introduction to asp.net what is asp.net and how is different from asp –asp: server side technology...
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Introduction to ASP.NET• What is ASP.NET and how is different from ASP
– ASP: server side technology for creating dynamic web pages using scripting languages eg vb script.
– ASP.NET: server side technology for creating dynamic web pages using Fully Fledged programming languages supported by .NET
– VB.NET: our chosen language for writing ASP.NET pages
What is .NET?• A Microsoft strategy and new technology for delivering software
services to the desktop and to the web• Components include:
– MS Intermediate Language; all code is complied into a more abstract, trimmed version before execution. All .NET languages are compiled to MSIL – the common language of .NET
– The CLR- common language runtime; responsible for executing MSIL code; interfaces to Windows and IIS
– A rich set of libraries (Framework Class Libraries) available to all .NET languages
– The .NET languages such as C#, VB.NET etc that conform to CLR– ASP.NET is how the Framework is exposed to the web, using IIS to
manage simple pages of code so that they can be complied into full .NET programs. These generate HTML for the browser.
• Built on open protocols (XML, SOAP)• Future for development of MS & non-MS based systems.• Also heading towards the “Internet Operating System”
Common Language Common Language Runtime Type SystemRuntime Type System
Compilers use the runtime type system to Compilers use the runtime type system to produce produce type compatibletype compatible componentscomponents
ComponentsComponents
CompilersCompilers
Common Type System
C#C# VBVB C++C++
Runtime EnvironmentRuntime Environment
Robust And SecureRobust And Secure
• Native code compilation MSIL No interpreter Install-time or run-time IL to native compilation
• Code correctness and type-safety IL can be verified to guarantee type-safety No unsafe casts, no uninitialized variables, no out-of-
bounds array indexing
• Evidence-based security Policy grants permissions based on evidence (signatures,
origin)
.NET Execution Model.NET Execution Model
VBVB VCVC ...... ScriptScript
ILILNativeNativeCodeCode
NativeNativeCodeCode
Common Language RuntimeCommon Language Runtime
Standard JITStandard JITCompilerCompiler
Common Language Runtime • Lightweight Just-in-time compiler:
– MSIL to Native machine language; Can be ported to numerous platforms
• The compiled code is transformed into an intermediate language called the Microsoft Intermediate Language (MSIL or IL)
• An integer in Visual Basic .NET or an int in C# are converted to the same .NET data type, which is Int32
• The IL that is created is the same for all languages• The assembly is the compiled .NET program• The assembly contains the IL along with additional information
called metadata• Metadata contains information about the assembly• Use the IL Disassembler (ildasm.exe) to view the IL within an
assembly
Framework OverviewFramework Overview
Base Class Library
Common Language Specification
Common Language Runtime
Data and XML
VB C++ C#V
isual S
tud
io.N
ET
Web Forms(ASP.NET)
JScript …
Win Forms
.NET Framework Architecture
Common Language Runtime
MetadataType System Execution
System Base Framework
IO Net Security ServiceProcess
ADO.NET XML SQL Threading
System.Web
Web Services Web Forms
ASP.NET Application Services
System.WinForms
Controls Drawing
Windows Application Services
Namespace• The base class libraries are organized into logical
groupings of code called namespaces • A namespace is a hierarchical way to identify
resources in .NET• The System object is at the top of the namespace
hierarchy, and all objects inherit from it– ASP.NET: System.Web namespace– WebForms: System.Web.UI namespace– HTML Server Controls:
System.Web.UI.Control.HTMLControl– ASP.NET Server Controls:
System.Web.UI.Control.WebControl
Importing Namespaces• Visual Studio .NET adds references to your projects’
commonly used namespaces by default• You can import the namespaces into your page using
the @Import directive• The following is the syntax for importing a .NET
namespace<%@ Import NamespaceName %>
• Below is a sample of how you would import the ASP.NET Page class<%@ Imports System.Web.UI.Page %>
Some ASP.NET namespacesSystem Defines fundamental data types eg
system.string
System.Collections Definitions and classes for creating various collections
System.IO File reading & writing operations
System.Web Support browser/server communication
System.Web.UI Creates the Page object whenever an .aspx page is requested
System.Web.UI.webcontrols
Classes and definitions to create server controls
ASP.NET – class browser
• ASP.NET provides a means of exposing the .NET Framework and its functionality to the WWW
• Contains a number of pre-built types that take input from .NET types and represents them in a form for the web (such as HTML)
• Class browser (over 9000 classes; lists the namespaces):
ASP.NET• The latest version of ASP is known as ASP.NET• Visual Studio .NET is a developer application used
to create ASP.NET Web applications• There are two main types of Web resources created
with ASP.NET applications– WebForms are ASP.NET pages within an ASP.NET
application– Web Services are ASP.NET Web pages that contain
publicly exposed code so that other applications can interact with them
– Web Services are identified with the file extension .asmx
WebForms
• The ASP.NET WebForm is separated into two logical areas:– The HTML template – A collection of code behind the WebForm
• The HTML template – Contains the design layout, content, and the controls – Creates the user interface, or presentation layer– Instructs the browser how to format the Web page– Is created using a combination of HTML controls, HTML
Server controls, Mobile Controls, and ASP.NET controls
Server Controls• HTML Server controls are similar to the HTML
controls, except they are processed by the server• Add runat = "server" to the HTML control to
transform it into an HTML Server control• HTML control: <input type="text">• HTML Server control:
<input type="text" runat="server"/> <input type=”radio” runat=”server” value=”Yes”/> Yes
• Server-side programs can interact with the control before it is rendered as a plain HTML control and sent to the browser
ASP.NET Controls• ASP.NET form controls will create the HTML code• ASP.NET Server controls are organized as:
