計(jì)算機(jī)外文翻譯---asp.net入門c#版

1、附錄 1Beginning ASP.NET 2.0 in C#ASP (Active Server Pages) is a relatively new technology that’s already leapt through several stages of evolution. It was introduced about seven years ago as an easy way to add dynamic cont

2、ent to ordinary web pages. Since then, it’s grown into something much more ambitious: a platform for creating advanced web applications, including e-commerce shops, data-driven portal sites, and just about anything els

3、e you can find on the Internet.ASP.NET 2.0 is the latest version of ASP, and it represents the most dramatic change yet. With ASP.NET, developers no longer need to paste together a jumble of HTML and script code in order

4、 to program the Web. Instead, you can create full-scale web applications using nothing but code and a design tool such as Visual Studio 2005. The cost of all this innovation is the learning curve. Not only do you need t

5、o learn how to use an advanced design tool (Visual Studio) and a toolkit of objects (the .NET Framework), you also need to master a programming language such as C#.The Internet began in the late 1960s as an experiment. I

6、ts goal was to create a truly resilient information network—one that could withstand the loss of several computers without preventing the others from communicating. Driven by potential disaster scenarios (such as nuclea

7、r attack), the U.S. Department of Defense provided the initial funding. The early Internet was mostly limited to educational institutions and defense contractors. It flourished as a tool for academic collaboration, allow

8、ing researchers across the globe to share information. In the early 1990s, modems were created that could work over existing phone lines, and the Internet began to open up to commercial users. In 1993, the first HTML br

9、owser was created, and the Internet revolution began. It would be difficult to describe early websites as web applications. Instead, the first generation of websites often looked more like brochures, consisting mostly o

10、f fixed HTML pages that needed to be updated by hand. Basic HTML page is a little like a word-processing document—it contains formatted content that can be displayed on your computer, but it doesn’t actually do anything

11、. The following example shows HTML at its simplest, with a document that contains a heading and single line of text: An HTML document has two types of content: the text and the tags that tell the browser how to format

12、it. The tags are easily recognizable, because they occur inside angled brackets (). HTML defines tags for different levels of headings, paragraphs, hyperlinks, italic and bold formatting, horizontal lines, and so on. Fo

13、r example, Some Text tells the browser to display Some Text in the Heading 1 style, which uses a large, bold font. Figure 1-1 shows the simple HTML page in a browser.HTML 2.0 introduced the first seed of web programmin

14、g with a technology called HTML forms. HTML forms expand HTML so that it includes not only formatting tags but also tags for graphical widgets, or controls. These controls include common ingredients such as drop-down l

15、ists, text boxes, and buttons. Here’s a sample web page created with HTML form controls:HTML forms allow web application developers to design standard input pages. When the user clicks the error-prone) deployment steps

16、. Instead, a web application can be used on any computer that has Internet access. But when developers use client-side technologies, they encounter a few familiar headaches. Suddenly, cross-browser compatibility become

17、s a problem. Developers are forced to test their websites with differ-net operating systems and browsers, and they might even need to distribute browser updates to their clients. In other words, the client-side model sa

18、crifices some of the most important benefits of web development. or that reason, ASP.NET is designed as a server-side technology. All ASP.NET code executes on the server. When the code is finished executing, the user re

19、ceives an ordinary HTML page, which can be viewed in any browser. Figure 1-3 shows the difference between the server-side and client-side model. These are some other reasons for avoiding client-side programming: Isolati

20、on: Client-side code can’t access server-side resources. For example, a client-side application has no easy way to read a file or interact with a database on the server (at least not without running into problems

21、with security and browser compatibility).Security: End users can view client-side code. And once malicious users understand how an application works, they can often tamper with it. me cases, ASP.NET allows you to com

22、bine the best of client-side programming with server-side programming. For example, the best ASP.NET controls can intelligently detect the features of the client browser. If the browser supports JavaScript, these contro

23、ls will return a web page that incorporates JavaScript for a richer, more responsive user interface. However, no matter what the capabilities of the browser, your code is always executed on the server. State limitations:

24、 To ensure optimum performance, the Web is built on stateless protocols, which means as soon as a page is sent to a user, the connection is closed and any user-specific information is discarded. ASP includes a session s

25、tate feature that allows programmers to work around this problem. Using session state, a web application can retain temporary information about each client in server memory. However, session state is useless in scenarios

26、 where a website is hosted by several separate web servers. In this scenario, a client might access server B while its session information is trapped on server A and essentially abandoned. ASP.NET corrects this problem

27、by allowing state to be stored in a central repository, such as a separate process or a database that all servers can access.ASP.NET deals with these problems (and many more) by introducing a completely new model for w

28、eb pages. This model is based on a remarkable piece of technology called the NET Framework. You should understand that the .NET Framework is really a cluster of several technologies: The .NET languages: These include C#

29、and VB .NET (Visual Basic .NET), the object-oriented and modernized successor to Visual Basic 6.0; these languages also include Script .NET (a server-side version of JavaScript), J# (a Java clone), and C++ with Managed

30、 Extensions. he CLR (Common Language Runtime): The CLR is the engine that executes all .NET programs and provides automatic services for these applications, such as security checking, memory management, and optimizatio

31、n. The .NET Framework class library: The class library collects thousands of pieces of rebuilt functionality that you can “snap in” to your applications. These features are sometimes organized into technology sets, such