Targeted Applications

1
Targeted Applications

• NET Framework to develop the following types of
  applications and services
• Console applications.
• Windows applications (Windows Forms).
• Web applications applications (ASP.NET).
• Mobile web applications (Mobile Web Form
  ASP.NET)
• XML Web services (can be consumed by Window
  applications and Web applications).
• Windows services.

2
ASP.NET Features

• Multiple Language Support
• Run ASP and ASPX side by side
• Simplified programming model
• Server Controls
• Event based programming (VB for the web)
• Increased Performance
• Compiled code
• Caching Cache output
• Web Services
• Improved Security
• Greater Scalability
• Cookie-less Sessions
• Classes and Namespaces
• Simplified Configuration and Deployment

3
Hello.aspx

• lthtmlgt
• ltscript language"VB" runat"server"gt
• Sub EnterBtn_Click(Src As Object, e As
  EventArgs)
• Message.Text "Hi " Name.Text ",
  welcome to ASP.NET!"
• End Sub
• lt/scriptgt
• ltbodygt
• ltform runat"server"gt
• Enter your name ltasptextbox id"Name"
  runatserver/gt
• ltaspbutton text"Enter" Onclick"EnterBtn_Cli
  ck" runat"server"/gt
• ltpgt
• ltasplabel id"Message" runatserver/gt
• lt/formgt
• lt/bodygt
• lt/htmlgt

Design time
Run time
4
Web Server Controls
ltaspbutton text"Enter" Onclick"EnterBtn_Click"
runat"server" /gt

• lthtmlgt
• ltscript language"VB" runat"server"gt
• Sub EnterBtn_Click(Src As Object, e As
  EventArgs)
• Message.Text "Hi " Name.Text _
• ", welcome to ASP.NET!"
• End Sub
• lt/scriptgt
• ltbodygt
• ltform runat"server"gt
• Enter your name
• ltasptextbox id"Name" runatserver/gt
• ltaspbutton text"Enter" Onclick"EnterBtn_Click"
  runat"server"/gt
• ltasplabel id"Message" runatserver/gt
• lt/formgtlt/bodygtlt/htmlgt

Use id attribute to assign a unique identifier to
each control in order to refer to it in your
program.
5
ASP.NET Pages Part Declarative, Part Code

• Combines declarative tags (HTML, ASPX directives,
  server controls tags, and static text) with code
  in a single file or in separate files.
• Unlike ASP, good separation provided between code
  and tags

?
single file
separate files (code-behind)
code
code
lttagsgt
lttagsgt
Form1.aspx
Form1.aspx
Form1.aspx.vb
6
Web.config

• lt?xml version"1.0" encoding"utf-8" ?gt
• ltconfigurationgt
• ltsystem.webgt
• ltcompilation defaultLanguage"vb"
  debug"true" /gt
• lt!-- CUSTOM ERROR MESSAGES
• Set customErrors mode"On" or
  "RemoteOnly" to enable custom error messages,
  "Off" to disable.
• Add lterrorgt tags for each of the errors
  you want to handle.
• --gt
• ltcustomErrors mode"Off"/gt
• ltauthentication mode"Windows" /gt
• ltauthorizationgt
• ltallow users"" /gt lt!-- Allow all users
  --gt
• lt/authorizationgt
• lttrace enabled"false" requestLimit"10"
  pageOutput"false" traceMode"SortByTime"
  localOnly"true" /gt
• ltsessionState
• mode"InProc"
• stateConnectionString"tcpip127.0.0.1
  42424"
• sqlConnectionString"data
  source127.0.0.1user idsapassword"
• cookieless"false"

A Web.config file is required in your web
application folder, a subfolder under the
application folder does not require a Web.config
file.
7
Runtime Compilation
8
ASP.NET Execution Model First Request
Client Server
9
Page/Control Event Execution
PostBack
First Request
Page DLL is loaded, control hierarchy initialized
They may be triggered on PostBack
Page_Load
Textbox1_Changed
1. Change Events
Button1_Click
2. Action Events
Control hierarchy (Dynamically generated HTML
page) is rendered
Page_Unload
Page is disposed
10
Postback

• ltform id"Form1" method"post" runat"server"gt
• Enter your nameltbrgt
• ltasptextbox id"TextBox1" runat"server"gtlt/aspte
  xtboxgt
• ltPgtltaspbutton id"Button1" runat"server"
  Text"Submit"gtlt/aspbuttongtlt/Pgt
• ltPgtltasplabel id"Label1" runat"server"gtlt/asplab
  elgtlt/Pgt
• ltPgt ltaspLabel id"Label2" runat"server"gtlt/aspLa
  belgt lt/Pgt
• lt/formgt

