Dr. Veer Sain Dixit
Deptt. Of Computer Science
Arsd College , University of Delhi Introduction: Introduction Internet is an interconnection between the computers cited at the remote locations in the world wide web (www) . The Internet is a huge network of computers, which links many different types of computers all over the world. Internet is a network of networks or collection of LANs (Local Area Networks) which share a common set of protocols for communications between two computers between the LANs.
The Internet has it’s root in the ARPANET system of the Advanced research Project Agency of the US Department of Defence . ARPANET was the first WAN (Wide Area Network) and had only four sites in 1969.
In the 1980s the National Science Foundation of USA officially created the Internet.
Intranet is the Interconnection between the computers cited at the remote locations pertaining to only one organization.
Services Provided by the Internet: Services Provided by the Internet
E-mail : E-mail provides a mechanism for groups of people who have common interests to establish and maintain contact.
FTP : FTP is an abbreviation for File Transfer Protocol. FTP is used to send a copy of a file from a one computer to another. The files can be sent across using FTP include spreadsheets , digitized pictures , sound files , programs , word – processed files etc.
TELNET : This service allows you to log-on to a remote machine , on which you have your account.
Usenet Newsgroups : There are many ways to meet people and share information – using Internet. One such way is Usenet newsgroups. These are special groups set up by people who want to share common interests ranging from current topics to cultural heritage. There are currently thousand of newsgroups. Network can be classified into two categories:: Network can be classified into two categories: Point to Point channel network : The two computers that are not connected by a cable can communicate only via other intermediate components. The information is stored in its entirety and later forwarded when the line is free. This is also called as packet switching.
Broadcast channel network : A single channel will be shared by all the machines on the network. There is an address field within the message that specifies the destination. This network is called multidrop network. Three most commonly used networks are: Three most commonly used networks are LAN: Uses broadcast channel for communication. Spans an area of not more than a few kilometers. Atotal data rate of several mbps. Owned by a single organization.
WAN : Uses point to point links. Spans the entire country. Has a data rate below 1 Mbps. Owned by multiple organizations.
MAN : This lies between LAN and WAN. Uses LAN technology. Spans the entire city.
TOPOLOGIES: TOPOLOGIES Star : A central hub is connected to various computers. The hub is in complete control of all computers and is responsible for routing traffic. It is easy to identify the fault points by isolating the lines.
Hierarchical : Also known as vertical network or tree network. The computer at the highest level of hierarchy is in control of the network. Any number of subordinate computers can be added to the network.
Bus : Asingle station broadcasts to multiple stations. Only one communication channel exists for all the devices on the network. If the main communication channel fails , the entire network crashes. It is difficult to isolate faults to one particular component that is connected to the bus. This is used in LAN.
Ring : It is widely used for network configuration. Data flow is in one direction only. One computer receives the signal and relays it to the next computer on the ring. It is a major drawback because if a channel between two nodes fails , the network is lost. We can build bypass switches to avoid such failures. Global Reach / Penetration of Interactive Services:: Global Reach / Penetration of Interactive Services: Total internet users in Europe and in the World: [Internet World Stats, January 2006]
Total internet users by country and share of world users:
202,888,307 (21.6% share) [Nielsen// NetRatings, June, 2005]
China: 103,000,000 (11%) [CNNIC, June, 2005]
Japan: 78,050,000 (8.3%) [C+I+A, March, 2005]
Germany: 47,127,725 (5.0%) [Nielsen// NetRatings , June, 2005]
India: 39,200,000 (4.2) [ C.I.Almanac , March, 2005]
UK: 35,807,929 (3.8%) [Nielsen// NetRatings, June, 2005]
There will be 1.07 billion internet users globally by 2005, 1.21 billion by 2006 and 1.35 billion by 2007. [ eTForecasts , Sept 2004]
Internet Usage and Population growth Statistics in India:: Internet Usage and Population growth Statistics in India: Internet Usage and Population growth Statistics in India:: Internet Usage and Population growth Statistics in India: India Internet and Telecommunications Reports : India Internet and Telecommunications Reports July 7, 2004 - Women lead rural India's internet rush. The internet is beginning to have a revolutionary effect on the 700 million people who live in villages in India - and the charge is being led by women. A project set up by one of India's leading technology institutes has put women in charge of forging the way across the digital divide as the proprietors of a fast-growing number of internet cafes or kiosks around the sub-continent. In total 80% of these new kiosks are run by women, many of whom have had very little or no acquaintance with technology before. ( BBC News). India - Internet and E-Services Market Report : India - Internet and E-Services Market Report Despite the considerable popular interest in Internet in India, the ISP market has been in disarray. According to the telecom regulator, there were around 180 operational ISPs in the