asp.net interview questions: state management
- What is the lifespan for items stored in ViewState?
Item stored in ViewState exist for the life of the current page. This includes postbacks (to the same page). - What is ViewState?
ViewState allows the state of objects (serializable) to be stored in a hidden field on the page. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. ViewState is used the retain the state of server-side objects between postabacks. - What are the different types of Session state management options available with ASP.NET?
ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session in memory on the web server. This requires the a "sticky-server" (or no load-balancing) so that the user is always reconnected to the same web server. Out-of-Process Session state management stores data in an external data source. The external data source may be either a SQL Server or a State Server service. Out-of-Process state management requires that all objects stored in session are serializable. - What does the "EnableViewState" property do? Why would I want it on or off?
It allows the page to save the users input on a form across postbacks. It saves the server-side values for a given control into ViewState, which is stored as a hidden value on the page before sending the page to the clients browser. When the page is posted back to the server the server control is recreated with the state stored in viewstate.
What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
Some of we developers may confused about these 2 method,
Server.Transfer() : client is shown as it is on the requesting page only, but the all the content is of the requested page. Data can be persist accros the pages using Context.Item collection, which is one of the best way to transfer data from one page to another keeping the page state alive.
Response.Dedirect() :client know the physical loation (page name and query string as well). Context.Items loses the persisitance when nevigate to destination page.
In earlier versions of IIS, if we wanted to send a user to a new Web page, the only option we had was Response.Redirect. While this method does accomplish our goal, it has several important drawbacks. The biggest problem is that this method causes each page to be treated as a separate transaction. Besides making it difficult to maintain your transactional integrity, Response.Redirect introduces some additional headaches. First, it prevents good encapsulation of code. Second, you lose access to all of the properties in the Request object. Sure, there are workarounds, but they’re difficult. Finally, Response.Redirect necessitates a round trip to the client, which, on high-volume sites, causes scalability problems. As you might suspect, Server.Transfer fixes all of these problems. It does this by performing the transfer on the server without requiring a roundtrip to the client.
Introduction to ASP.NET with C#
Classic Asp: 
Asp, which is now more commonly known as Classic Asp was used extensively in 1990's. The idea of creating dynamic pages and linking them with database was the main purpose of classic Asp. Asp used html controls for user interaction. Apart from the good features available in Asp programming, it also lacks in some of the major areas. These areas include clean coding as asp pages were incline pages and all the business logic as well as the interface was coded in a single page. This produces many problem when the code had to be updated or modified. Asp pages also lacked performance and scalability which were fixed in Asp.net. Lets see what Asp.net technology has to offer a developer to build dynamic pages much faster.
Language Options:
Asp.net provides lets you choose the scripting language between javascript and VbScript. This is beneficial for the java programmers as well as the VB programmers since they already have the basic background of the language.
Caching features:
Asp.net also introduces caching features which increases the performance of the application. Caching allows the developer to save the recently used data in a cache variable so that if does not have to spend any time looking for it in the future when anyone requests it.
Use of Controls:
Asp.net provides the developer with several controls to perform basic as well as advanced operations. Controls provided in Asp.net falls under HTML Controls, HTML Server Controls and Web Server Controls.
HTML Controls:
Html controls are the basic controls that are executed on the client machine. These controls include textbox, label , image etc. A simple example of html control can be given by the following code which renders an image.
As you see HTML controls are very easy to use but they don't provide much features. Microsoft decided to introduce HTML Server controls which extends the functionality of simple HTML Controls.
HTML Server Controls:
HTML Server Controls looks exactly like the HTML Controls with one difference that they are executed on the server rather than the client. A simple example of HTML Server controls is given below:
just add a runat server attribute with the image tag.
As you can see that the image tag or control looks exactly like the one that we have previously discussed. But it has an additional attribute which is runat. The runat attribute denotes that this is a HTML Server Control and will be executed on the Server rather than the client.
