http://groups.msn.com/MumbaiUserGroup/aspnetfaqs.msnw
What is view state and use of it?The current property settings of an ASP.NET page and those of any ASP.NET server controls contained within the page. ASP.NET can detect when a form is requested for the first time versus when the form is posted (sent to the server), which allows you to program accordingly.What are user controls and custom controls?Custom controls: A control authored by a user or a third-party software vendor that does not belong to the .NET Framework class library. This is a generic term that includes user controls. A custom server control is used in Web Forms (ASP.NET pages). A custom client control is used in Windows Forms applications.User Controls:In ASP.NET: A user-authored server control that enables an ASP.NET page to be re-used as a server control. An ASP.NET user control is authored declaratively and persisted as a text file with an .ascx extension. The ASP.NET page framework compiles a user control on the fly to a class that derives from the System.Web.UI.UserControl class.What are the validation controls?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 using client script.What's the difference between Response.Write() andResponse.Output.Write()?The latter one allows you to write formattedoutput.What methods are fired during the page load? Init() When the page is instantiated, Load() - when the page is loaded into server memory,PreRender () - the brief moment before the page is displayed to the user as HTML, Unload() - when page finishes loading.Where does the Web page belong in the .NET Framework class hierarchy?System.Web.UI.PageWhere do you store the information about the user's locale?System.Web.UI.Page.CultureWhat's the difference between Codebehind="MyCode.aspx.cs" and Src="MyCode.aspx.cs"?CodeBehind is relevant to Visual Studio.NET only.What's a bubbled event?When you have a complex control, likeDataGrid, 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.Suppose you want a certain ASP.NET function executed on MouseOver over a certain button.Where do you add an event handler?It's the Attributesproperty, the Add function inside that property. e.g. btnSubmit.Attributes.Add("onMouseOver","someClientCode();")What data type does the RangeValidator control support?Integer,String and Date.What are the different types of caching?Caching is a technique widely used in computing to increase performance by keeping frequently accessed or expensive data in memory. In context of web application, caching is used to retain the pages or data across HTTP requests and reuse them without the expense of recreating them.ASP.NET has 3 kinds of caching strategiesOutput CachingFragment CachingData
CachingOutput Caching: Caches the dynamic output generated by a request. Some times it is useful to cache the output of a website even for a minute, which will result in a better performance. For caching the whole page the page should have OutputCache directive.<%@ OutputCache Duration="60" VaryByParam="state" %>
Fragment Caching: Caches the portion of the page generated by the request. Some times it is not practical to cache the entire page, in such cases we can cache a portion of page<%@ OutputCache Duration="120" VaryByParam="CategoryID;SelectedID"%>
Data Caching: Caches the objects programmatically. For data caching asp.net provides a cache object for eg: cache["States"] = dsStates;What do you mean by authentication and authorization?Authentication is the process of validating a user on the credentials (username and password) and authorization performs after authentication. After Authentication a user will be verified for performing the various tasks, It access is limited it is known as authorization.What are different types of directives in .NET?@Page: Defines page-specific attributes used by the ASP.NET page parser and compiler. Can be included only in .aspx files <%@ Page AspCompat="TRUE" language="C#" %> @Control:Defines control-specific attributes used by the ASP.NET page parser and compiler. Can be included only in .ascx files. <%@ Control Language="VB" EnableViewState="false" %>@Import: Explicitly imports a namespace into a page or user control. The Import directive cannot have more than one namespace attribute. To import multiple namespaces, use multiple @Import directives. <% @ Import Namespace="System.web" %>@Implements: Indicates that the current page or user control implements the specified .NET framework interface.<%@ Implements Interface="System.Web.UI.IPostBackEventHandler" %>@Register: Associates aliases with namespaces and class names for concise notation in custom server control syntax.<%@ Register Tagprefix="Acme" Tagname="AdRotator" Src="AdRotator.ascx" %>@Assembly: Links an assembly to the current page during compilation, making all the assembly's classes and interfaces available for use on the page. <%@ Assembly Name="MyAssembly" %><%@ Assembly Src="MySource.vb" %>@OutputCache: Declaratively controls the output caching policies of an ASP.NET page or a user control contained in a page<%@ OutputCache Duration="#ofseconds" Location="Any | Client | Downstream | Server | None" Shared="True | False" VaryByControl="controlname" VaryByCustom="browser | customstring" VaryByHeader="headers" VaryByParam="parametername" %>@Reference: Declaratively indicates that another user control or page source file should be dynamically compiled and linked against the page in which this directive is declared.
How do I debug an ASP.NET application that wasn't written with Visual Studio.NET and that doesn't use code-behind?Start the DbgClr debugger that comes with the .NET Framework SDK, open the file containing the code you want to debug, and set your breakpoints. Start the ASP.NET application. Go back to DbgClr, choose Debug Processes from the Tools menu, and select aspnet_wp.exe from the list of processes. (If aspnet_wp.exe doesn't appear in the list,check the "Show system processes" box.) Click the Attach button to attach to aspnet_wp.exe and begin debugging.Be sure to enable debugging in the ASPX file before debugging it with DbgClr. You can enable tell ASP.NET to build debug executables by placing a<%@ Page Debug="true" %> statement at the top of an ASPX file or a <COMPILATION debug="true" />statement in a Web.config file. Can a user browsing my Web site read my Web.config or Global.asax files?No. The <HTTPHANDLERS>section of Machine.config, which holds the master configuration settings for ASP.NET, contains entries that map ASAX files, CONFIG files, and selected other file types to an HTTP handler named HttpForbiddenHandler, which fails attempts to retrieve the associated file. You can modify it by editing Machine.config or including an section in a local Web.config file.What's the difference between Page.RegisterClientScriptBlock and Page.RegisterStartupScript?RegisterClientScriptBlock is for returning blocks of client-side script containing functions. RegisterStartupScript is for returning blocks of client-script not packaged in functions-in other words, code that's to execute when the page is loaded. The latter positions script blocks near the end of the document so elements on the page that the script interacts are loaded before the script runs.<%@ Reference Control="MyControl.ascx" %>
Is it necessary to lock application state before accessing it?Only if you're performing a multistep update and want the update to be treated as an atomic operation. Here's an example: Application.Lock (); Application["ItemsSold"] = (int) Application["ItemsSold"] + 1; Application["ItemsLeft"] = (int) Application["ItemsLeft"] - 1; Application.UnLock (); By locking application state before updating it and unlocking it afterwards, you ensure that another request being processed on another thread doesn't read application state at exactly the wrong time and see an inconsistent view of it. If I update session state, should I lock it, too? Are concurrent accesses by multiple requests executing on multiple threads a concern with session state?Concurrent accesses aren't an issue with session state, for two reasons. One, it's unlikely that two requests from the same user will overlap. Two, if they do overlap, ASP.NET locks down session state during request processing so that two threads can't touch it at once. Session state is locked down when the HttpApplication instance that's processing the request fires an AcquireRequestState event and unlocked when it fires a ReleaseRequestState event.
