DOT NET JAVA
What is view state and use of it?
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()?
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 ()
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?
Where does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page
Where do you store the information about the user's locale?
Where do you store the information about the user's locale?
System.Web.UI.Page.Culture
What'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, 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 a certain button.
Where do you add an event handler?
What'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, 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 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?
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
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.
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.
Note: Few of the references are taken from other sites/sources
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.
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:
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:
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#
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.
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
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_End
You 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.
Application_PreSendRequestContent, Application_PreSendRequestHeaders, Application_ReleaseRequestState, Application_ResolveRequestCache, Application_UpdateRequestCache, Session_Start,Session_End
You 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.xml
Web.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.
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.
"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.
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
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.
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.Redirect()
: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?
·
Communicating through
a Firewall When building a distributed application with 100s/1000s of users
spread over multiple locations, there is always the problem of communicating
between client and server because of firewalls and proxy servers. Exposing your
middle tier components as Web Services and invoking the directly from a Windows
UI is a very valid option.
·
Application
Integration When integrating applications written in various languages and
running on disparate systems. Or even applications running on the same platform
that have been written by separate vendors.
·
Business-to-Business
Integration This is an enabler for B2B intergtation which allows one to expose
vital business processes to authorized supplier and customers. An example would
be exposing electronic ordering and invoicing, allowing customers to send you
purchase orders and suppliers to send you invoices electronically.
·
Software Reuse This
takes place at multiple levels. Code Reuse at the Source code level or binary
componet-based resuse. The limiting factor here is that you can reuse the code
but not the data behind it. Webservice overcome this limitation. A scenario
could be when you are building an app that aggregates the functionality of
serveral other Applicatons. Each of these functions could be performed by
individual apps, but there is value in perhaps combining the the multiple apps
to present a unifiend view in a Portal or Intranet.
·
When not to use Web
Services: Single machine Applicatons When the apps are running on the same
machine and need to communicate with each other use a native API. You also have
the options of using component technologies such as COM or .NET Componets as
there is very little overhead.
·
Homogeneous
Applications on a LAN If you have Win32 or Winforms apps that want to
communicate to their server counterpart. It is much more efficient to use DCOM
in the case of Win32 apps and .NET Remoting in the case of .NET Apps
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.
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
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
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.
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 code
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 code
Response.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
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.
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.
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 configures
the particular application. Web.config file is written in XML with specific tags having specific meanings.It includes databa which includes
connections,Session States,Error Handling,Security etc.
For example :
the particular application. Web.config file is written in XML with specific tags having specific meanings.It includes databa which includes
connections,Session States,Error Handling,Security etc.
For example :
< configuration
>
< 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
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.
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 transacted
Init - every time a page is processed
LoadViewState - Only on postback
ProcessPostData1 - Only on postback
Load - every time
ProcessData2 - Only on Postback
RaiseChangedEvent - Only on Postback
RaisePostBackEvent - Only on Postback
PreRender - everytime
BuildTraceTree - only if tracing is enabled
SaveViewState - every time
Render - Everytime
End Transaction - only if the request is transacted
Trace.EndRequest - only when tracing is enabled
UnloadRecursive - 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 web
applications."
"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 web
applications."
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/Authorization
2.
Encryption/Decryption
3.
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.
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
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.
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 mode
Limitations:
* 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.
Limitations:
* 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.
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.
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 succeeded
302 - Object moved.
400 - Bad request.
500.13 - Web server is too busy.
101 - Switching protocols.
200 - OK. The client request has succeeded
302 - 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.
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 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.
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 here
Dim str As System.Text.StringBuilder
str.Append("hi") ' Error Line as str is not instantiated
Response.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.
' 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).
(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 class
1.
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 Modes
b.
IP Address and Domain
Name Restriction
c.
DNS Lookups DNS
Lookups
d.
The Network ID and
Subnet Mask
e.
SSL
What is Web Gardening? How would using it affect a design?
The Web Garden Model
The 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.
The 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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