Web Development Softwares

Validate Phone Number

2011-03-22T21:15:00.000-07:00

In this blog, I am going to explain about validating phone number text box in ASP.NET using Java Script.

Create a Text Box control, given below.

<asp:TextBox ID="txtPhoneNumber" runat="server" Height="18px" Width="129px"

onchange = "this.value = ValidatePhone(this);"></asp:TextBox>

onchange() is used to call a JavaScript function, named as ValidatePhone(). Pass the TextBox control as an argument.

I use Regular Expression to validate phone number. Java Script function could be

function ValidatePhone(phonenumber) {

var regex = /^$?([2-9][0-8][0-9])$?[-. ]?([2-9][0-9]{2})[-. ]?([0-9]{4})$/;

if (regex.test(phonenumber.value)) {

var newPhoneNumber = phonenumber.value.replace(regex, "($1) $2-$3");

return newPhoneNumber;

} else {

alert(" Invalid phone number");

return phonenumber.value;

}

The basic Rules of Valid phone numbers according to the North American Numbering Plan are,

Area codes start with a number from 2–9, followed by 0–8, and then any third digit.
The second group of three digits, known as the central office or exchange code, starts with a number from 2–9, followed by any two digits.
The final four digits, known as the station code, have no restrictions.

These rules can easily be implemented with a few character classes:

^$?([2-9][0-8][0-9])$?[-. ]?([2-9][0-9]{2})[-. ]?([0-9]{4})$

Generally, the phone number format includes 4125671234, 412-567-1234, 412.567.1234, 412 567 1234, (412) 567 1234, and all related combinations. If the phone number is valid, you can convert it to your standard format, (412) 567-1234 for maintaining consistency. This can be done by using replace() method. The replacement is ($1) $2-$3. Now the phone number will be changed into (412) 567-1234.

Happy Coding!!!

How To

2011-03-21T11:37:00.000-07:00

Change the first letter of the Text Box into Upper Case

Validate Phone Number using Java Script

Change the first letter of the Text Box into Upper Case

2011-03-21T11:32:00.001-07:00

How to change the first letter of the Text Box into Upper Case

In this blog, I am going to explain how to change the first letter of the text box control into uppercase. For this, you need to write a JavaScript code.

First create an asp.net text box control in the page, as given below.

<asp:TextBox ID="FirstName" onchange = "convert(this);" runat="server"></asp:TextBox>

The method name convert() is used to call a JavaScript function. Define the method as given below.

function convert(controlname)

{

return;

}

</script>

When the text box lost its focus will change the first letter of the word into upper case.

Partial Page Rendering

2011-02-27T00:26:00.000-08:00

Partial Page Rendering

Partial-page rendering is a concept of rendering only a portion of a web page to avoid complete page refreshes and improve the user experience. It can be achieved using Microsoft ASP.NET Ajax without writing any client scripts. It is actually made possible through the interaction of the server controls with the Microsoft Ajax Client Library. The page updates are taken care of automatically by the client code injected into the server controls.
The communication between the server controls and the Microsoft Ajax Library for asynchronous postback is taken care of internally by the server control. In addition, the server controls invoke the appropriate client code that corresponds to a specific type of a browser with the help of the Microsoft Ajax Library, thus solving the compatibility issues with the client browser.

Benefits of Partial Page Rendering

· Improves user experience with web pages that behave more like a traditional client application.

· Improves the responsiveness upon user actions on a web page.

· Reduces complete page refreshes and makes only portions of the web page post back to avoid page flickering.

· Enables client-server communication without writing client scripts.

· Eliminates writing browser-compatible code.

UpdatePanel Server Control

This control is responsible for enabling partial-page rendering in a web page, thus enhancing the richness of the user interface and improving the performance and responsiveness.

Here is a simple example that illustrates how to display the current date of the server on a Label control when you click on a Button control in the web page.

In the Page_Load event of this web page, assign the current date to the Label control that we just created. The name of the Label control in our example is Label1.

protected void Page_Load(object sender, EventArgs e)

{

this.Label1.Text = DateTime.Now.ToString();

}

In the button click event, assign the current date to the Label control as stated below.

protected void Button1_Click(object sender, EventArgs e)

{

this.Label1.Text = DateTime.Now.ToString();

}

When you execute this application in the web browser, the current date and time are displayed. Upon the button click, the page is posted back to the server, and the latest date and time are rendered to the Label control.

In the preceding example, we have demonstrated a traditional ASP.NET page behavior, that is, the entire web page being posted back. Using UpdatePanelcontrol can make things simpler. In the same web page, drag and drop anUpdatePanelcontrol from the toolbox. Now, include a Label and Button control inside this UpdatePanelcontrol, and have the same code in the page load and button click events, as demonstrated earlier.

Figure 1 illustrates the UpdatePanel control in design time with a Label and Button control placed in it.

Figure 1

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">

</asp:Content>

<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">

<asp:ScriptManager ID="ScriptManager1" runat="server">

</asp:ScriptManager>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

<br />

<asp:Button ID="Button1" runat="server" Text="Button" Width="71px"

onclick="Button1_Click" />

</ContentTemplate>

</asp:UpdatePanel>

</asp:Content>

In the preceding markup, apart from the UpdatePanel control, a ScriptManager control also has been placed. This is done to support partial-page rendering. The ScriptManager control keeps track of all the UpdatePanel controls on the page and its triggers. Also it determines the portions of the page that have to be rendered as a result of an asynchronous postback operation. Figure 2 shows the result.

Figure 2

When the Button control is clicked, an updated date and time rendered on the page without any postback at all. The Label control holds the updated date and time of the server. During the execution of the button click event, the entire page is not posted back. Rather, only the portion of the page holding the UpdatePanel is posted back without any flickering.

ContentTemplate

The content of the UpdatePanel is declared in the ContentTemplate tag of the UpdatePanel. Any content defined in this tag will be posted back to the server asynchronously. In the preceding example, we have a Label and a Button control placed inside it at design time. In fact, this can even be done programmatically. All the controls inside the ContentTemplate tag are considered to be child controls.

The UpdatePanel works on an asynchronous postback operation, which the ScriptManager control intercepts by replacing the traditional postback. Internally during the postback operation, the page updates are governed by injecting JavaScript on the UpdatePanel control automatically.

The Render Modes of the UpdatePanelControl

The content in UpdatePanel is rendered to the page in <div> or <span> tags. The RenderMode property determines to which tag the content is rendered. The default setting for this property is Block, meaning that it renders to a <div> tag. The other option is the Inline setting, which renders the content to a <span> tag.

UpdateProgress Control

The UpdateProgress control of the ASP.NET Ajax extensions framework library can be used to display the progress status of one or more UpdatePanel controls when using partial-page rendering in an Ajax-enabled ASP.NET web page. You can use this control, together with the UpdatePanel control, to provide a visual feedback to the user, such as displaying the progress status of partial-page updates in an asynchronous mode of operation in an Ajax-enabled web application. You can even use your own template to display the progress status on such an operation in your user interface.

Example Listing and screen shot is given below.

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"

CodeBehind="Default.aspx.cs" Inherits="WebApplication1._Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">

</asp:Content>

<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">

<asp:ScriptManager ID="ScriptManager1" runat="server">

</asp:ScriptManager>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<asp:Label ID="Label1" runat="server" Text=""></asp:Label>

<asp:UpdateProgress ID="UpdateProgress1" runat="server">

</ProgressTemplate>

</asp:UpdateProgress>

<br />

<asp:Button ID="Button1" runat="server" Text="Button" Width="71px"

onclick="Button1_Click" />

</ContentTemplate>

</asp:UpdatePanel>

</asp:Content>

Add the following code in the Button Click event

protected void Button1_Click(object sender, EventArgs e)

{

System.Threading.Thread.Sleep(3000);

Label1.Text = DateTime.Now.ToString();

}

Figure 3 illustrates the result of UpdateProgress.

Figure 3

AJAX Interview Questions

2011-02-23T10:55:00.000-08:00

Q1 - What is AJAX?

A - Ajax stands for Asynchronous Javascript & XML. It is a web technology through which a postback from a client (browser) to the server goes partially, which means that instead of a complete postback, a partial postback is triggered by the Javascript XmlHttpRequest object. In such a scenario, web-application users won't be able to view the complete postback progress bar shown by the browser. In an AJAX environment, it is Javascript that starts the communication with the web server.
Ajax technology in a website may be implemented by using plain Javascript and XML. Code in such a scenario may tend to look little complex, for which the AJAX Framework in .NET can be embedded in ASP.NET web applications.
In addition to XML & Javascript, AJAX is also based on DOM - the Document Object Model technology of browsers through which objects of the browser can be accessed through the memory heap using their address.
JSON - Javascript Object Notation is also one of the formats used in AJAX, besides XML.
So basically, in an AJAX-based web application, the complete page does not need to reload, and only the objects in context of ajaxification are reloaded.
Ajax technology avoids the browser flickering.

Q2 - Can Ajax be implemented in browsers that do not support the XmlHttpRequest object?

A - Yes. This is possible using remote scripts.

Q3 - Can AJAX technology work on web servers other than IIS?

A - Yes, AJAX is a technology independent of web server the web application is hosted on. Ajax is a client (browser) technology.

Q4 - Which browsers support the XmlHttpRequest object?

A - Internet Explorer 5.0+, Safari 1.2, Mozilla 1.0/Firefox, Opera 8.0 +, Netscape 7

Q5 - How to we create an XmlHttpRequest object for Internet Explorer? How is this different for other browsers?

A - For Internet Explorer, an ActiveXObject is used for declaring an XmlHttpRequest object in Javascript.

//Code as below for IE:

xmlHttpObject = new ActiveXObject("Msxml2.XMLHTTP");

//For Other browsers, code as below:

xmlHttpObject = new XMLHttpRequest();

Note that XmlHttpObject used above is simply a variable that holds the XmlHttpRequest object for the respective browsers.

Q6 - What are the properties of the XmlHttpRequest object? What are the different types of readyStates in Ajax?

A - i) onreadyStateChange - This function is used to process the reply from the web server.

ii) readyState - This property holds the response status of the web server. There are 5 states:

0 - request not yet initialized

1 - request now set

2 - request sent

3 - request processing

4 - request completes

iii) responseText - Has the data sent back by the web server

Code snippet below shows an example how these there properties are used to implement ajax :

xmlHttpObject.onreadystatechange=function()
{
if(xmlHttpObject.readyState==4)
{
document.Form1.time.value=xmlHttpObject.responseText;
}
}

Q7 - What is the ASP.NET Ajax Framework? What versions have been released so far?

A - ASP.NET AJAX is a free framework to implement Ajax in asp.net web applications, for quickly creating efficient and interactive Web applications that work across all popular browsers.

The Ajax Framework is powered with

1 - Reusable Ajax Controls

2 - Support for all modern browsers

3 - Access remote services and data from the browser without tons of complicated script.

Versions of Ajax release

1 - ASP.NET Ajax Framework 1.0 (earlier release to this was called the Atlas)
2 - ASP.NET Ajax Framework 1.0 was available as a separate download for ASP.NET 2.0

Q8 - What are Ajax Extensions?

A - The ASP.NET Ajax Extensions are set of Ajax-based controls that work in ASP.NET 2 (or above) based applications.

Ofcourse,they also need the Ajax runtime which is actually the Ajax Framework 1.0.

ASP.NET Ajax Extensions 1.0 have to be downloaded to run with ASP.NET 2.0

The new ASP.NET 3.5 Framework comes with the Ajax Library 3.5 (containing the Ajax Extensions 3.5). So in order to use the latest Ajax, simply download .NET 3.5 Framework.

Summary :
ASP.NET Ajax Extensions 1.0 -> For ASP.NET 2.0
ASP.NET Ajax Extensions 3.5 -> For ASP.NET 3.5

Q9 - What is the ASP.NET Control Toolkit?

A - Besides the Ajax Framework (which is the Ajax engine) and Ajax Extensions (which contain the default Ajax controls), there is a toolkit called the Ajax Control Toolkit available for use & download (for free). This is a collection of rich featured, highly interactive controls, created as a joint venture between Microsoft & the Developer Community.

Q10 - What is Dojo?

A - Dojo is a third-party javascript toolkit for creating rich featured applications. Dojo is an Open Source DHTML toolkit written in JavaScript. It builds on several contributed code bases (nWidgets, Burstlib, f(m)), which is why we refer to it sometimes as a "unified" toolkit. Dojo aims to solve some long-standing historical problems with DHTML which prevented mass adoption of dynamic web application development.

Q11 - How to handle multiple or concurrent requests in Ajax?

A - For concurrent requests, declare separate XmlHttpRequest objects for each request. For example, for request to get data from an SQL table1, use something like this...

xmlHttpObject1.Onreadystatechange = functionfromTable1();

and to get data from another table (say table2) at the same time, use

xmlHttpObject2.Onreadystatechange = functionfromTable2();

Ofcourse, the XmlHttpObject needs to be opened & parameters passed too, like as shown below...

xmlHTTPObject1.open("GET","http://"localhost// " + "Website1/Default1.aspx" true);

Note that the last parameter "true" used above means that processing shall carry on without waiting for any response from the web server. If it is false, the function shall wait for a response.

Q12 - How to create an AJAX website using Visual Studio?

A - Using Visual Studio Web Developer Express 2005 & versions above it, Ajax based applications may easily be created. Note that the Ajax Framework & Ajax Extensions should be installed (In case of VS 2005). If using Visual Studio 2008 Web Developer Express or above, Ajax comes along with it (so no need of a separate installation).

Steps: Start Visual Studio, Click on File -> New Website -> Under Visual Studio Installed templates -> Select ASP.NET Ajax-Enabled Site. Enter a location & select OK.

Q13 - What is the role of ScriptManager in Ajax?