Do ASP.NET forms authentication cookies provide any protection against replay attacks? Do they, for example, include the client's IP address or anything else that would distinguish the real client from an attacker?No. If an authentication cookie is stolen, it can be used by an attacker. It's up to you to prevent this from happening by using an encrypted communications channel (HTTPS). Authentication cookies issued as session cookies, do, however,include a time-out valid that limits their lifetime. So a stolen session cookie can only be used in replay attacks as long as the ticket inside the cookie is valid. The default time-out interval is 30 minutes.You can change that by modifying the timeout attribute accompanying the <forms> element in Machine.config or a local Web.config file. Persistent authentication cookies do not time-out and therefore are a more serious security threat if stolen.
How do I send e-mail from an ASP.NET application? MailMessage message = new MailMessage (); message.From = <email>; message.To = <email>; message.Subject = "Scheduled Power Outage"; message.Body = "Our servers will be down tonight."; SmtpMail.SmtpServer = "localhost"; SmtpMail.Send (message);
MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's System.Web.Mail namespace. Due to a security change made to ASP.NET just before it shipped, you need to set SmtpMail's SmtpServer property to "localhost" even though "localhost" is the default. In addition, you must use the IIS configuration applet to enable localhost (127.0.0.1) to relay messages through the local SMTP service.
What are VSDISCO files?
VSDISCO files are DISCO files that support dynamic discovery of Web services. If you place the following VSDISCO file in a directory on your Web server, for example, it returns references to all ASMX and DISCO files in the host directory and any subdirectories not noted in <exclude> elements: <?xml version="1.0" ?> <dynamicDiscovery xmlns="urn:schemas-dynamicdiscovery:disco.2000-03-17"> <exclude path="_vti_cnf" /> <exclude path="_vti_pvt" /> <exclude path="_vti_log" /> <exclude path="_vti_script" /> <exclude path="_vti_txt" /> </dynamicDiscovery>
How does dynamic discovery work?ASP.NET maps the file name extension VSDISCO to an HTTP handler that scans the host directory and subdirectories for ASMX and DISCO files and returns a dynamically generated DISCO document. A client who requests a VSDISCO file gets back what appears to be a static DISCO document.Note that VSDISCO files are disabled in the release version of ASP.NET. You can reenable them by uncommenting the line in the <httpHandlers> section of Machine.config that maps *.vsdisco to System.Web.Services.Discovery.DiscoveryRequestHandler and granting the ASPNET user account permission to read the IIS metabase. However, Microsoft is actively discouraging the use of VSDISCO files because they could represent a threat to Web server security. Is it possible to prevent a browser from caching an ASPX page?Just call SetNoStore on the HttpCachePolicy object exposed through the Response object's Cache property, as demonstrated here: <%@ Page Language="C#" %> <html> <body> <% Response.Cache.SetNoStore (); Response.Write (DateTime.Now.ToLongTimeString ()); %> </body> </html>
SetNoStore works by returning a Cache-Control: private, no-store header in the HTTP response. In this example, it prevents caching of a Web page that shows the current time.
What does AspCompat="true" mean and when should I use it?AspCompat is an aid in migrating ASP pages to ASPX pages. It defaults to false but should be set to true in any ASPX file that creates apartment-threaded COM objects--that is, COM objects registered ThreadingModel=Apartment. That includes all COM objects written with Visual Basic 6.0. AspCompat should also be set to true (regardless of threading model) if the page creates COM objects that access intrinsic ASP objects such as Request and Response. The following directive sets AspCompat to true:
<%@ Page AspCompat="true" %>
Setting AspCompat to true does two things. First, it makes intrinsic ASP objects available to the COM components by placing unmanaged wrappers around the equivalent ASP.NET objects. Second, it improves the performance of calls that the page places to apartment- threaded COM objects by ensuring that the page (actually, the thread that processes the request for the page) and the COM objects it creates share an apartment. AspCompat="true" forces ASP.NET request threads into single-threaded apartments (STAs). If those threads create COM objects marked ThreadingModel=Apartment, then the objects are created in the same STAs as the threads that created them. Without AspCompat="true," request threads run in a multithreaded apartment (MTA) and each call to an STA-based COM object incurs a performance hit when it's marshaled across apartment boundaries.
Do not set AspCompat to true if your page uses no COM objects or if it uses COM objects that don't access ASP intrinsic objects and that are registered ThreadingModel=Free or ThreadingModel=Both.
Explain the differences between Server-side and Client-side code? Server side scripting means that all the script will be executed by the server and interpreted as needed. ASP doesn't have some of the functionality like sockets, uploading, etc. For these you have to make a custom components usually in VB or VC++. Client side scripting means that the script will be executed immediately in the browser such as form field validation, clock, email validation, etc. Client side scripting is usually done in VBScript or JavaScript. Download time, browser compatibility, and visible code - since JavaScript and VBScript code is included in the HTML page, then anyone can see the code by viewing the page source. Also a possible security hazards for the client computer.
What type of code (server or client) is found in a Code-Behind class?C#
Should validation (did the user enter a real date) occur server-side or client-side? Why?Client-side validation because there is no need to request a server side date when you could obtain a date from the client machine.
What are ASP.NET Web Forms? How is this technology different than what is available though ASP?Web Forms are the heart and soul of ASP.NET. Web Forms are the User Interface (UI) elements that give your Web applications their look and feel. Web Forms are similar to Windows Forms in that they provide properties, methods, and events for the controls that are placed onto them. However, these UI elements render themselves in the appropriate markup language required by the request, e.g. HTML. If you use Microsoft Visual Studio .NET, you will also get the familiar drag-and-drop interface used to create your UI for your Web application.
What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?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.
How can you provide an alternating color scheme in a Repeater control?AlternatingItemTemplate Like the ItemTemplate element, but rendered for every other row (alternating items) in the Repeater control. You can specify a different appearance for the AlternatingItemTemplate element by setting its style properties.
Which template must you provide, in order to display data in a Repeater control?ItemTemplate
What event handlers can I include in Global.asax?Application_Start,Application_End, Application_AcquireRequestState, Application_AuthenticateRequest, Application_AuthorizeRequest, Application_BeginRequest, Application_Disposed, Application_EndRequest, Application_Error, Application_PostRequestHandlerExecute, Application_PreRequestHandlerExecute, Application_PreSendRequestContent, Application_PreSendRequestHeaders, Application_ReleaseRequestState, Application_ResolveRequestCache, Application_UpdateRequestCache, Session_Start,Session_EndYou can optionally include "On" in any of method names. For example, you can name a BeginRequest event handler.Application_BeginRequest or Application_OnBeginRequest.You can also include event handlers in Global.asax for events fired by custom HTTP modules.Note that not all of the event handlers make sense for Web Services (they're designed for ASP.NET applications in general, whereas .NET XML Web Services are specialized instances of an ASP.NET app). For example, the Application_AuthenticateRequest and Application_AuthorizeRequest events are designed to be used with ASP.NET Forms authentication.