– ASP.NET Form Controls– Data Validation Controls– User Controls– Mobile Controls
• ASP.NET controls are usually identified with the prefix asp: followed by the name of the control
• ASP.NET button: <asp:Button id="ShowBtn" runat="server"
Text="Show the message." />
HTML Server Vs ASP.NET Server, Controls
• ASP.NET form controls can interact with client-side events such as when the user clicks on a button– When the event occurs, ASP.NET can trigger a script to run
on the server
• ASP.NET form controls also have different properties than their HTML server control counterparts – HTML Server label control
• Message1.InnerHTML = "Product 1"
– ASP server label control • Message2.Text = "Product 2"
User Controls• User controls are external files that can be included
within another WebForm• User controls allow you to reuse code across multiple
files• For example, you can create a user control that displays
the a navigation bar• You can use this control on the home page; they are
often used for creating self-contained code, headers, menus, and footers
• User controls replace the functionality of ASP server-side include pages
• They are identified with the file extension .asmx
Other ASP.NET Server Controls
• Data validation controls
– A series of controls that validate form data without extensive JavaScript programming
• Mobile controls
– A series of controls that provide form functionality within wireless and mobile devices
• Literal controls
– Page content that is not assigned to a specific HTML control such as a combination of HTML tags and text to the browser
Server Controls within Visual Studio .NET
• In Visual
Studio .NET most
of the ASP.NET
Server controls are
located on the Web
Forms tab in the
toolbox
Server controls with Visual Studio.NET
The Code Behind• Server programs are written in a separate file known as
the code behind the page• By separating the programming logic and presentation
layer, the application becomes easier to maintain• Only Server controls can interact with the code behind
the page– Written in any ASP.NET compatible language such as Visual
Basic .NET, C#, Perl, or Java– Filename is the same as the WebForm filename– Add a file extension that identifies the language
• Visual Basic .NET use .vb (mypage.aspx.vb)• C# use .cs (mypage.aspx.cs)
Code Behind file• The location of the code behind the page is determined
via a property that is set on the first line in the page using the @Page directive<%@ Page Language="vb" Codebehind="WebForm1.vb"
Inherits=“MyFirstApp.WebForm1"%>
• The @Page directive allows you to set the default properties for the entire page such as the default language
• The CodeBehind property identifies the path and filename of the code behind file
• The Inherits property indicates that the code behind the page inherits the page class
• This page class contains the compiled code for this page
Compiling the Page Class• The compiled code behind the page is the class
definition for the page– A class is a named logical grouping of code– The class definition contains the functions, methods, and
properties that belong to that class
• In Visual Studio .NET the process of compiling a class is called building– When you build the application, you compile the code
into an executable file– Visual Studio .NET compiles the code behind the page
into an executable file and places the file in the bin directory
Page Class Events
• The Page Class consists of a variety of methods, functions, and properties that can be accessed within the code behind the page
• The first time a page is requested by a client, a series of page events occurs
• The first page event is the Page_Init event which initializes the page control hierarchy
• The Page_Load event loads any server controls into memory and occurs every time the page is executed
Page class events
• Page_init
• Page_load
• Server_Controls
• Page_prerender
• Page_Unload
Web Services
• Web Services also provide a means to expose .NET functionality on the web but Web Services expose functionality via XML and SOAP (cf: function calls over the web)
Web Services• If your business partner is Course Technology and you
want to query that company’s product catalog from your Web site, you could:– Post a link– Scrape a Web site (use a program to view a Web site and capture
the source code)– Provide a Web Service to their catalog application
• Web Services are used to create business-to-business applications– Web Services allow you to expose part or all of your programs
over the Internet. The Web Service source file has the extension .asmx
– A public registry known as UDDI contains registered public Web Services. Third party Web Services are available at http://www.xmethods.com
Web application project filesAssemblyInfo.vb Info about the compiled project file stored in
/bin and named project.dll
Global.asax Event handler commands visible to all web forms in a project
Global.asax.resx Define application resources such as text strings, images. Can change without recompiling project.
Global.asax.vb Asp.net code for application events eg session.start
Project.sln Stores links to all project files
Project.suo VS.NET IDE configuration info for the proj.
Project.vbproj Configuration and build settings for project files.
Web application project files cont.Project.vbproj.webinfo URL to project web server
Project.vsdisco Enables search for web services
Styles.css Project style sheet
Web.config Project and folder configuration information
Webform.aspx Web form .aspx file;Html
Webform.aspx.resx Resources in corresponding web form
Webform.aspx.vb Code written for the form (code behind)
Bin\project.dll Compiled project output file (assembly)
Bin\project.pdb Debugging information used by developer
The lab environment.• Each machine is set up to be an IIS server –
http://localhost:1900/…..• You create your web projects with Visual Studio.Net.
VS.NET will create a subdirectory in c:/inetpub/wwwroot for your project. You must copy this subdirectory when moving to another machine or home.
• URL – http://localhost:1900/MyfirstApp/homepage.aspx
• Alternative to VS.Net is webmatrix
ASP.NET Vs PHPFeature PHP ASP.NET
HTML Yes Yes
CSS Yes Yes
‘php Templates’ Yes UserControlsServerControls (buttons,grids etc)
No Yes
Javascript Yes Yes + Validation controls
Database Conn Yes Yes
Cookies & Sessions Yes Yes
VIEWSTATE No Yes
POSTBACK No Yes