introduction to asp.net isys 512/812. web server web server: –internet information service:...

Introduction to ASP.Net

ISYS 512/812

Web Server

• Web Server:– Internet Information Service:

• ControlPanel/AdministrativeTools/Internet Information Services

– Built-in Web Server• VS 05 uses the built-in web server for debugging.

• IIS Default directory– C:\InetPub\wwwroot

• Default home page– Default.aspx, default.asp, default.htm

• ASP.Net project directory• Note: Using the Built-In web server, a web project

can be created in any folders.

Web Project

• Optional: Start Internet Information server• File/New Website/ ASP.Net Application• Website folder• Web form:

– default.aspx• Design view and source (HTML) view

– Default.Aspx.VB• CodeBehind• Inline coding

• To set start up page: – Point to the web page in the Solution Explorer and right

click to choose Set As Start Page.

VS WebForm Design View

• Layout/Position/Auto-Position Options– HTML Designer

• CSS Positioning– Absolutely positioned

Dynamic Page – Client-Side Script ExampleDemo: TimeNowClient.Htm

<html><head><title>New Page 1</title></head><body><p>The time is now <script language=vbscript>

document.write time()</script></p><script language=vbscript>iHour=hour(time())if iHour < 12 then

document.write "<h1>good morning</h1>"else

document.write "<h1>good afternoon</h1><br>"end if</script></body></html>

Dynamic Web Pages – Server-Side Script Example

• Demo: TimeNow.aspx– <body>– <p>The time is now <%=Now.TimeOfDay()%></p>– <p>The time is now <% response.write(Now.TimeOfDay())%></p>

– <%– dim iHour– iHour=Now.Hour()– if iHour < 12 then– response.write("<h1>good morning</h1><br>")– else– response.write ("<h1>good afternoon</h1><br>")– end if– %>– </body>

• Note: – Need web server; cannot open by File/Open Page.– Work for both Mozilla and IE.

Client-Side vs Server-Side Scripting

• Client-side scripting:– The browser requests a page.– The server sends the page to the browser.– The browser sends the page to the script engine.– The script engine executes the script.

• Server-side scripting:– The browser requests a page.– The server sends the page to the script engine.– The script engine executes the script to produce page.– The server sends the page to the browser.– The browser renders the page.

HTML Introduction

• Heading section– <head>, <title>, <meta>, <script>, etc.

• Body section– <body>, <p>, <h1> to <h6>, <a>, <br>– Formatting: <b>, <I>, <u>, <center>– Comment: – List <ul>– Image– Table: <table>, <tr>: a new row in table, <td>: a new cell

in a table row.– Form: <form>, <input>, <select>, <textarea>

META Tag

• The meta tag allows you to provide additional information about the page that is not visible in the browser:– <meta name=“Author” content=“D Chao”>– <meta name=“Keywords” content=“apple,

orange,peach”>

• Redirection:– <meta http-equiv=“refresh”

content=“3;url=http://www.sfsu.edu”>• “3” is number of seconds.• Demo using FrontPage

TABLE Tag

<table border="1" width="100%"> <tr> <td width="25%"></td> <td width="25%"> </td> <td width="25%"> </td> <td width="25%"> </td> </tr> <tr> <td width="25%"> </td> <td width="25%"> </td> <td width="25%"> </td> <td width="25%"> </td> </tr></table>

FORM Tag

• Form attribute:– Action: Specify the URL of a program on a server or an

email address to which a form’s data will be submitted.

– Method: • Get: the form’s data is appended to the URL specified by the

Action attribute as a QueryString.

• Post: A prefered method for database processing. Form’s data is sent separately from the URL.

– Name: Form’s name

• Demo: TestFormGet.Htm, TestFormPost.Htm

QueryString

• A QueryString is a set of name=value pairs appended to a target URL.

• It can be used to pass information from one webpage to another.

• To create a QueryString:– Add a question mark (?) immediately after a URL.– Followed by name=value pairs separated by

ampersands (&).

• Example: • <A Href=“http://my.com/Target.htm?CustID=C1&Cname=Chao”>

Creating a QueryString

• Entered with a URL:– http://dchaolaptop/testFormGet.aspx?cid=c2&cname=bbb

• As part of a URL specified in an anchor tag.– <A Href=“http://my.com/Target.htm?CustID=C1&Cname=Chao”>

• Via a form sent to the server with the GET method.

• Created by script

SCRIPT Tag

• Client-side script:– <SCRIPT LANGUAGE = VBSCRIPT>



</SCRIPT>

• Server-side script:– <script language=“VB” runat=“server”>

• statements

– </script>

ASP.NET

• ASP.NET is a server-side technology for creating dynamic web pages.

• ASP.NET allows you to use a selection of full programming languages. The default language is VB .NET.

• ASP.NET files have a .aspx extension.

ASP.NET in the .NET Framework

• 1. The client requests a web page.

• 2. The web server locates the page.

