the internet and its applications

1 Ch.9 - The Internet and its applications 1 What is the Internet? 2 The benefits of the Internet 3 History 4 Merging of computer technologies 5 Bandwidth 6 Client server Model 7 Main Services 8 Other Services 9 Finding information on the Internet 10 Relevant Documents and False Drops 11 Full search 12 Constrained search 13 Internet file formats 14 Compression and Archiving 15 Mail Encoding 16 Media 17 Handling file formats 18 URL 19 Protocols 20 Top-level domains 21 Present-day Ch.9 - The Internet and its applications 2 The Internet is the largest network of computers. These computers can be different platforms, like Windows, Mac, UNIX, Next, Amiga and so on, but they can still communicate with each other using TCP/IP, the "common language of the Internet". In 1999 there were about 130 million people connected to the Internet. In the year 2004 there may be as many as 1 billion users. Why are so many people getting connected? What are the benefits of the Internet, from the user’s point of view? Ch.9 - The Internet and its applications 3 The most important benefit of the Internet is the ability to get in touch with and communicate with other people. E-mail for instance, reduces the threshold for making contact with other people. One example is when I was going to attend a conference in Florida Tech in 1996. I wrote an e-mail to the person who was administrating the conference and asked her if there were any people in Florida Tech who were interested in Multimedia and Distance Learning. She sent me the names of four people and their e-mail addresses. One of them was the Dean of Florida Tech. I wrote e-mail messages to all four of them and they replied that they were willing to see me when I arrived. Another example was when we tried to find a teacher for the "Mobile Datacom" part of this course. There were people at Ericsson in Stockholm who knew this subject well, but no one had time to teach, since they were involved in other activities. So I made some searches on the Internet and found an Ericsson owned company in Gothenburg who worked with "Mobile Datacom". I read their home pages but they contained only superficial information. I then looked at their employment opportunities pages, and I found very detailed information about what different departments were working with. I found a department who were working with the parts which we wanted to cover in our course. I made contact with the manager of that department and engaged him as a teacher. Another benefit is information that you will find on the Internet. There are millions of web pages, news articles and so on. The information on the Internet differs from information that you will find in libraries and book stores. In libraries you only find broad information, that is information that interest a large number of people. There is an economic reason for this. No publisher will publish something which interests only a few people. But on the Internet it costs very little to publish, and you will often find this kind of narrow information, for instance a home page describing a single person or a small company. The information on the Internet is growing very rapidly. The number of web pages for instance is doubling every 53 days. Ch.9 - The Internet and its applications 4 A third benefit is all the software which you can find on the Internet. There is freeware, shareware and commercial software. The Internet is also an excellent source for updates. A fourth benefit is all the services which are popping up on the Internet. You can order books, groceries, send flowers, buy stocks and do your banking. These kind of services have just began to appear on the Internet, but we will see a lot more of them in the future. Ch.9 - The Internet and its applications 5 In October 1957 the former Soviet Union sent up Sputnik and took USA by surprise. To many Americans, Sputnik was proof of Russia's ability to launch intercontinental missiles, and pessimists predicted the destruction of democracy. As an answer to that threat, president Eisenhower formed ARPA, Advanced Research Project Agency, in January 1958. ARPA's mission was to make sure that the USA took the lead in research, especially research for military use. One of ARPA's project was ARPANET; a communication network that was built upon computers, and a communication technique that was invented in 1962 called packet switching. ARPANET had been built to protect the USA's communication structure in the face of a nuclear attack. If one communication path was destroyed, the information packets just took another path through the network. ARPANET consisted of four computers in 1969, and that was the seed from which the Internet grew. In those days computers were very expensive. The people who built the ARPANET thought that the main use was to use processor power from computers at a distance, through a service called Telnet. But it soon turned out that scientists were more interested in their colleagues’ brain power than in computers’ processor power. The users invented a service called e-mail and it soon turned out that e-mail traffic amounted to 75% of all the traffic. This trend has continued through the evolution of the Internet. The primary interest of people is to communicate with other people. In 1983 TCP/IP has been adopted as a standard and ARPANET became the Internet. The same year the TCP/IP was included in the operating system UNIX, which made it easy for system managers to connect to the Internet. In 1988 the IRC which stands for Internet Relay Chat was written. This was the first Internet service for real time communication. Up to the 1990’s the Internet was mostly a Ch.9 - The Internet and its applications 6 playground for students, scientists and