country, after a period of market rationalization . Despite the large number of providers, 10% of the ISPs have 90% of the subscribers. The state-owned – BSNL and MTNL – have grown rapidly to hold first and second place in terms of subscribers. The growing popularity of cyber cafes has been playing a big role in fuelling Internet development in India. This report looks at the ISPs and other aspects of India’s Internet market. There is also some information on Internet content and e-services. India - Broadband and Data Services Report : India - Broadband and Data Services Report February 16, 2006 - Broadband usage in India is growing 20% per month, according to the Internet Service Providers Association of India (ISPAI). Thanks to the progress in the past two years and especially, the Broadband Policy announced a year ago, the term 'broadband' has entered mass lexicon and most Internet users are aware of faster speeds. ( ISPAI Article). February 17, 2006 - An overview of Internet usage in India.: February 17, 2006 - An overview of Internet usage in India. The state-owned Videsh Sanchar Nigam Limited (VSNL) launched Internet Services in India in August 1995. For the first four years , VSNL was the sole provider of Internet Services in the Country. In November 1998, the Government ended VSNL’s monopoly and allowed provisioning of Internet Services by Private Operators. The Terms and Conditions of the ISP’s License were unusually liberal with no License Fee and allowed unlimited number of players. ISPs could set their own tariffs and even their own International Gateways. InternetAddresses: Internet Addresses The Internet is a interconnection between the computers cited at the remote site that are able to talk to each other in spite of the fact that they may be separated by large distances, may be very different computers built by different manufacturers, and may be running many different kinds of operating systems. This is similar to people in (say) India,Israel, Brazil, Japan, spain,the United States, and pakistan, each normally speaking a different language, being able to converse almost instantaneously with each other on very broad ranges of topics!
The computers of the Internet exchange packets of information using addresses . These addresses are called Internet Protocol (IP) addresses.
TCP/IP Protocols : TCP/IP Protocols
The communications between the computers are possible because of a set of protocols, which is a set of rules about exactly how information will be transferred between the computers of the Internet. The two most important protocols that allow networks to cooperate with one another and exchange information are called TCP (Transmission Control Protocol) and IP (Internet Protocol). Collectively, these two protocols are known as TCP/IP. Packets of Information : Packets of Information The information is transferred in terms of electronic packets. Packets must have an address. TCP/IP communication depends on addresses being included in each packet. these addresses are commonly termed 'IP addresses'. As these packets of information move through the network, electronic devices called routers use these IP addresses to decide whether to keep a packet in a local network or to forward it to a different network. This is a complex task, because there are many networks that either comprise the Internet, or that are attached to it through some gateway. Addresses : Addresses Each computer has a number that tells you many things about it. On the internet each machine is assigned a host number which is a 32-bit binary number: four numbers separated by dots.
Addresses for Internet information packets have four fields that contain numbers and are separated by periods. For example, 100.35.04.15 is an IP address. However, people generally can remember names better than numbers, so it is convenient to associate a name with such an IP address. In this case, the corresponding name is www.arsdcollege.net. The Naming System : The Naming System Let us consider as a typical example the internet address
www.arsdcollege.net , which is actually the name of the IP address 50.26.24.07. How did the people who run the Internet come up with that name, and how did we know that www.arsdcollege.net is really a nickname for 50.26.24.07?
The symbolic name of a site is determined by a naming standard known as the Domain Name System or DNS.
DNS is a textual addressing method.
Each field in a symbolic address corresponds to a single domain. The first field is a host name, which identifies a single computer. The last field is a top level domain. In between are things like department names, organization names, and so on in order of increasing generality. URL Details : URL Details
The URL(Uniform Resource Locator) provides a reasonably intelligent form to uniquely identify or address information on the internet.
URL addresses have 2 parts: (1) a portion specifying the method of file access, and (2) a portion specifying the Internet location of the file to be accessed. The example of the address
http://www.arsdcollege.net/index.html Search Engines : Search Engines A search engine is a program that can search the Web on a specific topic for you. By typing in a word or phrase (known as a keyword), the search engine will produce pages of links on that topic. Supposedly, the more relevant links are at the top of the list, but that is not always true. To understand more specifically how search engines, operate visit How Search Engines Work.
Example: the Searchalot Search Engine
An example of a search engine is the popular Searchalot Search Engine. The homepage of this web site includes a small window, which you can type a word or set of words on a topic you are interested in.