What is different b/w webconfig.xml & Machineconfig.xmlWeb.config & machine.config both are configuration files.Web.config contains settings specific to an application where as machine.config contains settings to a computer. The Configuration system first searches settings in machine.config file & then looks in application configuration files.Web.config, can appear in multiple directories on an ASP.NET Web application server. Each Web.config file applies configuration settings to its own directory and all child directories below it. There is only Machine.config file on a web server.
If I'm developing an application that must accomodate multiple security levels though secure login and my ASP.NET web appplication is spanned across three web-servers (using round-robbin load balancing) what would be the best approach to maintain login-in state for the users?Use the state server or store the state in the database. This can be easily done through simple setting change in the web.config. <SESSIONSTATE StateConnectionString="tcpip=127.0.0.1:42424" sqlConnectionString="data source=127.0.0.1; user id=sa; password=" cookieless="false" timeout="30" />
You can specify mode as “stateserver” or “sqlserver”.
Where would you use an iHTTPModule, and what are the limitations of any approach you might take in implementing one"One of ASP.NET's most useful features is the extensibility of the HTTP pipeline, the path that data takes between client and server. You can use them to extend your ASP.NET applications by adding pre- and post-processing to each HTTP request coming into your application. For example, if you wanted custom authentication facilities for your application, the best technique would be to intercept the request when it comes in and process the request in a custom HTTP module.
How do you turn off cookies for one page in your site?Since no Page Level directive is present, I am afraid that cant be done.
How do you create a permanent cookie? Permanent cookies are available until a specified expiration date, and are stored on the hard disk.So Set the 'Expires' property any value greater than DataTime.MinValue with respect to the current datetime. If u want the cookie which never expires set its Expires property equal to DateTime.maxValue.
Which method do you use to redirect the user to another page without performing a round trip to the client?Server.Transfer and Server.Execute
What property do you have to set to tell the grid which page to go to when using the Pager object?CurrentPageIndex
Should validation (did the user enter a real date) occur server-side or client-side? Why? It should occur both at client-side and Server side.By using expression validator control with the specified expression ie.. the regular expression provides the facility of only validatating the date specified is in the correct format or not. But for checking the date where it is the real data or not should be done at the server side, by getting the system date ranges and checking the date whether it is in between that range or not.
What does the "EnableViewState" property do? Why would I want it on or off? Enable ViewState turns on the automatic state management feature that enables server controls to re-populate their values on a round trip without requiring you to write any code. This feature is not free however, since the state of a control is passed to and from the server in a hidden form field. You should be aware of when ViewState is helping you and when it is not. For example, if you are binding a control to data on every round trip, then you do not need the control to maintain it's view state, since you will wipe out any re-populated data in any case. ViewState is enabled for all server controls by default. To disable it, set the EnableViewState property of the control to false.
What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other? 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 location (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.
Can you give an example of when it would be appropriate to use a web service as opposed to a non-serviced .NET component?
Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines? The Application_Start event is guaranteed to occur only once throughout the lifetime of the application. It's a good place to initialize global variables. For example, you might want to retrieve a list of products from a database table and place the list in application state or the Cache object. SessionStateModule exposes both Session_Start and Session_End events.
What are the advantages and disadvantages of viewstate?The primary advantages of the ViewState feature in ASP.NET are:
1. Simplicity. There is no need to write possibly complex code to store form data between page submissions. 2. Flexibility. It is possible to enable, configure, and disable ViewState on a control-by-control basis, choosing to persist the values of some fields but not others.
There are, however a few disadvantages that are worth pointing out:
1. Does not track across pages. ViewState information does not automatically transfer from page to page. With the session approach, values can be stored in the session and accessed from other pages. This is not possible with ViewState, so storing data into the session must be done explicitly.
2. ViewState is not suitable for transferring data for back-end systems. That is, data still has to be transferred to the back end using some form of data object.
Describe session handling in a webfarm, how does it work and what are the limits? ASP.NET Session supports storing of session data in 3 ways, i] in In-Process ( in the same memory that ASP.NET uses) , ii] out-of-process using Windows NT Service )in separate memory from ASP.NET ) or iii] in SQL Server (persistent storage). Both the Windows Service and SQL Server solution support a webfarm scenario where all the web-servers can be configured to share common session state store. 1. Windows Service :We can start this service by Start | Control Panel | Administrative Tools | Services | . In that we service names ASP.NET State Service. We can start or stop service by manually or configure to start automatically. Then we have to configure our web.config file
<CONFIGURATION><configuration> <system.web> <SessionState mode = “StateServer” stateConnectionString = “tcpip=127.0.0.1:42424” stateNetworkTimeout = “10” sqlConnectionString=”data source = 127.0.0.1; uid=sa;pwd=” cookieless =”Flase” timeout= “20” /> </system.web></configuration> </SYSTEM.WEB></CONFIGURATION>Here ASP.Net Session is directed to use Windows Service for state management on local server (address : 127.0.0.1 is TCP/IP loop-back address). The default port is 42424. we can configure to any port but for that we have to manually edit the registry. Follow these simple steps- In a webfarm make sure you have the same config file in all your web servers.- Also make sure your objects are serializable.- For session state to be maintained across different web servers in the webfarm, the application path of the web-site in the IIS Metabase should be identical in all the web-servers in the webfarm.
Which template must you provide, in order to display data in a Repeater control? You have to use the ItemTemplate to Display data. Syntax is as follows, < ItemTemplate > < div class =”rItem” > < img src=”images/<%# Container.DataItem(“ImageURL”)%>” hspace=”10” /> < b > <% # Container.DataItem(“Title”)%> < /div > < ItemTemplate >
How can you provide an alternating color scheme in a Repeater control? Using the AlternatintItemTemplate
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? Set the DataMember property to the name of the table to bind to. (If this property is not set, by default the first table in the dataset is used.)DataBind method, use this method to bind data from a source to a server control. This method is commonly used after retrieving a data set through a database query.
What method do you use to explicitly kill a user s session? You can dump (Kill) the session yourself by calling the method Session.Abandon.
ASP.NET automatically deletes a user's Session object, dumping its contents, after it has been idle for a configurable timeout interval. This interval, in minutes, is set in the <SESSIONSTATE>section of the web.config file. The default is 20 minutes.
How do you turn off cookies for one page in your site? Use Cookie.Discard property, Gets or sets the discard flag set by the server. When true, this property instructs the client application not to save the Cookie on the user's hard disk when a session ends.
Which two properties are on every validation control? We have two common properties for every validation controls 1. Control to Validate,2. Error Message.
What tags do you need to add within the asp:datagrid tags to bind columns manually?
