Courses/Computer Science/CPSC 203/CPSC 203 2008Winter L03/CPSC 203 2008Winter L03 Lectures/Lecture 3

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Lecture 3

  • House Keeping:
    • Extra Syllabus, Course Info Sheets at Front
    • Announcement for Natural Science Students
    • Term Project Intro and Tutorial Schedule on BB Course Documents


  • Today's Goals:
    • Recap Scale Free Network Core Ideas
    • Look at the Tier Structure of the Internet
    • Participatory Exercise: Develop an Alternate Internet Model
    • A bit about Wikis


  • TEXT READINGS
    • TIA 4th Edn: Chapter 13, pp 572-578
    • TIA 3rd Edn: Chapter 13, pp 546-552

Recap Scale Free Network Core Ideas

Core ideas from last lecture recapped on overhead.

Internet Tier Structure

While last lecture we studied the structure the Internet has "grown into", a scale free network, the Internet also has some basic design rules. Recall, the original design of the Arpnet was to survive a nuclear war, and this affected design considerations.

  • Tier One Internet Service Providers are required to connect to all other Tier One Internet Service Providers.
    • They form the Internet "Backbone", and include many of the original Arpnet sites.
  • Tier Two Internet Service Providers are required to connect to at least one Tier One Internet Service Provider
    • These constitute large organizations usually with regional or national focus.
  • Tier 3 Internet Service Providers must connect to at least one Tier 2 Internet Service Provider.
  • "Tier 4" -- the rest of us who connect to the Internet via a Tier 3 service provider.

Internet Tier Structure Exercise

Class is arranged into groups for this exercise. Use 1 page per group.

  1. What happens if the Internet Backbone were to 'be taken out' -- could the Internet still function? Give reasons for your answer.
  2. Can you design an alternate Tier structure for the Internet that you think would be more stable. Sketch this answer.
  3. For your alternate Internet design, list: its strong points, its weak points.

Internet Tier Structure Glossary

  • Routers -- devices that send data packets between networks
  • Internet Backbone -- the several dozen Tier 1 Internet Service Providers
  • T lines -- high speed fiber-optic lines used by Internet Service Providers
  • ISP -- Internet Service Providers
  • Network Access Points -- Points of connection between ISPs that contain groups of routers designed to quickly move large amounts of data


Wiki Wiki World

  • Invented by Ward Cunningham as "the simplest online database that could possibley work".
  • Wikiwiki is a Hawaiian verb meaning -- fast, speedy; to hurry, quick fast, swift.
  • Originally used for programmers -- Portland Pattern Repository
  • Essentially Form Based (Web 1.0) technology

Key Wiki Technical Features

  • Edittable Web Page
  • Small Markup Language for formatting and linking
  • Rollback "database" to previous state

Key Wiki Cultural Features

  • Open
  • Voluntary
  • Self-Policed and Editted (Wiki Gnomes and Gremlins).
  • Collaborative Writing and Editting -- goes to "collective we" voice.
  • Used for: Education, Business Tech Support, "Encylcopedic" overviews -- e.g. Wikipedia., or for learning purposes, such as this class


Only Connect : Finale

Only connect! That was the whole of her sermon.

Only connect the prose and the passion, and both will be exalted,

And human love will be seen at its height.

Live in fragments no longer.

Only connect ...

-- E.M. Forster, Howards End.


TEXT READINGS

  • TIA 4th Edn: Chapter 13, pp 572-578
  • TIA 3rd Edn: Chapter 13, pp 546-552

Resources

Original WikiWikiWeb at: http://c2.com/cgi/wiki -- this housed the original "Portland Pattern Repository" -- a discussion area for programmers to discuss "Design Patterns". If you're curious as to what Design Patterns may be -- see: http://en.wikipedia.org/wiki/Design_pattern_(computer_science). Ward Cunningham, creator of the Wiki concept also made a number of contributions in this area.

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