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Evolution of Data Applications in Communication Systems

Explore the categories of data applications, human-machine interactions, types of information, timeliness factors, and the evolution of data communication technologies from Teletype machines to modern unified messaging systems and image applications. Learn about disaster recovery plans and case studies in telecommunication applications.

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Evolution of Data Applications in Communication Systems

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  1. Chapter 4 Data Communications Applications

  2. Categories of Applications • Human-machine interaction • Type of information • Timeliness

  3. Human-Machine Interaction • Person-to-person • Machine can be in the middle • Ex.: phone call • Person-to-machine, machine-to-person • User interfaces to computer through terminals • Computer responds to user • ATM transaction • Machine-to-machine • File transfer between computers • Automated instrumentation communicating to computers

  4. Information Types • Voice • Structured data • Has records and fields • Used in data processing apps • Unstructured data • Word processing • Images • Video, photographs, FAX

  5. Timeliness • Online, realtime (fast) • Timesharing computers • Airline reservations • Store and forward (delayed) • Voice mail • e-mail • Batch (offline) • Collect data during day, transmit at end of day

  6. Data Application Evolution • Teletype machines (TTY) - electronic typewriters • Connected in networks to transmit information

  7. Administrative Message Switching • Connecting teletypes using telecom lines • Point-to-point • Teletypes in branch offices connect directly to a teletype in main office, one-to-one • Messages received by one teletype had to be typed into another to relay it • Improvement: • Store messages on paper tape • Relay using paper tape- don’t have to retype

  8. Administrative Message Switching

  9. Administrative Message Switching • Multi-point line • More than one TTY on a line • Messages seen by all TTYs on the line • Polling • Master TTY polls (asks) remote (slave) TTY if it has a message • Avoids message collisions • Requires address information in message (overhead) • Slaves must wait their turn

  10. Administrative Message Switching

  11. Computers and AMS (~1960) • First • Computer could read messages on one line and transmit on another like router • Second • Computers grew more powerful • Added storage and calculation capabilities • Third • Users interacted on-line with computer • Fourth • Multiple users timeshare with computer

  12. Computers and AMS (~1960)

  13. Distributed Processing • Began in late 1970s • Applications executed in parts on different computers • Didn’t work well

  14. Client-Server Computing • Server computers have data bases or run applications that Client computers access or use. • High-speed connections needed between clients and servers to handle multimedia • Most LANs use client-server model

  15. Small LAN

  16. Structured Data Applications • Delta Airlines reservation system (1985) • 4000 voice lines, 18 reservation centers • 66 data lines handling 350 transactions/second peak • 23,000 terminals in data network, including terminals in 2800 travel agencies • Automatic teller network • Retail checkout system • Point of sale terminals • Data collection at night • Accounting and inventory info updated in HQ computer

  17. Airline Reservation System

  18. Automatic Teller Machine Network

  19. Retail Checkout System

  20. Unstructured Data Applications • E-mail • Host computer holds user electronic mailboxes • Disk space is big issue • Security - company can read e-mails • TCP/IP uses Simple Mail Transfer Protocol (SMTP) • Disadvantages • Cannot send executable file with e-mail • Limited e-mail size • No foreign character sets • Multipurpose Internet Mail Extension (MIME) is an extension of SMTP

  21. Unified Messaging System • Some e-mail software allows • E-mail • Voice mail • Fax • Sends to single phone number or mailbox • Computer or phone can access • System can “read” e-mail message if you access via phone

  22. Image Application • Video conferencing • Meetings conducted between locations using cameras and TVs in conference rooms • One-way or two-way • Full motion or freeze frame • Freeze frame uses occasional updating • Reduces data rate • Corporate environment • Conference room with camera for people and camera (or computer) for slides • Compression technology helps data rate

  23. Data Communication Considerations • Response time • Security • Especially for business • Planning for failures • Have backup for computer/system • Disaster recovery - long term failure • Needs planning • Test the plan!

  24. Disaster Recovery Plan

  25. WTC Disaster

  26. Case Study: Dow’s Applications That Use Telecommunications • Dow Corning minimizes the number of mainframes used for business apps • Use a few computer centers accessed throughout company by telecom network • Unit cost of computing is cheaper even though telecom cost is higher percentage of total • Manufacturing centers use smaller computers linked to mainframes

  27. Case Study: Dow’s Applications That Use Telecommunications • Business apps • Customer order processing • Inventory management and control • Manufacturing planning and scheduling • Finance and accounting • Personnel and human resource management • Planning and budgeting • Mainframes handled e-mail starting in 1983 • Intranets growing • Voice mail and video conferencing

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