Chap. 6

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Database
-
Driven Web Sites, Second Edition

1

Chapter 6

INTRODUCTION TO
ASP.NET


Database
-
Driven Web Sites, Second Edition

2

Objectives

In this chapter, you will:


Learn about the .NET framework, ASP.NET, and
.NET server controls


Become familiar with the .NET class libraries


Learn how to create Web application projects


Learn how to use the Visual Studio .NET
integrated development environment to create
and manage Web application projects

Database
-
Driven Web Sites, Second Edition

3

Objectives

In this chapter, you will:


Learn how to create and modify Web application
project components


Learn how to access and reference Web forms


Learn how to move a Web application project's
files to a different physical folder

Database
-
Driven Web Sites, Second Edition

4

The .NET Framework



Web application: one or more files that
developers create to solve a problem or provide a
service through a Web site


.NET framework: a set of code, objects, and
standards for building computer applications

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-
Driven Web Sites, Second Edition

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The .NET Framework



Programs can be created within the .NET
framework using Visual Basic, Visual C++, C#,
and JScript languages


When a .NET program is created using any of
these languages, the code is compiled into a
common intermediate language called the
Microsoft Intermediate Language (MSIL)


The Common Language Runtime (CLR)
application runs the MSIL program

Database
-
Driven Web Sites, Second Edition

6

The .NET Framework



.NET framework


All elements are objects


Defines objects using a standard set of programs
that are called class libraries


ASP.NET: set of class libraries containing code
that defines objects used to create Web
applications


Web application project: contains all the related
files in a Web application

Database
-
Driven Web Sites, Second Edition

7

Introduction to ASP.NET



ASP text file


Has an .asp extension


Contains ASP server
-
side script commands
interleaved with HTML tags, Web page elements,
and client
-
side script commands


ASP had a number of limitations


To address these, Microsoft developed ASP.NET
pages, which are also called ASPX pages or Web
forms


Web form: text file with an .aspx file extension
that contains Web page elements


Database
-
Driven Web Sites, Second Edition

8

An Overview of ASP.NET Server
Controls


HTML designers: responsible for the HTML
components of an application


Web programmers: responsible for the program
components, such as the client
-
side scripts and
server
-
side programs


Server control:


An element that an HTML designer creates in a
Web form


Provides a more direct link between items on a
Web page and programs running on the Web
server

Database
-
Driven Web Sites, Second Edition

9

An Overview of ASP.NET Server
Controls


Server controls:


Have associated events that the Web server
associates with user actions


Enable Web developers to create modular Web
applications


Server
-
side event handler: contains program
commands that respond to events that the user
raises on Web server controls


Database
-
Driven Web Sites, Second Edition

10

An Overview of ASP.NET Server
Controls


The HTML tags, elements, and Web server
definitions exist in the Web form’s .aspx file


Commands that reference the Web server
controls exist in a separate VB .NET program file


Main types of ASP.NET server controls:


Rich server controls


HTML server controls


Validation server controls

Database
-
Driven Web Sites, Second Edition

11

The .NET Framework Class Libraries



The .NET framework is built on the object
-
oriented model


Object class: defines the properties and actions
of similar objects


Class: defined by its properties, events, and
methods


Object classes usually have a hierarchical
structure that defines parent classes and child
classes

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-
Driven Web Sites, Second Edition

12

The .NET Framework Class Libraries



The .NET framework defines all of its elements using similar
object classes, which are called namespaces


Figure 6
-
6 shows the ASP.NET namespace hierarchy

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-
Driven Web Sites, Second Edition

13

The .NET Framework Class Libraries


The .NET framework arranges its namespaces
hierarchically using parent and child classes


Dot syntax is used to reference child classes
within parent classes:



parent_class
.
child_class


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-
Driven Web Sites, Second Edition

14

Creating a Web Application Project



Visual Studio .NET can create and configure Web
application projects allowing developers to
manage and control all of the application files


When a new Web application project is created in
Visual Studio .NET, the IDE automatically creates
a project folder in a physical directory


Visual Studio .NET also automatically creates a
Web server application that it associates with the
project folder

Database
-
Driven Web Sites, Second Edition

15

Configuring the Web Server for Web
Application Projects



Application root: Web server application whose
associated folder contains the project folders for
the Web application projects that are being
created


To configure the application root, a Web server
application must be created and associated with
every folder in the folder path to the application
root


Database
-
Driven Web Sites, Second Edition

16

Creating Web Application Projects



Project: consists of multiple files that comprise a
Web application


Project files:


Solution: consists of one or more projects


Global files: visible to all project components


Resource files: data that supports the project


Project files: contain information about the project
structure and contents

Database
-
Driven Web Sites, Second Edition

17

Creating Web Application Projects



A project consists of one or more Web forms


Each Web form has an associated code behind
file, containing code that Web developers create
to interact with the Web form’s server controls


By default, Visual Studio .NET places all new
project folders in the default Visual Studio
Projects folder

Database
-
Driven Web Sites, Second Edition

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The Visual Studio .NET Integrated
Development Environment


Database
-
Driven Web Sites, Second Edition

19

The Visual Studio .NET Integrated
Development Environment


The main Web application project IDE windows
include:



Solution Explorer Window: lists the Web
application project components


Web Browser Window: displays the design area
and code window for the project's Web forms


Toolbox: used to add elements to a Web form such
as rich server controls, HTML server controls, and
HTML elements


Properties Window: lists the properties of the
object that is currently active

Database
-
Driven Web Sites, Second Edition

20

The Solution Explorer



When a Web application project is created or
opened in Visual Studio .NET, the Solution
Explorer displays the project and its components
as a hierarchical tree


