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Chapter 1 Introducing ASP.NET 2.0

Chapter 1 Introducing ASP.NET 2.0. What is ASP.NET?. ASP.NET 2.0 is the current version of ASP.NET, Microsoft’s powerful technology for creating dynamic Web content.

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Chapter 1 Introducing ASP.NET 2.0

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  1. Chapter 1Introducing ASP.NET 2.0

  2. What is ASP.NET? • ASP.NET 2.0 • is the current version of ASP.NET, Microsoft’s powerful technology for creating dynamic Web content. • is one of the key technologies of Microsoft's .NET Framework(which is both a development framework and software platform).

  3. Static vs Dynamic Web Pages • Static content: means that Web applications will deliver the same content of information to all users • Dynamic content: means that Web applications are personalized to the user and is responsive to the individual choices

  4. Static vs Dynamic Web Pages • Most Web pages that you view are not static HTML pages. • Instead they are dynamic generated content output from programs that run on servers. • These programs can interact with server resources like databases and XML Web services.

  5. Static Web Content

  6. Dynamic Web Content

  7. Dynamic Web Technologies • There are quite a number of different technologies for dynamically generating Web content. • ASP.NET • ASP • CGI • ColdFusion • JSP • PHP • Ruby on Rails • All of these technologies share one thing in common: • Using programming logic, they generate HTML on the server and send it back to the requesting browser.

  8. ASP.NET Advantages • ASP.NET provides a number of advantages compared to Microsoft’s earlier, "classic" ASP technology. • Better performance over ASP • because ASP.NET pages are compiled. • More powerful development environment. • It uses fully object oriented languages that work with a rich class library along with a very complete set of server-based controls that encapsulate common Web functionality that significantly reduces the amount of coding for Web developers. • Easier maintenance • Smoother deployment and configuration. • Due to the architecture of the .NET Framework.

  9. The .NET Framework • Many of the advantages that ASP.NET provides in comparison to other dynamic Web technologies are a result of its integration into Microsoft’s .NET Framework. • The .NET Framework is a development framework that provides a new programming interface to Windows services and APIs, and integrates a number of technologies that emerged from Microsoft during the late 1990s. • The .NET Framework is also a software platform for the running and deployment of Windows-based software systems

  10. Core Features of .NET • Language interoperability • A software system can be created using any combination of the available .NET languages. • Fully object-oriented languages • Common runtime engine shared by all languages • Base class library usable by all languages • Better security • Better performance

  11. .NET Architecture • The .NET Framework "sits" on top of the Windows operating system. • Consists of the following components: • Language compilers • Common Language Runtime • .NET Framework Base Class Library Source: Lam and Tai, .NET Framework Essentials, 3rd Edition (O'Reilly, 2003).

  12. ASP.NET Web Forms • An ASP.NET web application : • Consists of any number of web pages, controls, programming classes, web services, and other files • Residing within a single web server application directory • The principal component of an ASP.NET web application are its web pages. • These are text files with an .aspx extension and are called web forms. • Consist of two parts: • The declaratively-defined (i.e., by markup/tags) visual elements. • The programming logic.

  13. Web Form Programming Logic • A web form's programming logic can exist in either: • The same file as the visual elements • i.e., the .aspx file. • This code is contained within a code-declaration block. • In a separate class file. • The file is usually called a code-behind file. • By convention, its filename is same as .aspx file but with a language extension. • HelloWorld.aspx <- web form • HelloWorld.aspx.cs <- code-behind file

  14. HelloWorld.aspx Example <%@ Page Language="C#" %> <!DOCTYPE html PUBLIC … > <script runat="server"> protected void Page_Load(object sender, EventArgs e) { myDate.Text = DateTime.Now.ToShortDateString(); } </script> <html> <head><title>Hello World Embedded</title></head> <body> <form id="form1" runat="server" > <h1>Hello World</h1> The date is <em> <asp:Label ID="myDate" runat="server"></asp:Label> </em> </form> </body> </html> Page directive Code declaration block Necessary to make this a web form Web server control

  15. Page Directive • The Page directive is used to define page-specific instructions used by the ASP.NET environment. • This directive indicates that the programming code in any script blocks will be C#. • Directives are processing instructions for the parser and compiler when they process an ASP.NET page. • Although directives can be located anywhere in an .aspx file, the standard practice is to place them at the beginning of the file. • Directive statements are not case sensitive and quotation marks are not required around the attribute values. <%@ Page Language="C#" %>

  16. <script> Element <script runat="server"> protected void Page_Load(object sender, EventArgs e) { myDate.Text = DateTime.Now.ToShortDateString(); } </script> • Notice that the <script> element contains a runat="server" attribute. • This tells the ASP.NET environment that the code within the block is to be executed on the server (i.e., it is not client-side Javascript or VBScript). • The code itself declares a page-level event handler method that sets the Text property of a control named myDate to a short version of the current date.

