ASP.NET

Introduction

• Active Server Pages (ASP), also known as Classic ASP, was introduced in 1998 as Microsoft's first server side scripting engine.

• ASP is a technology that enables scripts in web pages to be executed by an Internet server.

• ASP pages have the file extension .asp, and are normally written in VBScript.

Introduction (cont.)

• ASP.NET is a new ASP generation. It is not compatible with Classic ASP, but ASP.NET may include Classic ASP.

• ASP.NET pages are compiled, which makes them faster than Classic ASP.• ASP.NET has better language support, a large set of user controls, XML-

based components, and integrated user authentication.• ASP.NET pages have the extension .aspx, and are normally written in VB

(Visual Basic) or C# (C sharp).• User controls in ASP.NET can be written in different languages, including

C++ and Java.• When a browser requests an ASP.NET file, the ASP.NET engine reads the

file, compiles and executes the scripts in the file, and returns the result to the browser as plain HTML.

ASP.NET Programming Languages

• ASP.NET can be written with the following programming languages:• Visual Basic (VB.NET)

• C# (Pronounced C sharp)

Introduction

• What is the different between ASP and ASP.NET• ASP is interpreted and ASP.Net is complied.

• Classic ASP uses a technology called ADO to connect and work with database. ASP.NET use the ADO.NET technology

• ASP has Mixed HTML and coding logic (like PHP) where in ASP.NET html and coding part are separated by code behind files .

• ASP.NET purely object oriented whereas ASP is partially object oriented.

• For ASP no in-build support for XML whereas in ASP.NET full XML support for easy data exchange.

ASP.NET

• ASP.NET supports three different development models:1. Web Pages,

• Web Pages is the easiest development model for developing ASP.NET web sites.• learn how to combine HTML, CSS, JavaScript and server code, using the latest Razor server markup

syntax with Visual Basic or C#.

2. MVC (Model View Controller), and • MVC is a model for building web applications using a MVC (Model View Controller) design.

• learn how to build web applications using a lightweight development model, integrated with all existing ASP.NET features, such as Master Pages, Security, and Authentication.

3. Web Forms• Web Forms is the traditional ASP.NET model, based on event driven Web Forms and post backs.

• Over the years, developers have used ASP.NET Web Forms to create many of the largest websites in the world.

• If you want to study the design model used by many web developers over the last 10 years, this is the place to start.

How it work!

• Fundamentally an ASP.NET page is just the same as an HTML page.

• An HTML page has the extension .htm. If a browser requests an HTML page from the server, the server sends the page to the browser without any modifications.

• An ASP.NET page has the extension .aspx. If a browser requests an ASP.NET page, the server processes any executable code in the page, before the result is sent back to the browser.

ASP.NET - Environment Setup

• Visual Studio is an integrated development environment for writing, compiling and debugging the code.

• It provides a complete set of development tools for building • ASP.Net web applications,

• web services,

• desktop applications

• and mobile applications.

The Visual Studio IDE:

• There are two ways to build code in ASP: • Creating Web Application

• Creating Website

What is the different between Web Application and Website?• Both function and perform similarly, but still differ in following ways:• Web application:

• We can't include C# and VB pages in single web application.• We can set up dependencies between multiple projects.• Can not edit individual files after deployment without recompiling.• Right choice for enterprise environments where multiple developers work unitedly

for creating, testing and deployment.

• Web site:• Can mix VB and C# page in single website.• Can not establish dependencies.• Edit individual files after deployment.• Right choice when one developer will responsible for creating and managing entire

website.

ASP.NET Page Life Cycle

• Following are the different stages of an ASP.Net page:• Page request . when ASP.Net gets a page request, it decides whether to parse and compile the page or there

would be a cached version of the page; accordingly the response is sent• Starting of page life cycle . at this stage, the Request and Response objects are set. If the request is an old

request or post back, the IsPostBack property of the page is set to true. The UICulture property of the page is also set.

• Page initialization . at this stage, the controls on the page are assigned unique ID by setting the UniqueIDproperty and themes are applied. For a new request postback data is loaded and the control properties are restored to the view-state values.

• Page load . at this stage, control properties are set using the view state and control state values.• Validation . Validate method of the validation control is called and if it runs successfully, the IsValid property

of the page is set to true.• Postback event handling . if the request is a postback (old request), the related event handler is called.• Page rendering . at this stage, view state for the page and all controls are saved. The page calls the Render

method for each control and the output of rendering is written to the OutputStream class of the Page's Response property.

• Unload . the rendered page is sent to the client and page properties, such as Response and Request are unloaded and all cleanup done.

Server Controls

• Server controls are tags that are understood by the server.

• There are three kinds of server controls:• HTML Server Controls - Traditional HTML tags

• Web Server Controls - New ASP.NET tags

• Validation Server Controls - For input validation

ASP.NET - HTML Server Controls

• All HTML server controls must be within a <form> tag with the runat="server" attribute.

• The runat="server" attribute indicates that the form should be processed on the server. It also indicates that the enclosed controls can be accessed by server scripts.

• Eg:

<form runat="server"><a id="link1" runat="server">Visit W3Schools!</a>

</form>

ASP.NET - Web Server Controls

• Like HTML server controls, Web server controls are also created on the server and they require a runat="server" attribute to work.

• However, Web server controls do not necessarily map to any existing HTML elements and they may represent more complex elements.

• Eg:

<form runat="server"><asp:Button id="button1" Text="Click me!"

runat="server" OnClick="submit"/></form>

ASP.NET - Validation Server Controls

• Validation server controls are used to validate user-input. If the user-input does not pass validation, it will display an error message to the user.

• Each validation control performs a specific type of validation (like validating against a specific value or a range of values).