A - ScriptManager class is the heart of ASP.NET Ajax. Before elaborating more on ScriptManager, note that ScriptManager is class and a control (both) in Ajax.

The ScriptManager class in ASP.NET manages Ajax Script Libraries, partial page rendering functionality and client proxy class generation for web applications and services. By saying client proxy class, this means an instance of the Ajax runtime is created on the browser.

This class is defined in the System.Web.Extensions.dll. You will find this DLL in your system's Global Assembly Cache at C:\Windows\Assembly (For XP)

The ScriptManager control (that we may drag on a web form) is actually an instance of the ScriptManager class that we put on a web page. The ScriptManager manages all the ASP.NET Ajax controls on a web page. Following tasks are taken care by the ScriptManager class:
1 - Managing all resources (all objects/controls) on a web page
2 - Managing partial page updates
3 - Download Ajax Script Library to the client (means to the browser). This needs to happen so that Ajax engine is accessible to the browsers javascript code.
4 - Interacting with UpdatePanel Control, UpdateProgress Control.
5 - Register script (using RegisterClientScriptBlock)
6 - Information whether Release OR Debug script is sent to the browser
7 - Providing access to Web service methods from the script by registering Web services with the ScriptManager control
8 - Providing access to ASP.NET authentication, role, and profile application services from client script after registering these services with the ScriptManager control
9 - Enable culture specific display of clientside script.
10 - Register server controls that implement IExtenderControl and IScriptControl interfaces.

ScriptManager class' EnablePartialRendering property is true by default.

Q14 - Can we override the EnablePartialRendering property of the ScriptManager class?

A - Yes. But this has to be done before the init event of the page (or during runtime after the page has already loaded). Otherwise an InvalidOperationException will be thrown.

Q15 - How to use multiple ScriptManager controls in a web page?

A - No. It is not possible to use multiple ScriptManager control in a web page. In fact, any such requirement never comes in because a single ScriptManager control is enough to handle the objects of a web page.

Q16 - Whats the difference between RegisterClientScriptBlock, RegisterClientScriptInclude and RegisterClientScriptResource?

A - For all three, a script element is rendered after the opening form tag. Following are the differences:
1 - RegisterClientScriptBlock - The script is specified as a string parameter.
2 - RegisterClientScriptInclude - The script content is specified by setting the src attribute to a URL that points to a script file.
3 - RegisterClientScriptResource - The script content is specified with a resource name in an assembly. The src attribute is automatically populated with a URL by a call to an HTTP handler that retrieves the named script from the assembly.

Q17 - What are type/key pairs in client script registration? Can there be 2 scripts with the same type/key pair name?

A - When a script is registered by the ScriptManager class, a type/key pair is created to uniquely identify the script.

For identification purposes, the type/key pair name is always unique for dentifying a script. Hence, there may be no duplication in type/key pair names.

Q18 - What is an UpdatePanel Control?

A - An UpdatePanel control is a holder for server side controls that need to be partial postbacked in an ajax cycle. All controls residing inside the UpdatePanel will be partial postbacked. Below is a small example of using an UpdatePanel.

As you see here after running the snippet above, there wont be a full postback exhibited by the web page. Upon clicking the button, the postback shall be partial. This means that contents outside the UpdatePanel wont be posted back to the web server. Only the contents within the UpdatePanel are refreshed.

Q19 - What are the modes of updation in an UpdatePanel? What are Triggers of an UpdatePanel?

A - An UpdatePanel has a property called UpdateMode. There are two possible values for this property: 1) Always 2) Conditional

If the UpdateMode property is set to "Always", the UpdatePanel control’s content is updated on each postback that starts from anywhere on the webpage. This also includes asynchronous postbacks from controls that are inside other UpdatePanel controls, and postbacks from controls which are not inside UpdatePanel controls.

If the UpdateMode property is set to Conditional, the UpdatePanel control’s content is updated when one of the following is true:
1 - When the postback is caused by a trigger for that UpdatePanel control.

2 - When you explicitly call the UpdatePanel control's Update() method.

3 - When the UpdatePanel control is nested inside another UpdatePanel control and the parent panel is updated.

When the ChildrenAsTriggers property is set to true and any child control of the UpdatePanel control causes a postback. Child controls of nested UpdatePanel controls do not cause an update to the outer UpdatePanel control unless they are explicitly defined as triggers for the parent panel.

Controls defined inside a <Triggers> node have the capability to update the contents of an UpdatePanel.

If the ChildrenAsTriggers property is set to false and the UpdateMode property is set to Always, an exception is thrown. The ChildrenAsTriggers property is intended to be used only when the UpdateMode property is set to Conditional.

Q20 - How to control how long an Ajax request may last?

A - Use the ScriptManager's AsyncPostBackTimeout Property.

For example, if you want to debug a web page but you get an error that the page request has timed out, you may set <asp:ScriptManager id="ScriptManager1" runat="server" AsyncPostBackTimeout="9000"/>

where the value specified is in seconds.

Q21 - What is ASP.NET Futures?

A - ASP.NET AJAX Futures

The new release includes support for managing browser history (Back button support), selecting elements by CSS selectors or classes, and information on accessing “Astoria” Web data services. The Futures (July 2007) release adds:

History support for the Safari browser, inclusion of “titles”, encoding and encrypting of server-side history state and the ability to handle history in the client without a server requirement.

CSS Selectors APIs have been modified to be applicable to W3C recommendations.

A script resource extraction tool that allows you to create script files on disk that originate from embedded resources in assemblies. Important: this version of the browser history feature is now outdated and should not be used. Instead, please download the ASP.NET 3.5 Extensions Preview, which contains the new version.

Q22 - What are limitations of Ajax?

A - 1) An Ajax Web Application tends to confused end users if the network bandwidth is slow, because there is no full postback running. However, this confusion may be eliminated by using an UpdateProgress control in tandem.
2) Distributed applications running Ajax will need a central mechanism for communicating with each other

Q23 - How to make sure that contents of an UpdatePanel update only when a partial postback takes place (and not on a full postback)?

A - Make use of ScriptManager.IsInAsyncPostBack property (returns a boolean value)

Q24 - How to trigger a postback on an UpdatePanel from Javascript?

A - Call the __doPostBack function. ASP.NET runtime always creates a javascript function named __doPostBack(eventTarget, eventArgument) when the web page is rendered. A control ID may be passed here to specifically invoke updation of the UpdatePanel.

Q25 - Which request is better with AJAX, Get or Post?

A - AJAX requests should use an HTTP GET request while retrieving data where the data does not change for a given URL requested. An HTTP POST should be used when state is updated on the server. This is in line with HTTP idempotency recommendations and is highly recommended for a consistent web application architecture.

Q26. Is it possible to set session variables from javascript?
It's not possible to set any session variables directly from javascript as it is purely a client side technology. You can use AJAX though to asyncronously...

Cannot parse XML generated by JSP I am generating an XML using JSP, when i run the JSP in IE it shows the XML as per DOM, but when i try to parse it using Javascript , the command xmldoc.documentElement...

This is working code I am using, it might help you. if (!isIE) xmldoc = req.responseXML; else { //IE does not take the responseXML as...

Q27. How do I handle concurrent AJAX requests?With JavaScript you can have more than one AJAX request processing at a single time. In order to insure the proper post processing of code it is recommended that you use JavaScript Closures. The example below shows an XMLHttpRequest object abstracted by a JavaScript object called AJAXInteraction. As arguments you pass in the URL to call and the function to call when the processing is done.
function AJAXInteraction(url, callback) {

var req = init();
req.onreadystatechange = processRequest;

function init() {
if (window.XMLHttpRequest) {
return new XMLHttpRequest();
} else if (window.ActiveXObject) {
return new ActiveXObject("Microsoft.XMLHTTP");}
}

function processRequest () {
if (req.readyState == 4) {
if (req.status == 200) {
if (callback) callback(req.responseXML);}
}
}

this.doGet = function() {
req.open("GET", url, true);
req.send(null);}

this.doPost = function(body) {
req.open("POST", url, true);
req.setRequestHeader("Content-Type", "
application/x-www-form-urlencoded");
req.send(body);}
}

function makeRequest() {
var ai = new AJAXInteraction("processme",
function() { alert("Doing Post Process");});
ai.doGet();}

The function makeRequest() in the example above creates an AJAXInteraction with a URL to of "processme" and an inline function that will show an alert dialog with the message "Doing Post Process". When ai.doGet() is called the AJAX interaction is initiated and when server-side component mapped to the URL "processme" returns a document which is passed to the callback function that was specified when the AJAXInteraction was created.
Using this closures insures that the proper callback function associated with a specific AJAX interaction is called. Caution should still be taken when creating multiple closure objects in that make XmlHttpRequests as to there is a limited number of sockets that are used to make requests at any given time. Because there are limited number of requests that can be made concurrently. Internet Explorer for example only allows for two concurrent AJAX requests at any given time. Other browsers may allow more but it is generally between three and five requests. You may choose to use pool of AJAXInteraction objects.
One thing to note when making multiple AJAX calls from the client is that the calls are not guaranteed to return in any given order. Having closures within the callback of a closure object can be used to ensure dependencies are processed correctly.

Q28. How do I submit a form or a part of a form without a page refresh?
When creating a form make sure that the "form" element "onSubmit" attribute is set to a JavaScript function that returns false.
<form onSubmit="doAJAXSubmit();return false;" >
<input type="text" id="tf1" />
<input type="submit" id="submit1" value="Update"/>
</>

You can also submit data by associating a function with a form button in a similar way.

<form onSubmit="doAJAXSubmit();return false;" >
<input type="text" id="tf1" />
<input type="button" id="button1" onClick="doAJAXSubmit()" value="Update"/>
</>

Note that the form "onSubmit" attribute is still set. If the user hits the enter key in the text field the form will be submitted so you still need to handle that case.
When updating the page it is recommend you wait to make sure that the AJAX update of the form data was successful before updating the data in the page. Otherwise, the data may not properly update and the user may not know. I like to provide an informative message when doing a partial update and upon a successful AJAX interaction I will then update the page.

Q29. Is the server or the client in control?It depends. With AJAX the answer is more in between. Control can be more centralized in a server-side component or as a mix of client-side and server-side controllers.

* Centralized server-side controller - When having a more centralized controller the key is to make sure the data in client-side page is in sync with that of the server. Some applications may keep all the state on the server and push all updates to client DOM via a simple JavaScript controller.
* Client and server-side controllers - This architecture would use JavaScript to do all presentation related control, event processing, page manipulation, and rendering of model data on the client. The server-side would be responsible for things such as business logic and pushing updated model data to the client. In this case the server would not have intimate knowledge of the presentation short of the initial page that would be sent to the client page request.

There are some use cases where an entire AJAX application can be written in a single page. Keep in mind if you choose this type of architecture that navigation and bookmarking should be considered.
Both methods are viable depending on what you are trying to accomplish. I tend to prefer spreading the control across the client and server.

Q30. Is Ajax just another name for XMLHttpRequest?
No. XMLHttpRequest is only part of the Ajax equation. XMLHttpRequest is the technical component that makes the asynchronous server communication possible; Ajax is our name for the overall approach described in the article, which relies not only on XMLHttpRequest, but on CSS, DOM, and other technologies.

Q31. How do I abort the current XMLHttpRequest?
Just call the abort() method on the request.

Q32. What is the minimum version of PHP that needs to be running in order to use HTML_AJAX?
The oldest PHP version i've fully tested HTML_AJAX is 4.3.11, but it should run on 4.2.0 without any problems. (Testing reports from PHP versions older then 4.3.11 would be appreciated.)

Q33. Why does HTML_AJAX hang on some server installs
If you run into an HTML_AJAX problem only on some servers, chances are your running into a problem with output compression. If the output compression is handled in the PHP config we detect that and do the right thing, but if its done from an apache extension we have no way of knowing its going to compress the body. Some times setting HTML_AJAX::sendContentLength to false fixes the problem, but in other cases you'll need to disabled the extension for the AJAX pages.
I've also seen problems caused by debugging extensions like XDebug, disabling the extension on the server page usually fixes that. Questions dealing with Using HTML_AJAX, and general JavaScript development

Q34. How do I get the XMLHttpRequest object?
Depending upon the browser... if (window.ActiveXObject) { // Internet Explorer http_request = new ActiveXObject("Microsoft.XMLHTTP"); } else if...

Q35. Are there any security issues with AJAX?
JavaScript is in plain view to the user with by selecting view source of the page. JavaScript can not access the local filesystem without the user's permission. An AJAX interaction can only be made with the servers-side component from which the page was loaded. A proxy pattern could be used for AJAX interactions with external services.
You need to be careful not to expose your application model in such as way that your server-side components are at risk if a nefarious user to reverse engineer your application. As with any other web application, consider using HTTPS to secure the connection when confidential information is being exchanged.

Acronyms in .NET

ADO - ActiveX Data Object - Microsoft ActiveX Data Objects (ADO) is a collection of Component Object Model objects for accessing different types of data sources.

AJAX - Asynchronouse Javascript and XML - Ajax is a web development technology used for creating interactive web pages with fast data rendering by enabling partial postbacks on a web page (That means a section of the web page is rendered again, instead of the complete web page. This is achieved using Javascript, XML, JSON (Javascript Notation Language) and the XMLHttpRequest object in javascript.

ASP - Active Server Pages - Microsoft's Server side script engine for creating dynamic web page.

C# - C Sharp - Microsoft Visual C# is an object oriented programming language based on the .NET Framework. It includes features of powerful languages like C++, Java, Delphi and Visual Basic.

CAO - Client Activated Object - Objects created on the server upon the client's request. This is used in Remoting.

CCW - COM Callable Wrapper - This component is used when a .NET component needs to be used in COM.

CIL - Common Intermediate Language - Its actually a low level human readable language implementation of CLI. All .NET-aware languages compile the source oode to an intermediate language called Common Intermediate Language using the language specific compiler.

