By : Khalid Alfalqi Department of Computer Science, Umm Al-Qura University

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1 By : Khalid Alfalqi Department of Computer Science, Umm Al-Qura University

2 History of Web History of the Internet Basic Web System Architecture URL DNS Creating Static and Dynamic Information Security 2

In 1989, Tim Berners-Lee had suggested a way to let all users, but

3 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. 3

4 History of Web Tim Berners-Lee developed both the first web server, and the first web browser - WorldWideWeb 4

5 Web Internet Many people think that the internet and the world wide web are the same thing. While they are closely linked, they are very different systems. The internet is a massive network of computers all connected together. The world wide web ( www or web for short) is: 1- a collection of webpages found on this network of computers. 2- all the resources and users on the Internet that are using the Hypertext Transfer Protocol (HTTP). Your web browser uses the internet to access the web 5

The internet is a massive network of computers all connected together.

6 Web Internet Key distinction: Internet is hardware; Web is software along with data, documents, and other media 6

7 History of the Internet the idea of a long-distance computer network traces back to early 60's Joseph Licklider at M.I.T. (a time-sharing network of computers ) Paul Baran at Rand (tasked with designing a survivable communications system that could maintain communication between end points even after damage from a nuclear attack) Donald Davies at National Physics Laboratory in U.K. in particular, the US Department of Defense was interested in the development of distributed, decentralized networks survivability (i.e., network still functions despite a local attack) fault-tolerance (i.e., network still functions despite local failure) contrast with phone system, electrical system which are highly centralized services in 1969, Advanced Research Project Agency funded the ARPANET connected computers at UC Los Angeles, UC Santa Barbara, Stanford Research Institute, and University of Utah allowed researchers to share data, communicate 56Kb/sec communication lines (vs. 110 b/sec over phone lines) 7

nuclear attack) Donald Davies at National Physics Laboratory in U.K.

8 History of the Internet throughout the 70's, the size of the ARPANET doubled every year first ARPANET sent in 1971 decentralization made adding new computers easy TCP/IP developed in the mid 1970s for more efficient packet routing migration of ARPANET to TCP/IP completed 1 January, 1983 ~1000 military & academic host computers connected by s, U.S. government took a larger role in Internet development created NSFNET for academic research in 1986 ARPANET was retained for military & government computers by 90's, Internet connected virtually all colleges & universities businesses and individuals also connecting as computing costs fell ~1,000,000 computers by , control of the Internet was transferred to a non-profit org Internet Society: Internet Engineering Task Force Internet Architecture Board Internet Assigned Number Authority World-Wide-Web Consortium (W3C) 8

government took a larger role in Internet development created NSFNET for academic research in 1986 ARPANET was retained for military & government computers by 90's, Internet connected virtually all

9 What is a Web? The Web is a shared information space. 9

10 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. 10

11 Web Browser The primary purpose is to bring information resources to the user. An application for retrieving, presenting, and traversing information resources. 11

12 History of Web Browsers 12

13 History of Web Browsers 13

14 History of Web Browsers 14

15 History of Web Browsers 15

16 History of Web Browsers 16

HTTP responses with optional data content.

17 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. Information Systems Department 17

18 Basic Web System Architecture This architecture depends on three key standards: HTML (HyperText Markup Language ) for encoding document content. URLs (Uniform resource locator) for naming remote information objects in a global namespace. HTTP (Hypertext Transfer Protocol) for transferring the information. 18

URLs (Uniform resource locator) for naming remote information objects in a

19 HTML Hypertext Markup Language Document layout language (not a programming language) Defines structure and appearance of Web pages 19

20 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. 20

machine name, the directory path and the file name.

HTTP Hyper Text Transfer Protocol HTTP is a request/response standard of a client and a server in the computing model. Typically, an HTTP client initiates a request.

21 HTTP Hyper Text Transfer Protocol HTTP is a request/response standard of a client and a server in the computing model. Typically, an HTTP client initiates a request. Then, the host (Server) responders. A web browser, for example, may be the client and an application running on a computer hosting a web site may be the server. The client submits an HTTP request message to the server. The server returns a response message to the client. The response contains completion status information about the request and may also contain requested content in its message body 21

22 Sample HTTP Request and Response Client request Server response 22

23 Server-side Processing In server-side processing, the Web server: Receives the Web page request Performs all of the processing necessary to create the Web page Sends the finished Web page to the client for display in the client s browser 23

24 Client-side Processing Client-side processing Some processing needs to be executed by the browser, either to form the request for the Web page or to create or display the Web page. 24

25 Server and Client side processing Server-side processing PHP ASP ASP.NET Perl J2EE Python, e.g. Django Ruby, e.g. Ruby on Rails ColdFusion Client-side processing CSS HTML JavaScript Adobe Flex Microsoft Silverlight 25

26 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

27 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. 27

Introduction to Web Technology. Content of the course. What is the Internet? Diana Inkpen

Introduction to Web Technology Content of the course Diana Inkpen The Internet and the WWW. Internet Connectivity. Basic Internet Services. University of Ottawa School of Information Technology and Engineering