Microsoft.NET

……………………………………………….Expertise in .NET Technologies

Introduction to Web Programming

Posted by Ravi Varma Thumati on March 18, 2009

What is a web server?


A Web server is a software program which serves web pages to web users (browsers).

A web server delivers requested web pages to users who enter the URL in a web browser. Every computer on the Internet that contains a web site must have a web server program.

The computer in which a web server program runs is also usually called a “web server”. So, the term “web server” is used to represent both the server program and the computer in which the server program runs.

Characteristics of web servers


A web server computer is just like any other computer. The basic characteristics of web servers are:

          It is always connected to the internet so that clients can access the web pages hosted by the web server.

          It has an application called ‘web server’ running always.

In short, a ‘web server’ is a computer which is connected to the internet/intranet and has software called ‘web server’. The web server program will be always running in the computer. When any user tries to access a website hosted by the web server, it is actually the web server program which delivers the web page which client asks for.

All web sites in the internet are hosted in some web servers sitting in different parts of the world.

Web Server is hardware or software? 

 Web Server – Behind the Scene 

From the above definition, you must have landed up in confusion “Web server is hardware or software”

Mostly, Web server refers to the software program, which serves the clients request. But as we mentioned earlier in this chapter, the computer in which the web server program is also called ‘web server”.

clientserver

Now that you are reading this page, have you ever had a thought how the page is made available to the browser?

Your answer would be, “I typed in the URL http://www.samplesite.com and clicked on some link, I dropped into this page.”

But what happed behind the scenes to bring you to this page and make you read this line of text.

So now, let’s see what is actually happening behind the scene. The first you did is, you typed the URL http://www.samplesite.com in the address bar of your browser and pressed your return key.

We could break this URL into two parts,

1. The protocol we are going to use to connect to the server (http)

2. The server name (www.samplesite.com)

The browser breaks up the URL into these parts and then it tries to communicate with the server looking up for the server name. Actually, server is identified through an IP address but the alias for the IP address is maintained in the DNS Server or the Naming server. The browser looks up these naming servers, identifies the IP address of the server requested and gets the site and gets the HTML tags for the web page. Finally it displays the HTML Content in the browser.

 

 

Where is my web server?


When you try to access a web site, you don’t really need to know where the web server is located. The web server may be located in another city or country, but all you need to do is, type the URL of the web site you want to access in a web browser. The web browser will send this information to the internet and find the web server. Once the web server is located, it will request the specific web page from the webserver program running in the server. Web server program will process your request and send the resulting web page to your browser. It is the responsibility of your browser to format and display the webpage to you.

How many web servers are needed for a web site?


Typically, there is only one web server required for a web site. But large web sites like Yahoo, Google, MSN etc will have millions of visitors every minute. One computer cannot process such huge numbers of requests. So, they will have hundreds of servers deployed in different parts of the world so that can provide a faster response.

How many websites can be hosted in one server?


A web server can host hundreds of web sites. Most of the small web sites in the internet are hosted on shared web servers. There are several web hosting companies who offer shared web hosting. If you buy a shared web hosting from a web hosting company, they will host your web site in their web server along with several other web sites for a Fee.

Examples of web server applications:

1.      IIS

2.      Apache

 

What is a browser?

Definitions for browser

·    Browser is an application, which helps us to view the Web sites and the web content.

·    Web sites are located in some remote systems, which needs a special kind of program or an application to access them, such an application is called browser.

·    A browser is an application which you can use to retrieve web pages from web sites and view.

·    When you type a URL in the browser, the browser will convert it into a web request which web server can understand. Browser will send the request to web server using the HTTP protocol.

·    When a web server returns a web page as a Response, the browser will understand the response and display the body of the response to the user in browser.

·    In simple terms a browser can be defined as “A software application used to locate and display Web pages”

·    You can create your own simple browser application using C++, C#, VB.NET or any other language you like. All you need to know is, how to compose a request which web server can understand, how to parse and display the response from web server and communicate with webserver using HTTP protocol.

·    Even though the basic job of browser is just send requests to web server and receive response from the server, modern browser provide several other enhanced features including Back/Forward buttons, save viewed files to disk so that they can be viewed later, cache images so that the same images need not be downloaded again and again etc.

·    Internet Explorer, Netspace, Mozilla are some of the popular web browsers currently available in the market.

·    Netscape was the most popular web browser till 4-5 years back, but currently more than 90% of the internet users use “Internet Explorer” to browse the websites.

 

ASP.NET is the new offering for Web developers from the Microsoft .It is not simply the next-generation of ASP; in fact, it is a completely re-engineered and enhanced technology that offers much, much more than traditional ASP and can increase productivity significantly.

Because it has evolved from ASP, ASP.NET looks very similar to its predecessor—but only at first sight. Some items look very familiar, and they remind us of ASP. But concepts like Web Forms, Web Services, or Server Controls gives ASP.NET the power to build real Web applications.

Browser Is a Thin Client

Browser’s main job is requesting pages from the server and displaying what the server has processed. Using HTTP as a transfer protocol, your browser parses (interprets) the HTML code it gets from the server, but otherwise does little processing. Because your HTTP client (browser) leaves most of the processing work to the server, it is considered a thin client. There’s nothing wrong with a thin client, and it can process JavaScript. With plug-ins, which virtually all browsers have built in, a thin client can also process certain kinds of files such as SWF (compiled Adobe Flash files), Java Applets, ActiveX Controls, as well as other files requiring that the browser have compatible plug-ins.

For the most part, though, the thin client model is one where the server does the processing, and your browser’s job is to display the contents it gets from the server. In addition to being a thin client, your HTTP client browser is stateless. As soon as a web page reaches your computer, the connection between your browser and the server is broken. The browser does not remember the last page—it does not hold state.

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One Response to “Introduction to Web Programming”

  1. I found so many entertaining stuff in your blog site, particularly its discussion. Through the tons of feedback on your articles, I guess I’m not the only one obtaining each of the satisfaction here!

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