Note: src attribute in the image tag denotes the path of the image it can be "C:MyDirectorymyImage.jpg"
Asp.net Web Applications:
Asp.net is based on the .NET framework for building web applications. Since Asp.net is a part of the Microsoft. NET Framework it has the ability to take advantage of rich class libraries provided by Microsoft. The question is that why should one use Asp.net and not use classic asp or any other web programming technology. Here are some of the features of Asp.net that makes it the best web application technology.
Web Server Controls
Web Server Controls are the most advanced controls in Asp.net. Each control comes with tons of features that allows the developer to complete the task in less time.Web Server Controls are executed on the Server. Web Server Controls include datagrid control, datalist control, calendar control and many many more.
Special Note:
When dealing with different types of controls one must always remember that when to use which control. If the control will only act as a static entity than you should always use HTML Controls. If the control will be dynamic you should useWeb Server Controls.
ADO.NET and Database Questions
- What is the wildcard character in SQL?
Let’s say you want to query database with LIKE for all employees whose name starts with La. The wildcard character is %, the proper query with LIKE would involve ‘La%’. - What is the role of the DataReader class in ADO.NET connections?
It returns a read-only, forward-only rowset from the data source. A DataReader provides fast access when a forward-only sequential read is needed. - What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET?
SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. OLE-DB.NET is universal for accessing other sources, like Oracle, DB2, Microsoft Access and Informix. OLE-DB.NET is a .NET layer on top of the OLE layer, so it’s not as fastest and efficient as SqlServer.NET. - What connections does Microsoft SQL Server support?
Windows Authentication (via Active Directory) and SQL Server authentication (via Microsoft SQL Server username and password). - Between Windows Authentication and SQL Server Authentication, which one is trusted and which one is untrusted?
Windows Authentication is trusted because the username and password are checked with the Active Directory, the SQL Server authentication is untrusted, since SQL Server is the only verifier participating in the transaction. - What does the Dispose method do with the connection object?
Deletes it from the memory.
To Do: answer better. The current answer is not entirely correct. - What is a pre-requisite for connection pooling?
Multiple processes must agree that they will share the same connection, where every parameter is the same, including the security settings. The connection string must be identical. - What does the Initial Catalog parameter define in the connection string?
The database name to connect to. - Explain ACID rule of thumb for transactions.
A transaction must be:
1. Atomic - it is one unit of work and does not dependent on previous and following transactions.
2. Consistent - data is either committed or roll back, no “in-between” case where something has been updated and something hasn’t.
3. Isolated - no transaction sees the intermediate results of the current transaction).
4. Durable - the values persist if the data had been committed even if the system crashes right after.
.NET Interview Questions on CLR
Overview of CLR integration.
The CLR (Common Language Runtime) integration is hosted in the Microsoft SQL Server 2005.
With CLR integration, stored procedures, triggers, user- defined functions, user-defined types, and user-defined aggregates in managed code, etc can be written.
As managed code compiles to native code before executing, significant performance can be achieved.
The SQL Server acts as an operating system for the CLR when it is hosted inside SQL Server.
Following are the steps to build a CLR stored procedure in SQL Server 2005
* Enable CLR integration in SQL Server 2005
* Create a CLR stored procedure Assembly
* Deploy the Assembly in SQL Server 2005
* Create and execute the CLR stored procedure in SQL Server 2005
Explain CLR in brief.
CLR stands for Common Language Runtime. The CLR is a development platform. It provides a runtime, defines functionality in some libraries, and supports a set of programming languages. The CLR provides a runtime so that the softwares can utilize its services. The CLR Base Class Library allows interaction with the runtime. The CLR supports various programming languages, several standards and is itself been submitted as an open standard.
Describe the parts of assembly.
An assembly is a partially compiled code library. In .NET, an assembly is a portable executable and can be an EXE (process assembly) or a DLL (library assembly). An assembly can consist of one or more files or modules in various languages. It is used in deployment, versioning and security.
