Collaboration Systems

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Collaboration Systems
Prasun Dewan
Department of Computer Science University of
North Carolina CB 3175 Sitterson Hall Chapel
Hill, NC 27599-3175 dewan_at_cs.unc.edu http/www.c
s.unc.edu/dewan
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Definition

• Oxford Work jointly esp at literary or artistic
  production
• Malone helps people work together more
  effectively
• Lynch et al makes users aware they are part of a
  group
• Wells software and hardware for shared
  interactive environment
• Ellis supports groups engaged in a common task
  and provides an interface to shared environment
• Peter Johnson-Lenz computer-mediated culture,
  intentional group processes plus supporting
  software
• Johansen specialized computer aids for
  collaborative work groups
• Winograd state of mind

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Definition
Collaborative Application

• Same output?
• Symmetric?
• N-User?

I/O
I/O
Coupling
User 2
User 1
Potentially Real-Time
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Traditional Collaborative Applications
File
Mail
Talk
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Benefits Towards Being There
Face-to-Face
Interaction
Computer-Supported
Interaction
Network
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Gesture Cam Remote Surrogate
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Benefits Beyond Being There
Face-to-Face
Hollan Stornetta 92
Interaction
Computer-Supported
Interaction
Network
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Action Workflow
Status By Candidate Workflow Step
Manage Review
Manager
Director
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Combining Both Goals?
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Collaboration vs. Virtual Environments
VE
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Collaboration vs. Real-Time Distributed Apps.
Collaborative Applications
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Collaboration vs. Mobile Apps.
Mobile Applications
Collaborative Applications
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Relationship with Object-Oriented and User
Interface- Technology
Interactive Applications
O-O Applications
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Traditional System Aspects
Applications
Shared Screen
FC vs. CC
Interoperability
Extensibility/Composability
Applications
Telepointer Jitter
Performance/Resource Management
Functionality/Abstraction
Coupling
System Support
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Views of Collaboration Systems

• Ensure actual needs met.
• Conceptual depth, avoid duplication.
• Build on existing knowledge.
• See integrated sets of features

• Problems
• Issues
• Disciplines
• Systems
• Applications and Infrastructures

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Problems Application Areas

• Business Management
• National Collaboratory
• Software Engineering
• Engineering/Design
• Writing

• Decision making, business processes, monitor
  state.
• Connected labs.
• Team development
• Just in time VR-based
• Distributed co-authoring.

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Problems Application Areas

• Education
• Medicine
• Air Traffic Control
• Command and Control
• Games/Casual Interaction
• Any complex task!

• Distance presentation, remote lab., colab
  projects
• Distance, sharing, workflow
• Coordinate controllers
• Coordination
• Sharing of information/actions
• Is collaborative

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Generic Tasks

• Social Interaction
• Information Exchange
• Presentation
• Consulting
• Comment/Discuss
• Compose Artifact

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Generic Tasks Product Life Cycle

• Design
• Implementation
• Debugging/Testing
• Inspection/Review

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Specific Experimental Tasks

• Annotate/discuss research article/software
  specs/video
• Present lecture to remote and local audience
• Rank job candidates
• Choose videos to rent, take on road trip
• Get status report on action items and feedback
  from each participant
• Choose name for new game
• Search for shopping list online

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Views of Collaboration Systems

• Problems
• Issues
• Disciplines
• Systems Applications and Infrastructures

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Issues Semantics

• Session Management How do distributed users
  create, destroy, join, and leave collaborative
  sessions?
• Single-User Interface What are the application
  semantics if there is a single user in the
  session?
• Coupling what feedback does a user receive in
  response to the input of another user?
• Access Control How do we ensure that users do
  not execute unauthorized commands?
• Concurrency Control How do we ensure that
  concurrent users do not enter inconsistent
  commands?

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Issues Semantics (Contd.)

• Process Control How do we ensure that users
  follow prescribed group processes?
• Merging How do we merge concurrent commands
  entered by different users?
• Undo/Redo What are the semantics of undo/redo
  in a collaborative session?
• Awareness How are users made aware of out of
  band'' activities of their collaborator?