This tree contains a node to represent each open
project, and nodes below the project to represent
the project components


The Solution Explorer window is used to add and
remove project items

Database
-
Driven Web Sites, Second Edition

21

The Web Browser Window



The Web Browser Window: where you create and
view HTML documents and write code for client
-
side scripts


Displays Web forms in Design view and HTML
view



Design view shows the form and its components
visually



A grid appears on the Web form display in the
Web Browser Window


This grid is used to align form objects

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-
Driven Web Sites, Second Edition

22

The Web Browser Window

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-
Driven Web Sites, Second Edition

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The Toolbox



To add rich server controls, HTML server
controls, and HTML elements to a Web form, a
developer can select a tool in the Toolbox and
draw the associated control on the Web form in
Visual view

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-
Driven Web Sites, Second Edition

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The Toolbox


Toolbox: contains tools to create controls and
other objects on Web forms


Default Toolbox tabs:



Data


Web Forms


Components


HTML


Clipboard Ring


General

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The Properties Window



Properties Window: lists the properties and their
current design time values for the project
component that is selected in the Solution
Explorer or for the Web form item that is selected
in the Web Browser Window in Visual view


Categorized button: shows the property names
under nodes that represent different property
categories

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26

The Properties Window



Alphabetic button: shows properties in an
alphabetized list


Property Pages button: opens a dialog box
containing tab pages that allow the developer to
set property values


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Driven Web Sites, Second Edition

27

Working With Project Components



HTML designers use Web form controls and other
Web page elements to create the visual elements
that appear on a Web page


After creating a Web form control, you can modify
the control’s properties to specify how the
control looks and behaves when the form first
opens


Then you can write the code behind the controls
to modify control properties at run time and
perform server
-
side processing


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-
Driven Web Sites, Second Edition

28

Creating Web Form Controls



To create a rich server control on a Web
form, the desired control is selected in the
Visual Studio .NET Toolbox, dragged onto the
form in Visual view, and then repositioned
and resized

Database
-
Driven Web Sites, Second Edition

29

Creating Web Form Controls


Web forms: uses a grid layout style so that Visual
Studio .NET specifies the element’s location on
the form using an absolute position


Absolute position: element’s location from top
left using values in the element’s style tag

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-
Driven Web Sites, Second Edition

30

Modifying Web Form Properties



To change a control’s design time property
values:


Control is selected in the Browser Window


Property values are changed in the Properties
Window


ID property: specifies how the Web form
internally references the control


Every Web form control must have a unique ID
value

Database
-
Driven Web Sites, Second Edition

31

Modifying Web Form Properties


Dynamic controls: controls whose properties
change while the form is running


Because Web programmers reference dynamic
controls in program commands, it is important to
assign descriptive ID attribute values to them


Both Label and TextBox rich server controls have
a Text property that specifies the text that the
control displays when the form first opens

Database
-
Driven Web Sites, Second Edition

32

Writing Server
-
Side Web Form
Programs



Every Web form has an associated code
behind file that contains the code that works
with the Web form controls


The code behind file is edited in the Browser
Window’s Code editor

Database
-
Driven Web Sites, Second Edition

33

Writing Server
-
Side Web Form
Programs


Database
-
Driven Web Sites, Second Edition

34

Writing Server
-
Side Web Form
Programs


Code editor: an environment to enter, display,
and edit program commands or text files



Code behind file: contains VB .NET commands
that define and process Web form components


Declarations block:


First set of commands in the code behind file


Contains the commands that define the Web form
and its components


Database
-
Driven Web Sites, Second Edition

35

Writing Server
-
Side Web Form
Programs


Code behind file also contains procedures, which
are self
-
contained code blocks written in one of
the .NET programming languages


Procedures can be functions and event handlers


VB .NET procedures can also be subroutines,
which are similar to functions and can receive
and manipulate parameter values, but do not
return a specific value


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36

Building and Testing the Project



Building the project: translates the project files
into machine
-
readable code that the Web server
can execute


Every time a change is made to a project, the
project assembly file must be rebuilt


Build Solution or Rebuild Solution: to rebuild the
project


Another way to build or rebuild the project files is
to run the project in the Visual Studio .NET IDE

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-
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37

Building and Testing the Project



Visual Studio .NET Debugger: to set breakpoints,
step through commands, and view variable
values during execution


Project Start Page: must be specified before
running a project in Visual Studio .NET

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-
Driven Web Sites, Second Edition

38

Accessing and Referencing Web
Forms



Users can access a Web form by entering the
form’s URL in the
Address
field in their Web
browser


Users can access Web forms through hyperlinks
in static Web pages

Database
-
Driven Web Sites, Second Edition

39

Moving Web Application Projects to
Different Locations



When a project is moved to a new location, some
modifications must be made both to the project
and to the Web server structure


To move a project to a new location successfully,
a new Web server application must be created
and it must be associated with the new project
folder


Then the project solution file needs to be
modified to specify the URL to the new Web
server application


Database
-
Driven Web Sites, Second Edition

40

Summary


.NET framework: set of code, objects, and
standards for building computer applications


ASP.NET can be used to create a Web application
project that contains all of the application’s
related files


Visual Studio .NET IDE: provides a visual
interface to access, configure, manage, and
debug the different application components in a
single integrated environment

Database
-
Driven Web Sites, Second Edition

41

Summary


Server controls: elements that an HTML designer
creates in a Web form


Server controls enable Web developers to create
modular Web applications


The .NET framework is built on the object
-
oriented model and contains an extensive class
library


Visual Studio .NET stores every Web form in a file
with an .aspx extension