How Does One Describe the Internet?

1. How Does One Describe the Internet? • It is a bit like describing a city: • Its Location on the map • The terrain • It’s architecture • The Kinds of people who Live in it • It’s Politics • The Business Climate • It’s History and so on.…

2. What is really the Internet? • Internet is network of networks. • The Internet is a peer-to-peer network • These computers communicate with one another in a consistent fashion • Users on one computer can access services from other computers. • You can access a wide variety of these services • Each service can give you many kinds of information. • In summary: The Internet is, a)A way to move data from one computer to another; b)A bunch of protocols.

3. Three is One • The Internet, technically, is also described as a Client/Server system. • Essentially, all that we speak about concerning the Internet falls in one of three categories: client,server or content. • To illustrate: the software/hardware that we use to surf the Web, or send mail, or upload files is called Client; the hardware/software that stores information in a format that can be accessed using Web client software and responds to client requests is called Web Server, similarly, the software/hardware that stores mail and forwards it to the client is referred to as mail server; likewise, that system, and the software that runs on it, which accepts uploaded files and also allows authorised users/clients download files from it is an FTP Server. • Content, as the name implies, is the actual content of the web page or the mail document or the file being uploaded/downloaded. Content can be either text, image, sound, video, animation and the like.

4. What really is a Service? • On the Internet, you can use many methods to communicate with a computer somewhere else on the Internet. These methods are called services because they service your requests. • A few of the most popular Internet services are: • Email: Electronic mail • FTP: File Transfer Protocol for transferring computer files • WWW: World Wide Web • Gopher: Searchable index, selectable index of documents • USENET: Newsgroups with different subjects enable people with common interest to share information • Telnet: Remote login into computer networks • Chat: Real-time communications between people on the Internet

5. Email • The most popular Internet technology with 70 million users • Email has become the de-facto standard of communication within the corporate and beyond • Email works between disparate systems like PC, UNIX, Mac, Mainframe, VAX, etc. • The latest Email standards let users attach files (even audio, video, animation etc) , and active URL addresses. • The volume of data transferred is reaching billions of bytes everyday.

6. Email (contd.) • Advantages • Standard way of communication for corporations • There is less interference or interrupts between work • Reply with a number of options • There is no cost within the environment • Less chances of miscommunication • Saving messages for future retrieval and records • Disadvantages • You need to have a computer and network connection • Less personal then voice

7. How E-Mail Works • Like other Internet services e-mail is yet another client-server system, called SMTP (Simple Message Transfer Protocol). • As the figure next indicates, you use a mail client program to send a message to a post office sever (an SMTP server). • The post office server identifies the recipient's address and sends the message through the Internet to the mail server that handles mail for each recipient's address. • The mail server stores the message in the recipient’s mailbox • The recipient uses an e-mail client program to request new messages from the mail sever. • The mail server sends the messages in the recipient’s mailbox back to the client. Click

8. How E-Mail Works Sender’s Mail Client Post OfficeServer (SMTP) MailServer(POP3) Recipient’sMailClient If the sender has an account on a system that does not use SMTP,such as a Novell MHS (Message Handling Service) e-mail network or an online service like AOL or CompuServe, there’s an additional step between the mail server: a gateway that converts the address information from SMTP format to the format used by the other system, or from the other format to SMTP.

9. Hotmail, Yahoo Mail, Rocket Mail …. • Well,Hotmail and it’s cousins which are all getting to be very popular because they offer free e-mail accounts, basically use Web-technology to help you receive mail, send mail and the like. • The disadvantage is that you have to wait longer to read every individual mail; and this can be quite a frustrating experience if the mail is plenty and the lines are slow--which they are anyway, most of the time! • The major advantage, however, is that these e-mail services offer people in corporate organisations and people on-the-move access to their mail from virtually anywhere they can access the WWW on the Internet. Moreover, for those who would like their personal mail to be private and beyond the reach of their colleagues in the office, these services offer total privacy because the mail is left on the mail companies server and not on the company server from where others in the organisation can access private mail.

10. FTP - File Transfer Protocol • The most common way for sending and receiving files on the Internet • You can store files in any format • All formats including Microsoft Word, Word-perfect, Excel, Pictures, Text, Raw data, etc. • Companies provide FTP sites for downloading of evaluation software, demos and beta software • FTP runs on all popular platforms • FTP can be run either via console, GUI or browser • ftp://ds.internic.net/ ( ask your instructor to actually demonstrate the sending and receiving of files via FTP).

