Web Development Using ASP .NET

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					Welcome to week – 1.1 of…


     Web Development
          Using
        ASP .NET
               CA – 240
              Kashif Jalal
Chapter – ONE: Objectives
 Static and Dynamic Web Applications

• Static Web pages
  – Created with HTML controls
• Dynamic Web pages
  – Allow user to interact with the Web page
  – Changes appearance or content
  – Created with Microsoft’s Active Server Pages
    .NET (ASP.NET)
    • Used to build server-side Web applications
Processing a Request for a Web Page
                     ASP .NET

• Main ASP.NET applications
  – Web Forms
    •   Used to process forms and develop cross-
        browser applications
    •   Uses .aspx file extension
  – Web Services
    •   Other applications can interact with your program
    •   Uses .asmx file extension
                    Web Forms

• ASP.NET pages within an ASP.NET
  application
  – Identified with file extension .aspx
• 2 logical areas:
  – HTML template
     • Contains design layout, content, and controls
  – Collection of code commonly located behind
    Web Form
               HTML Server Controls

• Similar to HTML controls except processed by server
• Write runat=“server” to transform HTML control into
  HTML Server control
• Controls have closing tag, or end with />
• HTML control:
   – <input type=“text”>
• HTML Server control:
   – <input type=“radio” runat=“server” value=“Yes”/>
     Yes
      ASP .NET Server Controls

• Creates HTML code
• ASP.NET controls usually identified with
  prefix asp: followed by name of the control
• Types of ASP.NET Server Controls
  – ASP.NET Form Controls (Web controls)
  – Data Validation Controls
  – User Controls
  – Mobile Controls
            Browser Source Code

• Look at the browser’s source code for each ASP.NET
  page to understand what the Web server is sending to
  the browser
   – ASP.NET code is never sent to the browser
   – Only HTML tags, along with client-side scripts, are
     sent to the browser
• Many errors are related to the syntax of the HTML that is
  sent to the browser, such as a missing closing tag, or a
  missing quotation mark
• You can quickly locate HTML syntax errors
Server Controls
 within Visual
 Studio .NET
         Code Behind the Page

• Written in an ASP.NET-compatible
  language
• File extension is .vb if code is written in
  Visual Basic .NET
• Compiled code behind the page is the
  class definition for the page
• When you build the application, you
  compile the code into an executable file
  stored in the bin directory
Code Behind the Page
                     Postback

• Posting back data into form
• The _ViewState hidden form field
   – Very long encoded string
   – Contains information required to maintain form data
     across multiple page requests
   – Value changes each time form is reposted
• EnableViewState property
   – Turns postback feature on or off. To turn off:
   – <%@ Page EnableViewState="false" %>
               Page Class Events
• The first time a page is requested by a client, a series of
  page events occurs
   – Page_Init – initializes page control hierarchy
   – Page_Load – loads any server controls into memory
     and occurs every time page is executed
   – Server control events – action and change events occur
     when page is posted back to the server
   – Page_PreRender – occurs immediately before control
     hierarchy is rendered and sent to the browser
   – Page_Unload –removes page from server’s memory
Page Class Event Cycle
Locating Your ASP.NET Application

• Web Server is called Internet Information
  Server
  – C:/Inetpub/wwwroot maps to http://localhost/
• Develop on local Web server or test server
• Deploy Web application to production Web
  server on the Internet
• You can transfer Web application files
  using File Transfer Programs (FTP)
              Web Services

• Exposes part of a program over the
  Internet
• Web Service file has .asmx file extension
• Uses open standards so it’s supported
  across applications and platforms
• Used to create business-to-business
  applications
• Can share data with other partners
Tara Store Web Services
          The .NET Framework

• An architectural model for creating
  programs that interface with the operating
  system and base class libraries
• Contains a hierarchical set of Base Class
  Libraries
• Base class libraries are code libraries that
  provide general functions
              Namespaces

• Organizes base class libraries
• Top namespace is System
• All Web Forms inherit the System.Web.UI
  namespace
• System.Web.UI contains classes for
  controls used on Web Forms
  – HTML Server controls
  – ASP.NET Server controls (Web controls)
HTML Server Controls
ASP .NET Server Controls
    Common Language Runtime

• Each .NET language compiles into a
  common intermediate language and
  common type system (CTS)
• Assembly contains compiled .NET
  program
• The compiled .NET program contains the
  intermediate language and metadata
• Metadata describes the assembly contents
Building the
application
              “Some” Definitions…
• Namespace: A namespace refers to a logical grouping of types or
  identifiers used in a program.
• Event Handler: An event handler is a method that is executed in
  response to an event.
• Array: An array is a collection of homogenous objects. It is a group
  of elements of the same type that share a common name. The size
  of an array is fixed and cannot be changed at runtime.
• ArrayList: An ArrayList is a collection of heterogeneous elements-
  elements of different types. Unlike an array, its size can be
  changed dynamically
• HashTable: A HashTable is a collection of heterogeneous objects
  that can be referred using either an index or a key. Elements of an
  ArrayList can be referred to using an index only
• Web Services: A web service is SOAP based, platform–
  independent software component that exposes itself through open
  communication channels of the web applications running on
  potentially different platforms.
• Application State: This is a state management technique that
  allows objects to be stored and then globally accessed or shared by
  multiple modules of the application. In ASP.NET, application state
  is maintained by the class HttpApplicationState.
                    “Some” Definitions…
•   Session State: A session is the period of a connection between a server and a
    client. The Session State allows storage of objects in a user’s session. A session
    can be stored in one of the following ways.
     –   InProc
     –   State Server
     –   SQL Server
•   VIEWSTATE: This is a client-side state management technique that continues the
    state of server controls by maintaining the state of pages across postbacks. The
    view state is an encoded hashed string and is stored in a hidden field called
    __VIEWSTATE.
•   Assembly: An assembly is a group of resources and types, along with the metadata
    about those resources and types, deployed as a single unit.
•   Just In Time Compiler: The Just In Time Compiler or the JIT is responsible for
    compiling units of code and caching them at runtime as and when they are
    needed. Since the compilation occurs at runtime, it is known as a Just In Time
    Compilation.
•   .NET Framework Class Library: The .NET Framework Class Library (FCL) is a set
    of managed classes that are responsible for providing access to the system services
    in the managed environment of Microsoft.NET
•   The Common Type System: (CTS) is a standard that defines the necessary rules
    for type interoperability for the languages targeting the .NET environment. The
    common type system supports the following types.
     –   Value Types
     –   Reference Types
                     Summary
• ASP.NET pages can contain programs written in a
  variety of programming languages.

• Web Forms end in .aspx. Web Services end in .asmx.
  User controls end in .ascx.

• The term “ASP.NET pages” and “Web Forms” are
  synonymous.

• The entire ASP.NET Web page is a class called the Page
  class.

• The .NET framework is the architectural framework in
  which ASP.NET applications are created.
            Summary (continued)
• Web Services allow you to expose a program interface
  publicly to other businesses and applications.
• At compile time, all languages must support the same
  common .NET data types.
• Page class renders HTML and Server code to the
  browser.
• The Page class contains the code behind the page,
  which is located in a separate file.
• You need a Web server to post your pages and a
  platform that supports the .NET Framework.
• There are a variety of help resources within Visual
  Studio .NET and on the Internet.

				
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