< asp:DataGrid id="dgCart" AutoGenerateColumns="False" CellPadding="4" Width="448px" runat="server" > < Columns >< asp:ButtonColumn HeaderText="SELECT" Text="SELECT" CommandName="select" >< /asp:ButtonColumn >< asp:BoundColumn DataField="ProductId" HeaderText="Product ID" >< /asp:BoundColumn >< asp:BoundColumn DataField="ProductName" HeaderText="Product Name" >< /asp:BoundColumn >< asp:BoundColumn DataField="UnitPrice" HeaderText="UnitPrice" >< /asp:BoundColumn >< /Columns >< /asp:DataGrid >
How do you create a permanent cookie? Permanent cookies are the ones that are most useful. Permanent cookies are available until a specified expiration date, and are stored on the hard disk. The location of cookies differs with each browser, but this doesn’t matter, as this is all handled by your browser and the server. If you want to create a permanent cookie called Name with a value of Nigel, which expires in one month, you’d use the following codeResponse.Cookies ("Name") = "Nigel"Response.Cookies ("Name"). Expires = DateAdd ("m", 1, Now ())
What tag do you use to add a hyperlink column to the DataGrid? < asp:HyperLinkColumn > </ asp:HyperLinkColumn>
Which method do you use to redirect the user to another page without performing a round trip to the client? Server.transfer
What is the transport protocol you use to call a Web service SOAP ?HTTP Protocol
Explain role based security ?Role Based Security lets you identify groups of users to allow or deny based on their role in the organization.In Windows NT and Windows XP, roles map to names used to identify user groups. Windows defines several built-in groups, including Administrators, Users, and Guests.To allow or deny access to certain groups of users, add the <ROLES>element to the authorization list in your Web application's Web.config file.e.g.<AUTHORIZATION>< authorization > < allow roles="Domain Name\Administrators" / > < !-- Allow Administrators in domain. -- > < deny users="*" / > < !-- Deny anyone else. -- >< /authorization >
How do you register JavaScript for webcontrols ?You can register javascript for controls using <CONTROL -name>Attribtues.Add(scriptname,scripttext) method.
When do you set "<IDENTITY impersonate="true" />" ?Identity is a webconfig declaration under System.web, which helps to control the application Identity of the web applicaton. Which can be at any level(Machine,Site,application,subdirectory,or page), attribute impersonate with "true" as value specifies that client impersonation is used.
What are different templates available in Repeater,DataList and Datagrid ?Templates enable one to apply complicated formatting to each of the items displayed by a control.Repeater control supports five types of templates.HeaderTemplate controls how the header of the repeater control is formatted.ItemTemplate controls the formatting of each item displayed.AlternatingItemTemplate controls how alternate items are formatted and the SeparatorTemplate displays a separator between each item displyed.FooterTemplate is used for controlling how the footer of the repeater control is formatted.The DataList and Datagrid supports two templates in addition to the above five.SelectedItem Template controls how a selected item is formatted and EditItemTemplate controls how an item selected for editing is formatted.
What is ViewState ? and how it is managed ? ASP.NET ViewState is a new kind of state service that developers can use to track UI state on a per-user basis. Internally it uses an an old Web programming trick-roundtripping state in a hidden form field and bakes it right into the page-processing framework.It needs less code to write and maintain state in your Web-based forms.
What is web.config file ? Web.config file is the configuration file for the Asp.net web application. There is one web.config file for one asp.net application which configuresthe particular application. Web.config file is written in XML with specific tags having specific meanings.It includes databa which includesconnections,Session States,Error Handling,Security etc.For example :
< configuration > < appSettings > < add key="ConnectionString" value="server=localhost;uid=sa;pwd=;database=MyDB" / > < /appSettings >< /configuration >
What is advantage of viewstate and what are benefits? When a form is submitted in classic ASP, all form values are cleared. Suppose you have submitted a form with a lot of information and the server comes back with an error. You will have to go back to the form and correct the information. You click the back button, and what happens.......ALL form values are CLEARED, and you will have to start all over again! The site did not maintain your ViewState.With ASP .NET, the form reappears in the browser window together with all form values.This is because ASP .NET maintains your ViewState. The ViewState indicates the status of the page when submitted to the server.
What tags do you need to add within the asp:datagrid tags to bind columns manually?Set AutoGenerateColumns Property to false on the datagrid tag and then use Column tag and an ASP:databound tag
< asp:DataGrid runat="server" id="ManualColumnBinding" AutoGenerateColumns="False" > < Columns > < asp:BoundColumn HeaderText="Column1" DataField="Column1"/ > < asp:BoundColumn HeaderText="Column2" DataField="Column2"/ > < /Columns >< /asp:DataGrid ><asp:DataGrid id=ManualColumnBinding runat="server" AutoGenerateColumns="False"><COLUMNS> <asp:BoundColumn HeaderText="Column2" DataField="Column2"></asp:BoundColumn></asp:DataGrid>Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box? DataTextField and DataValueField
Which control would you use if you needed to make sure the values in two different controls matched? CompareValidator is used to ensure that two fields are identical.
What is validationsummary server control?where it is used?.The ValidationSummary control allows you to summarize the error messages from all validation controls on a Web page in a single location. The summary can be displayed as a list, a bulleted list, or a single paragraph, based on the value of the DisplayMode property. The error message displayed in the ValidationSummary control for each validation control on the page is specified by the ErrorMessage property of each validation control. If the ErrorMessage property of the validation control is not set, no error message is displayed in the ValidationSummary control for that validation control. You can also specify a custom title in the heading section of the ValidationSummary control by setting the HeaderText property.You can control whether the ValidationSummary control is displayed or hidden by setting the ShowSummary property. The summary can also be displayed in a message box by setting the ShowMessageBox property to true.
What is the sequence of operation takes place when a page is loaded?BeginTranaction - only if the request is transactedInit - every time a page is processedLoadViewState - Only on postbackProcessPostData1 - Only on postbackLoad - every timeProcessData2 - Only on PostbackRaiseChangedEvent - Only on PostbackRaisePostBackEvent - Only on PostbackPreRender - everytimeBuildTraceTree - only if tracing is enabledSaveViewState - every timeRender - EverytimeEnd Transaction - only if the request is transactedTrace.EndRequest - only when tracing is enabledUnloadRecursive - Every request
Difference between asp and asp.net?."ASP (Active Server Pages) and ASP.NET are both server side technologies for building web sites and web applications, ASP.NET is Managed compiled code - asp is interpreted. and ASP.net is fully Object oriented. ASP.NET has been entirely re-architected to provide a highly productive programming experience based on the .NET Framework, and a robust infrastructure for building reliable and scalable webapplications."
Name the validation control available in asp.net?.RequiredField, RangeValidator,RegularExpression,Custom validator,compare Validator
What are the various ways of securing a web site that could prevent from hacking etc .. ?1) Authentication/Authorization2) Encryption/Decryption3) Maintaining web servers outside the corporate firewall. etc.,
What is the difference between in-proc and out-of-proc? An inproc is one which runs in the same process area as that of the client giving tha advantage of speed but the disadvantage of stability becoz if it crashes it takes the client application also with it.Outproc is one which works outside the clients memory thus giving stability to the client, but we have to compromise a bit on speed.
