MMGD0204 Web Application Technologies. Chapter 1 Introduction to Internet

Transcription

1 MMGD0204 Application Technologies Chapter 1 Introduction to Internet

2 Chapter 1 Introduction to Internet What is The Internet? The Internet is a global connection of computers. These computers are connected through Wide Area Network (WAN).

3 Chapter 1 Introduction to Internet The Internet Usages Exchange of data, news and opinion. Upload and download files. Electronic Mail ( ) Communicate and socialize Marketing Online banking Online shopping Entertainment

4 Chapter 1 Introduction to Internet History of The Internet The Internet originated in the late 1960s when the United States Defense Department developed ARPAnet (Advanced Research Projects Agency network), an experimental network of computers designed to withstand partial outages such as a bomb attack. The agency sought to create a web of computers that could continue to communicate with each other, even if some of the computers were disabled.

5 Chapter 1 Introduction to Internet History of The Internet In the mid-1980s, when desktop computer workstations became increasingly popular, organizations wanted to connect their local area networks (LANs) to ARPAnet. If computers could link together and share resources, everyone would benefit.

6 Chapter 1 Introduction to Internet History of The Internet 1991 was a big year for the Internet: The National Research and Education Network (NREN) was founded and the World Wide was released. The Internet is still dominated by scientists and other academics, but begins to attract public interest.

7 Chapter 1 Introduction to Internet History of The Internet With the release of the Mosaic browser in 1993 and Netscape in 1994, interest in and use of the World Wide exploded. More and more communities become wired, enabling direct connections to the Internet.

8 Chapter 1 Introduction to Internet How Does the Internet Works? The unique thing about the Internet is that it allows many different computers to connect and talk to each other. This is possible because of a set of standards, known as protocols, that govern the transmission of data over the network: TCP/IP (Transmission Control Protocol/Internet Protocol). All computers must use same protocol. To gain access to the Internet, the user need to register to any Internet Service Provider (ISP).

9 Chapter 1 Introduction to Internet How Does the Internet Works? Each computer on the Internet is called the host computer. Many of the host computer on the internet offer services to other computers on the Internet. Computer which provides services for other computers is called server. A host computer may run mail servers, web server, FTP server, IRC server, etc.

10 Chapter 1 Introduction to Internet The Internet Requirements Computer with modem / network card Internet connection Account with Internet Service Provider (ISP) browser Example: Internet Explorer, Firefox, Opera 3 rd -party software Example: Flash player, QuickTime Player, Adobe Reader

11 Chapter 1 Introduction to Internet Internet Connections Dialup is naturally the slowest type of connection to the Internet. It runs over analog telephone lines, and its speed is limited by the quality of these lines, which were designed for low-quality voice calls, not data transmissions. Dialup relies on modems (modulatordemodulators), which max out at bps (in practice, bps).

12 Chapter 1 Introduction to Internet Internet Connections ISDN (Integrated Services Digital Network) is a digital connection over a conventional telephone line. It is not in common use, because it has been supplanted by DSL. ISDN offers speeds up to twice as fast as dialup.

13 Chapter 1 Introduction to Internet Internet Connections DSL (digital subscriber line) sends signals on a higher frequency than voice signals over telephone lines. It offers high speeds, but bandwidth degrades as the length of the telephone line increases from the modem to the telephone company's central office DSL comes in two flavours: ADSL - Asynchronous DSL means that uploading is much slower than downloading. Internet service providers (ISPs) adopt this technology so that they can spend less on bandwidth and so that they discourage users from running bandwidth-intensive servers. SDSL - Synchronous DSL provides equally fast upstream/downstream bandwidth. SDSL is expensive and generally used by businesses hosting web servers.

14 Chapter 1 Introduction to Internet Internet Connections Cable uses television coaxial cable to connect to the Internet. Cable has the potential to offer very high speeds, but is limited because cable is shared in a neighbourhood. If the aggregate bandwidth being used by customers exceeds the bandwidth of the physical cable connection in a neighbourhood, then slowdowns are observed.

15 Chapter 1 Introduction to Internet Internet Connections Satellite also comes in two types: Modem-Satellite - A modem is used to send upstream data requests, while a dish receives data from a satellite. This method is plagued by latency, as it takes a long time for a request to travel via dial-up to the web server in question, and for the response to arrive through the satellite system. Satellite two-way - The satellite dish sends and receives data. This technology is more recent, but still suffers from latency problems, simply because satellites are far away.

16 Chapter 1 Introduction to Internet Internet Connections Corporations may use T1, T3, and above for hosting web servers, serving office users, and so forth. These lines are dedicated digital trunks, reliable, and fast, but prohibitively expensive for home users.

17 Chapter 1 Introduction to Internet Internet Connections

18 Chapter 1 Introduction to Internet Internet Applications An Internet application is an interactive, compiled application that can be accessed through a corporate or through the. Internet applications can perform complex business processes on either the client or the server. In a server-based Internet application, the application uses the Internet protocol to receive requests from a client, typically a browser, process associated code, and return data to the browser.