  17. <asp:Label> Web Control <asp:Label ID="myDate" runat="server"></asp:Label> • In the example’s markup, there is an element named <asp:Label>. • This is a predefined ASP.NET Web server control (covered in more detail later). • The markup for this Label control sets its ID property to the value myDate. • The Label control must contain the runat="server" attribute. • If it does not have it, the ASP.NET environment simply passes on the markup to the browser, where it will be ignored.

  18. <form> element <form id="form1" runat="server" > … </form> • All ASP.NET pages must contain a <form> element that contains this runat attribute. • All body content in a Web form should appear within this special <form> element.

  19. Result in the browser <html> <head><title>Hello World Embedded</title></head> <body> <form name="form1" method="post" action="HelloWorld.aspx" id="form1"> <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUJODExMDE5NzY5D2QWAgIDD2QWAgIBDw8WAh4EVGV4dAUKMDgvMDEvMjAwNmRkZDZPhFHJER4chf3nmlgfL+uq4W58" /> <h1>Hello World</h1> The date is <em> <span id="myDate">23/06/2006</span> </em> </form> </body> </html> Notice no <asp:Label> control. Notice also the hidden input tag with the name of __VIEWSTATE.

  20. Example using Code-Behind • Remember that a web form can alternately have its programming code contained in a separate class file called a code-behind file.

  21. Code Behind Version <%@ Page Language="C#" AutoEventWireup="true" CodeFile="HelloWorldCodeBehind.aspx.cs" Inherits="HelloWorldCodeBehind" %> <!DOCTYPE … > <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Hello World Code-</title> </head> <body> <form id="form1" runat="server" > <h1>Hello World</h1> The date is <em> <asp:Label ID="myDate" runat="server"></asp:Label> </em> </form> </body> </html> Page directive HelloWorldCodeBehind.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class HelloWorldCodeBehind : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { myDate.Text = DateTime.Now.Date.ToString(); } } HelloWorldCodeBehind.aspx

  22. Why use code-behind? • The real advantage of separating the code into its own file is that it may lead to more maintainable web forms. • One of the main benefits of ASP.NET is that a page’s programming logic can be conceptually separated from the presentation • by using a code-behind file a page’s programming logic can also be physically separated from the presentation/markup. • By placing the programming code into its own file, it is also potentially easier to make use of a division of labor in the creation of the site. • Use whichever model you want • However, all the examples in text use code-behind.

  23. Web Application Structure • An ASP.NET web application can simply consist of a folder containing web forms and other files. • You can, however, add any number of additional nested subfolders within this root folder. • ASP.NET in fact has a number of reserved application folder names, e.g. • App_Code • App_Data • App_Theme

  24. Configuration File • Every folder in a web application can contain an XML-format configuration file named web.config. • This configuration file is used to define security, connection strings, and other configuration information.

  25. Visual Studio • While you can create an ASP.NET application in any text editor, using Visual Studio will make developing ASP.NET applications easier. • Can also use the free Visual Web Developer 2005 Express Edition. • All files, folders, and settings in a Web application created with Visual Studio are contained within conceptual containers called solutions and projects. • Depending upon which way you use Visual Studio to construct your Web application, a solution may contain one or more additional projects as well as additional files and metadata about the project.

  26. Web Server Options • To test or run ASP.NET Web applications, web server software is necessary. • One of the advantages of using Visual Studio 2005 for ASP.NET development is that your site can be run and tested with or without using IIS. Visual Studio supports a variety of configurations: • local IIS, file system, FTP, remote IIS sites • Microsoft’s production web server software is Internet Information Services (IIS). • In order to run IIS, your computer’s operating system must be one of the following: • Windows 2000, • Windows XP Professional (not XP Home), • Windows Vista Business or Ultimate (not Vista Home Basic), • Windows Server 2003.

  27. Web Server Options • With Visual Studio 2005, we could say that your computer is a development server (available only to yourself). • Alternately, you might upload your work to a staging server running IIS for team testing. • Of course, if you want others to see this Web application, it must eventually be uploaded to a production server (available to your Web application’s audience).

  28. Web Server Options

  29. Introducing Server Controls • Normal HTML tags such as <input>, <H1> and <select> are not processed by the server but are sent to and displayed by the browser. • Server controls, in contrast, are tags that can be understood by the server. • Each ASP.NET server control has an object model containing properties, methods, and events.

  30. Introducing Server Controls • There are five kinds of server controls: • HTML server controls • Web server controls • Validation server controls • User controls • Custom server controls • All five of these different types of controls can be used within a single given Web form.