When you’re running a component within ASP.NET, what process is it running within on Windows XP? Windows 2000? Windows 2003?On Windows 2003 (IIS 6.0) running in native mode, the component is running within the w3wp.exe process associated with the application pool which has been configured for the web application containing the component.
On Windows 2003 in IIS 5.0 emulation mode, 2000, or XP, it's running within the IIS helper process whose name I do not remember, it being quite a while since I last used IIS 5.0.
What does aspnet_regiis -i do ?Aspnet_regiis.exe is The ASP.NET IIS Registration tool allows an administrator or installation program to easily update the script maps for an ASP.NET application to point to the ASP.NET ISAPI version associated with the tool. The tool can also be used to display the status of all installed versions of ASP. NET, register the ASP.NET version coupled with the tool, create client-script directories, and perform other configuration operations. When multiple versions of the .NET Framework are executing side-by-side on a single computer, the ASP.NET ISAPI version mapped to an ASP.NET application determines which version of the common language runtime is used for the application. The tool can be launched with a set of optional parameters. Option "i" Installs the version of ASP.NET associated with Aspnet_regiis.exe and updates the script maps at the IIS metabase root and below. Note that only applications that are currently mapped to an earlier version of ASP.NET are affected
What is a PostBack? The process in which a Web page sends data back to the same page on the server.
What is ViewState? How is it encoded? Is it encrypted? Who uses ViewState? ViewState is the mechanism ASP.NET uses to keep track of server control state values that don't otherwise post back as part of the HTTP form. ViewState Maintains the UI State of a Page ViewState is base64-encoded. It is not encrypted but it can be encrypted by setting EnableViewStatMAC="true" & setting the machineKey validation type to 3DES. If you want to NOT maintain the ViewState, include the directive < %@ Page EnableViewState="false" % > at the top of an .aspx page or add the attribute EnableViewState="false" to any control.
What is the < machinekey > element and what two ASP.NET technologies is it used for? Configures keys to use for encryption and decryption of forms authentication cookie data and view state data, and for verification of out-of-process session state identification.There fore 2 ASP.Net technique in which it is used are Encryption/Decryption & Verification
What three Session State providers are available in ASP.NET 1.1? What are the pros and cons of each? ASP.NET provides three distinct ways to store session data for your application: in-process session state, out-of-process session state as a Windows service, and out-of-process session state in a SQL Server database. Each has it advantages.
1.In-process session-state modeLimitations: * When using the in-process session-state mode, session-state data is lost if aspnet_wp.exe or the application domain restarts. * If you enable Web garden mode in the < processModel > element of the application's Web.config file, do not use in-process session-state mode. Otherwise, random data loss can occur. Advantage: * in-process session state is by far the fastest solution. If you are storing only small amounts of volatile data in session state, it is recommended that you use the in-process provider.
2. The State Server simply stores session state in memory when in out-of-proc mode. In this mode the worker process talks directly to the State Server
3. SQL mode, session states are stored in a SQL Server database and the worker process talks directly to SQL. The ASP.NET worker processes are then able to take advantage of this simple storage service by serializing and saving (using .NET serialization services) all objects within a client's Session collection at the end of each Web request Both these out-of-process solutions are useful primarily if you scale your application across multiple processors or multiple computers, or where data cannot be lost if a server or process is restarted.
What is the difference between HTTP-Post and HTTP-Get?As their names imply, both HTTP GET and HTTP POST use HTTP as their underlying protocol. Both of these methods encode request parameters as name/value pairs in the HTTP request. The GET method creates a query string and appends it to the script's URL on the server that handles the request. The POST method creates a name/value pairs that are passed in the body of the HTTP request message.
Name and describe some HTTP Status Codes and what they express to the requesting client. When users try to access content on a server that is running Internet Information Services (IIS) through HTTP or File Transfer Protocol (FTP), IIS returns a numeric code that indicates the status of the request. This status code is recorded in the IIS log, and it may also be displayed in the Web browser or FTP client. The status code can indicate whether a particular request is successful or unsuccessful and can also reveal the exact reason why a request is unsuccessful. There are 5 groups ranging from 1xx - 5xx of http status codes exists.101 - Switching protocols.200 - OK. The client request has succeeded302 - Object moved. 400 - Bad request.500.13 - Web server is too busy.
Explain < @OutputCache% > and the usage of VaryByParam, VaryByHeader. OutputCache is used to control the caching policies of an ASP.NET page or user control. To cache a page @OutputCache directive should be defined as follows < %@ OutputCache Duration="100" VaryByParam="none" % >
VaryByParam: A semicolon-separated list of strings used to vary the output cache. By default, these strings correspond to a query string value sent with GET method attributes, or a parameter sent using the POST method. When this attribute is set to multiple parameters, the output cache contains a different version of the requested document for each specified parameter. Possible values include none, *, and any valid query string or POST parameter name.
VaryByHeader: A semicolon-separated list of HTTP headers used to vary the output cache. When this attribute is set to multiple headers, the output cache contains a different version of the requested document for each specified header.
What is the difference between repeater over datalist and datagrid?
The Repeater class is not derived from the WebControl class, like the DataGrid and DataList. Therefore, the Repeater lacks the stylistic properties common to both the DataGrid and DataList. What this boils down to is that if you want to format the data displayed in the Repeater, you must do so in the HTML markup. The Repeater control provides the maximum amount of flexibility over the HTML produced. Whereas the DataGrid wraps the DataSource contents in an HTML < table >, and the DataList wraps the contents in either an HTML < table > or < span > tags (depending on the DataList's RepeatLayout property), the Repeater adds absolutely no HTML content other than what you explicitly specify in the templates.While using Repeater control, If we wanted to display the employee names in a bold font we'd have to alter the "ItemTemplate" to include an HTML bold tag, Whereas with the DataGrid or DataList, we could have made the text appear in a bold font by setting the control's ItemStyle-Font-Bold property to True.The Repeater's lack of stylistic properties can drastically add to the development time metric. For example, imagine that you decide to use the Repeater to display data that needs to be bold, centered, and displayed in a particular font-face with a particular background color. While all this can be specified using a few HTML tags, these tags will quickly clutter the Repeater's templates. Such clutter makes it much harder to change the look at a later date. Along with its increased development time, the Repeater also lacks any built-in functionality to assist in supporting paging, editing, or editing of data. Due to this lack of feature-support, the Repeater scores poorly on the usability scale.
However, The Repeater's performance is slightly better than that of the DataList's, and is more noticeably better than that of the DataGrid's. Following figure shows the number of requests per second the Repeater could handle versus the DataGrid and DataList
Can we handle the error and redirect to some pages using web.config?