• By default, page validation is performed when a Button, ImageButton, or LinkButton control is clicked. You can prevent validation when a button control is clicked by setting the CausesValidation property to false.

ASP.NET - Validation Server Controls (cont.)

<html><body>

<form runat="server"><p>Enter a number from 1 to 100:<asp:TextBox id="tbox1" runat="server" /><br /><br /><asp:Button Text="Submit" runat="server" /></p>

<p><asp:RangeValidatorControlToValidate="tbox1"MinimumValue="1"MaximumValue="100"Type="Integer"Text="The value must be from 1 to 100!"runat="server" /></p></form>

</body></html>

Basic Controls - Button Control

• ASP .Net provides three types of button controls: buttons, link buttons and image buttons. As the names suggest a button displays text within a rectangular area, a link button displays text that looks like a hyperlink. And an Image Button displays an image.

• When a user clicks a button control, two events are raised Click and Command.

Text Boxes and Labels:

• Text box controls are typically used to accept input from the user. A text box control can accept one or more lines to text depending upon the setting of the TextMode attribute.

• Label controls provide an easy way to display text which can be changed from one execution of a page to the next. If you want to display a text that does not change, you use the literal text.

Check Boxes and Radio Buttons:

• A check box displays a single option that the user can either check or uncheck and radio buttons present a group of options from which the user can select just one option.

• To create a group of radio buttons, you specify the same name for the GroupName attribute of each radio button in the group. If more than one group is required in a single form specify a different group name for each group.

• If you want a check box or radio button to be selected when it's initially displayed, set its Checked attribute to true. If the Checked attribute is set for more than one radio button in a group, then only the last one will be selected.

List Controls:

• ASP.Net provides the controls: drop-down list, list box, radio button list, check box list and bulleted list. These control let a user choose from one or more items from the list.

• List boxes and drop-down list contain one or more list items. These lists could be loaded either by code or by the ListItem Collection Editor.

The List Item Collections:

• The ListItemCollection object is a collection of ListItem objects. Each ListItem object represents one item in the list. Items in a ListItemCollectionare numbered from 0.

• When the items into a list box are loaded using strings like: lstcolor.Items.Add("Blue") . then both the Text and Value properties of the list item are set to the string value you specify. To set it differently you must create a list item object and then add that item to the collection.

• The ListItem Collection Editor is used to add item to a drop-down list or list box. This is used to create a static list of items. To display the Collection Editor select Edit item from the smart tag menu, or select the control and then click the ellipsis button from the Item property in the Properties window.

Bulleted lists and Numbered lists:

• The bulleted list control creates bulleted lists or numbered lists. These controls contain a collection of ListItem objects that could be referred to through the Items property of the control.

HyperLink Control:

Image Control:

ASP.NET - Validators

• ASP.Net validation controls validate the user input data to ensure that useless, unauthenticated or contradictory data don.t get stored.

• ASP.Net provides the following validation controls:• RequiredFieldValidator

• RangeValidator

• CompareValidator

• RegularExpressionValidator

• CustomValidator

• ValidationSummary

The BaseValidator Class:

The RequiredFieldValidator:

• The RequiredFieldValidator control ensures that the required field is not empty. It is generally tied to a text box to force input into the text box.

The RangeValidator:

The CompareValidator:

The RegularExpressionValidator

• The RegularExpressionValidator allows validating the input text by matching against a pattern against a regular expression. The regular expression is set in the ValidationExpression property.

The CustomValidator:

• The CustomValidator control allows writing application specific custom validation routines for both the client side and the server side validation.

• The client side validation is accomplished through the ClientValidationFunction property. The client side validation routine should be written in a scripting language, like JavaScript or VBScript, which the browser can understand.

• The server side validation routine must be called from the control.sServerValidate event handler. The server side validation routine should be written in any .Net language, like C# or VB.Net.

The ValidationSummary Control

• The ValidationSummary control does not perform any validation but shows a summary of all errors in the page. The summary displays the values of the ErrorMessage property of all validation controls that failed validation.

• The following two mutually inclusive properties list out the error message:• ShowSummary: shows the error messages in specified format.

• ShowMessageBox: shows the error messages in a separate window.

ASP.NET – Database

• ASP.Net allows the following sources of data to be accessed and used:• Databases (e.g., Access, SQL Server, Oracle, MySQL)• XML documents• Business Objects• Flat files

• ASP.Net hides the complex processes of data access and provides much higher level of classes and objects through which data is accessed easily. These classes hide all complex coding for connection, data retrieving, data querying and data manipulation.

• ADO.Net is the technology that provides the bridge between various ASP.Net control objects and the backend data source. We will come to ADO.Net in due time. In this tutorial, we will look at data access and working with the data without going into the details of its inner workings.

ASP.NET - File Uploading

• ASP.Net has two controls that allow the users to upload files to the web server. Once the server receives the posted file data, the application can save it, check it or ignore it. The following controls allow the file uploading:• HtmlInputFile - an HTML server control

• FileUpload - and ASP.Net web control

• Both the controls allow file uploading, but the FileUpload control automatically sets the encoding of the form, whereas the HtmlInputFile does not do so.

Example

Cookie in ASP.NET

• Cookies are small pieces of text, stored on the client's computer to be used only by the website setting the cookies.

• This allows web applications to save information for the user, and then re-use it on each page if needed.

• Here is an example where we save a users choice of background color:

• Delete cookie

Session in ASP.NET

• Sessions can be used to store even complex data for the user just like cookies. Actually, sessions will use cookies to store the data, unless you explicitly tell it not to.

• Sessions can be used easily in ASP.NET with the Session object. We will re-use the cookie example, and use sessions instead.

• Keep in mind though, that sessions will expire after a certain amount of minutes, as configured in the web.config file.

• Delete session