(Click a title or small image to see the full-size slide)

• Collaboration Transparency
  • Single-user legacy applications shared without developer awareness. The sharing is unknown, or “transparent,” to the application.
  • Examples: NetMeeting, SharedX, SharedApp, XTV

• Collaboration Awareness
  • Applications designed for collaborative use
  • Examples: Editors (SASSE), whiteboards, chat, multi-player games (Diablo, Doom)

• Problem
  • Conventional collaboration transparency has low development cost, but provides inflexible support of collaboration

• User inputs can interleave and conflict

• Solution of conventional collaboration transparency: take turns
  • but that prevents concurrent work

• Sequential shared editing
  • Taking turns restricts text editing to only one user at a time.

• Concurrent shared editing
  • Multiple users may simultaneously edit text.

• What You See Is What I See (WYSIWIS)
  • Collaboration transparency has strict WYSIWIS
    • All participants have exact same view at same time.
  • Collaboration awareness relaxes WYSIWIS
    • Participants have independent views of shared data.
    • Allows independent simultaneous work

• Group Awareness
  • Information about participants locations and activity in shared application.

Telepointers to represent remote mouse cursors

“radar” views to indicate remote scroll positions

• Common to conventional collaboration transparency
• One central copy of shared application
• Graphics output sent to each remote participant
• Remote inputs merged
• Higher network traffic

• System Goals
  • Lower network bandwidth requirement
  • Concurrent work allowed in application

• Usage Goals
  • Support multiple collaboration styles
  • Relaxed What You See Is What I See (WYSIWIS)
  • Detailed group awareness information

• Approach
  • Replicated network architecture
  • Replace single-user interface objects with multi-user equivalents
  • Optimistic distributed algorithm for concurrent text editing
  • Automate “turn taking” where still required

• Used by new approach
• Each person has a copy of the shared application
• Remote inputs are merged
• Lower network traffic
• Enables:
  • Independent views
  • Concurrent work

Multi-user equivalent objects are substituted for single-user originals

A single-user editor application containing a scrollable panel …

… becomes a shared editor containing a multi-user scrollable panel

• New system, JAMM, versus conventional, NetMeeting

• Two tasks
  • Text Entry: two authors simultaneously enter text
  • Copy Edit: editor leads author to make changes in a text

• Results
  • Text Entry: less time using JAMM (223.75 seconds) than NetMeeting (353.50) (p<.001)
  • Copy Edit: no difference, as expected (p = 0.7905)