CLI - Common Language Infrastructure - This is a subset of CLR and base class libraries that Microsoft has submitted to ECMA so that a third-party vendor can build a .NET runtime on another platform.

CLR - Common Language Runtime - It is the main runtime machine of the Microsoft .NET Framework. It includes the implementation of CLI. The CLR runs code in the form of bytes, called as bytecode and this is termed MSIL in .NET.

CLS - Common Language Specification - A type that is CLS compliant, may be used across any .NET language. CLS is a set of language rules that defines language standards for a .NET language and types declared in it. While declaring a new type, if we make use of the [CLSCompliant] attribute, the type is forced to conform to the rules of CLS.

COFF - Common Object File Format - It is a specification format for executables.

COM - Component Object Model - reusable software components. The tribe of COM components includes COM+, Distributed COM (DCOM) and ActiveX® Controls.

CSC.exe - C Sharp Compiler utility

CTS - Common Type System - It is at the core of .NET Framework's cross-language integration, type safety, and high-performance code execution. It defines a common set of types that can be used with many different language syntaxes. Each language (C#, VB.NET, Managed C++, and so on) is free to define any syntax it wishes, but if that language is built on the CLR, it will use at least some of the types defined by the CTS.

DBMS - Database Management System - a software application used for management of databases.

DISCO - Discovery of Web Services. A Web Service has one or more. DISCO files that contain information on how to access its WSDL.

DLL - Dynamic Link Library - a shared reusable library, that exposes an interface of usable methods within it.

DOM - Document Object Model - is a language independent technology that permits scripts to dynamically updated contents of a document (a web page is also a document).

ECMA - European Computer Manufacturer's Association - Is an internation organisation for computer standards.

GC - Garbage Collector - an automatic memory management system through which objects that are not referenced are cleared up from the memory.

GDI - Graphical Device Interface - is a component in Windows based systems, that performs the activity of representing graphical objects and outputting them to output devices.

GAC - Global Assembly Cache - Is a central repository of reusable libraries in the .NET environment.

GUI - Graphic User Interface - a type of computer interface through which user's may interact with the Computer using different types of input & output devices with a graphical interface.

GUID - Globally Unique Identifier - is a unique reference number used in applications to refer an object.

HTTP - Hyper Text Transfer Protocol - is a communication protocol used to transfer information in the internet. HTTP is a request-response protocol between servers and clients.

IDE - Integrated Development Environment - is a development environment with source code editor with a compiler(or interpretor), debugging tools, designer, solution explorer, property window, object explorer etc.

IDL - Interface Definition Language - is a language for defining software components interface.

ILDASM - Intermediate Language Disassembler - The contents of an assembly may be viewed using the ILDASM utility, that comes with the .NET SDK or the Visual Studio.NET. The ildasm.exe tool may also be used in the command line compiler.

IIS - Internet Information Server - Is a server that provides services to websites and even hosts websites.

IL - Intermediate Language - is the compiled form of the .NET language source code. When .NET source code is compiled by the language specific compiler (say we compile C# code using csc.exe), it is compiled to a .NET binary, which is platform independent, and is called Intermediate Language code. The .NET binary also comprises of metadata.

JIT - Just in Time (Jitter) - is a technology for boosting the runtime performance of a system. It converts during runtime, code from one format into another, just like IL into native machine code. Note that JIT compilation is processor specific. Say a processor is X86 based, then the JIT compilation will be for this type of processor.

MBR - MarshallByReference - The caller recieves a proxy to the remote object.

MBV - MarshallByValue - The caller recieves a copy of the object in its own application domain.

MDI - Multiple Document Interface - A window that resides under a single parent window.

MSIL - Microsoft Intermediate Language - now called CIL.

Orcas - Codename for Visual Studio 2008

PE - Portable Executable - an exe format file that is portable.

RAD - Rapid Application Development

RCW - Runtime Callable Wrapper - This component is used when a .NET needs to use a COM component.

SAX - Simple API for XML - It is a serial access parser API for XML. The parser is event driven and the event gets triggered when an XML feature is encountered.

SDK - Software Development Kit

SMTP - Simple Mail Transfer Protocol - a text based protocol for sending mails.

SN.exe - Strong Name Utility - a tool to make strong named assemblies.

SQL - Structured Query Language - a language for management of data in a relational structure.

SOAP - Simple Object Access Protocol - a protocol used for exchange of xml based messages across networks.

TCP - Transmission Control Protocol - data exchange protocol across networks using streamed sockets.

UI - User Interface

URI - Uniform Resource Identifier

URL - Uniform Resource Locator

UDDI - Universal Description, Discovery and Integration - it is a platform independent business registration across the internet.

WAP - Wireless Access Protocol - a protocol that enables access to the internet from mobile phones and PDAs.

WC - Windows Cardspace - Part of .NET 3.0 framework, that enables users to secure and store digital identities of a person, and a provision to a unified interface for choosing the identity for a particular transaction, like logging in to a website.

WCF - Windows Communication Foundation - Part of .NET 3.0 framework, that enables communication between applications across machines.

WF - Windows Workflow Foundation - Part of .NET 3.0 framework, used for defining, execution and management of reusable workflows.

WKO - Well Known Object - These are MBR types whose lifetime is controlled by the server's application domain.

WPF - Windows Presentation Foundation - Part of .NET 3.0 framework, is the graphical subsystem of the .NET 3.0 framework.

WSDL - Web Services Description Language - is an XML based language for describing web services.

WML - Wireless Markup Language - is a content format for those devices that use Wireless Application Protocol.

VB.NET - Visual Basic .NET - .NET based language. Its the .NET implementation of VB6, the most widely used language in the world.

VBC.exe - VB.NET Compiler

VES - Virtual Execution System - It provides the environment for execution of managed code. It provides direct support for a set of built in data types, defines a hypothetical machine with an associated machine model and state, a set of control flow constructs, and an exception handling model. To a large extent, the purpose of the VES is to provide the support required to execute the Common Intermediate Language instruction set.

VS - Visual Studio

VSS - Visual Source Safe - An IDE by Microsoft, to maintain source code versions and security.

VSTS - Visual Studio Team Suite - Visual Studio Team System - it is an extended version of Visual Studio .NET. It has a set of collaboration and development tools for software development process.

XML - Extensible Markup Language - is a general purpose well formed markup language.

AJAX Tutorials

2011-02-21T13:13:00.000-08:00

ScriptManger

Partial Page Rendering

AJAX ScriptManager

2011-02-21T13:08:00.000-08:00

ScriptManager

The core technology of the whole AJAX paradigm is the XMLHttpRequest object. Any AJAX frameworks you might happen to work with will use this object under the hood. If you end up using a different application programming interface (API), well, its only an abstraction layer built to overcome browser differences and simplify programming.

By this definition, the programming model of AJAX applications seems to be clear and unquestionable. You write code that captures client-side events, conduct an operation on the server via XMLHttpRequest, get the results, and update the user interface. All the client-side programming is done through JavaScript. XMLHttpRequest is a small but critical object; its a building block and it is essential.

AJAX applications require a change of paradigm and some imagination. When it comes to rewriting Web applications for AJAX, nearly all aspects of the application need to be redesigned, reconsidered, refactored, and often rewritten. A simpler way to work with AJAX involves using a new set of server controls that surround an area of the page and refresh that independently from the rest of the page.

A simpler way to AJAX passes through a component that, using XMLHttpRequest, could exchange HTML messages with the Web server having the same page URL as its server-side counterpart. In ASP.NET AJAX, this approach goes under the name of partial rendering. ASP.NET partial rendering is centered around a new container control—the UpdatePanel control—that you use to surround portions of existing pages, or portions of new pages developed with the usual programming model of ASP.NET. A postback request that originates within any of these updatable regions is captured by the UpdatePanel control and resolved asynchronously using XMLHttpRequest. In this way, fresh HTML is downloaded for the selected region, bypassing the browser and reducing page ﬂickering.

The ScriptManager Control

ScriptManager is by far the most important control in the server infrastructure of ASP.NET AJAX because it performs a number of essential tasks. For example, the ScriptManager control manages and delivers common script resources, such as the ﬁles that form the Microsoft JavaScript client library. It also enables or disables general features such as partial rendering, page method calls, and history management. The ScriptManager is also the component that triggers the creation of JavaScript proxies for invoking Web services and Windows Communication Foundation (WCF) services from within a client page.

Regardless of its numerous capabilities, the ScriptManager control is primarily a helper control made available for the convenience of an army of ASP.NET developers. It represents a sort of declarative interface for a number of common tasks in an ASP.NET AJAX page.

To link the Microsoft JavaScript client library to a page, you can certainly use the <script> tag again and make it point to all the ﬁles in the library that you need. However, by simply dropping a ScriptManager control in the page, you have it for free and without needing to have any intimate knowledge of the library details.

The following code shows the simplest and most common way to insert the script manager in an ASP.NET page:

<asp:ScriptManager runat="server" ID="ScriptManager1" />

The control produces no user interface, works exclusively on the server, and doesn’t add any extra bytes to the page download.

The control should be considered as a sort of script console in the page; as such, you don’t need to have multiple instances of it in the same page. If multiple script managers are deﬁned in the same page, you are going to get an exception.

The best practice is to place ScriptManager in the master page using the most common conﬁguration. Next, when you need to write a content page that requires different settings, you get a proxy for the manager and enter changes through the proxy. The proxy is a control named ScriptManagerProxy. From a syntax standpoint, it’s allowed to have ScriptManager in the master and ScriptManagerProxy in the content page. And the proxy can overwrite settings deﬁned in the manager. Note, though, that the ScriptManagerProxy supports only a subset of the properties deﬁned on the ScriptManager control. To override just one of the manager’s properties that are not replicated through the proxy, you might want to write some code in the Page_Load event of the page and access the local script manager instance through the following code:

// Find a reference to the script manager defined for this page

ScriptManager proxy = ScriptManager.GetCurrent(this);

Once you hold the reference to the real manager, you can enter your changes safely. Note that the same ScriptManagerProxy control uses this technique internally.

Partial Rendering

The ScriptManager control organizes partial rendering. It exposes a Boolean property—the EnablePartialRendering property—through which developers can enable and disable partial rendering on a given page. Partial rendering is enabled by default. As a result, the ScriptManager injects ad hoc pieces of script code in the HTML of the host page to initialize the partial rendering, client-side engine.

In addition, the ScriptManager control exposes a server-side interface for various tasks related to partial rendering. For example, it offers a property—the AsyncPostBackSourceElementID property—to check whether the current postback is because of a standard ASP.NET request

Or a partial rendering request. Likewise, it lets you set a timeout for the partial rendering operation and offers to capture any resulting exception.

The ScriptManager also lets you programmatically register triggers for updatable panels, and it supplies a mechanism to return server-generated data along with the updated markup. Finally, the script manager is also responsible for coordinating the process that generates the fragment of fresh HTML to send to the requesting browser.

Adding Service References to Pages

The ScriptManager control also plays a role in creating the conditions for some client-side JavaScript function to invoke a remote Web or WCF service. The Services section of the control hosts references to .asmx or .svc endpoints that refer to ASP.NET XML Web services and WCF services, respectively.

<asp:ScriptManager ID="ScriptManager1" runat="server">

<asp:ServiceReference Path="~/LiveQuotes.svc" />

<asp:ServiceReference Path="~/DataService.asmx" />

</Services>

</asp:ScriptManager>

The Services section also has a programmatic counterpart in the Services collection exposed by the ScriptManager control.

Defining History Points within Pages

An AJAX application tends to replace classic URL-to-URL browser navigation with script-driven HTTP requests. The history feature of an AJAX application doesn’t necessarily coincide with the list of visited URLs. More likely, the history of an AJAX application is a list of action points scattered through one or a few pages. In a nutshell, AJAX breaks the assumption that the previous state of a Web application coincides with the previously visited URL.

The net effect is that all the user interaction with an AJAX page produces a single entry in the browser’s history. Hence, when you click the Back button you are redirected to the previously visited distinct URL, which might be an entirely new page—even a page in a different application.

There’s no simple solution to this problem; there are only hacks to work around it. The most common hack that works is adding a hash string to the URL whenever the page moves to a state that you want to track. A hash is a string appended to the URL preﬁxed by a pound sign (#) symbol. Here’s a sample AJAX-trackable URL:

http://www.samplewebsite.com/default.aspx#s=1

When you change the URL to simply add or modify a hash, the browser doesn’t navigate away from the current page. In addition, it also adds the new URL to its history list. As a result, the user now can navigate back and forward to the URL with the hash and can even bookmark it.

Adding a hash to the current URL at a given point is a practice referred to as “adding a history point.” A history point refers to a state of the page that is signiﬁcant for the page and the application. This state is so signiﬁcant that you want to bookmark it for a future reference. For example, if you offer a pageable control such as a DetailsView, any page change is a possible history point. Here’s the corresponding code:

protected void DetailsView1_PageIndexChanged(object sender, EventArgs e)

{

// Get significant information to create the hash (that is, the page index)

string state = (sender as DetailsView).PageIndex.ToString();

// Add the history point(s) (Name/Value) ScriptManager.GetCurrent(this).AddHistoryPoint("s", state);

}

A history point is a set of name/value pairs, where the name is an arbitrary but unique string and the value is a string-based representation of any information that will let you restore the bookmarked state.

Whenever the browser navigates to a URL with an attached hash, the ScriptManager control detects it and ﬁres a Navigate event. By handling this event, you read the hash, ﬁgure out the page state to restore, and restore it.

protected void ScriptManager1_Navigate(object sender, HistoryEventArgs e){

string key = e.State.AllKeys[0]; // First key string state = String.Empty;

if (String.Equals(key, "s"))

{

// Get the hash and convert to an integer (uses an extension method)

state = e.State[key];

int pageIndex = state.ToInt32();

// Restore the state

DetailsView1.PageIndex = pageIndex;

}

In classic Back/Forward navigation, the browser retrieves and restores the page. In AJAX navigation, the browser can provide us only with the hash string we associated with a visited pseudo-URL. It’s up to the page to re-create the desired state based on the information stored in the hash.

