Introduction to

Web Servers

Who am I

Med Amine Ben Asker

Nickname : Yuri Laaziz

-

Software Engineering student

Twitter : @asker_amine

website : yurilz.com

1 Web Server Definition

2 Web site Vs Web Server

3 Steps in handling a Client Request

4 Access Control

Plan

Web server definition

A web server is a program that generates and transmits responses to client requests for web resources

Handling a client request

1. Checking that the request 
   is authorized
2. Associating the URL in 
   the request with a file name
3. Constructing the response 
   message
4. Transmitting the response
   message to the requesting 
   client

Web site Vs Web server

A Web site consists of a collection of Web pages associated with a particular host name.

A Web server is a program to satisfy client requests for Web resources.

Web site Vs Web server

A Web site consists of a collection of Web pages associated with a particular host name.

A Web server is a program to satisfy client requests for Web resources.

1. Read and parse the HTTP request message

2. Translate the URL to a file name

3. Determine whether the request is authorized

4. Generate and transmit the response that includes header to show the status information

Access Control

 A Web server may limit which users can access certain resources. 

Authentication identifies the user who originated the request.

Authorization determines which users have access to a particular resource.

AUTHENTICATION

• Most client-server systems authenticate a user by asking for a name and password.
• Web server must perform authentication for every request for a resource that has access restrictions.
• The server returns an HTTP response that indicates that the request requires authorization.
• The response also identifies what kind of authentication is required.
• The response also identifies the realm a string that associates a collection of resources at the server

AUTHORIZATION

• To control access to Web resources, the server must employ an authorization policy.

• A policy typically expressed in terms of an access control list that enumerates the users who are granted or denied access to the resources.

• In addition to checking the user name, the server may allow or deny access to the resource based on other information associated with the HTTP request, such as the host name or IP address of the requesting client.

WWW

In 1989, Tim Berners-Lee had suggested a way to let all users, but particularly scientists, browse each others’ papers on the Internet.
He developed HTML, URLs, and HTTP.

HTML

HyperText Markup Language

Document layout language (not a programming language).
Defines structure and appearance of Web pages.

HTML files are viewed using a web browser.

Server Side

PHP
ASP
ASP.NET
Perl
J2EE
Python, e.g. Django
Ruby, e.g. Ruby on Rails
ColdFusion

Client Side

CSS
HTML
JavaScript
Adobe Flex
Microsoft Silverlight