• 3. If the page is an ASP.NET page, it is sent to the Common Language Runtime for compilation and execution.

• 4. The HTML produced by the CLR is returned to the browser.

Benefits of Server-Side Technology

• Browser compatibility: Every browser reads HTML.

• Protection of source code.• Controls are server-side objects with properties,

methods and events.• Separating code from content.

– Embedded code– CodeBehind

Elements of an ASP.Net Page

• Directives

• Code blocks

• ASP.NET controls

• HTML tags and text

Directives

• A directive controls how an ASP.Net page is compiled.– Page directives: Specify default language, enable

tracing and debugging for a page.– <%@ Page Language=“VB” %>, <%@ Page Language=“C#” %>– <%@ Page Trace=“True” %>

– Imports name spaces– To process Access database, we need to import:– <%@ Import Namespace=“System.Data” %>– <%@ Import Namespace=“System.Data.Oledb” %>

Inserting ASP.NET Code into Web Pages• Place ASP.NET code between <script> and </script> with a RUNAT

attribute.– <script language=“VB” runat=“server”>

• Your script– </script>

• <script runat="server"> ---- ASPNET/ADD2.ASPX• sub clickHandler(Sender As Object, E As EventArgs)• sum.text=cstr(cdbl(num1.text)+cdbl(num2.text))• end sub• </script>

• Inline Code Block: ASP code is placed between <% and %>.– <p>The time is now <%=Now.TimeOfDay()%></p>– <p>The time is now <% response.write(Now.TimeOfDay())%></p>

• “=“ is shorthand for response.write• Server-side comments:

– <%-- Comments --%>• CodeBehind file (Partial class):

– <%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default2.aspx.vb" Inherits="Default2" %>

ASP.NET Object Model

Client Server

Request Object

Response Object

Server Object

SessionObject

Application

Object

ASP.NET Request Object• When a page is requested, much

information is passed along with the request, such as the URL, queryString, and data from a form. The request object allows you to get the information passed along with the request.

• It is created from the System.Web.HttpRequest class.

• Demo: testRequest.Htm, TestRequest.aspx

<body><%response.write ("<h1> cid=" & request.form("cid") & "</h1><br>")response.write ("<h1> cname=" & request.form("cname")& "</h1><br>") Response.Write("<h1> filepath " & Request.FilePath & "</h1><br>") Response.Write("<h1> httpMethod " & Request.HttpMethod & "</h1><br>") Response.Write("<h1> path " & Request.Path & "</h1><br>") Response.Write("<h1> Url " & Request.Url.ToString & "</h1><br>") Response.Write("<h1> urlReferer " & Request.UrlReferrer.ToString & "</h1><br>") Response.Write("<h1> HostName " & Request.UserHostName & "</h1><br>") Response.Write("<h1> HostAddress " & Request.UserHostAddress & "</h1><br>")%></body>

Note: In Request.Form(“cid”), the CID is the Name property of the tetbox, not ID property.

Request Object Collections• QueryString

– http://my.com/Target.htm?CustID=C1&CustName=Chao– cid = Request.queryString(“CustID”)– cName=Request.queryString(“CustName”)

• Form– A form with two text boxes:CustID, CustName– cid = Request.Form(“CustID”)– cName=Request.Form(“CustName”)

• Cookies• ClientCertificates• Path, ApplicationPath, PhysicalApplicationPath,

etc.• Demo: testReqForm.htm, testReqForm.aspx

http://my.com/Target.htm?CustID=C1&CustName=Chao

TestReqForm<form method="POST" action="testReqForm.aspx?myquery=testquery">

<p>EnterCID:<input type="text" name="CID" size="20"></p>

<p>EnterName:<input type="text" name="CNAME" size="20"></p>

<p><input type="checkbox" name="C1" value="ON">checkbox1 <input type="checkbox" name="C2" value="ON">checkbox

2</p>

<p><input type="radio" value="V1" checked name="R1">radio1</p>

<p><input type="radio" name="R1" value="V2">radio 2</p>

<p><select size="1" name="D1">

<option value="A">A</option>

<option value="B">B</option>

<option value="C">C</option>

</select>listbox</p>

<p><input type="submit" value="Submit" name="B1"><input type="reset" value="Reset" name="B2"></p>

<input type="hidden" name="hidden1" value="Hi, it's me!">

</form>

TestReqForm.Aspx<%

response.write ("<h1> cid=" & request.form("cid") & "</h1><br>")

response.write ("<h1> cname=" & request.form("cname")& "</h1><br>")

response.write ("<h1> hidden variable=" & request.form("hidden1")& "</h1><br>")

if request.form("C1")="ON" then

response.write ("<h1>You select checkbox 1</H1><br>")

end if

if request.form("C2")="ON" then

response.write ("<h1>You select checkbox 2</H1><br>")

end if

if request.form("R1")="V1" then

response.write ("<h1>You select Radio 1</H1><br>")

else

response.write ("<h1>You select Radio 2</H1><br>")

end if

response.write ("<h1> listBox=" & request.form("D1")& "</h1><br>")

response.write ("<h1>" & request.queryString("myquery")& "</h1><br>")

%>

ASP.NET Response Object

• This object allows you to send information back to client.