History management is disabled by default. To turn it on, you must set the property EnableHistory of the ScriptManager to true. Finally, note that in ASP.NET AJAX managing history also can be done from within JavaScript in the client side.

C# Interview Questions

2011-02-18T11:02:00.000-08:00

Explain the elements of the .NET Framework.

a.          CLR (Common Language Runtime): It is a common managed environment where all the .net programs run. Supports multiple languages and has the garbage collector.

b.        .Net Framework Class Libraries:  For each source code compiler (VB.NET, C#.NET, etc.), there is a minimum set of coding standards that must be met. The minimum set of coding standards that must be met to compile .NET code into MSIL code is known as CLS - Common Language Specification. The role of the Common Language Specification is to ensure that all generated code (MSIL) that meets the minimum set of coding standards can operate successfully within the .NET framework. THE CTS (Common Type System) handles conversion of programming-language data types into .NET compatible (MSIL) data types. The implicit benefit of the CTS is the reduction of development time when attempting to coordinate data types between two sets of different programming-language code.

c.          Data and XML: Support for disconnected programming model and XML.

d.          XML webservices: creating webservices for distributed architecture.

e.          Webforms: Provides support and functionality for Web based UI.

f.           Windows forms: Provides support and functionality for Windows based UI.

What is assembly manifest? What is the information it provides.

Assembly Manifest is a file that contains data that describes how the elements present inside an assembly are connected to each other. The assembly manifest contains assembly metadata to define the scope of the assembly and resolve references to resources and classes.

Information provided by Assembly Manifest:

a.    Assembly Name

b.    Version Number

c.    Culture

d.    Strong name

e.    List of files inside the assembly

f.     Reference information

Explain how a .NET application is compiled and executed

Any code written in any .NET complaint languages when compiled, converts into MSIL (Microsoft Intermediate Language) code in form of an assembly through CLS, CTS. IL is the language that CLR can understand. On execution, this IL is converted into binary code by CLR’s just in time compiler (JIT) and these assemblies or DLL are loaded into the memory.

Describe the .NET base class library

.NET’s Base class library exists in order to encapsulate huge number of common functions and makes them easily accessible to the developer. .NET base class library provides the functionality like ADO.NET, XML, Threading, IO, Security, Diagnostics, Resources, Globalization, collections etc. It serves as the main point of interaction between developer and runtime.

Explain the difference between value types and reference types

Value Type:

a.    Stores the data.

b.    The value of value types is stored on the managed stack.

c.    One variable can have just one value.

d.    They are lighter objects.

Reference Type:

a.    Stores the reference to the data.

b.    A reference type is allocated on the heap.

c.    several variables can reference the same data

d.    They are heavier objects.

Explain the importance of Imports and Using Statements.


Import statement: creates a property on the global object with the name supplied as namespace and initializes it to contain the object that corresponds to the namespace being imported. Any properties created using the import statement cannot be assigned to, deleted, or enumerated. All import statements are executed when a script starts.

Using statements:  mainly defines the namespaces whose objects will be used in the form. This clearly solves 2 purposes: Defines all the namespaces that will be used in a form. Secondly, reduces the hassle for the programmer to type the name of namespace again and again while using classes/objects that belong to the namespace.

Explain the difference between a class and a structure

Class:

a.    It is reference type.

b.    Null value can be assigned to a variable in a class

c.    It can have destructor.

d.    All variables in classes are by default private.

e.    Good to be used from architecture view as it provides high flexibility.

Structure:

a.    It is value type.

b.    Null value assignment is not feasible here.

c.    Cannot have destructor.

d.    All variables in structures are public.

e.    Good to be used for simple data structures.

Explain how garbage collection manages the reclamation of unused memory.


The garbage collector assumes that all objects in the managed heap are garbage. It starts walking the roots and builds a graph of all objects reachable from the roots recursively. It stops when it attempts to add an object to the graph that it previously added. The graph contains the set of all objects that are reachable from the application's roots. Any object/s that is not in the graph is not accessible by the application, and is considered garbage. Collection only occurs when the heap is full. In such a case, each and every garbage object calls the Finalize method and reclaims the unused memory. 55. Explain how garbage collection deals with circular references.

Explain how garbage collection deals with circular references.

The .Net runtime knows about all the references between the objects. It can identify all the circular references that are reachable from the root and hence finalize them to free them all at once if and when needed.

Explain the process of creating a menu using the MainMenu component.

MainMenu component is a component that allows the display of Menus at runtime on a form.

Process of creating Menu using MainMenu Component:

a.    Add MainMenu component on Windows Form.

b.        Menu designer allows deciding the structure of the main menu by selecting the Type Here area and adding the Menu Items to be displayed on the menu.

c.        Add functionality to Menu Items as required.

Explain the process of creating a context menu using the ContextMenu component

ContextMenu component provides the users with the ability to access some very frequently used commands. Context menu works by right click of mouse. They mainly provide access to commands particular to the control that has been clicked upon.

Process for creating context menus:

Open the windows form application.
Select ContextMenu component from toolbox.
A menu is added. Click on Type here and type in new Menu Items to be placed on the Menu.
Provide the functionality.
Associate the context menu with the form or the control it is supposed to be related to.

What is a delegate? Explain how to create it.

A delegate declares a ref type that references a named of anonymous method. Delegates are secure and type-safe. Consider them as type safe function pointers.

public delegate void Del<T>(T item);

Del<int> d1 = new Del<int>(Notify);

Explain how to declare and raise events from your application.

Declare Events: “Event” keyword is used to declare an event.

public delegate void MyCustomHandler(object o, MyEventArgse);

public class MyEventArgs: EventArgs

    public readonly int Age;

    public MyEventArgs(int age)

        Age = age;

public class MyCustomListener

    public void Show(object o, MyEventArgs e)

        Console.WriteLine(

            "Age is {0}",

            e.Age);

Describe how to implement event handlers and associate them with events.


public class MyClass

    public static event MyCustomHandler MyEvent;

    public static void Main()

        MyCustomListener mcll = new MyCustomListener();

        MyEvent += new MyCustomHandler(mcl1.Show);

        GetAge();

    public static void OnMyEvent(MyEventArgse)

        if(MyEvent!=null)

            MyEvent(new object(),e);

    public static void GetAge()

        MyEventArgse1 = new MyEventArgs(25);

        OnMyEvent(e1);

What is Break Mode? How to set breakpoints?

Break mode is the state of an application when the execution gets paused and allows the developer to edit the value in the current state. To attain a break mode we can do any of the following steps:

a.    Selecting Break from the Run menu (Ctrl+Break) or pressing the pause button.

b.    Reaching to break point.

Setting up the break points:

a.     Go to the line where you need to mark the breakpoint.

b.     Click with mouse on left corner margin of that line.

c.     Another way is to press F9

Describe how to step through code in .NET.

Steps to step through the code in .NET:

a.       Start the program in debug mode.

b.      When the first breakpoint is reached then step through can be done in one of the two ways:

i.             Press F10 to move to next line.

ii.            Select debug menu and click on step over. This would step over the breakpoint to next level.

c.       Other options are: “Step Into” and “Step Out”.

Describe the debugging windows available in .NET.

Debug->Windows:

Breakpoints: displays a list of all the breakpoints and where they are. Shows condition when that breakpoint will be hit if a condition exists and the Hit Count shows the number of times that breakpoint has been hit.

Output: Displays the status messages for various features in the IDE. It shows the output form a list of objects throughout debug mode of the application.

Immediate: This window allows the programmer to write code and verify values through programming while debugging the application. It helps in checking the values of objects/controls etc, and the conditions throughout the application in debug mode.

What are Debug and Trace classes? Explain how to use them to display error classes.

Both are used to help programmers find errors, occurring events and flow of code. In release mode, however, debug class is disabled and only Trace class is valid to trap things in a live application.

Both have assert functions to validate values.

Trace.WriteLine(variable value or comment).

Debug.WriteLine(variable value or comment).

We could create error handlers to trap unhandled exceptions trapped by Trace and Debug class.

Describe how to create Trace Listeners and log Trace output.

 [Conditional("TRACE")]

public static void InitializeUnhandledExceptionHandler()

    AppDomain.CurrentDomain.UnhandledException +=

             new UnhandledExceptionEventHandler(CutomExceptionHandler);

public static void CustomExceptionHandler(object sender,

                                       UnhandledExceptionEventArgs args)

    Exception e=(Exception) args.ExceptionObject;

    Trace.WriteLine("Exception: "+e.Message+"\n"+e.GetType() +

                    "\nStack Trace:\n"+e.StackTrace);

    MessageBox.Show(

        "An error has occurred:"+e.Message+"\nin: "+e.GetType(),

        "Fatal",

        MessageBoxButtons.OK,

        MessageBoxIcon.Stop,

        MessageBoxDefaultButton.Button1);

    Trace.Close();

    Process.GetCurrentProcess().Kill();

[Conditional("DEBUG")]

public static void TrapDebug(string str)

    Debug.WriteLine("Debug error: "+str);

What are Trace switches? Describe how to create and use Trace switches.

Trace switches allow us to filter, enable/disable the outputs through Trace. We can configure them through the config file. 3 types of trace switches:

BooleanSwitch: Enable/Disable trace statements.

TraceSwitch and SourceSwitch: used for trapping particular Trace levels.

BooleanSwitch dataSwitch =

   new BooleanSwitch("Comment", "module1");

TraceSwitch generalSwitch =

   new TraceSwitch("comment",

   "module1");

Explain how to configure Trace switches in the application’s .config file.

switches are configured using the .config file

<system.diagnostics>

   <switches>

      <add name="MyTraceSwitch" value="1" />

      <add name="TraceSwitch2" value="1" />

   </switches>

</system.diagnostics>

 both are on.

Explain how exceptions are handled by the common language runtime in .NET.

The CLR uses a technique generally referred to as a two-pass exception review process. What this means is that the CLR will process an exception in two passes. In the first pass, the CLR will determine if there is a handler for the exception. This is done by reviewing the entries in the SEH table; specifically it looks at the Try Offset and Try Length flags to see if the exception occurred within a guarded block, and if so, whether the Flags entry dictates that a handler exists for this type of occurrence. Let's assume that the CLR did find a handler during the first pass. At that point the CLR begins a second pass of the SEH table during which it will work through the execution phase of the exception management process. So we can divide the two passes into a discovery pass, in which we determine whether there is a handler in this method context to handle the exception; and an execution pass, in which we actually execute the handler and any special rules.

When code throws an exception, the CLR looks up the call stack looking for a catch filter to handle the exception. When it finds the relevant catch block, before executing the code, it will execute all code in all finally blocks - starting from the try block that threw the exception and stopping with the catch filter that matches the exception. when the CLR encounters an exception for a method it will use the descriptors in the SEH table to determine how to handle the exception, which code block is affected, and what handler should be invoked.

Describe the different types of user-authored controls in NET.

User authored controls are which not part of the .net framework library. It includes both custom controls and user controls.

a.    Custom Controls: They look similar to ASP.NET controls. They can be created in one of the 3 ways:-

a.    Deriving a custom control from existing custom control.

b.    Making a composite custom control by combining 2 or more existing controls

c.    By creating a new control from scratch by deriving the control from its base class.

b.     User Controls: enables a part of ASP.NET page to be reused. The reusable part is in form of a control with the extension .ascx. They look like to be a group of ASP.NET controls which can be used over and over again.

Explain with code sample how to create an inherited control.

Steps to create inherited Control:-

a.    Create a new project.

b.    Add a custom control to the project.

c.    Change the name of the class you need to inherit the control from the base class. E.g. inherit the class from System.Windows.Forms.Button if the control s to be inherited from a button class.

d.    Implement the control with custom properties and featured needed by the control.

e.    Override the OnPaint method if the control’s appearance needs to be changed.

f.     Save the build the control

g.    Reference you control into another or the same project and use the control.

Explain with code sample how to create a user control.

Steps to create a User control:

a.    Select a project

b.    Right click and add a new item (User Control - .ascx) to the selected project.

c.    Add @Control Directive

d.    Add all the controls that you want to be displayed on the User control as a part of one or more web pages.

e.    Write the code for all the tasks to be performed by the user control.

f.     Create accessor methods for the outside world accessing this user control.

Using the User control:

a.    Register the control on the webpage it needs to be used by putting @Register directive.

b.    Specify the following attributes to the register directive:

a.    TagPrefix: defines the namespace in which the control would reside

b.    TagName: defines the name with which control is referred

c.    Src: Path of where the control is kept.

c.    Control is then used on the page using the following code:

   <TagPrefix:TagName />

Explain with code sample how to create a custom control.

Steps to create a custom control:

a.    Create a new project.

b.    Add a custom control to the project.

c.    Change the name of the class you need to inherit the control from the base class. E.g. inherit the class from System.Windows.Forms.Button if the control s to be inherited from a button class.

d.    Implement the control with custom properties and featured needed by the control.

e.    Override the OnPaint method if the control’s appearance needs to be changed.

f.     Save the build the control

g.    Reference you control into another or the same project and use the control.

Describe the .NET Framework architecture.

.Net framework has two components:

1.    .Net framework class library

2.    Common language runtime.

FCL facilitates the types through CTS which are common to all the supported languages. 
The CLS ensures that all languages are interoperable. This ensures that all code is managed .i.e. code which is converted to MSIL.

The CLR has the class loader that load the MSIL code of an application into runtime, which is then converted into native code by the JIT complier. The CLR manages code and provide services such as memory management, threading, remoting, type safety, security, Exception handling etc.

What is the managed execution process?

