Mastering the Internet, XHTML, and JavaScript

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Mastering the Internet, XHTML, and JavaScript

• Chapter 1
• Overview of the Internet

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Outline

• Goals and Objectives
• Chapter headlines
• Introduction
• Internet and WWW
• Client/Server Model
• Diagnostic commands
• Evolution of Internet
• Transmission
• IP Addresses and URLs
• Internet Domain Names

• E-mail addresses
• File Protocols
• File Compression and Decompression
• Intranets and Extranets
• Connecting to the Internet
• Types of Modems
• Internet Tools
• Summary

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Goals and Objectives

• Goals
• Understand and master some of the basic concepts
  of Internet and World Wide Web, to be able to use
  them effectively in ordinary life, as well as in
  professional activities
• Objectives
• Client/Server Model
• Data and file transmission
• URLs and IP addresses
• E-mail addresses
• File protocols, compression and decompression
• Intranets and Extranets
• Internet connections
• Modems

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Chapter Headlines

• 1.1 Introduction
• The Internet is dubbed as a new mode of
  transportation
• 1.2 The Internet and the World Wide Web
• The web is the section of internet that features
  multimedia capabilities
• 1.3 Internet Jargon
• Learn the internet jargon as you go
• 1.4 Client Server Model
• This model allows two networked computers to talk
  to each other
• 1.5 Client/Server Diagnostic Commands
• These are useful to probe communication with a
  server

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Chapter Headlines

• 1.6 Evolution of the internet and the World Wide
  Web
• The internet has been evolving since the 1960s
• 1.7 Transmission across the Internet
• The TCP/IP protocol and its packets are central
  to internet use
• 1.8 IP Addresses and URLs
• Computers use IP addresses and humans use URLs
• 1.9 Internet domain Names
• An internet domain is a part of a URL
• 1.10 E-mail Addresses
• An E-mail address extends the naming scheme of a
  domain name

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Chapter Headlines

• 1.11 File protocols on the Internet
• Formats and rules of exchanging files on the
  Internet
• 1.12 File Compression and Decompression
• Keeping file size small to speed up downloads and
  uploads
• 1.13 Intranets and Extranets
• Companies use these private networks for security
  reasons
• 1.14 Connecting to the Internet
• Companies use T lines while homes use dial-up
  connection
• 1.15 Types of Modems
• Analog (phone), cable, and DSL modems
• 1.16 Internet Tools
• These tools depend on you interest

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Introduction

• The internet provides an instant mode of
  information and communication
• Internet had more users in its first five years
  than telephone did in its first thirty years
• E-mails already outnumbers regular mails

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Internet and World Wide Web

• Internet is a network of networks
• It is known as information superhighway
• Internet links powerful servers in every part of
  the world
• World Wide Web (WWW) is the driving force of
  internet that features multimedia capabilities,
  such as, text, audio, video, graphics, and images
• The heart of internet is its dynamic nature and
  randomness of information

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Client/Server Model

• Client/Sever model uses two computer programs
  installed on separate, but networked, computers
  located at different locations
• The client requests services from the server
• Multiple clients can access a server concurrently

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Two-tier/Three-tier Architecture

• Client/Server databases are used extensively on
  web.
• Two-tier architecture is the most common model.
• In three-tier model, a middle server is added
  between the database and the client for security
  purposes.

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Client/Server Diagnostic Commands

• The three important commands are
• finger Allows you to find who is currently
  logged into a given host or whether a particular
  user is logged ine.g. finger
  hostname finger username_at_hostname
• ping Allows a client to check whether a server
  is up and runninge.g. ping hostname
• tracert Traces the transmission route of data
  from client to a servere.g. tracert hostname

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Evolution of the Internet

• Early research on the concept of internet began
  in 1962 at Advanced Research Project Agency
  (ARPA)
• The sequence of Internet development is
• 1960s ? ARPANET
• 1970s-1980s ? CSNET, USENET, BITNET,
  NSFNET
• 1990s ? World Wide Web
• In 1989, WWW was conceived by Berner-Lee
• The Web exploded when Mosaic (first
  graphically-oriented browser) became available
  from the NCSA Center at the University of
  Illinois, Urbana-Champaign in 1992

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Transmission across the Internet

• Data, such as Web pages and e-mail messages, are
  transmitted from one computer to another across
  the Internet via the TCP/IP protocol
• The TCP/IP protocol is embedded in TCP/IP
  software that is part of the OS (operating
  system) of any computer
• Each computer on the Internet has a unique IP
  address that is used to identify it. The TCP/IP
  software uses this IP address in data transmission

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Transmission across the Internet