11. Anonymous FTP • FTP servers are fairly straightforward; when a server receives a file request from an FTP client, it sends a copy of that file back to the client. Other commands instruct the server to send the client a directory of files or to accept an upload from the client. • Most often you will use FTP to download files from public file archives on FTP servers. These archives are sometimes known as “anonymous FTP” archives, because they accept the word “anonymous” as a login name, with the user’s e-mail address as a password. • Not all FTP servers accept “anonymous” as a login name.

12. Gopher • Uses client-server architecture to browse through the directory and file information • Automatically opens the application depending upon the file once downloaded • The menu can point to FTP archives, telnet services, gopher servers, and more • Weakness: • Does not allow intermixing of graphics and text • Does not allow links from certain positions • ‘Gopherspace’ is the equivalent of the term “the web”. • Web overcomes the weaknesses of Gopher gopher://gopher.proper.com/11/pc

13. Usenet Newsgroups • The most interactive, personal and fun of all the services on the Internet. • The content in Usenet is created by anyone who wants to talk. • Thousands of Newsgroups available on every single subject you can imagine • soc.culture.india,comp.pc, comp.unix • You can subscribe to selective newsgroups and get only the necessary news. • Netscape 2.0 has made handling Usenet news very simple and easy. • VSNL, our Internet Service Provider (ISP) has just begun to support this service). • You may connect to many newsgroup servers and access newsgroups.

14. Telnet • Remote login into computer networks and compute on the remote computer • Connection can be established using SLIP, PPP or dedicated lines • Usually available in the universities and Internet Service Providers • Weakness • Only console applications can be run. No GUI support unless X terminals are used • Security risk because hackers can trap the IP address of the network • Least used part of the Web. • Cannot use existing Web Browsers to Telnet.

15. World Wide Web • The most graphical and powerful of the Internet technologies • Powerful linking features allow you to browse or surf, hence the name browsers. • Most easiest to use. Just click and and you will go from one page to another, from one server to another without geographical barriers • World Wide Web = Text + Graphics + Multimedia + Communications.

16. World Wide Web (contd.) • Current Technologies include audio, video, 3D, Virtual reality, secure transactions, plug-ins • Near Future technologies: Web enabled applications, Client-server, Electronic commerce. • Uses Client-Server architecture • Created in 1991-92 by Tim Berners-Lee at CERN, Geneva.

17. How the Web Works: HTTP • The most interesting part of the way the Web works is its simplicity. The transaction takes place in four basic phases, all part of the underlying HTTP (Hyper Text transfer Protocol): • Connection • Request • Response • Close

18. How the Web Works: The Connection Phase • In the connection phase, the Web client (for example Netscape) attempts to connect with the server. This appears on the status line of most of the browsers in the form of Connecting to HTTP server. If the client can’t perform the connection, nothing further happens. Usually, in fact, the connection attempt times out, yielding an explanatory messge saying Unable to connect to server, try again, etc.

19. How the Web Works: The Request Phase • Once the connection to the HTTP server is established, the client sends a request to the server. The request specifies which protocol is being used (including which version of HTTP, but it can also be FTP, NNTP, Gopher, etc. Included in the request is the method, which essentially is the client’s command to the server. The most common method is GET, which is basically a request to retrieve the object in question.

20. How the Web Works: The Response Phase • Assuming the server can fulfill the request (it sends error messages if it can’t), it then executes the response. You’ll see this phase of the transaction in your browser’s status line, usually in the form Reading Response. Like the request, the response indicates the protocol being used, and it also offers a reason line,which appearson the browser’s status line. Depending on the browser, you’ll see exactly what is going on at this point, usually represented by a Transferring message.

21. How the Web Works:The Close Phase • Finally, the connection is closed. • At this stage, the browser springs into action. Effectively, it loads and displays the requested data, saves the data to a file, or launches a viewer or helper application if the need arises. If the object is a text file, the browser will display it as a nonhypertext ASCII document. If it is a graphic image (such as a BMP file), the browser will launch the graphics viewer specified in its configuration settings. If it’s a sound or video file (AU, WAV, MPEG, AVI, FLI, AIFF, ) the browser will launch a similarly configured helper application or plug-in. Usually, however the browser displays an HTML document. These documents show the graphics, links, icons, and formatting for which the Web has become so famous.

