Introduction to Internet and World Wide Web Eastern Mediterranean University School of Computing and Technology Department of Information Technology ITEC229 Client-Side Internet and Web Programming Introduction to Internet and World Wide Web CHAPTER 1 Prepared by: R. Kansoy

Contents 1.1 What is Internet? 1.2 History and Development of the Internet 1.3 Internet Standards & Coordination 1.4 Anatomy of the Internet 1.5 Bacis Internet Protocols 1.6 Technologies/Tools of the Internet 1.7 World Wide Web http://sct.emu.edu.tr/it/itec229

1.1 What is Internet? The Internet, sometimes called simply "the Net," is a worldwide system of computer networks - a network of networks in which users at any one computer can, if they have permission, get information from any other computer (and sometimes talk directly to users at other computers). Originally the Internet served to interconnect laboratories engaged in government research, and since 1994 it has been expanded to serve millions of users and a multitude of purposes in all parts of the world. In a matter of very few years, the Internet has consolidated itself as a very powerful platform that has changed the way we do business, and the way we communicate. http://sct.emu.edu.tr/it/itec229

1.1 What is Internet? The Internet, as no other communication medium, has given an International or, if you prefer, a "Globalized" dimension to the world. Internet has become the Universal source of information for millions of people, at home, at school, and at work. Internet is actually the most democratic of all the mass media. With a very low investment, anyone can have a web page in Internet. This way, almost any business can reach a very large market, directly, fast and economically, no matter the size or location of the business. With a very low investment, almost anybody that can read and write can have access to the World Wide Web. http://sct.emu.edu.tr/it/itec229

1.2 History and Development of the Internet It was conceived by the Advanced Research Projects Agency (ARPA) of the U.S. government in 1969 and was first known as the ARPANet. The original aim was to create a network that would allow users of a research computer at one university to be able to "talk to" research computers at other universities. In time, ARPANET computers were installed at every university in the United States that had defense related funding. Gradually, the Internet had gone from a military pipeline to a communications tool for scientists. As more scholars came online, the administration of the system transferred from ARPA to the National Science Foundation. http://sct.emu.edu.tr/it/itec229

1.2 History and Development of the Internet Brief History of the Internet 1960 - US government seeks nuclear war proof communications, briefs project to APRA 1968 - DARPA (Defense Advanced Research Projects Agency) contracts with BBN (Bolt, Beranek & Newman) to create ARPAnet 1969 - Birth of Internet. Universities and researches connected to ARPAnet. 1970 - First five nodes: UCLA Stanford UC Santa Barbara University of Utah, and BBN http://sct.emu.edu.tr/it/itec229

1.2 History and Development of the Internet ARPANET Implemented in late 1960’s by ARPA (Advanced Research Projects Agency of DOD) Networked computer systems of a dozen universities and institutions with 56KB communications lines Grandparent of today’s Internet Intended to allow computers to be shared Became clear that key benefit was allowing fast communication between researchers – electronic-mail (email) http://sct.emu.edu.tr/it/itec229

1.2 History and Development of the Internet Brief History of the Internet 1971 - Ray Tomlinson creates first network email application. E-mail - a program to send messages across a distributed network. 1972 – Telnet - Computers can connect more freely and easily 1973 – FTP - computers send and receive data. 1974 - TCP specification by Vint Cerf 1977 - ARPAnet engineers realise the network is going to grow beyond expectations 1983 - ARPAnet switched NCP to TCP/IP 1984 - Domain Name System (DNS) was introduced. 1989 - Tim Berners-Lee proposes a new set of Internet protocols 1991 - World-Wide Web - developed released by CERN; within the UK academic network. 1992/93 - Mosaic/Netscape - User Friendly Graphical Front 1995 - US government releases Internet for commercial use http://sct.emu.edu.tr/it/itec229

1.3 Internet Standards & Coordination ICANN - The Internet Corporation for Assigned Numbers & Names Non-profit organization Main function is to coordinate the assignment of: Internet domain names IP address numbers Protocol parameters Protocol port numbers. http://sct.emu.edu.tr/it/itec229