Managed execution process is a process where CLR executes the managed code. The steps involved in this process are:

a.    Choosing the right compiler

b.    Compiling the code to MSIL. This also generates the required metadata.

c.    Compile the MSIL ode to native machine code.

d.    Executing the code with the variety of services available.

What are assemblies? Describe the types of assemblies.

Assembly is a compiled output of program which are used for easy deployment of an application. They are executables in the form of exe or dll. It also is a collection of resources that were used while building the application and is responsible for all the logical functioning.

Types of assemblies:

a.    Private Assemblies: are accessible by a single application. They reside within the application folder and are unique by name. They can be directly used by copying and pasting them to the bin folder.

b.    Shared Assemblies: are shared between multiple applications to ensure reusability. They are placed in GAC.

c.    Satellite Assemblies: are the assemblies to provide the support for multiple languages based on different cultures. These are kept in different modules based on the different categories available.

Explain the role of assemblies in .NET.


Assemblies are main building blocks. An assembly maybe defined as a unit of deployment. A single assembly is a collection of types, and resources. The CLR does not understand any types that are outside assemblies. The CLR executes the code in assemblies as they contain MSIL code. They define type, version and security boundaries. 

Assemblies in .Net are a solution to the Dll hell problem as one can use different versions of same assembly in different applications at the same time. To make a shared assembly, we need to register it with GAC where as private assemblies reside in applications directory.

What are windows services? How are they differ from other .NET application?

Windows services are a way to create continuously running applications in the background. They don’t interfere with other applications and can be run whenever a machine starts. They can be paused if and when needed and quietly run in the background without the need of any user intervention. Windows services can be configured to run under specific user accounts. They run under their own windows sessions and are ideal for tasks that need to be performed periodically or for monitoring requirements.

Chart Server Control

2011-02-14T13:22:00.000-08:00

One of the newest controls available to you now with ASP.NET 4 is the Chart server control. This control made its way into the core part of ASP.NET through a previous acquisition of the Dundas charting company and is a great control for getting you up and running with some good-looking charts.

The new Chart server control supports many chart types including:

➤ Point

➤ FastPoint

➤ Bubble

➤ Line

➤ Spline

➤ StepLine

➤ FastLine

➤ Bar

➤ StackedBar

➤ StackedBar100

➤ Column

➤ StackedColumn

➤ StackedColumn100

➤ Area

➤ SplineArea

➤ StackedArea

➤ StackedArea100

➤ Pie

➤ Doughnut

➤ Stock

➤ CandleStick

➤ Range

➤ SplineRange

➤ RangeBar

➤ RangeColumn

➤ Radar

➤ Polar

➤ ErrorBar

➤ BoxPlot

➤ Renko

➤ ThreeLineBreak

➤ Kagi

➤ PointAndFigure

➤ Funnel

Those are a lot of different chart styles! You can find the Chart server control in the toolbox of Visual Studio 2010 underneath the Data tab. It is part of the System.Web.DataVisualization namespace. When you drag it from the toolbox and place it on the design surface of your page, you are presented with a visual representation of the chart type that are you going to use. See Figure 1 for an example.

Figure 1

Open up the smart tag for the control, and you find that you can assign a data provider for the chart as well as select the chart type you are interested in using. Changing the chart type gives you a sample of what that chart looks like (even if you are not yet working with any underlying data) in the design view of the IDE.

Create a new web application and add the AdventureWorks database to your App_Data folder within the application. After that is accomplished, drag and drop the Chart server control onto the design surface of your page. From the smart tag of the control, select <New Data Source> from the drop-down menu when choosing your data source. Work your way through this wizard making sure that you are choosing a SQL data source as your option. As you work through the wizard, you are going to want to choose the option that allows you to choose a custom SQL statement and use the following SQL for this operation:

SELECT TOP (5) Production.Product.Name, Sales.SalesOrderDetail.OrderQty

FROM Sales.SalesOrderDetail

INNER JOIN Production.Product

ON Sales.SalesOrderDetail.ProductID = Production.Product.ProductID

ORDER BY Sales.SalesOrderDetail.OrderQty DESC

With that in place and the new chart server control bound to this data source control, you now find that you have more options in the smart tag of the chart server control. This is presented in Figure 2. Now you can select the series data members and choose what is on the x-axis and what is on the y-axis. I have assigned the Name of the product to be on the x-axis and the quantity ordered to be on the y-axis.

Figure 2

Code for Charting with the new Chart server control

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebServerControls.WebForm1" %>

<%@ Register Assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" Namespace="System.Web.UI.DataVisualization.Charting" TagPrefix="asp" %>

<title>MultiView Server Control</title>

</head>

<body>

<div>

<asp:Chart ID="Chart1" runat="server" DataSourceID="SqlDataSource1"

Width="500px">

<asp:Series ChartType="Bar" Name="Series1" XValueMember="Name"

YValueMembers="OrderQty" YValuesPerPoint="2">

</asp:Series>

</Series>

<asp:ChartArea Name="ChartArea1">

</asp:ChartArea>

</ChartAreas>

</asp:Chart>

<asp:SqlDataSource ID="SqlDataSource1" runat="server"

ConnectionString="<%$ ConnectionStrings:ConnectionString %>"

SelectCommand="SELECT TOP (5) Production.Product.Name,

Sales.SalesOrderDetail.OrderQty FROM Sales.SalesOrderDetail

INNER JOIN Production.Product ON

Sales.SalesOrderDetail.ProductID =

Production.Product.ProductID ORDER BY

Sales.SalesOrderDetail.OrderQty DESC">

</asp:SqlDataSource>

</div>

</form>

</body>

</html>

From this, you can see that there isn’t much code needed to wire everything up. Most notably, you can see that putting this Chart server control on your page actually added a @Register directive to the top of the page. This is unlike most of the ASP.NET server controls. Within the <Series> element of this control, you can have as many series as you want, and this is something that is quite common when charting multiple items side by side (such as a time series of prices for two or more stocks).

Running this code, you get results similar to what is presented here in Figure 3.

Figure 3

HTML Server Controls

2011-02-14T12:10:00.000-08:00

HTML Server Controls map to their corresponding HTML tags and simply output the HTML tags at run time. HTML elements in ASP.NET files are, by default, treated as text. To make these elements programmable, add a runat="server" attribute to the HTML element. This attribute indicates that the element should be treated as a server control.

If there's an HTML server control that corresponds to the HTML tag you've "contol-ized," the HTML tag becomes the corresponding type of server control. Otherwise it will simply default to an HTML control of type HtmlGenericControl.

Standard Controls

2011-02-14T12:09:00.000-08:00

All the standard ASP.NET controls are contained in the System.Web.UI.Webcontrols namespace. The prefix asp: represents this namespace.

The ASP.NET Framework version 2.0 includes a new feature called Control State. Control State is similar to View State except that it is used to preserve only critical state information. For example, the GridView control uses Control State to store the selected row. Even if you disable View State, the GridView control remembers which row is selected.

ASP.NET Tutorials

2011-02-14T11:41:00.000-08:00

Controls
Web User Control
Tree View Control
Chart Server Control

Web User Control

2011-02-11T08:57:00.000-08:00

Introduction

Let's create a simple calendar control using web user control.

Starting with user controls

So we decided to write our own control for selecting month/year pair. Then we will use it on our page.

Let's start by creating new web-site in Visual Studio 2005 and adding new Web user control to it.

Web user control consists of two parts: .ascx file, which is face of our control and contains HTML and ASP.NET 2.0 tags and code-behind partial class.

Now let's create a simple design for our control in .ascx file. Let's start by creating div, and placing a table inside of it. We will have 4 rows and 3 columns in our table (for 12 month).

Let's make a field for year input and place it on top of our table in separate div.

For a simple navigation of year let's create a simple JavaScript function to skip to next or previous year.

To validate date we will use regular expressions in JavaScript. It's really ease to use regular expressions - you just need to provide a patter and tell RegExp class to test your input value against pattern. Here is JavaScript function which will do all this for us:

First of all it's getElementById which is standard JavaScript function. But if you look at its body you will notice the use of ASP.NET script as the parameter to getElementById function. ASP.NET renders its controls in respective HTML tags (and even several HTML tags) and gives them unique IDs. To ensure uniqueness ASP.NET may modify string provided in ID attribute of each ASP.NET control, adding this control id or page id. So our month calendar's text box on different pages can have different ids. That's why we use txtYear.ClientID, which returns the actual id of rendered input field.

Next thing worth to have a look at, is a RegExp. RegExp stands for Regular Expression and allows performing several operations (replace, split, test, etc) on input strings using patterns. Pattern defines the format of the string. In our case \d ("\\d" in JavaScript, because "\" is escape sequence) is built-in class, which denotes numbers. Number 4 in {4} means that \d class should appear in text exactly 4 times. This expression can be rewritten to several other forms (for example [0-9][0-9][0-9][0-9] or \d\d\d\d or [0-9]{4} etc).

If year in the input is correct, we then increase or decrease it by 1. But if test was not passed we simply get the current year (newDate.getFullYear()).

Next step is binding script we wrote to some simple control. I choose to use simple left-right-arrow images. Now let's modify our header div (where the year text box is) to make it look like:

<div style="background-color: rgb(255,238,187); padding-top: 2px;">
<img src="<%= Page.ResolveUrl("~/images/prev1.gif") %>" border=0 onclick="nextYear(false);">
<asp:TextBox ID=txtYear Runat=server style="width: 50px; border: 1px solid; text-align: center;" MaxLength="4"></asp:TextBox>
<img src="<%= Page.ResolveUrl("~/images/next1.gif") %>" border=0 onclick="nextYear(true);">
<hr style="border: black 1px solid;" size=1>
</div>

Now our text box is bound to our script by means of small arrows which allow user to go back and forth in year selection.

Making months work

Now we approach to core functionality of our control. Now we should make months which are just static text for now to be ASP.NET link button control.

Replace month's table with the following one:

As you can see I wrapped month names in Link button and added event handler to all links. Now our work with .ascx file is done it's time to switch to code-behind class. In code behind we should first of all set the initial date of calendar and provide a value field so that pages and other controls can retrieve value from month calendar. Let's create a field and a property to hold value:

private DateTime _Value = DateTime.Now;
public DateTime Value
{
get { return _Value; }
set { _Value = value; }
}

Next step is to create even handler to our source. Paste next fragment in code-behind class.

public void lnkMonthClick(object sender, EventArgs e)
{
int Month = 1;
      LinkButton btn = (LinkButton)sender;
      if (btn.Text == "Jan")Month = 1;
      if (btn.Text == "Feb")Month = 2;
      if (btn.Text == "Mar")Month = 3;
      if (btn.Text == "Apr")Month = 4;
      if (btn.Text == "May")Month = 5;
      if (btn.Text == "Jun")Month = 6;
      if (btn.Text == "Jul")Month = 7;
      if (btn.Text == "Aug")Month = 8;
      if (btn.Text == "Sep")Month = 9;
      if (btn.Text == "Oct")Month = 10;
      if (btn.Text == "Nov")Month = 11;
      if (btn.Text == "Dec")Month = 12;

      int Year;
      try {
      Year = Int32.Parse(txtYear.Text);
      } catch { Year = DateTime.Now.Year; }
      this.Value = new DateTime(Year, Month, 1, 0, 0, 1);
      if (DateChanged != null)
      DateChanged.Invoke(this, new EventArgs());
}

public event EventHandler DateChanged;

Using Month select control

Now let's add control to our Default.aspx page. Just drag-n-drop your month select control file from right panel to Default.aspx content pane. You should see something like this:

Now we should register event for month change. To do this, simply add this line to Page_Load:

MonthSelect1.DateChanged += new EventHandler(MonthSelect1_DateChanged);

And then add event handler code. For example:

void MonthSelect1_DateChanged(object sender, EventArgs e)
{
Label1.Text = MonthSelect1.Value.ToString();
}

TreeView control

2011-02-11T08:02:00.000-08:00

Introduction

ASP.Net 2.0 introduces many new controls including a TreeView Control, which can be used to consume information from hierarchical data sources like an XML file and then display that information. In this tutorial, I am going to statically data bind the TreeView control with the contents of an XML file.

TreeView Control Example

Create a new web application, and open the Default.aspx page in design view. Locate the TreeView control in the toolbox and drag it onto the form. Here is what it looks like by default:

Click on the small box located in the upper right-hand corner of the control, choose Auto Format, and select Contacts style:

This will update the control to look like the above. There are many pre-defined formats for you to choose from, take a few moments to look at each of them.

The next step is to add a new XML file to the project and create your data file:

<?xml version="1.0" encoding="utf-8" ?>

<Contacts>
<Contact Name="Sample 1">
    <Description Value="Phone#, EMail Address, Web-Site">
    </Description>
</Contact>
<Contact Name=" Sample 2">
    <Description Value="Phone#, EMail Address, Web-Site">
    </Description>
</Contact>
<Contact Name=" Sample 3">
    <Description Value="Phone#, EMail Address, Web-Site">
    </Description>
</Contact>

</Contacts>

Switch back to Default.aspx and add an XMLDataSource object to the form. Set its DataFile to the new

Select the DataBindings property and open the TreeView DataBindings Editor. It will automatically have loaded the nodes. Select "Description" and click ADD. Set ValueField to Value. (Note: you can set value field and display field separately. Like for instance, you could display Client Names, but set the node's value equal to their ID.)

Click on Apply and exit the Editor. Switch to the XML file and set some real-time entries, and run the application.

That's all there is to it. Simple and clear... now switch back to the Default.aspx page and open the TreeView DataBindings Editor again. This time add databinding settings for the Contact nodes.

Save and run the application again.Change the values in the XML file, and refresh your web-page to see the changes in the tree.

Interview Questions

2011-02-10T10:55:00.001-08:00

Method and Property Questions

1. What’s the implicit name of the parameter that gets passed into the set Method/property of a class?         Value. The data type of the value parameter is defined by whatever data type the property is declared .