• The TCP/IP software breaks the data to be
  delivered into TCP packets (similar to letters),
  bundles them, labels them with the sender and
  receiver IP addresses (similar to envelopes), and
  sends them to the receivers IP address
• The TCP/IP software of the receiving computer
  unpacks the TCP packets (similar to opening an
  envelope), connects them to construct the
  original data (such as an e-mail message), and
  makes it available for an application program to
  read (such as an e-mail tool)

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The Internet
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IP Addresses and URLs

• An IP address is a 32 bit integer represented by
  four 8-bit numbers, separated by periods
• A typical IP address is 155.33.227.141
• An IP address is assigned to one and only one
  host
• A URL (uniform resource locator) is the name
  version of IP address
• A typical URL is http//www.neu.edu whose IP
  address is the one given above
• We use URLs because IP addresses are difficult to
  remember
• DNS (Domain Name System) software converts URLs
  to IP addresses and vice-versa.

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Internet Domain Names

• URLs are also known as domain names
• Domain name consists of sub-domains (usually less
  than 5)
• The first sub-domain is host name
• The last sub-domain is top-level domain (TLD)
• Second level domain excludes the host name
• Example

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Internet Domain Names

• TLD can also be geographic i.e. country codes,
  such as au for Australia, uk for England,
  etc.
• The most common top-level domain names are
• .com commercial organization
• .edu educational institution
• .gov government agency
• .org nonprofit organization
• .net network service provider
• .mil U.S. military

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E-mail Addresses

• Each user on the internet has a unique e-mail
  address
• The format of e-mail address is username_at_second-
  levelDomainName
• The username in the format above is selected by
  the user and it can be a combination of letters,
  numbers and certain special characters
• Some example e-mail addresses are a.smith_at_neu.ed
  u
• zeid_at_coe.neu.edu a_smith_at_mit.edu smith01_at_harva
  rd.edu

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File Protocols

• File protocols determine the formats and rules of
  exchanging files between the server and client
• The file protocols used on the web are
• http Allows client to request a webpage from
  server
• https Secure http for secure communication
• smtp/pop/imap Sends an e-mail message to a
  specified address
• nntp Allows client to read and post messages on
  newsgroups
• ftp Allows downloads and uploads for files
• telnet Allows access to a remote computer
• file Displays a file existing on client local
  drive

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File Compression and Decompression

• File transfer through internet depends on
  internet connection speed, file size and server
  traffic.
• File size affects both transfer time and disk
  space
• File compression and decompression allow us to
  control the file size
• File compression softwares, e.g. winzip, use
  complex algorithms to decode (decompress) and
  encode (compress) a file.
• For example, the file AAAAAAAGGGWZZZZ can be
  compressed as 7A3G1W4Z
• Multiple files can be compressed together to
  create archives that maintain file directory
  structure

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Intranets and Extranets

• Intranet and Extranet are same as internet, the
  difference being in their geographical domains
  and level of security they use
• Intranet is a network that is contained within an
  organization. Outside intruders are not allowed
  to access this network
• Firewalls are installed around intranets for
  security
• Extranet is an organization network that allows
  access to outside networks
• Extranet may be viewed as an intermediate network
  between internet and intranet

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Intranets and Extranets
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Connecting to the Internet

• Internet Service Providers (ISPs) provide access
  to the internet by dial-up connection, DSL, or
  Cable connection
• AOL and MSN are ISPs who offer access and content
• Phone and cable companies are ISP who offer
  access only. Finding the content is users task
• Some ISP selection guidelines are
• Maximum connection speed
• Type of connection (dial-up or broad band)
• Available help line
• Software provided
• Costs and charges

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Types of Modems

• Modem is a device used to transfer data from one
  location to another through phone lines
• The types of modems are
• Telephone (analog) modem
• Cable modem
• DSL and ADSL modem
• ISDN (digital) modem
• B-ISDN modem
• Satellite modem
• Wireless (cellular) modem

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Internet Tools

• Internet tools allow effective use of the
  internet
• These tools are computer programs
• Some of these tools are shareware and the others
  are freeware
• The basic internet tools are
• Web browsers
• Virus scan programs
• File compression and decompression programs
• FTP and Telnet programs
• Graphics programs

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Summary

• The Internet and WWW are simple and enjoyable
  concepts to learn
• TCP/IP protocol and software transmit data (Web
  pages, e-mail messages) across the Internet
• Computers use IP addresses and humans use URLs
• DNS software provides URL-to-IP-address
  conversion
• Top-level domains .com, .edu, .gov, .org, .net,
  and .mil
• E-mail addresses use username_at_DNS-domain format
• Intranets and Extranets are private networks