1.3 Internet Standards & Coordination Internet Engineering Task Force (IETF) http://www.ietf.org/ Founded 1986 Request For Comments (RFC) at http://www.ietf.org/rfc.html http://sct.emu.edu.tr/it/itec229

1.3 Internet Standards & Coordination W3C – World Wide Web Consortium Develops recommendations and prototype technologies related to the Web Produces specifications, called Recommendations, in an effort to standardize web technologies http://sct.emu.edu.tr/it/itec229

1.4 Anatomy of the Internet Internet Backbone A high capacity communication link that carries data gathered from smaller links that interconnect with it. NAP – Network Access Point Access points or junctions to the Internet Backbone in major cities. http://sct.emu.edu.tr/it/itec229

1.4 Anatomy of the Internet Client/Server can describe a relationship between two computer programs – the "client" and the "server". Client requests some type of service (such as a file or database access) from the server. Server fulfills the request and transmits the results to the client over a network The Internet Client/Server Model Client -- Web Browser Server -- Web Server http://sct.emu.edu.tr/it/itec229

1.4 Anatomy of the Internet Web Client Connected to the Internet when needed Usually runs web browser (client) software such as Internet Explorer or Netscape Uses HTTP (Hypertext Transfer Protocol) Connect to a web server using URL information Requests web pages from server Receives web pages and files from server Display the formatted information http://sct.emu.edu.tr/it/itec229

1.4 Anatomy of the Internet Web Server Continually connected to the Internet Runs web server software (such as Apache or Internet Information Server) Uses HTTP (Hypertext Transfer Protocol) Receives request for the web page Responds to request and transmits status code, web page, and associated files http://sct.emu.edu.tr/it/itec229

1.5 Basic Internet Protocols Protocols : rules that describe the methods used for clients and servers to communicate with each other over a network. There is no single protocol that makes the Internet and Web work. A number of protocols with specific functions are needed. http://sct.emu.edu.tr/it/itec229

1.5 Basic Internet Protocols FTP (File Transfer Protocol) A set of rules that allow files to be exchanged between computers on the Internet. Web developers commonly use FTP to transfer web page files from their computers to web servers. FTP is also used to download programs and files from other servers to individual computers. E-mail Protocols Sending E-mail SMTP Simple Mail Transfer Protocol Receiving E-mail POP (POP3) Post Office Protocol IMAP Internet Mail Access Protocol http://sct.emu.edu.tr/it/itec229

1.5 Basic Internet Protocols Transmission Control Protocol/Internet Protocol TCP/IP TCP/IP has been adopted as the official communication protocol of the Internet. TCP and IP have different functions that work together to ensure reliable communication over the Internet. http://sct.emu.edu.tr/it/itec229

1.5 Basic Internet Protocols Transmission Control Protocol (TCP) Purpose is to ensure the integrity of communication Breaks files and messages into individual units called packets Internet Protocol (IP) A set of rules that controls how data is sent between computers on the Internet. IP routes a packet to the correct destination address. The packet gets successively forwarded to the next closest router (a hardware device designed to move network traffic) until it reaches its destination. http://sct.emu.edu.tr/it/itec229

1.5 Basic Internet Protocols HTTP - Hypertext Transfer Protocol A set of rules for exchanging files such as text, graphic images, sound, video, and other multimedia files on the Web. Web browsers send HTTP requests for web pages and their associated files. Web servers send HTTP responses back to the web browsers. HTTP Request HTTP Response http://sct.emu.edu.tr/it/itec229

1.6 Technologies/Tools of the Internet World Wide Web: a branch of the Internet that provides access to hyperlinked information. E-mail: electronic message containing information sent from one computer to another over networks. Listservs/mailing lists: a facility that allows participation in ongoing discussions via e-mail. Usenet Newsgroups and discussion groups:  world-wide distributed system of online discussion groups in which people continuously participate. Newsgroups allow people with a common interest to subscribe to one or more groups for posting, reading and replying to electronic mail. http://sct.emu.edu.tr/it/itec229

