Introduction to web Programming World
Business empires were founded on the simplest ideas— a search engine (Google) or an online store for buying books (Amazon). Everyone wanted to know how to build a web site for themselves. HTML (Hyper Text Markup Language) enabled them to do that, but it was soon obvious that it only went so far. You could display pictures and text, but what happened if you wanted more than that? What happened if you wanted a site that was reactive, that received information from your users and was automatically updated without someone having to beaver away writing new web pages every time? What if you wanted to attach a database to the Internet, or you wanted to display a stock catalogue, or you wanted to personalize your site to everyone who visited it, or you just wanted it to look good for your family and friends who visited it?
The race was on and several competing technologies were created for doing this from CGI and PHP to Java. Microsoft’s own entry into the race was ASP and what made it particularly attractive was that it was simpler to pick up and learn than most of its rivals, but it also had some exciting features—the ability to store details of users as they moved through pages on a web site, and controls such as calendars and ad rotators that you could just stick into your pages like HTML tags. ASP was a huge success. Microsoft went one step further—it created the .NET Framework and ASP.NET became a “grown up” version of its ASP technology, using its mature programming languages VB.NET and C#. The leap forward in power was amazing, but Microsoft lost partial site of one critical aim—simplicity. Web sites suddenly became things you needed expensive consultants to build and cutting-edge designers to visualize. It was out of the hands of those who so empowered the boom.
ASP.NET 2.0 is the big step back in the right direction. Microsoft recognized that one thing people who build web sites don’t want to do is have to code. Code is dull; code is geeky. However, Microsoft also recognized that some people still have to code for a living. And more than that, these coders have to build the same things, over and over again: a login mechanism, a menu system, a shopping cart, a funky theme for your site’s backdrop applied to every page—something every web site requires. Two guiding principles seem to be at work here: make it easier for the novice to use and reduce the amount of repetitive work the developer has to do. Claims for ASP.NET 2.0 boast “70 percent less code” is needed;
ASP.NET 2.0 also comes with a multitude of controls to enable the developer to create login systems and menus in minutes.
Late in 2003 we saw the previews of the new version of Active Server Pages named ASP.NET 2.0.
Everyone knew that these claims weren’t just hyperbole and that the way developers create web applications was going to change fundamentally. Microsoft expanded the powerful features of earlier ASP versions while greatly reducing the effort to implement those features. The ease of implementation meant a reduction in the cost of developing complex sites. Or, put another way, there would now be a large expansion of the number of people that have the capability to build a complex site.
In addition to ASP.NET 2.0 comes a new, affordable tool for creating these web sites: Visual Web Developer Express. Microsoft’s previous attempts at providing tools for helping create dynamic web sites have been clunky (Front Page) or have never really taken off (Visual Interdev), but this time they’ve got it right. Visual Web Developer is part of the Visual Studio.NET suite, but a scaled-down version of Visual Web Developer Express will be free in the foreseeable future. It allows you to drag and drop a site together within minutes, is instantly recognizable to developers, and allows easy creation and management of your web pages.
Understanding Web Servers and Browsers
One crucial point to understand about Web applications is that they work by using both client and server software:
✦ The client is a Web browser that runs on the end-user’s computer. In most cases, the Web browser is Microsoft Internet Explorer, but other programs such as Mozilla Firefox can be used as the client.
✦ The server is software that runs on the server computer that hosts the Web application. For ASP.NET applications, the server software is always
Microsoft Internet Information Services (also known as IIS). The server computer must also have Microsoft .NET Framework software installed, as ASP.NET is a part of the .NET Framework.
The server computer also typically has database server software (such as Microsoft SQL Server) installed. In some cases, the database server may run on a separate computer to improve the main server machine’s performance.
You’ll run into these two other alphabet-soup buzzwords constantly as you develop ASP.NET applications:
✦ HTML (short for Hypertext Markup Language) is a standardized set of markup tags used to format the Web pages displayed by a Web browser.
✦ HTTP (short for Hypertext Transfer Protocol) is the standardized protocol that Web browsers and Web servers use to communicate with each other. You’ll learn more about how HTTP works in the next section.
The Difference between Static and Dynamic Web Sites
· Static page is a page that does not change with user/time
· Dynamic Page is a page that changes with user and/or time
· For delivering a static page, all we require at the server side is the Web Server and the HTML file
· Dynamic page, apart from the Web Server, we require a program to generate the dynamic content
· Require an extra software component that can execute this program.
Understanding Static Web Pages
The World Wide Web was originally designed to display static pages — that is, pages that are the same every time they are displayed. In fact, many pages available on the Internet today are still static pages.
A typical way to initiate display of a static Web page is for a user to enter the Web address of the page in a browser’s address bar, or for a user to click a link that leads to the page. Either way, the browser sends an HTTP message called an HTTP request to the server specified by the Web address. This request message includes the name of the HTML file that defines the page being requested by the user. In addition, the request message includes the address of the browser that’s requesting the file.
When the server machine receives the request, it locates the HTML file on its disk and sends the HTML back to the browser by way of an HTTP Response message. Then, when the browser receives the response, it decodes the HTML file and displays the Web page.
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