Suppose you wanted to locate information about Cricket on the Web. You could go to the searchalot site and enter your query in the entry field: Slide21: Slide22: You then press on ' Search' (other search engines will have slightly different forms). The search engine will respond by providing you with a list of all the documents in its database that contain the word 'cricket'. Your browser will display a page with your keyword(s) and a list of documents in which the engine found the word(s). For a searchalot search on 'cricket', the results will look like: Slide23: Sharpening the Search: Sharpening the Search If the keyword you specify for the search is a rather common term, you may be presented with an enormous number of Web documents that contain that term. In this case many of the hits may contain the term but in only one or two instances. Rather than wasting a lot of your time looking through the long list and visiting links that may turn out to have little or nothing to do with the topic you are really interested in, you can let the search engine do the sifting by repeating your search with additional and more specific keywords. General tips to help your search: : General tips to help your search: Be as specific as possible. For example, maybe you are really only interested in cricket information on the delhi clubs, then you should use the term 'delhi clubs' instead of the general term of 'cricket.'
If you're truly interested in the 'Delhi clubs' wrap the term in quotes. This means you want both words together. Otherwise you will pull travel web sites about the city of Delhi .On most search engines adding a plus sign (+) next to any term means to be sure and include the term in the results. If you want very specific information about the ‘Delhi clubs’ 2007 season , put a plus sign (+) next to both terms. For example +'Delhi clubs ' and +2007 means that you want only links that have both information about the clubsand their activities during the year 2007. Other Search Engines: Other Search Engines There are many search engines besides the Search alot service available on the Web. Here are the links for some other popular ones: AltaVista (www.altavista.com) Northern Light (www.northernlight.com) Excite (www.excite.com)
There may be minor differences in the details of their use, most of these engines behave in a similar way, accepting a list of keywords from you and returning a list of documents that contain those keywords. Keep in mind that if you don't find the results you're looking for in one search engine, try another because each search engine analyzes the Web a different way. Slide27: Search engines can access a broad range of material on the Web, depending on search strings used. Thus, unsupervised use of search engines by students can lead to access of inappropriate material.
If you intend to use search engines directly in your classes . There are some search engines try to prevent this. Searchenginewatch.com has a list of the search engines on their web site that attempt to screen inappropriate material.
Also, you may find it useful to warn your students that it is possible to go back and find out from the computer which files and addresses have been accessed by the Web browser on that computer . Directories : Directories A directory is built by someone looking at a web site to determine if it's worthy of being added to their database and if so, under what category it should fall. Regular search engines are not so discerning. As you might suspect, directories don't cover as much of the Web as a search engine, and there is the potential element of human bias in categorization.
Many directories have search tools to help you find specific items within each category.
For Example Looksmart and yahoo. Slide29:
COPY RIGHT LAWs
1. Something appears on the Internet does not mean that it is legal for you to copy it.
2. The law generally holds that it is your responsibility to determine the legality of copying something, irrespective of whether the source from which you copy it has broken the law or not.
3. A related point to keep in mind is that when, as in the case of the Tutorial, someone gives you permission to use their material, this permission does not extend to material that may be accessed by a link from the original material. The question of how material accessed in an external link may be used clearly must be put to its owner. Slide30: 4. You should Notice carefully the distinction: you may usually insert a link to someone else's Web material in your pages without restriction; the issue of ownership becomes important only when you attempt to download material from other Web sites and incorporate it directly into your Web material. Cyber Laws in India : Cyber Laws in India In May 2000, both the houses of the Indian Parliament passed the Information Technology Bill. The Bill received the assent of the President in August 2000 and came to be known as the Information Technology Act, 2000. Cyber laws are contained in the IT Act, 2000. This Act aims to provide the legal infrastructure for e-commerce in India. The Act states that unless otherwise agreed, an acceptance of contract may be expressed by electronic means of communication and the same shall have legal validity and enforceability (DIT). Advantages of Cyber Laws : Advantages of Cyber Laws The IT Act 2000 provides ways to deal with cyber crimes. We need such laws so that people can perform purchase transactions over the Net through credit cards without fear of misuse. In view of the growth in transactions and communications carried out through electronic records, the Act seeks to empower government departments to accept filing, creating and retention of official documents in the digital format. The Act has also proposed a legal framework for the authentication and origin of electronic records / communications through digital signature (DIT). Slide33: From the perspective of e-commerce in India, the IT Act 2000 and its provisions contain many positive aspects. Firstly, the implications of these provisions for the e-businesses would be that email would now be a valid and legal form of communication in our country that can be duly produced and approved in a court of law.
Companies shall now be able to carry out electronic commerce using the legal infrastructure . Digital signatures have been given legal validity and sanction in the Act.
The Act throws open the doors for the entry of corporate companies in the business of being Certifying Authorities for issuing Digital Signatures Certificates.
The Act now allows Government to issue notification on the web thus heralding e-governance.