22. How to find information on the Web • The most common way to find information is using the following services • Yellow pages • Yahoo, GNN • Search Engines • InfoSeek, WebCrawler, Alta-Vista, Lycos

23. Web- Directories and Web-Indexes • A Web-directory, like Yahoo, maintains a database of all the Web sites by recording the company name and other important information from the Web-pages like captions, etc. • On the other hand, a Web Index, like Alta-Vista, maintains exhaustive information of every Web-site by picking up all important and key-words from every single page of the site. • A Web directory can be compared to the contents page and a Web-Index to the index pages of a book. • If you are looking for Ajmals then you can find it easily using a Web Index but if you are looking for Hamrayn Centre, chances are that Yahoo won’t find it for you. But, ofcourse, Yahoo refers things it cannot find to AltaVista.

24. Domain Name • On the Internet every computer has a unique address and a unique name • Unique address is called IP address. For example 205.184.60.1 (the numbers are alwaysbetween 0 and 255) • The unique name is called Domain name. For example webplaza.com • Domain names enable us to easily remember the server or network • For example webplaza.com is more easy to remember than 205.184.60.1

25. What’s in a Domain Name? • When a domain name is specified, software converts that name to an IP address by looking up the name in a table of addresses. • If I want to know the address for the name xxx.yyy.zzz, I’ll ask the computer at yyy.zzz because it knows the address of everything that ends with yyy.zzz. • If I don’t know the address of yyy.zzz, I’ll ask the computer at zzz because it knows the address of everything that ends with zzz. • The names in zzz are predefined by a committee. • Some of the most common names in place of zzz are com, edu, and net. • “com” in webplaza.com is referred to as the root domain or top-level domain.

26. Top Level Domains The top level domainsin the world are : • .com (company) • .edu (educational Institutes) • .gov (government) • .int • .mil • .org (organizations)

27. What’s in a Domain Name? • The computer identified by a particular domain name is not necessarily always the same. • The server whose address is www.PCS Computer Academy.com today, for example,may be a computer in New York , but that server may change addresses tomorrowto a computer in Boston while keeping the same name. • The physical location of the computer identified by the name is not important. • Moreover, one domain name can point to more than one IP address. • This feature helps server administrators create duplicates of their servers to speed up access for Internet users.

28. Applying for an Internet Domain Contact: • Your local Service Provider • Your country’s network Information Centrehttp://www.apnic.net/ • The InterNIChttp://www.internic.net/

29. Applying for an Internet Domain in India domain-reg@sangam.ncst.ernet.in or Domain Registrar National Centre for Software Technology 8th. Floor, Air India Building Nariman Point Bombay-400 021 Telephone: 91-22-2024641, 91-22-2836924 Fax: 91-22-6210139

30. Applying for an IP Address in India India Network Information Centre ERNET Project ECE Department Indian Institute of Science Bangalore560 012 Telephone: 91-80-3312312, 91-80-3340855 Fax 3347991

31. URLs or Uniform resource Locator • URL is the current method for specifying the addresses of things on the Web. • A URL tells the Web client the following three things: • The type of Internet service that your client uses to get the item. • The name of the computer on which the service resides. • The request for the item you want (this part may be blank). http://www.msn.com/tutorial/default.html

32. WWW Browsers • WWW browsers are applications which display Web Pages • Netscape Navigator, Microsoft Internet Explorer, NCSA’s Mosaic are some of the popular browsers or Web clients. • They interpret HTML language, display graphics, play audio and video, simulate virtual reality... • Netscape and Microsoft are moving towards defining browser-centric computing where the browser becomes the OS itself for doing everything

33. Popular Web Browsers • First GUI Web browserMosaic from the NCSA. Still used by many. • Netscape Communicator (current version 4.0) is the most popular Web browser. Netscape Communications claims that it has sold 40 million copies. • Microsoft’s free Internet Explorer 4.0 soon catching up. • Lynx is the most commonly used Web browser for text-based browsing (Shell A/c.users)

34. HTML • Stands for Hyper Text Markup Language • The basis for World Wide Web because different computer systems can display the information in the same manner of the common HTML language they speak • HTML is a subset of SGML the comprehensive standard for documentation in large corporations • HTML is easy to use, similar to shell scripts • Proliferation of HTML WYSIWYG editors • HTML 3.2 due for release • HTML+, Enhanced HTML expected soon

