Control Toolkit
□ Deploy your web application to a web server
About ASP.NET
In the early days of the web, the contents of web pages were largely static. Pages needed to be constantly — and manually — modified. To create web sites that were dynamic and would update automatically, a number of server-side technologies sprouted up, including Microsoft's Active Server Pages (ASP). ASP executed on the server side, with its output sent to the user's web browser, thus allowing the server to generate dynamic web pages based on the actions of the user.
These server-side technologies are important contributions to the development of the web. Without them, web applications that users are accustomed to today, such as Amazon.com and eBay.com, would not be possible.
Microsoft ASP began as a public beta (v1.0) in October 1996 as an upgrade to Internet Information Server (IIS) 2.0. In the initial three versions, ASP used a scripting language, VBScript, as the default language. Using a scripting language had its flaws — code is interpreted rather than compiled, and using VBScript as the default language turned some people off (although technically you could configure ASP to use other languages such as JScript and Perl, but this was not commonly done). This interpreted code model of ASP seriously limited performance.
In early 2000, Microsoft introduced the.NET Framework and, together with it, the upgrade of ASP: ASP.NET 1.0 (previously known as ASP+). Over the last few years, ASP.NET has evolved to ASP.NET 3.5.
In ASP.NET, you are not limited to scripting languages; you can use the following .NET languages:
□ C#
□ VB.NET
How ASP.NET Works
When a web browser requests a page from a web server, the web server (IIS) first checks whether the request is for an HTML page. If it is, the request is filled by fetching the files from the hard drive and returning them to the client (web browser). If the client is requesting an ASP.NET page, IIS passes the request to the ASP.NET runtime, which then processes the application and returns the output to the client.
ASP.NET pages use the .aspx extension, which ensures that ASP.NET can run side by side with classic ASP, which uses the extension .asp.
One of the inherent problems with the HTTP protocol is its stateless nature. Put simply, a request made by a user is loaded into memory, fulfilled, and then unloaded. Subsequent requests by the same user are treated just like any other request; the server makes no attempt to remember what the user has previously requested. This stateless nature makes writing web applications a challenge because the application developer must explicitly devise mechanisms to enable the server to remember the previous state of the application. Several mechanisms have been devised over the years, including cookies and query strings for passing information to and from the server and the client.
In classic ASP, you typically need to write pages of code to preserve the state of the page after the user has posted a value back to the server. In ASP.NET, all of these mundane tasks (collectively known as state management) are accomplished by the ASP.NET runtime.
What Do You Need to Run ASP.NET?
ASP.NET is supported on the following operating systems:
□ Microsoft Windows 2000 Professional and Server (SP2 recommended)
□ Microsoft Windows XP Professional
□ Microsoft Windows Server 2003/2008
□ Microsoft Windows Vista
To run ASP.NET applications, you need to install IIS on your computer (IIS is not installed by default; you can install IIS on your computer by running the Add or Remove Programs application in the Control Panel and then selecting the Add/Remove Windows Components tab). To obtain the ASP.NET runtime, you must install the .NET Framework on your machine. You can obtain the latest .NET Framework from the following site: http://microsoft.com/downloads.
Data Binding
One of the most common tasks a web application does is display records from a database. For example, you may have an inventory web application with which your staff can check the latest pricing information and stock availability. This chapter explains how to retrieve records from a database and use data binding in ASP.NET to display them on a page. In addition, it shows how to use the new LinqDataSource control, which enables you to use LINQ to talk to databases without needing to write complex SQL queries.
To start, launch Visual Studio 2008 and create a new ASP.NET Web Site project (see Figure 17-1).
Figure 17-1
The default location is File System (see Figure 17-2), which means that you can save your ASP.NET project in any folder on your local drive so that during debugging a built-in web server is automatically launched to host your ASP.NET application. Alternatively, you can choose the HTTP option, which means that your ASP.NET application will be hosted by a web server (most commonly the local IIS), or the FTP option, which uses an FTP Server. For this example, use File System, the default option.
Figure 17-2
Modeling Databases Using LINQ to SQL
The example web application will display records from two tables in the pubs sample database. Because you are going to use LINQ to access the database, you do not connect to the database directly. Instead, you generate classes that represent the database and its tables and then use those classes to interact with the data. To begin, add a new item to the project and select the LINQ to SQL Classes template (see Figure 17-3).
Figure 17-3
Use the default name of DataClasses.dbml. When prompted to save the item in the App_Code folder, click Yes. The DataClasses.dbml file is created in the App_Code folder of your project (see Figure 17-4).
