Kingdom of Saudi Arabia
Ministry of Higher Education
Al-Imam Muhammad Ibn Saud Islamic University
College of Computer and Information Sciences
Chapter 1
Introduction to Web
IS 203:Web Programming
Table of contents
• History of Web
• Web System Architecture
• URL
• DNS
• Protocols governing the Web
• HTTP Request Response
• Creating Static and Dynamic Websites
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History of Web
• In the 1960's, Ted Nelson
popularized the hypertext concept,
and Douglas Engelbart created the
first working hypertext systems.
• 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.
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What is a Web ?
• The Web is a shared information space.
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Basic Web System Architecture
• The web is a two-tiered architecture.
• A web browser displays information content,
• and a web server that transfers information to the client.
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Web Browser
• The primary purpose is
to bring information
resources to the user.
• An application for
retrieving, presenting,
and traversing
information resources.
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History of Web Browsers
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History of Web Browsers
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History of Web Browsers
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History of Web Browsers
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History of Web Browsers
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Web Server
• The term web server or webserver can mean one of two
things:
• A computer program that accepts HTTP requests and return HTTP
responses with optional data content.
• A computer that runs a computer program as described above.
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Basic Web System Architecture
• This architecture depends on three key standards:
• HTML for encoding document content.
• URLs for naming remote information objects in a global namespace.
• HTTP for staging the transfer.
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HTML
Hypertext Markup Language
• Document layout
language (not a
programming
language)
• Defines structure
and appearance of
Web pages
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URL
Uniform Resource Locator
• URLs are location dependent
• It contains four distinct parts: the protocol type, the
machine name, the directory path and the file
name.
• There are several kinds of URLs: file URLs, FTP
URLs, and HTTP URLs.
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HTTP
Hyper Text Transfer Protocol
• HTTP is a request/response standard of a client and a
server.
• Typically, an HTTP client initiates a request.
• Resources to be accessed by HTTP are identified using
Uniform Resource Identifiers (URIs).
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HTTP
Request Methods
• HTTP defines eight methods (sometimes referred
to as "verbs") indicating the desired action to be
performed on the identified resource.
•
•
•
•
•
•
•
•
HEAD
GET
POST
PUT
DELETE
TRACE
OPTIONS
CONNECT
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Sample HTTP Request and Response
• Client request
• Server response
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Web Architecture Extension
• CGI extends the
architecture to threetiers by adding a backend server that
provides services to
the Web server.
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Database Driven Website
Architecture
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Server-side Processing
• In server-side processing, the Web server:
• Receives the dynamic Web page request
• Performs all of the processing necessary to create the dynamic Web
page
• Sends the finished Web page to the client for display in the client’s
browser
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Client-side Processing
• Client-side processing
• Some processing needs to be “executed” by the browser, either to
form the request for the dynamic Web page or to create or display the
dynamic Web page.
Eg. Javascript code to validate user input
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Server and Client side processing
• Server-side processing

Client-side processing
• PHP

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• ASP
• ASP.NET
• Perl
• J2EE
CSS
HTML
JavaScript
Adobe Flex
Microsoft Silverlight
• Python, e.g. Django
• Ruby, e.g. Ruby on Rails
• ColdFusion
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Domain Name System
DNS
• Each host on the Internet has a range of IP (or Internet
protocol) numbers.
• The Domain name system (DNS) maps the numbers to
names of hosts or websites (eg www.google.com,
www.hotmail.com).
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Protocols Governing the Web
• TCP/IP, or Transmission Control Protocol-Internet Protocol. Essentially,
TCP/IP describes a protocol which will work on any sort of computer and
operating system for transportation of data across the internet between
different systems.
• SMTP, or the Simple Message Transfer Protocol, is the basic standard
for email, and again exists since the 1980s when the Internet was small
and honest.
• Another important protocol which dates from pre 1972 is FTP, or the file
transfer protocol. This simply is the way to upload or download a file from
an Internet computer.
• With the coming of the World Wide Web, we see another powerful
protocol - http, or hypertext transfer protocol. HTTP allows us to click on
the name of a site and visit it. Simple, but very powerful.
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Static vs Dynamic Sites
• A static web site is a web site where the content, the HTML
and graphics, are always static—it is served up to any visitor
the same, unless the person who created the web site
decides to manually change the copy of it on the server.
• On a dynamic web site on the other hand, the content on the
server is the same, but instead of just being HTML, it also
contains dynamic code, which may display different data
depending on information you feed to the web site. Another
thing to note is that special software must be installed on the
server to create a dynamic web site.
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