Postback
When an ASP.NET page's ltformgt tag does not have
the action attribute, the "Submit" button, submit
the form variables (controls' data) to the same
page to be processed by its server-side
event-handling methods.
11
Handling Postback Forms

• ViewState Control maintains the state of a page
  during Postback
• Page_Load fires on every request
• Test Page.IsPostBack to execute conditional
  logic

Sub Page_Load(s As Object, e As EventArgs) If
Not Page.IsPostBack Then ' executes only on
initial page load End If ' The rest of code
executes on ' Post-Back every request End Sub
12
Effect of Post Back
Design View
Hello2.aspx
lt_at_ Page Language"vb" AutoEventWireup"false"
Codebehind"Hello2.aspx.vb" Inherits"WebApplicati
on1.Hello2" gt .
13
Hello2.aspx

• lt_at_ Page Language"vb" AutoEventWireup"false"
• Codebehind"Hello2.aspx.vb" Inherits"WebApplicat
  ion1.Hello2"gt
• lt!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0
  Transitional//EN"gt
• ltHTMLgt
• ltHEADgt
• lttitlegtHello2lt/titlegt
• ltmeta content"Microsoft Visual Studio.NET 7.0"
  name"GENERATOR"gt
• ltmeta content"Visual Basic 7.0"
  name"CODE_LANGUAGE"gt
• ltmeta content"JavaScript" name"vs_defaultClien
  tScript"gt
• ltmeta content"http//schemas.microsoft.com/inte
  llisense/ie5" name"vs_targetSchema"gt
• lt/HEADgt
• ltbodygt
• ltform id"Form1" method"post" runat"server"gt
• Enter your nameltbrgt
• ltasptextbox id"TextBox1" runat"server"gtlt/aspte
  xtboxgt
• ltPgtltaspbutton id"Button1" runat"server"
  Text"Submit"gtlt/aspbuttongtlt/Pgt
• ltPgtltasplabel id"Label1" runat"server"gtlt/asplab
  elgtlt/Pgt
• ltPgt ltaspLabel id"Label2" runat"server"gtlt/aspLa
  belgt lt/Pgt
• lt/formgt

14
Hello2.aspx.vb

• Public Class Hello2
• Inherits System.Web.UI.Page
• Protected WithEvents Button1 As
  System.Web.UI.WebControls.Button
• Protected WithEvents TextBox1 As
  System.Web.UI.WebControls.TextBox
• Protected WithEvents Label2 As
  System.Web.UI.WebControls.Label
• Protected WithEvents Label1 As
  System.Web.UI.WebControls.Label
• Private Sub Page_Load(ByVal sender As
  System.Object, _
• ByVal e As System.EventArgs) Handles
  MyBase.Load
• ' Put user code to initialize the page
  here
• If Not Page.IsPostBack Then
• Label2.Text "First Time"
• Else
• Label2.Text "Post back"
• End If
• End Sub
• Private Sub Button1_Click(ByVal sender As
  System.Object, _
• ByVal e As System.EventArgs) Handles
  Button1.Click
• Label1.Text TextBox1.Text

15
Control Event Processing

• Events are
• Triggered on the client by the user
• Handled in server code
• Requires a postback to the same page
• ViewState of controls saves page and control
  properties between round trips, therefore helps
  restore control to its previous state.
• Implemented as a hidden form field
• Disable via setting the EnableViewState attribute
• EnableViewStatefalse
• Data Binding resets control state

16
The Files in a Web Application
http//localhost/hello/HelloForm3.aspx
Request
Response
17
WebForm1.aspx
18
Converting String to Number and Formatting

• ltHTMLgtltHEADgtlttitlegtWebForm1lt/titlegt
• ltscript language"vb" runat"server"gt
• Sub EnterBtn_Click(Src As Object, e As EventArgs)
• Dim DollarInput as String
• Dim DollarConverted as Double
• Try
• DollarInput Request.Params.Get("amount")
  
• DollarConverted CType(DollarInput,
  Double)
• Response.Write("The amount you entered
  is" DollarConverted.ToString("C"))
• Catch ex as Exception
• Response.Write("You did not enter a
  proper dollar amount!")
• End Try
• End Sub
• lt/scriptgt
• lt/HEADgt
• ltbodygt
• ltform id"Form1" method"post"
  runat"server" gt
• ltPgtEnter the amount ltINPUT
  type"text" name"amount" size"20"gtlt/Pgt
• ltINPUT type"submit" value"Submit"