CS 407 Human Computer Interface

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CS 407 Human Computer Interface

• Class 41
• Wednesday, December 1, 1999

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Thought for End of Semester

• Triumph is directly proportional
• to the amount of umph
• that goes behind the try.
• Penny Pennington

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A New View of Y2K
The cartoon that was on this page in class was
found at Todays Cartoon by Randy Bergen.
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Todays Topics

• Chapter 13 Groupware
• Start Chapter 14 CSCW

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Project 2 Assignment

• On the web site
• Any questions about Project 2?
• Due Monday, December 6.

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Chapter 13

• Groupware

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Shared Calendars (Diaries)

• Idea
• Make calendars more easily shared.
• Allow automatic meeting scheduling etc.
• Issues for cooperation
• Privacy who can see my diary entries?
• Control who can write in my diary?
• Similar to file sharing issues.
• Many systems have failed because they ignored
  social needs issues.

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Communication through the artifacts

• When you change a shared application
• You can see the effect feedback
• Your colleagues can too feed through
• Feed through enables
• communication
• through the artifact

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Communication through the artifacts

• Not just with real groupware. Shared data is
  pervasive
• Shared files and databases
• Casework files (often nonelectronic)
• Passing electronic copies of documents
• Passing copies of spreadsheets
• Central Indirect communication through the
  artifacts is central. May need direct, too.
• Few examples of explicit design for cooperation.
• Liveware is an exception, a database with
  merging' of copies.

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Time/space matrix revisited
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Refined time/space matrix

• Mobile workers and home workers have infrequent
  communications. They require unsynchronized
  groupware.
• Few research' systems address this area.
• NO current system allows fluid movement between
  synchronized / unsynchronized operation.

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Shared information

• Granularity of sharing
• Chunk size
• Small edit same word or sentence
• Large section or whole document
• Update frequency
• Frequent every character
• Infrequent upon explicit send'

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Shared information (2)

• Level of sharing
• Output shared object
• Shared view
• Shared presentation
• Input single insertion point
• Shared virtual keyboard
• Multiple insertion points
• Other participants visible
• Group pointer
• No visibility

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Integrating communication and work

• New arcs
• deixis reference to work objects
• feed thorough for communication through the
  artifact
• Groupware is classified by the functions it
  supports.
• Good groupware allows all aspects of cooperation
  communication.

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Implementing Groupware

• First, consider one user.
• Then several users

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Implementing Groupware (2)
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Architectures for groupware

• Different architectures
• Centralized single copy of application and data
  
• Clientserver simplest case
• Masterslave special case of clientserver
• Replicated copy on each workstation
• Also called peerpeer
• Local feedback
• - Race conditions

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Feed through

• Need to inform all other clients of changes.
• Few networks support broadcast messages, so n
  participants ? n 1 network messages!
• Solution Increase granularity, reducing the
  feedback, but
• Poor feedthrough ? loss of shared context
• Example systems text and/or graphics

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Robustness and scalability

• Consider the consequences
• Crash in singleuser interface one sad user.
• Crash in groupware can mean disaster!
• But groupware is complex networks, graphics,
  etc.
• Network or server fails standard solutions
• Client fails three R's for server
• Robust server should survive client crash.
• Reconfigure detect and respond to failure.
• Resynchronize catch up when client restarts.

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Robustness and scalability(2)

• Errors in programming
• Defensive programming
• Simple algorithms
• Formal methods to prove programs correct.
• Need a Reset command, to re-synchronize the
  server and all the clients.

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Robustness and scalability(3)

• Unforeseen sequences of events
• Deadlock never use blocking I/O
• Never assume particular orders
• Network packet ltgt logical message
• Scaling up to large numbers of users?
• Testing and debugging hard!

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Chapter 13 Summary

• Three types of groupware
• Computer mediated communication
• Meeting decision support
• Shared applications/artifacts

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Chapter 13 Summary (2)

• Classifying
• Time/space matrix more complex than it seemed
  at first.
• Granularity of communication.
• Different paths of communication. (Good groupware
  should support all paths!)
• Groupware systems are more complex than
  single-user systems.