1.6 Technologies/Tools of the Internet Internet Relay Chat and web chatting: having a conversation with many people on a variety of topics in real time. All the parties to the conversation are participating simultaneously regardless of the time zone they are in. Channels: Channels on the web are a pre-selected information source that can send information to your computer automatically according to a predetermined schedule. FTP:  File Transfer Protocol allows you to copy files from one computer connected to the Internet to another computer connected to the Internet. It allows you to download information, upload web pages and transfer information between computers. Telnet: The Telnet protocol is an application that allows a remote connection to another computer. http://sct.emu.edu.tr/it/itec229

1.6 Technologies/Tools of the Internet Intranet: are private networks that help an organization to share information between departments, units and regions across a network Internet Phone: allows one to put a number of calls on the same line without sacrificing sound quality. Video Conferencing: allows you to chat with one or more people in real time and/or to see live images as you speak or type. Blogs: Blogs or web logs are personal web pages that contain personal thoughts and links to other sites that are of particular interest to a blog owner. Wikis: Wikis are collaborative websites where the community participate in writing a publication, like an encyclopaedia or a general purpose website. http://sct.emu.edu.tr/it/itec229

1.7 World Wide Web (WWW) Development of the Web 1989-1991: Web invented by Tim Berners-Lee at European Physics Laboratory (CERN). 1993: Marc Andreesen and others at NCSA create Mosaic, a Web browser with a graphical user interface that could run on Windows, Macintosh, or Unix computer. 1994: Andreesen and Jim Clark found Netscape, and create first commercial Web browser, Netscape Navigator. August 1995: Microsoft introduces its version of Web browser, Internet Explorer. Bill Clinton ”When I took office, only high energy physicists had ever heard of what is called the World Wide Web... Now even my cat has it's own page.” http://sct.emu.edu.tr/it/itec229

1.7 World Wide Web (WWW) What is WWW? is a way of accessing information over the medium of the Internet. is one of the major services of the internet who hosts information of almost about anything one might like to search for. computer network consisting of a collection of Internet sites that offer text and graphics and sound, video and animation resources through the hypertext transfer protocol. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. Web services, which use HTTP to allow applications to communicate in order to exchange business logic, use the Web to share information. The Web also utilizes browsers, such as Internet Explorer or Firefox, to access Web documents called Web pages that are linked to each other via hyperlinks. http://sct.emu.edu.tr/it/itec229

1.7 World Wide Web (WWW) Web Browsers a programme used to locate, display, browse and view information on a website. when you request a web page by entering the URL in the location field of the browser, the browser contacts the web server and asks for a copy of the page. The browser displays the page when it arrives. a browser can be text based in which case you would only be able to view web pages in text mode or could have a graphical user interface in which case you would be able to view the web page in graphical mode. http://sct.emu.edu.tr/it/itec229

1.7 World Wide Web (WWW) Web Addresses Each Web page has a unique address called the Uniform Resource Locator (URL). The URL tells the computer how and where to look for a document. Example: http://www.cnn.com/world/index.html The hypertext links are attached to Web addresses. http://sct.emu.edu.tr/it/itec229

1.7 World Wide Web (WWW) Web Pages A Web page is a file on the Web. A Web site is a collection of Web pages maintained by a college, government agency, company or individual. A Web page is created by using a computer language called Hypertext Markup Language (HTML). HTML is a set of codes used to format Web pages and create links. http://sct.emu.edu.tr/it/itec229

1.7 World Wide Web (WWW) Hypertext Web pages are hypertext documents. A hypertext document is one that contains highlighted text or links that connect to other pages on the Web. By clicking on the hypertext link you can go to another Web page on the same computer, or a Web page on a computer across the world. The Web uses a protocol called Hypertext Transfer Protocol (HTTP) to transfer documents containing hypertext. HTTP's job is similar to that of TCP/IP. HTTP and TCP/IP, both protocols, or standards, tell computers how to communicate with each other. Highlighted means that the text is usually underlined and displayed in a different color than the surrounding text. Graphics can also be links. You simply point to and click on the text with your mouse to follow that link. http://sct.emu.edu.tr/it/itec229

Introduction to Internet and World Wide Web Thank You ! Introduction to Internet and World Wide Web END of CHAPTER 1 http://sct.emu.edu.tr/it/itec229