2. What does the keyword “virtual” declare for a method or property?
         The method or property can be overridden.

3. How is method overriding different from method overloading?
            When overriding a method, you change the behavior of the method for the derived class. Overloading a method simply involves having another method with the same name within the class.

4. Can you declare an override method to be static if the original method is not static?              No. The signature of the virtual method must remain the same. (Note: Only the keyword virtual is changed to keyword override)

5. What are the different ways a method can be overloaded?
            Different parameter data types, different number of parameters, different order of parameters.

6. If a base class has a number of overloaded constructors, and an inheriting class has a number of overloaded constructors; can you enforce a call from an inherited constructor to a specific base constructor?          Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

C# Interview Questions

2011-02-10T10:54:00.000-08:00

Events and Delegates

1. What’s a delegate?           A delegate object encapsulates a reference to a method.

2. What’s a multicast delegate?
         A delegate that has multiple handlers assigned to it. Each assigned handler (method) is called.

3. What’s the implicit name of the parameter that gets passed into the class’ set method?
         Value, and it’s datatype depends on whatever variable we’re changing.

4. How do you inherit from a class in C#?
          Place a colon and then the name of the base class.

5. Does C# support multiple inheritance?
           No, use interfaces instead.

6. When you inherit a protected class-level variable, who is it available to?             Classes in the same namespace.

7. Are private class-level variables inherited?
          Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited.

8. Describe the accessibility modifier protected internal.?
          It’s available to derived classes and classes within the same Assembly (and naturally from the base class it’s declared in).

9. C# provides a default constructor for me. I write a constructor that takes a string as a parameter, but want to keep the no parameter one. How many constructors should I write?
          Two. Once you write at least one constructor, C# cancels the freebie constructor, and now you have to write one yourself, even if there’s no implementation in it.

10. How’s method overriding different from overloading?                   When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.

11. Can you override private virtual methods?
             No, moreover, you cannot access private methods in inherited classes, have to be protected in the base class to allow any sort of access.

12. Can you prevent your class from being inherited and becoming a base class for some other classes?               Yes, that’s what keyword sealed in the class definition is for. The developer trying to derive from your class will get a message: cannot inherit from Sealed class WhateverBaseClassName. It’s the same concept as final class in Java.

13. Can you allow class to be inherited, but prevent the method from being over-ridden?
                Yes, just leave the class public and make the method sealed.

14. When do you absolutely have to declare a class as abstract (as opposed to free-willed educated choice or decision based on UML diagram)?            When at least one of the methods in the class is abstract. When the class itself is inherited from an abstract class, but not all base abstract methods have been over-ridden.

15. What’s an interface class?              It’s an abstract class with public abstract methods all of which must be implemented in the inherited classes.

16. Why can’t you specify the accessibility modifier for methods inside the interface?                  They all must be public. Therefore, to prevent you from getting the false impression that you have any freedom of choice, you are not allowed to specify any accessibility, it’s public by default.

17. What’s the difference between an interface and abstract class?                In the interface all methods must be abstract, in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.

18. How can you overload a method?               Different parameter data types, different number of parameters, different order of parameters.

19. If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited            constructor to an arbitrary base constructor?
             Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

20. Is it namespace class or class namespace?
             The .NET class library is organized into namespaces. Each namespace contains a functionally related group of classes so natural namespace comes first.

21. Are private class-level variables inherited?

Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are.

22. Why does DllImport not work for me?

All methods marked with the DllImport attribute must be marked as public static extern.

23. Why does my Windows application pop up a console window every time I run it?

Make sure that the target type set in the project properties setting is set to Windows Application, and not Console Application. If you’re using the command line, compile with /target:winexe, not /target:exe.

24. Why do I get an error (CS1006) when trying to declare a method without specifying a return type?

If you leave off the return type on a method declaration, the compiler thinks you are trying to declare a constructor. So if you are trying to declare a method that returns nothing, use void. The following is an example: // This results in a CS1006 error public static staticMethod (mainStatic obj) // This will work as wanted public static void staticMethod (mainStatic obj)

25. Why do I get a syntax error when trying to declare a variable called checked?

The word checked is a keyword in C#.

26. Why do I get a security exception when I try to run my C# app?

Some security exceptions are thrown if you are working on a network share. There are some parts of the frameworks that will not run if being run off a share (roaming profile, mapped drives, etc.). To see if this is what’s happening, just move the executable over to your local drive and see if it runs without the exceptions. One of the common exceptions thrown under these conditions is System.Security.SecurityException. To get around this, you can change your security policy for the intranet zone, code group 1.2, (the zone that running off shared folders falls into) by using the caspol.exe tool.

27. Why do I get a CS5001: does not have an entry point defined error when compiling?

The most common problem is that you used a lowercase ‘m’ when defining the Main method. The correct way to implement the entry point is as follows: class test { static void Main(string[] args) {} }

28. What optimizations does the C# compiler perform when you use the /optimize+ compiler option?

The following is a response from a developer on the C# compiler team: We get rid of unused locals (i.e., locals that are never read, even if assigned). We get rid of unreachable code. We get rid of try-catch with an empty try. We get rid of try-finally with an empty try. We get rid of try-finally with an empty finally. We optimize branches over branches: gotoif A, lab1 goto lab2: lab1: turns into: gotoif !A, lab2 lab1: We optimize branches to ret, branches to next instruction, and branches to branches.

29. What is the syntax for calling an overloaded constructor within a constructor (this() and constructorname() does not compile)?

The syntax for calling another constructor is as follows: class B { B(int i) { } } class C : B { C() : base(5) // call base constructor B(5) { } C(int i) : this() // call C() { } public static void Main() {} }

30. What is the equivalent to regsvr32 and regsvr32 /u a file in .NET development?

Try using RegAsm.exe. Search MSDN on Assembly Registration Tool.

31. What is the difference between a struct and a class in C#?

From language spec: The list of similarities between classes and structs is as follows. Longstructs can implement interfaces and can have the same kinds of members as classes. Structs differ from classes in several important ways; however, structs are value types rather than reference types, and inheritance is not supported for structs. Struct values are stored on the stack or in-line. Careful programmers can sometimes enhance performance through judicious use of structs. For example, the use of a struct rather than a class for a Point can make a large difference in the number of memory allocations performed at runtime. The program below creates and initializes an array of 100 points. With Point implemented as a class, 101 separate objects are instantiated-one for the array and one each for the 100 elements.

32. Is there regular expression (regex) support available to C# developers?

Yes. The .NET class libraries provide support for regular expressions. Look at the System.Text.RegularExpressions namespace.

33. Is there any sample C# code for simple threading? –

Yes:

1.  using System;

2.  using System.Threading;

3.  class ThreadTest

4.  {

5.    public void runme()

6.    {

7.           Console.WriteLine("Runme Called");

8.    }

9.    public static void Main(String[] args)

10.  {

11.         ThreadTest b = new ThreadTest();

12.         Thread t = new Thread(new ThreadStart(b.runme));

13.         t.Start();

14.  }

34. Is there an equivalent of exit() for quitting a C# .NET application?

Yes, you can use System.Environment.Exit(int exitCode) to exit the application or Application.Exit() if it’s a Windows Forms app.

35. Is there a way to force garbage collection?

Yes. Set all references to null and then call System.GC.Collect(). If you need to have some objects destructed, and System.GC.Collect() doesn’t seem to be doing it for you, you can force finalizers to be run by setting all the references to the object to null and then calling System.GC.RunFinalizers().

36. Is it possible to restrict the scope of a field/method of a class to the classes in the same namespace? –

There is no way to restrict to a namespace. Namespaces are never units of protection. But if you’re using assemblies, you can use the ‘internal’ access modifier to restrict access to only within the assembly.

37. Can you store multiple data types in System.Array?

No.

38. What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?

The first one performs a deep copy of the array, the second one is shallow.

39. How can you sort the elements of the array in descending order?

By calling Sort() and then Reverse() methods.

40. What’s the .NET datatype that allows the retrieval of data by a unique key?

HashTable.

41. What’s class SortedList underneath?

A sorted HashTable.

42. Will finally block get executed if the exception had not occurred?

Yes.

43. What’s the C# equivalent of C++ catch (…), which was a catch-all statement for any possible exception?

A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.

44. Can multiple catch blocks be executed?

No, once the proper catch code fires off, the control is transferred to the finally block (if there are any), and then whatever follows the finally block.

45. Why is it a bad idea to throw your own exceptions?

Well, if at that point you know that an error has occurred, then why not write the proper code to handle that error instead of passing a new Exception object to the catch block? Throwing your own exceptions signifies some design flaws in the project.

46. How do I declare inout arguments in C#?

The equivalent of inout in C# is ref. , as shown in the following

example: public void MyMethod (ref String str1, out String str2)

{

...

}

When calling the method, it would be called like this: String s1;

String s2;

s1 = "Hello";

MyMethod(ref s1, out s2);

Console.WriteLine(s1);

Console.WriteLine(s2);

Notice that you need to specify ref when declaring the function and calling it.

47. How do I make a dll in C#?

Open the property page of the Project File and then

open CommonProperties -> Genaral ->Output Type

change the output type to class library and build the application then u'll get a dll file.

also in the Configuartion Properties ->Build -> Output Path

u mention the path where u wnat to store your dll file.

48. How do I register my code for use by classic COM clients?

Use the regasm.exe utility to generate a type library (if needed) and the necessary entries in the Windows Registry to make a class available to classic COM clients. Once a class is registered in the Windows Registry with regasm.exe, a COM client can use the class as though it were a COM class.

49. Describe the difference between a Thread and a Process? Threads are similar to processes, but differ in the way that they share resources. Threads are distinguished from processes in that processes are typically independent, carry considerable state information and have separate address spaces. Threads typically share the memory belonging to their parent process.

50. What is the difference between an EXE and a DLL? An exe runs in it's own address space / process but Dll gets loaded into the exe's process address space.

51. What is CLR?
As part of Microsoft's .NET Framework, the Common Language Runtime (CLR) is programming that manages the execution of programs written in any of several supported languages, allowing them to share common object-oriented classes written in any of the languages.

52. What are Namespaces?
Logical Container, which will organize your classes, is called namespaces.

53. What is boxing?

Conversion of a value type to a reference type is called Boxing. The vice versa is called UnBoxing. Boxing is implicit conversion. Unboxing is Explicit conversion.

54. What’s the difference between the System.Array.CopyTo() and System.Array.Clone() ?
The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identacle object.

55. Can you store multiple data types in System.Array?
No.

56. How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods.

57. Can multiple catch blocks be executed for a single try statement?
No. Once the proper catch block processed, control is transferred to the finally block (if there are any).

58. Describe the accessibility modifier “protected internal”.
It is available to classes that are within the same assembly and derived from the specified base class.

59. Can you declare the override method static while the original method is non-static?

No, you can’t, the signature of the virtual method must remain the same, only the keyword virtual is changed to keyword override.

60. What's the implicit name of the parameter that gets passed into the class' set method?

Value :parameter gets passed into the class' set method

61. Is it mandatory to implement all the methods which are there in abstract class if we inherit that abstract class..?

No only function marked as abstract shoud be implemented.the following code runs fine abstract public class baseclass { public abstract void method1(); public void method2(){Console.WriteLine("Base Method 2");} } public class derivedclass:baseclass { public override void method1(){Console.WriteLine("Derived Method 1");} //public override void method2(){Console.WriteLine("Derived Method 1");;} }

62. What is CLS?

Common Language Specification. The Common Language Specification (CLS) describes a set of features that different languages have in common.
The CLS includes a subset of the Common Type System (CTS).

63. What is Reflection? Used to Get assembly metadata using code. To organize the assemblies at runtime we use System.Reflection name space. To Load,to get the information about the assemblies at runtime according to need this can be done using System.Reflection.

64. What is the use of fixed statement?

The fixed statement sets a pointer to a managed variable and "pins" that variable during the execution of statement. Without fixed, pointers to managed variables would be of little use since garbage collection could relocate the variables unpredictably. (In fact, the C# compiler will not allow you to set a pointer to a managed variable except in a fixed statement.)

Eg: Class A { public int i; }

A objA = new A; // A is a .net managed type

fixed(int *pt = &objA.i) // use fixed while using pointers with managed

// variables

{

*pt=45; // in this block use the pointer the way u want

}

65. What is wrapper class?is it available in c#?

Wrapper Classes are the classes that wrap up the primitive values in to a class that offer utility method to access it . For eg you can store list of int values in a vector class and access the class. Also the methods are static and hence you can use them without creating an instance . The values are immutable .

66. What is the difference between shadow and override?

Overriding is used to redefines only the methods.but shadowing redefines the entire element.

In case of Shadow : TO access the Base/Parent class elements use the MyBase Keyword
In case of Overriding : TO access the Base/Parent class elements use the Me Keyword

67. Is it possible to have different access modifiers on the get/set methods of a property?

No. The access modifier on a property applies to both its get and set accessors. What you need to do if you want them to be different is make the property read-only (by only providing a get accessor) and create a private/internal set method that is separate from the property.

68. How do you implement thread synchronization (Object.Wait, Notify,and CriticalSection) in C#?

You want the lock statement, which is the same as Monitor Enter/Exit:

lock(obj) { // code }

      translates to

try {

        CriticalSection.Enter(obj);

        // code

finally

        CriticalSection.Exit(obj);

69. How does assembly versioning in .NET prevent DLL Hell?

The runtime checks to see that only one version of an assembly is on the machine at any one time.
.NET allows assemblies to specify the name AND the version of any assemblies they need to run.
The compiler offers compile time checking for backward compatibility.
It doesn.t.

70. What do you know about .NET assemblies?

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.

71. What’s the difference between private and shared assembly?

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.

72. What’s a strong name?

A strong name includes the name of the assembly, version number, culture identity, and a public key token.

