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NET is a web development platform, which provides a programming model, a comprehensive software infrastructure and various services required to build up robust web applications for PC, as well as mobile devices. NET works on top of the HTTP protocol, and uses the HTTP commands and policies to set a browser-to-server bilateral communication and cooperation. All client side user activities are forwarded to the server for stateful processing. NET framework helps in storing the information regarding the state of the application, which consists of: The page state is the state of the client, i.e., the content of various input fields in the web form. Click the button to see effect: We have studied the page life cycle and how a page contains various controls. The page class has the following extremely useful properties that correspond to intrinsic objects: We will discuss each of these objects in due time. However, this object helps in checking some information such as the client browser and cookies. The content file: Run the page to see the following result: Controls are small building blocks of the graphical user interface, which include text boxes, buttons, check boxes, list boxes, labels, and numerous other tools. Net server controls inherit all properties, events, and methods of the Web Control and System. Other Navigation controls are: Menu control and Site Map Path control. Write a few lines of code to ensure that when a particular node is selected, the label control displays the node text and the text box displays all child nodes under it, if any. If more than one group is required in a single form, then specify a different group name for each group.
The browser submits a web form to the web server and the server returns a full markup page or HTML page in response. The label shows page load, page initialization and, the page pre-render events. The methods and properties of the Http Server Utility class are exposed through the intrinsic Server object provided by ASP. The following table provides a list of the properties: The request object is an instance of the System. The information presented by this object is wrapped by the higher level abstractions (the web control model). However, the Http Response object still provides some important functionalities, like the cookie feature and the Redirect() method. Redirect() method allows transferring the user to another page, inside as well as outside the application. The following table provides some noteworthy properties of the Response object: The following simple example has a text box control where the user can enter name, a button to send the information to the server, and a label control to display the URL of the client computer. A Tree view control comes under navigation controls. task allows you to format the tree view as shown: Add a label control and a text box control on the page and name them lblmessage and txtmessage respectively. To create a group of radio buttons, you specify the same name for the Group Name attribute of each radio button in the group.
It consists of a large number of controls such as text boxes, buttons, and labels for assembling, configuring, and manipulating code to create HTML pages. NET web forms extend the event-driven model of interaction to the web applications. The Http Server Utility class provides numerous properties and methods to perform various jobs. It represents the values and properties of the HTTP request that makes the page loading into the browser. NET, the response object does not play any vital role in sending HTML text to the client, because the server-side controls have nested, object oriented methods for rendering themselves. The following table shows the inherited properties, common to all server controls: Let us look at a particular server control - a tree view control. Edit each of the nodes using the Tree view node editor as shown: Once you have created the nodes, it looks like the following in design view: The Auto Format... 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.
NET applications are compiled codes, written using the extensible and reusable components or objects present in . These codes can use the entire hierarchy of classes in . NET is used to produce interactive, data-driven web applications over the internet. Single Line creates a standard text box, Multi LIne creates a text box that accepts more than one line of text and the Password causes the characters that are entered to be masked. The mostly used attribute for a label control is 'Text', which implies the text displayed on the label.
take place, it sends a message, which is displayed by the label control. These controls contain a collection of List Item objects that could be referred to through the Items property of the control. NET directives are instructions to specify optional settings, such as registering a custom control and page language.
When the button is clicked, the Button_Click event is raised and that also sends a message to be displayed on the label. These settings describe how the web forms (.aspx) or user controls (.ascx) pages are processed by the . The syntax for declaring a directive is: In this section, we will just introduce the ASP.
The following table shows some of the default events for common controls: This example includes a simple page with a label control and a button control on it. These controls contain a collection of List Item objects that could be referred to through the Items property of the control.
They are specifically converted to a server control by adding the attribute runat="server" and adding an id attribute to make them available for server-side processing.
By default, Visual Studio creates an event handler by including a Handles clause on the Sub procedure. To set it differently you must create a list item object and then add that item to the collection.
This clause names the control and event that the procedure handles. Some events are not posted back to the server immediately, these are called non-postback events. The nonpostback events could be made to post back immediately by setting their Auto Post Back property to true. The List Item Collection Editor is used to add item to a drop-down list or list box. 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.
NET application codes can be written in any of the following languages: ASP. Basic syntax of text control: Specifies the type of text box.
The server processes the output of the client actions and triggers the reactions. The session state is the collective information obtained from various pages the user visited and worked with, i.e., the overall session state. The page itself is instantiated as a control object. In this tutorial we will explore the Server object, the Request object, and the Response object. The following table provides some noteworthy properties of the Request object: The Response object represents the server's response to the client request. Using these tools, the users can enter data, make selections and indicate their preferences. The code behind the file should look like this: using System; using System. If you want check box or radio button to be selected when the form is initially displayed, set its Checked attribute to true.