• It is created from the System.Web.HttpResponse class.

• Properties:– Buffer– Cookies (a collection)

• Methods:– Response.Write (“…..”) *** MessageBox is not

available for web project ***.– Response.Clear(), Response.Flush(): clear/flush buffer– Response.Redirect (“URL”)

Buffer

• When ASP.Net is running the code, it gradually builds up the HTML that will be sent back to the browser. As the HTML is generated, it is placed in a buffer. Normally, the HTML is held in the buffer so that it isn’t sent to the browser until the page finishes executing.

• Response.Buffer: The default value for this property is true which means the page is buffered and sent in one block.– Response.Buffer=False sends html as it is

generated.

The Application and Session Objects

• Application state: A central, site-wide store of variables that we can get from any page.

• A session is a single visit to a web site, and normally includes visits to a number of pages. Each time a visitor comes to your web site, a session object is created for the visitor. Session state is a store of variables that relates to a session.

Examples of Using the Application and Session Objects

• Examples of session variables are: user’s id, user’s name, Shopping cart, etc.

• Examples of application variables are: visitor counter.

Working with the Application and Session

• To place a value into the Application and Session simply assign it a key and then assign the value:– Application (“Name”)=“Smith”

– Session (“Age”)=25

• To read values from the Application and Session:– Cname=Application(“Name”)

– myAge = Session(“Age”)

• To remove an item, or all items: Remove, RemoveAll()– Application.Remove(“Name”)

– Session.RemoveAll()

ApplicationState/SessionState Properties

• ApplicationState:– Lock, Unlock

• SessionState:– SessionID– TimeOut

The Events of the Application and Session Objects

• Application_OnStart– Web site start, and the first view

• Application_OnEnd– Web site shut down

• Session_OnStart

• Session_OnEnd

The Global.ASAX File

• Every ASP.NET application has this special script file.

• Must reside in the web site’s root directory.• It can contain script code that belongs to the

application, or each session.• The event handler of the application and

session objects must be placed in the Global.asax file.

Web Form vs HTML Form

• HTML Form: A web page that contains one or more HTML form controls such as textbox, checkbox, dropdown list, and button inside an HTML <form> tag.

• Web Form: A web page that contains:– ASP.NET server controls, and/or HTML form

controls inside a <form runat=“server”> tag.– ASP.NET code that produces dynamic content

to be displayed within the web form.

Web Form Events• Every time a page is called the page object goes

through a series of stage: initializing, loading, processing and disposing of information. It happens every time a round trip to the server occurs.– Page_Init

– Page_Load: Occurs when a page is visible.

– Control Events

– Page_Unload

• Note: A webform is handled by itself.• Demo: web form with regular HTML controls –

ASPNET/TestRequestFormHTML.ASPX

ASP.NET Server Controls

• Intrinsic Controls: These controls correspond to their HTML counterparts. – Ex. Textbox, listbox, button, etc.

• Data-Centric Controls: Controls used for binding and displaying data from a data source, such as the DataGrid control.

• Rich Controls: Such as Calendar, AdRotator.• Validation Controls: Such as

RequiredFieldValidator.• Namespace:System.Web.UI.Webcontrols

Example of ASP.Net Control Tag

• Textbox:– <asp:TextBox ID="TextBox1" runat="server"

Style="z-index: 100; left: 80px; position: absolute; top: 64px"></asp:TextBox>

• Properties:– Control type– ID– BackColor, ForeColor, Height, Width– Runat=“server”

ASP.Net Composite Controls• DropdownList:

– Control tag + ListItem tag•<asp:dropdownlist id="list1" runat="server">

•<asp:listitem>Apple</asp:listitem>•<asp:listitem>Orange</asp:listitem>•<asp:listitem>Banana</asp:listitem>•</asp:dropdownlist>

• <asp:listbox/>– Demo:TestListBox.aspx

• <asp:radiobuttonlist/>

• <asp:checkboxlist/>

Server Control Events

• Object Browser– System.Web.UI.Webcontrols

Postback

• Postback is the process by which the browser posts information back to the server telling the server to handle the event, the server does so and sends the resulting HTML back to the browser.

The effects of Postback

• Remember the state of the form by adding a hidden _VIEWSTATE variable.

• Enable to write event handler.• Page.ISPostBack property.

– IF Not Page.ISPostBack Then• This is the first time the page is loaded.

• Demo: Display welcome message only once.

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load If Not Page.IsPostBack Then Response.Write("Welcome to this demo page") End If End Sub

ASP.Net Controls’ AutoPostBack Property

• Button always triggers postback.

• Other controls, by default, this property is set to false.

introduction to asp.net isys 512/812. web server web server: –internet information service:...

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