73. Can you prevent your class from being inherited and becoming a base class for some other classes?

Yes, that is what keyword sealed in the class definition is for. The developer trying to derive from your class will get a message: cannot inherit from Sealed class WhateverBaseClassName. It is the same concept as final class in Java.

74. If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor?

Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

75. Is it possible to inline assembly or IL in C# code?
No.

C# Interview Questions

2011-02-10T10:52:00.001-08:00

Class Questions

1.What is the syntax to inherit from a class in C#?            Place a colon and then the name of the base class.
Example: class MyNewClass : MyBaseClass

2.Can you prevent your class from being inherited by another class?           Yes. The keyword “sealed” will prevent the class from being inherited.

3.Can you allow a class to be inherited, but prevent the method from being over-ridden?          Yes. Just leave the class public and make the method sealed.

4.What’s an abstract class?          A class that cannot be instantiated. An abstract class is a class that must be inherited and have the methods overridden. An abstract class is essentially a blueprint for a class without any implementation.

5.When do you absolutely have to declare a class as abstract?       1. When the class itself is inherited from an abstract class, but not all base abstract methods have been overridden.
       2. When at least one of the methods in the class is abstract.

6.What is an interface class?       Interfaces, like classes, define a set of properties, methods, and events. But unlike classes, interfaces do not provide implementation. They are implemented by classes, and defined as separate entities from classes.

7.Why can’t you specify the accessibility modifier for methods inside the interface?       They all must be public, and are therefore public by default.

8.Can you inherit multiple interfaces?        Yes. .NET does support multiple interfaces.

9.What happens if you inherit multiple interfaces and they have conflicting method names?         It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.

10. What’s the difference between an interface and abstract class?           In an interface class, all methods are abstract - there is no implementation. In an abstract class some methods can be concrete. In an interface class, no accessibility modifiers are allowed. An abstract class may have accessibility modifiers.

11. What is the difference between a Struct and a Class?         Structs are value-type variables and are thus saved on the stack, additional overhead but faster retrieval. Another difference is that structs cannot inherit.

C# Interview Questions

2011-02-10T10:51:00.001-08:00

Part III

1) What’s the difference between an interface and abstract class?

In the interface all methods must be abstract, in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.

2) How can you overload a method?

Different parameter data types, different number of parameters, different order of parameters.

3) If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor?

Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

4) What’s the difference between System.String and System.StringBuilder classes?

System.String is immutable, System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.

5) Is it namespace class or class namespace?

The .NET class library is organized into namespaces. Each namespace contains a functionally related group of classes so natural namespace comes first.

6) Does C# support multiple-inheritance?           No. But you can use Interfaces.

7) Where is a protected class-level variable available?          It is available to any sub-class derived from base class

8) Are private class-level variables inherited?         Yes, but they are not accessible.

9) Describe the accessibility modifier “protected internal”.          It is available to classes that are within the same assembly and derived from the specified base class.

10) Which class is at the top of .NET class hierarchy?            System.Object.

11).What does the term immutable mean?             The data value may not be changed.
            Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory.

12) What’s the difference between System.String and System.Text.StringBuilder classes?             System.String is immutable. System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.

13) What’s the advantage of using System.Text.StringBuilder over System.String?            StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created.

14) Can you store multiple data types in System.Array?              No.

15) What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?             The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identacle object.

16) How can you sort the elements of the array in descending order?           By calling Sort() and then Reverse() methods.

17) What’s the .NET collection class that allows an element to be accessed using a unique key?         HashTable.

18) What class is underneath the SortedList class?         A sorted HashTable.

19) Will the finally block get executed if an exception has not occurred?         Yes.

20) What’s the C# syntax to catch any possible exception?         A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.

21) Can multiple catch blocks be executed for a single try statement?         No. Once the proper catch block processed, control is transferred to the finally block .

22) Explain the three services model commonly know as a three-tier application?           Presentation (UI), Business (logic and underlying code) and Data (from storage or other sources).

C# Interview Questions

2011-02-10T10:47:00.000-08:00

Part II

1) Is goto statement supported in C#? How about Java?

Gotos are supported in C#to the fullest. In Java goto is a reserved keyword that provides absolutely no functionality.

2) Describe the compilation process for .NET code?

Source code is compiled and run in the .NET Framework using a two-stage process. First, source code is compiled to Microsoft intermediate language (MSIL) code using a .NET Framework-compatible compiler, such as that for Visual Basic .NET or Visual C#. Second, MSIL code is compiled to native code.

3)Name any 2 of the 4 .NET authentification methods.

ASP.NET, in conjunction with Microsoft Internet Information Services (IIS), can authenticate user credentials such as names and passwords using any of the following authentication methods:

Windows: Basic, digest, or Integrated Windows Authentication (NTLM or Kerberos).
Microsoft Passport authentication
Forms authentication
Client Certificate authentication

4)How do you turn off SessionState in the web.config file?

In the system.web section of web.config, you should locate the httpmodule tag and you simply disable session by doing a remove tag with attribute name set to session.

5)What is main difference between Global.asax and Web.Config?

ASP.NET uses the global.asax to establish any global objects that your Web application uses. The .asax extension denotes an application file rather than .aspx for a page file. Each ASP.NET application can contain at most one global.asax file. The file is compiled on the first page hit to your Web application. ASP.NET is also configured so that any attempts to browse to the global.asax page directly are rejected. However, you can specify application-wide settings in the web.config file. The web.config is an XML-formatted text file that resides in the Web site’s root directory. Through Web.config you can specify settings like custom 404 error pages, authentication and authorization settings for the Web site, compilation options for the ASP.NET Web pages, if tracing should be enabled, etc.

6) What’s the implicit name of the parameter that gets passed into the class’ set method?

Value, and it’s datatype depends on whatever variable we’re changing.

7) How do you inherit from a class in C#?

Place a colon and then the name of the base class.

8) Does C# support multiple inheritance?

No, use interfaces instead.

9) When you inherit a protected class-level variable, who is it available to?

Classes in the same namespace.

10) Are private class-level variables inherited?

Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited. But they are.

11) Describe the accessibility modifier protected internal.

It’s available to derived classes and classes within the same Assembly (and naturally from the base class it’s declared in).

12) C# provides a default constructor for me. I write a constructor that takes a string as a parameter, but want to keep the no parameter one. How many constructors should I write?

Two. Once you write at least one constructor, C# cancels the freebie constructor, and now you have to write one yourself, even if there’s no implementation in it.

13) What’s the top .NET class that everything is derived from?

System.Object.

14) How’s method overriding different from overloading?

When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.

15) What does the keyword virtual mean in the method definition?

The method can be over-ridden.

16) Can you declare the override method static while the original method is non-static?

No, you can’t, the signature of the virtual method must remain the same, only the keyword virtual is changed to keyword override.

17) Can you override private virtual methods?

No, moreover, you cannot access private methods in inherited classes, have to be protected in the base class to allow any sort of access.

18) Can you prevent your class from being inherited and becoming a base class for some other classes?

Yes, that’s what keyword sealed in the class definition is for. The developer trying to derive from your class will get a message: cannot inherit from Sealed class WhateverBaseClassName. It’s the same concept as final class in Java.

19) Can you allow class to be inherited, but prevent the method from being over-ridden?

Yes, just leave the class public and make the method sealed.

20) What’s an abstract class?

A class that cannot be instantiated. A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden. Essentially, it’s a blueprint for a class without any implementation.

21) When do you absolutely have to declare a class as abstract (as opposed to free-willed educated choice or decision based on UML diagram)?

When at least one of the methods in the class is abstract. When the class itself is inherited from an abstract class, but not all base abstract methods have been over-ridden.

22) What’s an interface class?

It’s an abstract class with public abstract methods all of which must be implemented in the inherited classes.

23) Why can’t you specify the accessibility modifier for methods inside the interface?

They all must be public. Therefore, to prevent you from getting the false impression that you have any freedom of choice, you are not allowed to specify any accessibility, it’s public by default.

24) Can you inherit multiple interfaces?

Yes, why not.

25) And if they have conflicting method names?

It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.

C# Interview Questions

2011-02-10T10:41:00.000-08:00

Part I

1) How big is the datatype int in .NET?

32 bits.

2) How big is the char?

16 bits (Unicode).

3) How do you initiate a string without escaping each backslash?

Put an @ sign in front of the double-quoted string.

4) What are valid signatures for the Main function?

public static void Main()
public static int Main()
public static void Main( string[] args )
public static int Main(string[] args )

5) Does Main() always have to be public? No.

6) How do you initialize a two-dimensional array that you don’t know the dimensions of?

int [, ] myArray; //declaration
myArray= new int [5, 8]; //actual initialization

7) What’s the access level of the visibility type internal?

Current assembly.

8) What’s the difference between struct and class in C#?

Structs cannot be inherited.
Structs are passed by value, not by reference.
Struct is stored on the stack, not the heap.

9) Explain encapsulation.

The implementation is hidden, the interface is exposed.

10) What data type should you use if you want an 8-bit value that’s signed?

sbyte.

11) Speaking of Boolean data types, what’s different between C# and C/C++?

There’s no conversion between 0 and false, as well as any other number and true, like in C/C++.

12) Where are the value-type variables allocated in the computer RAM?

Stack.

13) Where do the reference-type variables go in the RAM?

The references go on the stack, while the objects themselves go on the heap. However, in reality things are more elaborate.

14) What is the difference between the value-type variables and reference-type variables in terms of garbage collection?

The value-type variables are not garbage-collected, they just fall off the stack when they fall out of scope, the reference-type objects are picked up by GC when their references go null.

15) How do you convert a string into an integer in .NET?

Int32.Parse(string), Convert.ToInt32()

16) How do you box a primitive data type variable?

Initialize an object with its value, pass an object, cast it to an object

17) Why do you need to box a primitive variable?

To pass it by reference or apply a method that an object supports, but primitive doesn’t.

18) What’s the difference between Java and .NET garbage collectors?

Sun left the implementation of a specific garbage collector up to the JRE developer, so their performance varies widely, depending on whose JRE you’re using. Microsoft standardized on their garbage collection.

19) How do you enforce garbage collection in .NET?

System.GC.Collect();

20) Can you declare a C++ type destructor in C# like ~MyClass()?

Yes, but what’s the point, since it will call Finalize(), and Finalize() has no guarantees when the memory will be cleaned up, plus, it introduces additional load on the garbage collector. The only time the finalizer should be implemented, is when you’re dealing with unmanaged code.

21) What’s different about namespace declaration when comparing that to package declaration in Java?

No semicolon. Package declarations also have to be the first thing within the file, can’t be nested, and affect all classes within the file.

22) What’s the difference between const and readonly?

You can initialize readonly variables to some runtime values. Let’s say your program uses current date and time as one of the values that won’t change. This way you declare

public readonly string DateT = new DateTime().ToString().

23) Can you create enumerated data types in C#?

Yes.

24) What’s different about switch statements in C# as compared to C++?

No fall-throughs allowed.

25) What happens when you encounter a continue statement inside the for loop?

The code for the rest of the loop is ignored, the control is transferred back to the beginning of the loop.

C# Tutorials

2011-02-08T00:06:00.001-08:00

E-Books

2011-02-07T23:43:00.000-08:00

Professional ASP.NET 4 in C# and VB.NET

Wrox Beginning ASP.NET 4.0 CS &VB

Microsoft Press ASP.NET and AJAX

Teach Yourself ASP.NET 4.0 in 24 hours

Teach Yourself ASP.NET Ajax in 24 Hours

Linq

Interview Questions

2011-02-07T23:39:00.000-08:00

ASP.NET Part I

ASP.NET Part II

ASP.NET Part III

ASP.NET Part IV

C# Part I

C# Part II

C# Part III

C# - Class Questions

C# - Events/Delegates

C# - Method/Property

AJAX

Interview Questions

2011-02-02T10:31:00.000-08:00

ASP.NET

Part IV

76. What is a profile object, why is it used?
Using the new personalization services in ASP.NET 2.0 you can easily create customized experiences within Web applications. The Profile object enables developers to easily build strongly-typed, sticky data stores for user accounts and build highly customized, relationship based experiences. At the same time, a developer can leverage Web Parts and the personalization service to enable Web site visitors to completely control the layout and behavior of the site, with the knowledge that the site is completely customized for them. Personalizaton scenarios are now easier to build than ever before and require significantly less code and effort to implement.

77. What is Configuration API?
ASP.NET 2.0 contains new configuration management APIs, enabling users to programmatically build programs or scripts that create, read, and update Web.config and machine.config configuration files.

78. What is MMC Admin Tool?
ASP.NET 2.0 provides a new comprehensive admin tool that plugs into the existing IIS Administration MMC, enabling an administrator to graphically read or change common settings within our XML configuration files.

79.Explain the use of Pre-compilation Tool?
ASP.NET 2.0 delivers a new application deployment utility that enables both developers and administrators to precompile a dynamic ASP.NET application prior to deployment. This precompilation automatically identifies any compilation issues anywhere within the site, as well as enables ASP.NET applications to be deployed without any source being stored on the server (one can optionally remove the content of .aspx files as part of the compile phase), further protecting your intellectual property.　

80.How is application management and maintenance improved in Asp.net 2.0?
ASP.NET 2.0 also provides new health-monitoring support to enable administrators to be automatically notified when an application on a server starts to experience problems. New tracing features will enable administrators to capture run-time and request data from a production server to better diagnose issues. ASP.NET 2.0 is delivering features that will enable developers and administrators to simplify the day-to-day management and maintenance of their Web applications.

81.What are Provider-driven Application Services? explain in detail?ASP.NET 2.0 now includes built-in support for membership (user name/password credential storage) and role management services out of the box. The new personalization service enables quick storage/retrieval of user settings and preferences, facilitating rich customization with minimal code. The new site navigation system enables developers to quickly build link structures consistently across a site. As all of these services are provider-driven, they can be easily swapped out and replaced with your own custom implementation. With this extensibility option, you have complete control over the data store and schema that drives these rich application services.