Yes, we can do this, but to handle errors, we must know the error codes; only then we can take the user to a proper error message page, else it may confuse the user. CustomErrors Configuration section in web.config file:The default configuration is:< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" > < error statusCode="404" redirect="Notfound.aspx" / > < /customErrors >If mode is set to Off, custom error messages will be disabled. Users will receive detailed exception error messages.If mode is set to On, custom error messages will be enabled. If mode is set to RemoteOnly, then users will receive custom errors, but users accessing the site locally will receive detailed error messages.Add an < error > tag for each error you want to handle. The error tag will redirect the user to the Notfound.aspx page when the site returns the 404 (Page not found) error.
[Example]
There is a page MainForm.aspx
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'Put user code to initialize the page hereDim str As System.Text.StringBuilderstr.Append("hi") ' Error Line as str is not instantiatedResponse.Write(str.ToString)End Sub
[Web.Config]
< customErrors mode="On" defaultRedirect="Error.aspx"/ >' a simple redirect will take the user to Error.aspx [user defined] error file.
< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" > < error statusCode="404" redirect="Notfound.aspx" / > < /customErrors >'This will take the user to NotFound.aspx defined in IIS.
How do you implement Paging in .Net?
The DataGrid provides the means to display a group of records from the data source (for example, the first 10), and then navigate to the "page" containing the next 10 records, and so on through the data.
Using Ado.Net we can explicit control over the number of records returned from the data source, as well as how much data is to be cached locally in the DataSet.1.Using DataAdapter.fill method give the value of 'Maxrecords' parameter (Note: - Don't use it because query will return all records but fill the dataset based on value of 'maxrecords' parameter).2.For SQL server database, combines a WHERE clause and a ORDER BY clause with TOP predicate.3.If Data does not change often just cache records locally in DataSet and just take some records from the DataSet to display.
What is the difference between Server.Transfer and Response.Redirect?
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 across 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 knows the physical location (page name and query string as well). Context.Items loses the persistence when navigate 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. Response.Redirect sends a response to the client browser instructing it to request the second page. This requires a round-trip to the client, and the client initiates the Request for the second page. Server.Transfer transfers the process to the second page without making a round-trip to the client. It also transfers the HttpContext to the second page, enabling the second page access to all the values in the HttpContext of the first page.
Can you create an app domain?
Yes, We can create user app domain by calling on of the following overload static methods of the System.AppDomain class1. Public static AppDomain CreateDomain(String friendlyName)2. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo)3. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, AppDomainSetup info)4. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, String appBasePath, String appRelativeSearchPath, bool shadowCopyFiles)
What are the various security methods which IIS Provides apart from .NET ?
The various security methods which IIS provides are
a) Authentication Modesb) IP Address and Domain Name Restrictionc) DNS Lookups DNS Lookupsd) The Network ID and Subnet Maske) SSL
What is Web Gardening? How would using it affect a design?
The Web Garden ModelThe Web garden model is configurable through the section of the machine.config file. Notice that the section is the only configuration section that cannot be placed in an application-specific web.config file. This means that the Web garden mode applies to all applications running on the machine. However, by using the node in the machine.config source, you can adapt machine-wide settings on a per-application basis.
Two attributes in the section affect the Web garden model. They are webGarden and cpuMask. The webGarden attribute takes a Boolean value that indicates whether or not multiple worker processes (one per each affinitized CPU) have to be used. The attribute is set to false by default. The cpuMask attribute stores a DWORD value whose binary representation provides a bit mask for the CPUs that are eligible to run the ASP.NET worker process. The default value is -1 (0xFFFFFF), which means that all available CPUs can be used. The contents of the cpuMask attribute is ignored when the webGarden attribute is false. The cpuMask attribute also sets an upper bound to the number of copies of aspnet_wp.exe that are running.
Web gardening enables multiple worker processes to run at the same time. However, you should note that all processes will have their own copy of application state, in-process session state, ASP.NET cache, static data, and all that is needed to run applications. When the Web garden mode is enabled, the ASP.NET ISAPI launches as many worker processes as there are CPUs, each a full clone of the next (and each affinitized with the corresponding CPU). To balance the workload, incoming requests are partitioned among running processes in a round-robin manner. Worker processes get recycled as in the single processor case. Note that ASP.NET inherits any CPU usage restriction from the operating system and doesn't include any custom semantics for doing this.
All in all, the Web garden model is not necessarily a big win for all applications. The more stateful applications are, the more they risk to pay in terms of real performance. Working data is stored in blocks of shared memory so that any changes entered by a process are immediately visible to others. However, for the time it takes to service a request, working data is copied in the context of the process. Each worker process, therefore, will handle its own copy of working data, and the more stateful the application, the higher the cost in performance. In this context, careful and savvy application benchmarking is an absolute must.
Changes made to the section of the configuration file are effective only after IIS is restarted. In IIS 6, Web gardening parameters are stored in the IIS metabase; the webGarden and cpuMask attributes are ignored.
What is view state?.where it stored?.can we disable it?The web is state-less protocol, so the page gets instantiated, executed, rendered and then disposed on every round trip to the server. The developers code to add "statefulness" to the page by using Server-side storage for the state or posting the page to itself. When require to persist and read the data in control on webform, developer had to read the values and store them in hidden variable (in the form), which were then used to restore the values. With advent of .NET framework, ASP.NET came up with ViewState mechanism, which tracks the data values of server controls on ASP.NET webform. In effect,ViewState can be viewed as "hidden variable managed by ASP.NET framework!". When ASP.NET page is executed, data values from all server controls on page are collected and encoded as single string, which then assigned to page's hidden atrribute "< input type=hidden >", that is part of page sent to the client.
ViewState value is temporarily saved in the client's browser.ViewState can be disabled for a single control, for an entire page orfor an entire web application. The syntax is:
Disable ViewState for control (Datagrid in this example)< asp:datagrid EnableViewState="false" ... / >
Disable ViewState for a page, using Page directive< %@ Page EnableViewState="False" ... % >
Disable ViewState for application through entry in web.config< Pages EnableViewState="false" ... / >
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How many languages .NET is supporting now?
Ans :When .NET was introduced it came with several languages. VB.NET, C#, COBOL and Perl, etc. The site DotNet Languages. Net says 44 languages are supported..
How is .NET able to support multiple languages?
Ans :A language should comply with the Common Language Runtime standard to become a .NET language. In .NET, code is compiled to Microsoft Intermediate Language (MSIL for short). This is called as Managed Code. This Managed code is run in .NET environment. So after compilation to this IL the language is not a barrier. A code can call or use a function written in another language..
How ASP .NET different from ASP?
Ans :Scripting is separated from the HTML, Code is compiled as a DLL, and these DLLs can be executed on the server.
What is smart navigation?
Ans :The cursor position is maintained when the page gets refreshed due to the server side validation and the page gets refreshed.
What is view state?
Ans :The web is stateless. But in ASP.NET, the state of a page is maintained in the in the page itself automatically. How? The values are encrypted and saved in hidden controls. this is done automatically by the ASP.NET. This can be switched off / on for a single control.
