ASP.NET 4.5.1 server

An Introduction to ASP .NET 4.5.1 server

 ASP .NET 4.5.1 server is describe here When you type a URL like www.wrox.com in your web browser and press Enter, the browser sends a request to the web server at that address. This is done through HTTP, the HyperText Transfer Protocol. HTTP is the protocol by which web browsers and web servers communicate. When you request the URL, you send a request to the server. When the server is active and the request is valid, the server accepts the request, processes it, and then sends the response back to the client browser. The relationship between the request and response is shown in Figure 1-8. Because you are using IIS Express, the server and the client are really the same machine. However, in a real-world scenario, you’ll host your website on an external web server where it can be accessed by many different clients.For simple, static files, like HTML files or images, the web server 

reads the file from its local hard drive and sends it to the browser. However, for dynamic files, such as ASPX pages, this is obviously not good enough. If the web server were to send the ASPX file directly to the browser as a text file, you wouldn’t have seen the current date and time in the browser, but instead you would have seen the actual code (<%: DateTime .Now.ToString() %>). So, instead of sending the file directly, the web server hands over the request to another piece of software that is able to process the page. This is done with a concept called Application Mapping or Handler Mapping, where an extension of a file (.aspx in this example) is mapped to an application that is capable of handling it. In the case of an .aspx page, the request is eventually handled and processed by the ASP.NET run time, part of the Microsoft .NET Framework designed specifically to handle web requests.

During the processing of the page, three main areas can influence the way the page eventually ends up in the browser:

➤➤ Static text. Any static text, like HTML, CSS, or JavaScript code you place in a page, is sent to the browser directly. You learn more about HTML, CSS, and JavaScript (a programming language used at the client) in this and subsequent chapters, including Chapter 3, which gives you a detailed look at CSS.

➤➤ ASP.NET Server Controls. These controls are placed in your ASPX page and when they are processed, they emit HTML that is inserted in the page.

➤➤ Programming code. You can embed code, like Visual Basic .NET or C#, directly in a page, as you saw in the previous Try It Out. In addition, you can place code in a separate code file. The official term for this code file is Code Beside. However, most developers refer to this as the Code Behind file, which is the term I’ll stick to in this book. This code can be executed by the run time automatically, or based on a user’s action. Either way, execution of the code can greatly influence the way the page is displayed, by accessing databases, performing calculations, hiding or showing specific controls, and much more. You learn more about this Code Behind file in the next chapter, and programming, Once the page is done processing, and all the HTML for the page has been collected, the HTML is sent back to the browser. The browser then reads it, parses it, and, finally, displays the page for you to look at. Because HTML is so critical for displaying web pages, the next section gives you an overview of HTML.

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