35. Connecting to the Internet • Things needed to connect to the Internet • Computer • PC, SUN, Mac or other • ISP connection • Dial-up connection • Telephone connection, ISDN • Dedicated leased lines • TI, EI, ATM, SONET • Software • Email client • WWW browser • tcp/ip network software

36. Internet Service Providers • Provide connection to the Internet, just like telephone companies give connection to Telephone network. • Connection Options: • Dial-up Connection: Data over telephone lines, speeds upto 33 KBPS • ISDN: Integrated Service Digital Network: Even though around for a long time, getting very popular now, Speeds upto 128 Kbits/sec

37. Internet Service Providers • Connection options: • Leased Lines: The most popular way to connect for bigger companies, Speeds start at 56 KBits/sec • T1: Large companies or companies with huge bandwidth requirements, 1.5 MBits/sec • E1: Multinationals like IBM or Back-bone providers / Large Internet Service Providers like Netcom, PSInet or UUNET

38. Internet Presence Providers • Concentrate on creating and hosting content • Services include: • Home Page creation including Graphics • Integration of Databases with WWW • Hosting, maintaining web sites • Co-location of Server for WWW, FTP, etc. • Internet Presence Providers are, most of the time, the deciding factor of failure or success of marketing the products on the Web

39. Dial-Up Options:Accessing Internet Services via a Dial-up Terminal Providers Premises User’s Premises S E R V E R INTERNET RS232C PSTN TCP/IP RS232C M M Shell Provider

41. S E R V E R PSTN Leased Line Option:Accessing an Internet Server via a TCP/IP enabled User system Provider’s Premises User’s Premises SLIP/PPP SLIP/PPP Internet HDLC HDLC M M Leased Line Leased Line

42. Origins of the Internet • Result of research project of US Defense during 1970’s called ARPA. • ARPAnet = Advanced Research Projects Agency • Goal of the project: • 1. Connecting dissimilar computer systems to communicate • 2. Route data through multiple communication paths so that the network would be able to run even if many of the computers or the connections between them failed.

43. Origins of the Internet • In 1980’s National Science Foundation(NSF) started promoting its own network called NSFNET using ARPA technology and a high speed back-bone network. • These networks increased emails and information sharing between universities and research centers. • To overcome the problem of connecting dissimilar computers, by 1983, all computers on the ARPAnet were required to use TCP/IP. • This gave birth to Internet with many changes. • Any computer that uses the TCP/IP networking protocol and is physically connected to another computer on the Internet is itself on the Internet.

44. The NSFnet Backbone • Some of the computers on the Internet are directly connected to each other through the NSFnet backbone. • The backbone is a series of cable and connecting hardware that pass data at very high speeds (45 million bits per second). • About 10 sites throughout the US form the basis for this backbone. • Any computer connected directly or indirectly to the backbone can be considered part of the Internet. • As long as a single computer in one country is connected to another computer that is connected to the backbone , that country has access.

45. The NSFnet Backbone

46. Who Runs the Internet • No one owns or runs the Internet • Every computer connected to the Internet is responsible for its own part. • The National Science Foundation is responsible for maintaining only the backbone. • If something doesn’t work, you do not complain to the ‘management’ of the Internet. Instead you talk to the system administrators of the computer you are connected to.

47. Internet Technical Groups • The Internet is not really a free-for-all with no one guiding it. • There are a few organizations who give the Internet some structure while creating a minimum number of restrictions.

48. Internet Technical Groups • IETF: develops and maintains the Internet’s communication protocols. • IRTF: looks into long-term research problems. • IAB: oversees the IETF and IRTF and ratifies any major changes to the Internet that come from the IETF.

49. The INTERNET SOCIETY • The three groups discussed above mostly facilitate the technical structure and details of the Internet. • In 1992, the Internet Society (also called ISOC) was formed to help connect the user-oriented people with the technical people. • It is the parent society to the IETF and appoints the members of the IAB. • Unlike the other societies the Internet Society doesn’t control anything. It keeps its members informed about the Internet.

50. Internet Demographics • Sex • Still dominated by men • Age • Wider use in 20 - 40 age group • User growth • Huge • Income • Affluent • Country • USA still dominates hence constitute the prime target for markets