INTRODUCTION TO ASP.NET

1
Chapter 6

• INTRODUCTION TO ASP.NET

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

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

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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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

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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

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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

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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

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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

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An Overview of ASP.NET Server Controls

• The HTML tags, elements, and Web server
  definitions exist in the Web forms .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

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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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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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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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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

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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

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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

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

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The Visual Studio .NET Integrated Development
Environment
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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

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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

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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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The Web Browser Window
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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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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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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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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 controls 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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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

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Creating Web Form Controls

• Web forms uses a grid layout style so that
  Visual Studio .NET specifies the elements
  location on the form using an absolute position
• Absolute position elements location from top
  left using values in the elements style tag

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Modifying Web Form Properties

• To change a controls 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

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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

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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
  Windows Code editor

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Writing Server-Side Web Form Programs
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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

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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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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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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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Accessing and Referencing Web Forms

• Users can access a Web form by entering the
  forms URL in the Address field in their Web
  browser
• Users can access Web forms through hyperlinks in
  static Web pages

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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

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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 applications
  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

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