The Act enables the companies to file any form, application or any other document with any office, authority, body or agency owned or controlled by the appropriate Government in electronic form by means of such electronic form as may be prescribed by the appropriate Government.
The IT Act also addresses the important issues of security, which are so critical to the success of electronic transactions. The Act has given a legal definition to the concept of secure digital signatures that would be required to have been passed through a system of a security procedure, as stipulated by the Government at a later date.
Under the IT Act, 2000, it shall now be possible for corporates to have a statutory remedy in case if anyone breaks into their computer systems or network and causes damages or copies data. The remedy provided by the Act is in the form of monetary damages, not exceeding Rs. 1 crore. ( Department Of Information technology.)
Ways to speedup download time:: Ways to speedup download time: When there is an addition of graphic ,audio and video files to a web site and if any user wants to access this website then there will be delay in downloading.
Cut out unnecessary HTML such as comments , font changes and table elements that are needed.
Use cascading Style Sheet to control appearance rather than changing fonts and appearance on every page.
Always use correct width and height attributes in image tags.
Resize and resample the graphics.
Lower the quality settings of JPEG files.
Use GIFs instead of JPGs when possible.
Lower the resolution of a high resolution graphic.
Display a low-resolution verson of a graphic while downloading.
Display alt text.
Split content into more pages.
Avoid unnecessary use of multimedia content like java applets, movies, images,animation and other elements Uses of the Internet:: Uses of the Internet: On-line communication
Exchange of views on topic of common interest
Posting of information of general interest
Feed back about products
Customer support service
On-line journals and magazines
On- line shopping
World wide video conferencing
Education and training
Banking and financial transactions What user expect to find on website:: What user expect to find on website: The user should be involved in clicking and entering there choices rather than being static watchers. The level of success is based on the level of user satisfaction:
1. Users do not enjoy getting lost, having system lockup or being tricked.
2. Users like to be able to click any where at any time and get what they want.
3. Users enjoy being in control and having easy navigation and multiple choices.
4. User demand fast loading pages and go elsewhere if they do not get them.
5.User cannot see image maps or graphics due to technology limitations.
6. Users often dislikes clumsy frames and bothersome drop down menus.
7. User likes hyper text links but hate entry tunnels like 'Click here to enter'.
8. Users often do not have 256 colors so many graphics look bad in just 16.
9. Users say they return to site that treat them well as a web customer.
10. Users prefer to click through multiple short pages than wait for long one.
11. Users love pictures prefer being told how big they are so they can deside whether to load them or not.
12. Users have little idea about how internet magic works but know instantly which sites they prefer and which they will bookmark for for later viewing.
13. Users know the Internet is not Television ,but still expect the web to grab their attention in engaging and interactive way.
14. Users enjoy being part of an online community so chat features bolted on to a site can triple session lengths, double Kb per user and page impression downloads per session , bolster visit frequency by over 50 % , and work a site’s servers a great deal harder. Most web users are simply not Cookie Monsters and are turned off if they are constantly being bombard with them. Some Important Internet Terms: Some Important Internet Terms Archie : A program used to search files at FTP sites .There are currently 30 Archie servers in the world.
Web site : Collection of web pages.
Home page: The main page of a web site.
Host : A computer system that is the source of network services.
HTTP: The client server protocol upon which the www is based.
IP : Allows a packet to travel through multiple networks on the way to its destination.
IP Address: A unique number assigned to every computer directly connected to internet.
Browser : System Program that allows you to surf the web.
Site : A place on the Internet. Every web page has a location where it resides, which is called its site.
Spam : Spamming is sending the message to a large number of users, usually to advertise something means the Internet version of junk mails.
Surfing: The process of 'looking around' the Internet.
URL : Address of web site.
WWW : Is a universal mass of web pages connected together through links.
WIRELESS TECHNOLOGIES: WIRELESS TECHNOLOGIES Over recent years, the market for wireless communications has enjoyed tremendous growth. Wireless technology now reaches vertually every location on the face of the earth. Types of wireless: Types of wireless Wireless Local Area Networks
802.11b (Wireless Eathernet)
802.11a , HiperLAN ii , and homeRF
Fixed Broadband Wireless Multiservice Wide Area Networks.
Wireless Personal Area Networks
Based on Bluetooth technologies :Bluetooth in its most basic form is cable replacement. Where cable now connect many devices, Awireless bluetooth connection will provide low cost wireless communications and networking between PCs, mobile phones and other devices. Bluetooth is an RF (radio frequency) technology for short- range wireless networking. WAP: WAP WAP is wireless application protocol which allows web-like content to be sent to mobile devices. Slide41: Dr. Veer Sain Dixit
Deptt. Of Computer Science
ARSD College, University of Delhi