How do you validate the controls in an ASP .NET page?
Ans :Using special validation controls that are meant for this. We have Range Validator, Email Validator.
Can the validation be done in the server side? Or this can be done only in the Client side?
Ans :Client side is done by default. Server side validation is also possible. We can switch off the client side and server side can be done..
How to manage pagination in a page?
Ans :Using pagination option in DataGrid control. We have to set the number of records for a page, then it takes care of pagination by itself..
What is ADO .NET and what is difference between ADO and ADO.NET?
Ans :ADO.NET is stateless mechanism. I can treat the ADO.Net as a separate in-memory database where in I can use relationships between the tables and select insert and updates to the database. I can update the actual database as a batch..
Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exein the page loading process.
Ans :inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received (usually a file with .aspx extension),the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe..
What’s the difference between Response.Write() and Response.Output.Write()?
Ans :The latter one allows you to write formatted output..
What methods are fired during the page load?
Ans :Init() - when the pageis instantiated, Load() - when the page is loaded into server memory,PreRender() - the brief moment before the page is displayed to the user asHTML, Unload() - when page finishes loading..
Where does the Web page belong in the .NET Framework class hierarchy?
Ans :System.Web.UI.Page .
Where do you store the information about the user’s locale?
Ans :System.Web.UI.Page.Culture .
What’s the difference between Codebehind="MyCode.aspx.cs" andSrc="MyCode.aspx.cs"?
Ans :CodeBehind is relevant to Visual Studio.NET only.
What’s a bubbled event?
Ans :When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button,row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of its constituents..
Suppose you want a certain ASP.NET function executed on MouseOver over acertain button. Where do you add an event handler?
Ans :It’s the Attributesproperty, the Add function inside that property. So btnSubmit.Attributes.Add("onMouseOver","someClientCode();") A simple”Javascript:ClientCode();” in the button control of the .aspx page will attach the handler (javascript function)to the onmouseover event..
What data type does the RangeValidator control support?
Ans :Integer,String and Date..
Where would you use an iHTTPModule, and what are the limitations of anyapproach you might take in implementing one?
Ans :One of ASP.NET’s most useful features is the extensibility of the HTTP pipeline, the path that data takes between client and server. You can use them to extend your ASP.NET applications by adding pre- and post-processing to each HTTP request coming into your application. For example, if you wanted custom authentication facilities for your application, the best technique would be to intercept the request when it comes in and process the request in a custom HTTP module..
Explain what a diffgram is and a good use for one?
Ans :A DiffGram is an XML format that is used to identify current and original versions of data elements. The DataSet uses the DiffGram format to load and persist its contents, and to serialize its contents for transport across a network connection. When a DataSet is written as a DiffGram, it populates the DiffGram with all the necessary information to accurately recreate the contents, though not the schema, of the DataSet, including column values from both the Original and Current row versions, row error information, and row order..
What is datagrid?
Ans :The DataGrid Web server control is a powerful tool for displaying information from a data source. It is easy to use; you can display editable data in a professional-looking grid by setting only a few properties. At the same time, the grid has a sophisticated object model that provides you with great flexibility in how you display the data..
What’s the difference between the System.Web.UI.WebControls.DataGrid and and System.Windows.Forms.DataGrid?
Ans :The Web UI control does not inherently support master-detail data structures. As with other Web server controls, it does not support two-way data binding. If you want to update data, you must write code to do this yourself. You can only edit one row at a time. It does not inherently support sorting, although it raises events you can handle in order to sort the grid contents. You can bind the Web Forms DataGrid to any object that supports the IEnumerable interface. The Web Forms DataGrid control supports paging. It is easy to customize the appearance and layout of the Web Forms DataGrid control as compared to the Windows Forms one..
How do you customize the column content inside the datagrid?
Ans :If you want to customize the content of a column, make the column a template column. Template columns work like item templates in the DataList or Repeater control, except that you are defining the layout of a column rather than a row. .
How do you apply specific formatting to the data inside the cells?
Ans :You cannot specify formatting for columns generated when the grid’s AutoGenerateColumns property is set to true, only for bound or template columns. To format, set the column’s DataFormatString property to a string-formatting expression suitable for the data type of the data you are formatting..
How do you hide the columns?
Ans :One way to have columns appear dynamically is to create them at design time, and then to hide or show them as needed. You can do this by setting a column’s Visible property.
How do you display an editable drop-down list?
Ans :Displaying a drop-down list requires a template column in the grid. Typically, the ItemTemplate contains a control such as a data-bound Label control to show the current value of a field in the record. You then add a drop-down list to the EditItemTemplate. In Visual Studio, you can add a template column in the Property builder for the grid, and then use standard template editing to remove the default TextBox control from the EditItemTemplate and drag a DropDownList control into it instead. Alternatively, you can add the template column in HTML view. After you have created the template column with the drop-down list in it, there are two tasks. The first is to populate the list. The second is to preselect the appropriate item in the list — for example, if a book’s genre is set to “fiction,” when the drop-down list displays, you often want “fiction” to be preselected.
How do you check whether the row data has been changed?
Ans :The definitive way to determine whether a row has been dirtied is to handle the changed event for the controls in a row. For example, if your grid row contains a TextBox control, you can respond to the control’s TextChanged event. Similarly, for check boxes, you can respond to a CheckedChanged event. In the handler for these events, you maintain a list of the rows to be updated. Generally, the best strategy is to track the primary keys of the affected rows. For example, you can maintain an ArrayList object that contains the primary keys of the rows to update..
What do you know about .NET assemblies?
Ans :Assemblies are the smallest units of versioning and deployment in the .NET application. Assemblies are also the building blocks for programs such as Web services, Windows services, serviced components, and .NET remoting applications.
What’s the difference between private and shared assembly?
Ans :Private assembly is used inside an application only and does not have to be identified by a strong name. Shared assembly can be used by multiple applications and has to have a strong name..
What’s a strong name?
Ans :A strong name includes the name of the assembly, version number, culture identity, and a public key token..
How can you tell the application to look for assemblies at the locations other than its own install?
Ans :Use the directive in the XML .config file for a given application. should do the trick. Or you can add additional search paths in the Properties box of the deployed application..
How can you debug failed assembly binds?
Ans :Use the Assembly Binding Log Viewer (fuslogvw.exe) to find out the paths searched..
Where are shared assemblies stored?
Ans :Global Assembly Cache..
How can you create a strong name for a .NET assembly?
Ans :With the help of Strong Name tool (sn.exe)..
Where’s global assembly cache located on the system?
Ans :Usually C:\winnt\assembly or C:\windows\assembly..
Can you have two files with the same file name in GAC?
Ans :GAC is a very special folder, and while normally you would not be able to place two files with the same name into a Windows folder, GAC differentiates by version number as well, so it’s possible for MyApp.dll and MyApp.dll to co-exist in GAC if the first one is version 1.0.0.0 and the second one is 1.1.0.0..
