Data hierarchy (Figure 6.1)

1

• Data hierarchy (Figure 6.1)
• bit - smallest piece of data
• byte character
• field - group of bytes
• record - related fields
• file - related records
• database - related files and data about them

2
File Processing vs Database

• Data independence
• Data redundancy
• Data consistency
• Data sharing

3
Database Management Systems

• A software that organizes data for easy retrieval
  and access
• 3 components (relational)
• Data definition language (tables)
• Data manipulation language (SQL)
• Data dictionary (fields, field types, keys )

4
Telecommunications

• Communications by electronic means over some
  distance
• Telecommunication systems functions
• transmits information
• establishes a path/connection between the sender
  and receiver
• directs messages along the most efficient paths
• ensures messages reaching the right receiver
• edits data by performing error checking and
  reformatting
• converts messages from one device to another
• controls information flow

5

• Figure 7.5 Five Components of a
  Telecommunication System
• Computer (process information)
• Software (network, access, transmission, error,
  and security control)
• Processor (modems, mulitplexer, )
• Channel (fiber-optic, cable, satellite, )
• Input/Output Devices (send/receive data)

6
Figure 7.2 MOdulation/DEModulation
7
Networks

• Ways of organizing telecommunications components
• Topology
• Star
• Bus
• Ring
• Scope
• Private branch exchange (PBX), e.g., UKs phone
  systems
• Local area networks (LAN), e.g., BEIC lab
• Wide area networks (WAN), e.g., UKs web
• Value-added networks (VAN), e.g., AOL
• The Internet

8
Figure 7.8 A Local Area Network (LAN)
9
History of the Internet

• ARPANET (1969-1990)
• the U.S. Defense Departments Advanced Research
  Projects Agency (ARPA) to facilitate data sharing
  
• NSFNET (1986-1995)
• the National Science Foundations (NSF) national
  network for university communications
• Internet (1990)
• Business use of the Internet promotes the
  development of World Wide Web

10
World Wide Web

• A system and a set of standards for storing,
  retrieving, formatting, and displaying
  information in a networked environment using
  graphical user interfaces and dynamic links to
  documents

11
Web Terms

• HTML (Hypertext Markup Language) is a standard
  language for Web site programming so that
  navigation tools are able to display the Web site
  as it was designed without the need to coordinate
  software packages. Simple html can be created
  directly through word processing and presentation
  packages. Special Web authoring tools exist to
  create more elaborate pages.

12
Web Terms

• Uniform Resource Locator is the address of a
  specific resource on the Internet
• A Web browser is a tool for navigation and
  display of sites. There are many Web browsers
  with Mosaic being the first.
• Search engines help users locate information on
  specific topics

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• Standards
• Transmission Control Protocol/Internet Protocol
  (TCP/IP), DOE, 1972
• Layered protocol (Link, Network, Transport,
  Application) that sends data as packets
• Integrated Services Digital Network (ISDN)
• Standards for transmitting voice data, and video
  over phone lines

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Applications

• E-mail, voice mail, fax
• Teleconferencing, videoconferencing
• Electronic data interchange direct electronic
  exchange of business transaction documents
  between two separate organizations
• Electronic commerce