the military. But in the 1990’s it all changed. One reason was that commercial companies and the general public were allowed to connect to the Internet. Another reason was that WWW and Mosaic were invented and the use of the Internet became much friendlier. In 1994 there was a break through for presence of commercial companies on the Internet. In 1996 there were 54 million users connected to the Internet and by 1999 that number had increased to 130 millions. As we look into the future we see that the Internet is continuing to grow and that new services are appearing all the time. Ch.9 - The Internet and its applications 7 This picture shows how different computer technologies fit together. The vertical axis is time, which flows from top to bottom. The core technology of the Internet is computer network technology. As you can see, some interesting key events are marked. ARPANET represents the beginning of the Internet and it is followed by the invention of the Internet services like Telnet, E-mail, Usenet and so on. There is another technology called Hypertext which was invented by Vannevar Bush, president Roosevelt’s science advisor. In 1945 he wrote an article called "As we may think", where he described a device called "Memex" which used this hypertext or linking technology. Two people read Bush's article and were profoundly influenced by it. One of them was Douglas Engelbart, the inventor of the mouse, groupware and many other things. In the sixties he built the first computer based machine called NLS which used this linking technology. The other person was Theodore Nelson and it was he who coined the term hypertext. Theodore Nelson also had the idea to use this technology through the telephone network to link all the literature in the world, and make it accessible to people. HyperCard, which appeared in 1987, was the first program on ordinary personal computers which used hypertext technology. Hypertext technology merged with the Internet when World Wide Web was invented. World Wide Web uses network technology together with the linking mechanism of hypertext. There is another technology called Graphical User Interface which was first invented by Xerox when they developed their Star machine. This technology was later adopted by Apple on the Macintosh and still later by Microsoft with Windows. All these technologies merged with the Internet when Marc Andreesen, a 23 year old student, wrote a program called Mosaic and later its successor called Netscape. Multimedia is another technology that was started by Philips when they invented the Laser Discs. Other storage devices, like CD-ROM and DVD (Digital Video Disc) appeared later. Ch.9 - The Internet and its applications 8 Multimedia means using several media, like text, graphics, sound, animation, video and so on, in combination with each other to present information. Even if there are multimedia elements on the Internet today, the multimedia technology has not yet merged with the Internet. In order to do so, you need to be able to transfer full screen, full motion video through the Internet, and that requires a bandwidth of approximately 500 kbps. But that will happen in the next few years. Expert system technology will also merge into the Internet. Expert systems are intelligent programs that can use rules to reason and act intelligently. Fuzzy Logic is one powerful technique used in expert systems. One of the first applications of expert system technology on the Internet will be something called intelligent agents. An agent is a program that keeps track of you and your interests. It will go out on the Internet and seek information that might interest you. In summary, what this picture is saying is that many powerful computer technologies are merging into the Internet, which will be extremely powerful in the future, and people will probably associate the information age with the Internet rather than with computers. Ch.9 - The Internet and its applications 9 This is a table from the Popular Science magazine that predicts what will happen to bandwidth in the next couple of years. Today most people have ordinary modems with 28.8 kbps. Some have modems with 56 kbps, Those who have access to ISDN use from 64 up to 128 kbps. You can also have access to the Internet through television cable network. In 1998 some people had 500 kbps through that network, and that speed will increase to 1 Mbps in year 2000. But you can also use the ordinary telephone network for higher speeds. A promising technology is ADSL (Asynchronous Digital Subscriber Loop) which can give a bandwidth of up to 8 Mbps. Ch.9 - The Internet and its applications 10 Most services on the Internet use the Client Server Model. A Client Server Model is a distributed system in which software is split between server tasks and client tasks. A client sends requests to a server, according to some protocol, asking for information or action, and the server responds. A server typically serves many clients. A client can request services from different servers. This model allows clients and servers to be placed independently on nodes in a network, on different hardware and operating systems. . What are the benefits of the Internet, from the user’s point of view? Ch.9 - The Internet and its applications 3 The most important benefit of the Internet is the ability to get in touch with and communicate. - The Internet and its applications 1 What is the Internet? 2 The benefits of the Internet 3 History 4 Merging of computer technologies 5 Bandwidth 6 Client server Model 7 Main Services 8 Other. was the first Internet service for real time communication. Up to the 1990’s the Internet was mostly a Ch.9 - The Internet and its applications 6 playground for students, scientists and the military.