19 Chapter 1 Introduction to Internet Internet Applications 1. World Wide 2. Search Engine FTP 5. WHOIS 6. Telnet 7. WAIS 8. Gopher 9. Ping 10. Traceroute

20 Internet Applications - World Wide The World Wide, or simply, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The uses the HTTP (HyperText Transfer Protocol), only one of the languages spoken over the Internet, to transmit data.

21 Internet Applications - World Wide The also utilizes browsers, such as Internet Explorer or Firefox, to access documents called pages that are linked to each other via hyperlinks. The web documents are formatted in a markup language called HTML (HyperText Markup Language) that supports links to other documents, as well as graphics, audio, and video files.

22 Internet Applications - World Wide Advantages of World Wide Easy linking of documents to other documents. Content is simple to create and make available for use. Support for mixed multimedia elements. Open standards. Accessible for everyone. Facilities the publication, dissemination and sharing of information on a global basis.

23 Internet Applications - World Wide site vs. page A website is a collection of one or more web pages designed to convey information on a particular subject or theme to a web user. A web page is one screen full of information (from a web site) that may contain links to other pages in the web site or links to external information. The web page will normally be written as (or rendered as) an HTML document.

24 Internet Applications - World Wide Uniform Resource Locator (URL) The global address of documents and other resources on the World Wide. A URL can be typed into the address bar. It consists of three parts: A protocol name A host part A document name Example:

25 Internet Applications - Search Engine Search engines are programs that search documents for specified keywords and returns a list of the documents where the keywords were found. Examples: Yahoo!, Google, Altavista, Lycos, Metacrawler, and Hotbot.

26 Internet Applications - Search Engine Search engines work by sending out a spider to fetch as many documents as possible. Another program, called an indexer, then reads these documents and creates an index based on the words contained in each document.

27 Internet Applications - Gopher A system that pre-dates the World Wide for organizing and displaying files on Internet servers. A Gopher server presents its contents as a hierarchically structured list of files.

28 Internet Applications - File Transfer Protocol (FTP) The protocol for exchanging files over the Internet. FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server.

29 Internet Applications - Telnet Telnet is an application used on the internet to connect to a remote computer, enabling access to the computer and its resources. A protocol that enables a user on one machine to log onto another networked machine. This enables you to control the server and communicate with other servers on the network.

30 Internet Applications - Short for Electronic Mail. The transmission of messages over communications networks. allows you to: Sent and Receive message Forward message Send attachment Used two different protocols: Simple Mail Transfer Protocol (SMTP) Post Office Protocol (POP) / Internet Message Access Protocol (IMAP)

31 Internet Applications - address consist of three parts: User sign Server name Example: Harris@ftms.edu.my

32 Internet Applications - Client An application that runs on a personal computer or workstation and enables you to send, receive and organize . The advantage of using an client is that the s are stored on your computer and are accessible faster than using a web based interface.

33 Internet Applications - Client Examples: Outlook Outlook Express Thunderbird

34 Internet Applications - mail mail (or -based ) is an service intended to be primarily accessed via a web browser. They allow you to check your from any computer that has an Internet connection.

35 Internet Applications - mail Example: Gmail Yahoo! Mail Hotmail.

36 Internet Applications - WHOIS An Internet utility that returns information about a domain name or IP address. NSLOOKUP is another application that has similar function as WHOIS.

37 Internet Applications - Finger A program that takes an address as input and returns information about the user who owns that e- mail address.

38 Internet Applications - Wide Area Information Server (WAIS) Wide Area Information Server (pronounced ways), is a program for finding documents on the Internet. WAIS is rather primitive in its search capabilities.

39 Internet Applications - Usenet/Newsgroup A worldwide bulletin board system that can be accessed through the Internet or through many online services. It consists of a set of "newsgroups" with names that are classified hierarchically by subject. "Articles" or "messages" are "posted" to these newsgroups by people on computers with the appropriate software. It uses a protocol called Network News Transfer Protocol (NNTP).

40 Internet Applications - Usenet/Newsgroup

41 Internet Applications - Ping Ping is a computer network administration utility used to test the reachability of a host on an Internet Protocol (IP) network and to measure the round-trip time for messages sent from the originating host to a destination computer. A utility to determine whether a specific IP address is accessible. It works by sending a packet to the specified address and waiting for a reply. PING is used primarily to troubleshoot Internet connections.

42 Internet Applications - Ping

43 Internet Applications - Traceroute A utility that traces a packet from your computer to an Internet host, showing how many hops the packet requires to reach the host and how long each hop takes. If you're visiting a site and pages are appearing slowly, you can use traceroute to figure out where the longest delays are occurring.

44 Internet Applications - Traceroute