What is delay signing?
Ans :Delay signing allows you to place a shared assembly in the GAC by signing the assembly with just the public key. This allows the assembly to be signed with the private key at a later stage, when the development process is complete and the component or assembly is ready to be deployed. This process enables developers to work with shared assemblies as if they were strongly named, and it secures the private key of the signature from being accessed at different stages of development..
What’s the difference between code-based security and role-based security? Which one is better?
Ans :Code security is the approach of using permissions and permission sets for a given code to run. The admin, for example, can disable running executables off the Internet or restrict access to corporate database to only few applications. Role-based security most of the time involves the code running with the privileges of the current user. This way the code cannot supposedly do more harm than mess up a single user account. There’s no better, or 100% thumbs-up approach, depending on the nature of deployment, both code-based and role-based security could be implemented to an extent..
How can you work with permissions from your .NET application?
Ans :You can request permission to do something and you can demand certain permissions from other apps. You can also refuse permissions so that your app is not inadvertently used to destroy some data..
How can C# app request minimum permissions?
Ans :Using System.Security.Permissions;[assembly:FileDialogPermissionAttribute(SecurityAction.RequestMinimum, Unrestricted=true)].
What’s a code group?
Ans :A code group is a set of assemblies that share a security context..
What’s the difference between authentication and authorization?
Ans :Authentication happens first. You verify user’s identity based on credentials. Authorization is making sure the user only gets access to the resources he has credentials for..
What are the authentication modes in ASP.NET?
Ans :None, Windows, Forms and Passport..
Are the actual permissions for the application defined at run-time or compile-time?
Ans :The CLR computes actual permissions at runtime based on code group membership and the calling chain of the code..
Explain the differences between Server-side and Client-side code?
Ans :Server side scripting means that all the script will be executed by the server and interpreted as needed. ASP doesn’t have some of the functionality like sockets, uploading, etc. For these you have to make a custom component usually in VB or VC++. Client side scripting means that the script will be executed immediately in the browser such as form field validation, clock, email validation, etc. Client side scripting is usually done in VBScript or JavaScript. Download time, browser compatibility, and visible code - since JavaScript and VBScript code is included in the HTML page, then anyone can see the code by viewing the page source. Also a possible security hazards for the client computer..
Should validation (did the user enter a real date) occur server-side or client-side? Why?
Ans :Client-side validation because there is no need to request a server side date when you could obtain a date from the client machine..
What does the "EnableViewState" property do? Why would I want it on or off?
Ans :Enable ViewState turns on the automatic state management feature that enables server controls to re-populate their values on a round trip without requiring you to write any code. This feature is not free however, since the state of a control is passed to and from the server in a hidden form field. You should be aware of when ViewState is helping you and when it is not. For example, if you are binding a control to data on every round trip (as in the datagrid example in tip #4), then you do not need the control to maintain it’s view state, since you will wipe out any re-populated data in any case. ViewState is enabled for all server controls by default. To disable it, set the EnableViewState property of the control to false..
Can you give an example of what might be best suited to place in the Application_Start and Session_Start subroutines?
Ans :The Application_Start event is guaranteed to occur only once throughout the lifetime of the application. It’s a good place to initialize global variables. For example, you might want to retrieve a list of products from a database table and place the list in application state or the Cache object. SessionStateModule exposes both Session_Start and Session_End events..
What are ASP.NET Web Forms? How is this technology different than what is available though ASP?
Ans :Web Forms are the heart and soul of ASP.NET. Web Forms are the User Interface (UI) elements that give your Web applications their look and feel. Web Forms are similar to Windows Forms in that they provide properties, methods, and events for the controls that are placed onto them. However, these UI elements render themselves in the appropriate markup language required by the request, e.g. HTML. If you use Microsoft Visual Studio .NET, you will also get the familiar drag-and-drop interface used to create your UI for your Web application..
How does VB.NET/C# achieve polymorphism?
Ans :By using Abstract classes/functions..
Can you explain what inheritance is and an example of when you might use it?
Ans :Inheritance is a fundamental feature of an object oriented system and it is simply the ability to inherit data and functionality from a parent object. Rather than developing new objects from scratch, new code can be based on the work of other programmers, adding only new features that are needed..
What’s an assembly?
Ans :Assemblies are the building blocks of .NET Framework applications; they form the fundamental unit of deployment, version control, reuse, activation scoping, and security permissions. An assembly is a collection of types and resources that are built to work together and form a logical unit of functionality. An assembly provides the common language runtime with the information it needs to be aware of type implementations. To the runtime, a type does not exist outside the context of an assembly..
Describe the difference between inline and code behind - which is best in a loosely coupled solution?
Ans :ASP.NET supports two modes of page development: Page logic code that is written inside "script runat=server" blocks within an .aspx file and dynamically compiled the first time the page is requested on the server. Page logic code that is written within an external class that is compiled prior to deployment on a server and linked "behind" the .aspx file at run time..
Explain what a diffgram is, and a good use for one?
In what order do the events of an ASPX page execute. As a developer is it important to undertsand these events?
Ans :Every Page object (which your .aspx page is) has nine events, most of which you will not have to worry about in your day to day dealings with ASP.NET. The three that you will deal with the most are: Page_Init, Page_Load, Page_PreRender..
Which method do you invoke on the DataAdapter control to load your generated dataset with data?
Ans :System.Data.Common.DataAdapter.Fill(System.Data.DataSet);If my DataAdapter is sqlDataAdapter and my DataSet is dsUsers then it is called this way: sqlDataAdapter.Fill(dsUsers);.
How can you provide an alternating color scheme in a Repeater control?
Ans :AlternatingItemTemplate Like the ItemTemplate element, but rendered for every other row (alternating items) in the Repeater control. You can specify a different appearance for the AlternatingItemTemplate element by setting its style properties..
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?
Ans :You must set the DataMember property which Gets or sets the specific table in the DataSource to bind to the control and the DataBind method to bind data from a source to a server control. This method is commonly used after retrieving a data set through a database query..
What method do you use to explicitly kill a user’s session?
Ans :The Abandon method destroys all the objects stored in a Session object and releases their resources. If you do not call the Abandon method explicitly, the server destroys these objects when the session times out.Syntax: Session.Abandon .
How do you turn off cookies for one page in your site?
Ans :Use the Cookie.Discard Property which Gets or sets the discard flag set by the server. When true, this property instructs the client application not to save the Cookie on the user’s hard disk when a session ends.
How is a property designated as read-only?
Ans :In VB.NET:Public ReadOnly Property PropertyName As ReturnTypeGet ‘Your Property Implementation goes in hereEnd GetEnd PropertyIn C# :public returntype PropertyName{get{//property implementation goes here}// Do not write the set implementation}.
Which control would you use if you needed to make sure the values in two different controls matched?
Ans :Use the CompareValidator control to compare the values of 2 different controls..