
Often this layer is divided into two sub layers: the Business Logic Layer (BLL), and the Data Access Layers (DAL). Business Logic Layers are above Data Access Layers, meaning BLL uses DAL classes and objects. DAL is responsible for accessing data and forwarding it to BLL.
In ASP.NET it might be using SqlClient or OleDb to retrieve the data and sending it to BLL in the form of a DataSet or DataReader. BLL is responsible for preparing or processing the data retrieved and sends it to the presentation layer. In ASP.NET it might be using the DataSet and DataReader objects to fill up a custom collection or process it to come up with a value, and then sending it to Presentation Layer. BLL sometimes works as just transparent layer. For example, if you want to pass a DataSet or DataReader object directly to the presentation layer.
Data Tier
Data tier is the database or the source of the data itself. Often in .NET it's an SQL Server or Access database, however it's not limited to just those. It could also be Oracle, mySQL or even XML. In this article we will focus on SQL Server, as it has been proven to be the fastest database within a .NET Application.

Logical Layers vs. Physical Layers (Distributed)
Logical Layers and Physical Layers are the ones that confuse people. Firstly, a logical layer means that layers are separate in terms of assembly or sets of classes, but are still hosted on the same server. Physical layer means that those assemblies or sets of classes are hosted on different servers with some additional code to handle the communication between the layers. E.g. remoting and web services.

Deciding to separate the layers physically or not is very important. It really depends on the load your application expects to get. I think it's worth mentioning some of the facts that might affect your decision.
Please DO note that separating the layers physically WILL slow your application down due to the delay in communicating between the servers throughout the network, so if you are using the physical layer approach, make sure the performance gain is worth the performance loss from this.

Hopefully you would have designed your application using the n-Tier approach. If this is the case, then note that you can separate the layers in the future.

Cost for deploying and maintaining physically separated applications is much greater. First of all, you will need more servers. You also need network hardware connecting them. At this point, deploying the application becomes more complex too! So decide if these things will be worth it or not.

Another fact that might affect your decision is how each of the tiers in the application are going to be used. You will probably want to host a tier on a separate server if more than 1 service is dependent on it, e.g. You might want to host business logic somewhere else if you have multiple presentation layers for different clients. You might also want a separate SQL server if you have other applications using the same data.

New Controls added in ASP.NET 3.5

2009-07-03T23:57:00.000-07:00

Microsoft released ASP.NET 3.5 on November 19, 2007. Along with it, was released Visual Studio 2008. This evolution from ASP.NET 2.0 to ASP.NET 3.5 is quiet gradual. ASP.NET 3.5 uses the same engine as that of ASP.NET 2.0, with some extra features added on top of it. In this article, we will explore the new features added to ASP.NET 3.5. This article assumes that you have been working on ASP.NET 2.0.

New Features in ASP.NET 3.5

ASP.NET AJAX

In ASP.NET 2.0, ASP.NET AJAX was used as an extension to it. You had to download the extensions and install it. However in ASP.NET 3.5, ASP.NET AJAX is integrated into the .NET Framework, thereby making the process of building cool user interfaces easier and intuitive.

The integration between webparts and the update panel is much smoother. Another noticeable feature is that you can now add ASP.NET AJAX Control Extenders to the toolbox in VS2008. Even though this is an IDE specific feature, however I feel it deserves a mention over here for developers, who had to add extenders using source view earlier. It is also worth noting that Windows Communication Foundation (WCF) now supports JSON along with other standard protocols like SOAP, RSS and POX.

New Controls

The ListView and DataPager are new controls added along with a new datasource control called the LinqDataSource.

ListView

The ListView control is quiet flexible and contains features of the Gridview, Datagrid, Repeater and similar list controls available in ASP.NET 2.0. It provides the ability to insert, delete, page (using Data Pager), sort and edit data. However one feature of the ListView control that stands apart, is that it gives you a great amount of flexibility over the markup generated. So you have a complete control on how the data is to be displayed. You can now render your data without using the tag. You also get a rich set of templates with the ListView control.

DataPager

DataPager provides paging support to the ListView control. The best advantage is that you need not have to keep it ‘tied’ with the control on which the paging is being done. You can keep it anywhere on the page.

DataPager gives you a consistent way of paging with the controls that support it. Currently only ListView supports it as it implements the IPageableItemContainer. However support is likely to be added to other List controls as well.

LINQ

LINQ (Language Integrated Query) adds native data querying capability to C# and VB.NET along with the compiler and Intellisense support. LINQ is a component of .NET 3.5. LINQ defines operators that allow you to code your query in a consistent manner over databases, objects and XML. The ASP.NET LinqDataSource control allows you to use LINQ to filter, order and group data before binding to the List controls.

You can learn more about LINQ over here.

ASP.NET Merge Tool

ASP.NET 3.5 includes a new merge tool (aspnet_merge.exe). This tool lets you combine and manage assemblies created by aspnet_compiler.exe. This tool was available earlier as an add-on.

New Assemblies

The new assemblies that would be of use to ASP.NET 3.5 developers are as follows:

· System.Core.dll - Includes the implementation for LINQ to Objects

· System.Data.Linq.dll - Includes the implementation for LINQ to SQL

· System.Xml.Linq.dll - Includes the implementation for LINQ to XML

· System.Data.DataSetExtensions.dll - Includes the implementation for LINQ to DataSet

· System.Web.Extensions.dll: Includes the implementation for ASP.NET AJAX (new enhancements added) and new web controls as explained earlier.

Some Other Important Points

1. ASP.NET 3.5 provides better support to IIS7. IIS7 and ASP.NET 3.5 modules and handlers support unified configuration.

2. You can have multiple versions of ASP.NET on the same machine.

3. For those who are wondering what happened to ASP.NET 3.0, well there isn’t anything called ASP.NET 3.0.

4. VS 2002 worked with ASP.NET 1.0, VS 2003 worked with ASP.NET 1.1, and VS 2005 worked with ASP.NET 2.0. However VS 2008 supports multi-targeting, i.e it works with ASP.NET 2.0, and ASP.NET 3.5.