Session 3 TP2

8/8/2019 Session 3 TP2

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Session 3

Objects in ASP.NET


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Exploring ASP.NET / Session 3 / 2 of 30

Review Active Server Pages (ASP) is a server-side scripting environment that

provides a web server with the capability to process applicationlogic, and return standard HTMLpages to the browser.

Web Forms provides a form designer, an editor and debugging tools,which can be used to rapidly build server-based, programmable userinterfaces for browsers and Web client devices.

The Design view displays the page layout of the web page as itwould be displayed in the browser.

The HTML view displays the code that is automatically generated tocreate the Web page.

AssemblyInfo.cs is the file that contains information about theproject. It contains information such as name, version, and cultureinformation.

Once the code has been compiled, the CLR further compiles the IL tonative code, when the request for the web page is encountered,providing improved performance.


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Review Contd Web.config is an XML based file. It holds unique configuration

information about each URL used in the project. Global.asax is an optional file that is used for handling application-

level events. The web page created either using the editor or Web Forms, is first

complied to Intermediate Language (IL), including server scripts. The different web pages of an application created using Web Forms,

and the program code within it, are compiled into a single assembly /dynamic link library (.dll) file.

In the editor based web application, separate dynamic link libraries(.dll's) are created for each file. The web pages created using Web Forms, will have the Codebehind

attribute that informs Web Forms IDE about the code file that has tobe changed whenever a change is made to the Design, or the HTMLview of the Web Form.


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Objectives Explain the basics of ASP.NET

Discuss the process flow ofa .aspxpage

Explain the Page_Loadevent

Discuss the IsPostBack propertyof

the Page object Use the Request andResponse

Objects


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An ASP.NET Page

Page Directive

section

Page_Load Event

Event Handler

HTML Control

Web Control


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An ASP.NET Page - Output

Output after the Page

Load Event

Output after the Button

Click Event


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Starting with ASP.NET


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User Interface


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Event Handlers - Example

void Page_Load(Object sender, EventArgs e){

//code for page load}

void buttonRefresh(Object sender, EventArgs e){

Page_Load(sender,e);}


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Example Contd


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_VIEWSTATE

Name

E- mail

Password

Submit

King

[email protected]

******

Name

E- mail

Password

Submit


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Page_Load Event

Database Hello

World


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Process Flow

Execution on

the server

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4

5a

HTTP

Request

HTM

L

Page

Values

after

Postback

Changes are

processed

6

7

HTM

L

Page5b

User causes

Postback


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ASP.NET Objects


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ASP.NET Objects More

Details


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ASP.NET Objects More

Details Contd


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Virtual Directories ASP.NET application is a collection of text files that are

stored in a directory and its sub-directories on the Webserver

The base directory is called the virtual root, and thedirectory in which the application files are stored is calledthe virtual directory

The web server manages the virtual directory settings,permissions and user access

The advantage of using a virtual directory is that the userdoes not have to know the exactpath of a page when

making a request.


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Virtual Directory - Permissions

Permissions


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To create a virtual directory :

1. Open the Internet Services ManagerMMC

snap in.2. Expand Server name.

3. Right click on Default Web Site, and selectNew Virtual Directory from the pop up

menu.4. Click Next on the Welcome to the Virtual

Directory Creation Wizard.

Creating Virtual Directory


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5. Enter an alias in the Virtual Directory Aliasscreen. Click Next.

6. Type in or Browse the physical path of theapplication root directory (which containsthe files for the web site) in the Web SiteContent Directory screen. Click Next.


Contd


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7. Set the appropriate access permissions

in the Access Permissions screen.

8. Click Finish to complete the creation of

the virtual directory.


Contd


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HTTP Protocol

HTTP Response

HTTP Request

The browser and the Web servercommunicate using the HTTP protocol .

When the browser opens a page from aWeb site, the browser establishes aconnection to the Web server andissues a request.

The Web server processes the request,and responds by sending the requiredpage. Thus, the communicationbetween the client and the server takesplace through a series of requests-and-responses.


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Request & Response A request contains information about the client and some

parameters These parameters are essentially the data that is passed

from the client, and is to be processed at the server. A response contains the information requested by the client

browser ASP.NET recognizes this request-and-response

communication through two built-in objects that correspond

to the request and response messages of the HTTPprotocol. The Request object corresponds to the request message of

the HTTP protocol, and the Response object correspondsto the response message of the HTTP protocol.


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Request & Response - ExampleInput.htm

Input Page

Enter your name


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Request & Response - ExampleEnter your country name


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Request & Response - ExampleWelcome.aspx

void Page_Load( Object src,EventArgs e){

String s,s1;s= Request.Form.Get ("name");Response.Write ("Hi " + s + ", Welcome to

ASP.NET!
");}


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Request & Response


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Summary The @ Page directive is used to specify attributes that affect the code

in the .aspxpage. The section is where most of the code for providing the

required functionality is written. There are two types of server controls:

HTML Controls Web Controls

All eventprocedures receive two arguments from the events: The event sender The class instance that holds data for the event

The _VIEWSTATE control is a hidden control that is added to theform when the form is submitted to the server.

It is possible to check whether a .aspxpage is posted back to theserver with the help of the IsPostBack property of the page.


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Summary Contd ASP.NET has several built-in objects that are used to provide the

required functionality in an ASP.NET application. They are the following: Request Response Application Session Server ObjectContext

The base directory is called the virtual root, and the directory in whichwe store the application files is called the virtual directory.

The Request object corresponds to the request message of the HTTPprotocol, and the Response object corresponds to the responsemessage of the HTTP protocol.

The Form.Get method of the Request object is used to retrieve thedata submitted by the user.

The Redirect method of the Response object is used to redirect the

user to another page.

Date post:	10-Apr-2018
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Session 3 TP2

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