82.Explain Server Control Extensibility with reference to Asp.net 2.0 ?ASP.NET 2.0 includes improved support for control extensibility, such as more base classes that encapsulate common behaviors, improved designer support, more APIs for interacting with client-side script, metadata-driven support for new features like themes and accessibility verification, better state management, and more.

83.What are the Data Source Controls?Data access in ASP.NET 2.0 is now performed declaratively using data source controls on a page. In this model, support for new data backend storage providers can be easily added by implementing custom data source controls. Additionally, the SqlDataSource control that ships in the box has built-in support for any ADO.NET managed provider that implements the new provider factory model in ADO.NET.

84.What are Compilation Build Providers?Dynamic compilation in ASP.NET 2.0 is now handled by extensible compilation build providers, which associate a particular file extension with a handler that knows how to compile that extension dynamically at runtime. For example, .resx files can be dynamically compiled to resources, .wsdl files to web service proxies, and .xsd files to typed DataSet objects. In addition to the built-in support, it is easy to add support for additional extensions by implementing a custom build provider and registering it in Web.config.

85. What is Expression Builders, why would you use it?ASP.NET 2.0 introduces a declarative new syntax for referencing code to substitute values into the page, called Expression Builders. ASP.NET 2.0 includes expression builders for referencing string resources for localization, connection strings, application settings, and profile values. You can also write your own expression builders to create your own custom syntax to substitute values in a page rendering.

86. Is ASP.NET 64-Bit enabled? How?ASP.NET 2.0 is now 64-bit enabled, meaning it can take advantage of the full memory address space of new 64-bit processors and servers. Developers can simply copy existing 32-bit ASP.NET applications onto a 64-bit ASP.NET 2.0 server and have them automatically be JIT compiled and executed as native 64-bit applications (no source code changes or manual re-compile are required).

87. Explain how Caching in Asp.net 2.0 is different from Caching in Asp.net 1.1?ASP.NET 2.0 also now includes automatic database server cache invalidation. This powerful and easy-to-use feature allows developers to aggressively output cache database-driven page and partial page content within a site and have ASP.NET automatically invalidate these cache entries and refresh the content whenever the back-end database changes. Developers can now safely cache time-critical content for long periods without worrying about serving visitors stale data.

88. How to add client side event to server side? And how to register client script to sever side? Difference these two
We can register client script in serverside also....if u want to make it in serverside use this code...
ClientScript.RegisterStartupScript(Me.GetType (), "script", "<script language=""javascript"">function1() </script>")
(or)
Me.Page.RegisterClientScriptBlock("close", "<script language=javascript>javascriptcode......</script>")
I think there is no difference b/n those two....depending
upon the situatio we can use any of these....

89. What does the "EnableViewState" property do? Why would I want it on or off?
Enableviewstate propery is on for page or any control then it holding or catching or storing data in memory as well as client side hedden value. when u post back data remains in control or page.If Enableviewstate property false then data remove when
Post back.

90. How many types of cookies are there in .NET ?Two type of cookeies.
a) single valued eg request.cookies("UserName").value="dotnetquestion"
b)Multivalued cookies. These are used in the way collections are used example
request.cookies("CookieName")("UserName")="dotnetquestionViji"
request.cookies("CookieName")("UserID") = "interview"
91. What is Finalizer in .NET?. Define dispose and finalize.

Finalizer are the methods that helps in cleanup the code before object is garbage collected. This process is called finalization . There are two methods of finalizer Dispose and Finalize .There is little diffrenet between two of this method . When we call Dispose method is realse all the resources hold by an object as well as all the resources hold by the parent object.When we call Dispose method it clean managed as well as unmanaged resources.
Finalize method also cleans resources but finalize call dispose clears only the unmanaged resources because in finalization the garbage collecter clears all the object hold by managed code so finalization fails to prevent those one of method is used that is: GC.SuppressFinalize.

92. What is Viewstate? View state is used by the ASP.NET page framework to automatically save the values of the page and of each control just prior to rendering to the page. When the page is posted, one of the first tasks performed by page processing is to restore view state.
State management is the process by which you maintain state and page information over multiple requests for the same or different pages.
Client-side options are:
* The ViewState property * Query strings * Hidden fields * Cookies Server-side options are:
* Application state * Session state * DataBase Use the View State property to save data in a hidden field on a page. Because ViewState stores data on the page, it is limited to items that can be serialized. If you want to store more complex items in View State, you must convert the items to and from a string.
ASP.NET provides the following ways to retain variables between requests:
Context.Handler object Use this object to retrieve public members of one Web form’s class from a subsequently displayed Web form.
Query strings Use these strings to pass information between requests and responses as part of the Web address. Query strings are visible to the user, so they should not contain secure information such as passwords.
Cookies Use cookies to store small amounts of information on a client. Clients might refuse cookies, so your code has to anticipate that possibility.
View state ASP.NET stores items added to a page’s ViewState property as hidden fields on the page.
Session state Use Session state variables to store items that you want keep local to the current session (single user).
Application state Use Application state variables to store items that you want be available to all users of the application.

93. What is ado.net ?
ADO.NET is the primary relational data access model for Microsoft .NET-based applications. It may be used to access data sources for which there is a specific .NET Provider,or, via a.NET Bridge Provider, for which there is a specific OLE DB Provider, ODBC Driver, or JDBC Driver.

94. What is EnabledViewState?
"EnableViewState" property - holds the state of the web control. View state holds the proprty details as a group of a particular web control. And can be sent via HTTPEnable view state must eb enableed for transfering throught he HTTP requests.If, the webserver control is using the database request, then it is advisable to make the Enable viewState = false, to improve the processor performance, cause the database will overide the state.

95. What is PostBack & Callback?
One technique that current ASP.NET 1.0/1.1 developers use to overcome this postback problem is to use the Microsoft XMLHTTP ActiveX object to send requests to server-side methods from client-side JavaScript. In ASP.NET 2.0, this process has been simplified and encapsulated within the function known as the Callback Manager.
The ASP.NET 2.0 Callback Manager uses XMLHTTP behind the scenes to encapsulate the complexities in sending data to and from the servers and clients. And so, in order for the Callback Manager to work, you need a web browser that supports XMLHTTP. Microsoft Internet Explorer is, obviously, one of them.

96. Diffrence between Viewstate and Session?
View State are valid mainly during postbacks and information is stored in client only. Viewstate are valid for serializable data only. Moreover Viewstate are not secured as data is exposed to client. although we canconfigure page directive and machine key to make view state encrypted.
Where in case of session this is user specific data that is stored in server memory . Session state is valid for any type of objects. We can take help of session through different web pages also.

97. Diffrence between DataReader and DataAdapter
DateReader is an forward only and read only cursor type if you are accessing data through DataRead it shows the data on the web form/control but you can not perform the paging feature on that record(because it's forward only type).Reader isbest fit to show the Data (where no need to work on data)
DataAdapter is not only connect with the Databse(through Command object) it provide four types of command (InsertCommand, UpdateCommand, DeleteCommand, SelectCommand), It supports to the disconnected Architecture of .NET show we can populate the records to the DataSet. where as Dataadapter is best fit to work on data.

98. Type of garbage collector?
There are two types of Garbage Collector
Managed garbage collector see we will declaring variable ,object in our programs once this kind of variable, object goes out of the scope ,they are put into the heap and they are checked for the further existence. once its being no longer used garbage collector will reallocate memory for that variable and objects.
Unmanaged garbage collector
This was done manually and u will be happen to open a connection with database, will be open the file etc. While this kind of the thing goes out of the scope we have to explicitly call the garage collector by calling the close command of the database once the connection is closed it puts this memory into the heap and process follows the same

99. How can we load multiple tables in to Dataset?
Write the select queries required in fill statement.
e.g.
Adp.Fill("Select * from Table1;Select * from Table2;Select * from Table3",DS)
This statement wil generate Dataset with 3 datatables.

100. what is the difference between serializable and MarshalByRefObject
In .net Remoting if ypu want your class to be participated in remoting it has to inherit from MarshalByRefObject class so that class definition can be passed by reference Where as [seraliazable] attribute is preceded before class that is can be seralized but this is used in conjuction with MarshalByValue class. Because when we pass by value then only we require this attribute.

Interview Questions

2011-02-02T10:09:00.000-08:00

ASP.NET

Part III

51. How do you apply specific formatting to the data inside the cells?
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.

52. How do you hide the columns?
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.

53. How do you display an editable drop-down list?
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.

54. How do you check whether the row data has been changed?
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.

55. What is the transport protocol you use to call a Web service?
SOAP. Transport Protocols: It is essential for the acceptance of Web Services that they are based on established Internet infrastructure. This in fact imposes the usage of of the HTTP, SMTP and FTP protocols based on the TCP/IP family of transports. Messaging Protocol: The format of messages exchanged between Web Services clients and Web Services should be vendor neutral and should not carry details about the technology used to implement the service. Also, the message format should allow for extensions and different bindings to specific transport protocols. SOAP and ebXML Transport are specifications which fulfill these requirements. We expect that the W3C XML Protocol Working Group defines a successor standard.

56. 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 itsconstituents.

57. List the event handlers that can be included in Global.asax?
Application start and end event handlers
Session start and end event handlers
Per-request event handlers
Non-deterministic event handlers

58. Can the view state be protected from tampering?
This can be achieved by including an @ Page directive with an EnableViewStateMac="true" attribute in each ASPX file that has to be protected. Another way is to include the <pages enableViewStateMac="true" /> statement in the Web.config file.

59. Can the view state be encrypted?
The view state can be encrypted by setting EnableViewStateMac to true and either modifying the <machineKey> element in Machine.config to <machineKey validation="3DES" /> or by adding the above statement to Web.config.

60. When during the page processing cycle is ViewState available?
The view state is available after the Init() and before the Render() methods are called during Page load.

61. Do Web controls support Cascading Style Sheets?
All Web controls inherit a property named CssClass from the base class System.Web.UI.WebControls.WebControl which can be used to control the properties of the web control.

62. Session state vs. View state:
In some cases, using view state is not feasible. The alternative for view state is session state. Session state is employed under the following situations:
Large amounts of data - View state tends to increase the size of both the HTML page sent to the browser and the size of form posted back. Hence session state is used.
Secure data - Though the view state data is encoded and may be encrypted, it is better and secure if no sensitive data is sent to the client. Thus, session state is a more secure option.
Problems in serializing of objects into view state - View state is efficient for a small set of data. Other types like DataSet are slower and can generate a very large view state.

63. What classes are needed to send e-mail from an ASP.NET application?
The classes MailMessage and SmtpMail have to be used to send email from an ASP.NET application. MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's System.Web.Mail namespace.

64. Why do some web service classes derive from System.Web.WebServices while others do not?
Those Web Service classes which employ objects like Application, Session, Context, Server, and User have to derive from System.Web.WebServices. If it does not use these objects, it is not necessary to be derived from it.

65. How do I initialize a TextBox whose TextMode is "password", with a password?
The TextBox’s Text property cannot be used to assign a value to a password field. Instead, its Value field can be used for that purpose.
<asp:TextBox Value="imbatman" TextMode="Password"
ID="Password" RunAt="server" />

66. Why does the control's PostedFile property always show null when using HtmlInputFile control to upload files to a Web server?
This occurs when an enctype="multipart/form-data" attribute is missing in the <form> tag.

67. How can the focus be set to a specific control when a Web form loads?
This can be achieved by using client-side script:
document.forms[0].TextBox1.focus ()
The above code will set the focus to a TextBox named TextBox1 when the page loads.

68. How does System.Web.UI.Page's IsPostBack property work?
IsPostBack checks to see whether the HTTP request is accompanied by postback data containing a __VIEWSTATE or __EVENTTARGET parameter. If there are none, then it is not a postback.

69. Describe the difference between inline and code behind.
Inline code is written along side the HTML in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

70. What are the new Data Controls in Asp.net 2.0?
Data access in ASP.NET 2.0 can be accomplished completely declaratively (no code) using the new data-bound and data source controls. There are new data source controls to represent different data backends such as SQL database, business objects, and XML, and there are new data-bound controls for rendering common UI for data, such as gridview, detailsview, and formview.

71. What are the new Navigation Controls in Asp.net 2.0?
The navigation controls provide common UI for navigating between pages in your site, such as treeview, menu, and sitemappath. These controls use the site navigation service in ASP.NET 2.0 to retrieve the custom structure you have defined for your site.

72.What are the new Login Controls in Asp.net 2.0?
The new login controls provide the building blocks to add authentication and authorization-based UI to your site, such as login forms, create user forms, password retrieval, and custom UI for logged in users or roles. These controls use the built-in membership and role services in ASP.NET 2.0 to interact with the user and role information defined for your site.

73.What are the new Web Part Controls in Asp.net 2.0 ?
Web parts are an exciting new family of controls that enable you to add rich, personalized content and layout to your site, as well as the ability to edit that content and layout directly from your application pages. These controls rely on the personalization services in ASP.NET 2.0 to provide a unique experience for each user in your application.

74.What are Master Pages?
This feature provides the ability to define common structure and interface elements for your site, such as a page header, footer, or navigation bar, in a common location called a "master page", to be shared by many pages in your site. In one simple place you can control the look, feel, and much of functionality for an entire Web site. This improves the maintainability of your site and avoids unnecessary duplication of code for shared site structure or behavior.

75.What are Themes and Skins in 2.0, explain usgae scenario?
The themes and skins features in ASP.NET 2.0 allow for easy customization of your site's look-and-feel. You can define style information in a common location called a "theme", and apply that style information globally to pages or controls in your site. Like Master Pages, this improves the maintainability of your site and avoid unnecessary duplication of code for shared styles.