  31. 1.HTML Server Controls • Most standard HTML tags can be turned into HTML server controls simply by adding the runat="server" attribute. • This runat attribute indicates that the element is to be processed on the server. • You can this programmatically respond to events or bind data. • HTML server controls can be useful for: • situations in which you need complete control over how the HTML element will be rendered in the browser, or • when migrating an existing ASP page to ASP.NET. • Web server controls are almost always preferable to HTML server controls due to their richly typed object model.

  32. 2.Web Server Controls • Web server controls are also created on the server and they require a runat="server" attribute to work. • Some Web server controls represent traditional HTML form elements such as buttons and drop-down lists. • Other Web server controls represent more complex or abstract elements such as calendars, data lists, data sources, and tree views. <asp:Button ID="myButton" runat="server" />

  33. 3.Validation Controls • These controls allow you to test a user’s input for validity. • They are actually a special type of Web server control. • Validation controls encapsulate common user input validation checks required by most Web applications: • ensuring that a required field is not empty, • comparing an input value against another value, • checking if a value falls within a range, • verifying that an input value matches a given pattern.

  34. 4.User Controls • These are developer-created controls that use the same programming techniques used to write Web forms pages. • They typically allow the encapsulation of the functionality of multiple server controls along with other ASP.NET or HTML content in a single unit.

  35. 5.Custom Server Controls • A custom server control is a Web server control that you can create. • A custom control is a compiled class and may combine multiple existing server controls. • A custom control, unlike a user control, contains no declarative elements, and can be extended, use templates, support data binding, and be redistributed in a precompiled assembly.

  36. Web Server Control Overview • Web server controls are added to a Web form in the same way as any HTML element: • You can type the markup code in Source view in VS. • You can use drag-and-drop from Source or Design view. • As well, you can programmatically add controls at runtime. • Web Server Control Syntax: <asp:controlNameid="some_id" runat="server" «other attributes» > </asp:controlName>

  37. List of the Common Web Server Controls

  38. List of the Common Web Server Controls

  39. List of the Common Web Server Controls

  40. Common Members • Learning how to work with all of these controls might seem a daunting prospect. • Thankfully, Web server controls share a common object model which make the process of learning how to use Web server controls easier. Object Model

  41. Common Members • Most Web server controls inherit from the WebControl class. • This WebControl class in turn inherits from the Control class. • Both of these base classes define a variety of properties, methods, and events that are available to all controls derived from them. • Most of these modify the formatting and display of the controls.

  42. Some Properties of the WebControl Class

  43. Some Properties of the Control Class

  44. Subproperties • Properties can also have properties; • these are called subproperties. • For instance, the Font property is a complex object with properties of its own, such as Name and Size. • When working with subproperties programmatically, you use dot notation. • e.g., somecontrol.Font.Size=10; • When working with subproperties declaratively, you use hyphen (-) notation. • e.g., <asp:Label id="acontrol" Font-Size="10" runat="server" />

  45. Event Properties • All controls support events. • You can specify the event handler method for a given event declaratively by affixing the Onprefix to the event property name. • E.g., if you have an event handling method named btnOne_Clickthat you want to run when the user clicks a button, you would use: <asp:button id="btnOne" runat="server" OnClick="btnOne_Click" />

  46. Event Methods • All event methods in the .NET Framework are void methods with two parameters: • the source object that raised the event • the data for the event, usually contained within an EventArgs object (or an object derived from it). • Thus, the method signature for the event handler would be: public void btnOne_Click(object source, EventArgs e) { // code goes here }

  47. Color-Based Properties • All color-based properties use the Color structure. • The Color structure defines: • all the HTML 4.0 system-defined colors • the color names supported by most browsers • methods for retrieving and specifying color using different color models (such as HSB and RGB).

  48. Color-Based Properties • Acolor can be specified in at least four different ways, as shown here: // Set the color using predefined value labMsg.ForeColor = Color.Gold; // Set the color using a predefined name labMsg.ForeColor = Color.FromName("Gold"); // Set the color using RGB labMsg.ForeColor = Color.FromArgb(204, 153, 0); // Set the color using hexadecimal HTML color labMsg.ForeColor = Color.FromName("#CC9900");

  49. Collection Properties • Some properties are not a single structure, primitive, or enumerated type, but a collection of other objects. • An example of such a property is the Items collection of the DropDownList control. • This collection contains zero or more ListItem objects. • These collection properties have their own methods and properties for determining the size of the collection, as well for adding, retrieving, and removing items from the collection. DropDownListdrpSample = new DropDownList(); // Create the item, then add to collection ListItem li = new ListItem("Item 2"); drpSample.Items.Add(li); // Combine the creation and addition to collection steps drpSample.Items.Add(new ListItem("Item 1"));

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