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Issues Implementation

• Objects What kind of objects are composed in a
  collaborative application?
• Collaboration Awareness Which of these objects
  are collaboration aware and how are these objects
  integrated with existing, collaboration-unaware
  objects?
• Layers How are these objects arranged in
  layers?
• Concurrency How is the application decomposed
  into concurrent threads?
• Distribution How are the application objects
  placed in different address spaces and hosts?

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Issues Implementation (Contd.)

• Replication/Migration Which of these objects
  are centralized and which are replicated? Which
  of the centralized objects can migrate?
• Display Consistency How to ensure actions are
  executed in the same order on computers that
  share them?
• Real-Time Support What kind of services are
  provided to ensure real-time interaction with
  tolerable jitter and latency?

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Views of Collaboration Systems

• Problems
• Issues
• Disciplines
• Systems Applications and Infrastructures

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Computer Science Disciplines

• Operating Systems
• Database Management Systems
• Programming Languages
• User Interface Systems
• Software Engineering

• Distributed file, memory, scheduling, OS-based
  IM
• Concurrency Control, Recovery
• Shared object constructs
• I/O distribution of window systems, toolkits
• Application area, process control, patterns

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Views of Collaboration Systems

• Problems
• Issues
• Disciplines
• Systems Applications and Infrastructures

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Systems Applications

• RTCALendering
• Cognoter whiteboard
• CES (Transaction-based Collaborative Editing
  System)
• Grove Outline Editor
• Information Lens Typed Email
• Coordinator Speech-Act Workflow
• Quilt Editor Annotations
• IBIS Discussions
• Video Walls
• Hydra
• GroupDraw optimistic CC
• PREP Diff-based Editor
• MUDs (Multiuser Dungeons)
• DIVE (Distributed Interactive
• Virtual Environment)/ MASSIVE

• MIT (Sarin Greif)
• Xerox (Stefik et al)
• MIT (Liskov)
• MCC (Ellis)
• MIT (Malone)
• Stanford (Winograd)
• Bellcore (Leland)
• MCC (Ellis)
• Xerox (Abel)
• U. Toronto (Buxton)
• U. Calgary (Greenberg)
• CMU (Neuwirth)
• Xerox (Curtis)
• Sweden (Fahlen)/ Nottingham (Benford)

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Systems Infrastructures

• NLS (Engelbart 68)
• Colab (Stefik 85)
• VConf (Lantz 86)
• Rapport (Ahuja 89)
• XTV (Abdel-Wahab, Jeffay Feit 91)
• Rendezvous (Patterson 90)
• Suite (Dewan Choudhary 92)
• TeamWorkstation (Ishii 92)
• Weasel (Graham 95)
• Habanero (Chabert et al 98)
• JCE (Abdel-Wahab 99)
• Disciple (Marsic 01)

• Post Xerox
• Xerox
• Stanford
• Bell Labs
• UNC/ODU
• Bellcore
• Purdue
• Japan
• Queens
• U. Illinois
• ODU
• Rutgers

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Systems Products

• VNC (Li, Stafford-Fraser, Hopper 01)
• NetMeeting
• Groove
• Advanced Reality
• LiveMeeting (Pay by minute service model)
• Webex (service model)

• ATT Research
• Microsoft
• Microsoft

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Multiple Views
Coupling
Cognoter
WYSIWIS Interaction
Database Transactions
NetMeeting
Software Engineering
Design
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Course Goals

• State-of-the-art
• Applications
• Shared Word, Browser
• Infrastructure
• Groove, Shared Objects
• Project
• Writing
• Integrate with 291
• Programming
• Integrate with 243/RAship
• Presentation
• Research

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Projects

• Infrastructure-based
• Application-/usage- based

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Infrastructure-based

• Replication vs. centralization
• Existing system can change it dynamically.
• Hypothesis Transition to centralized when
  conference gets less interactive and larger
• Dynamic policies for transitions
• Formal performance model
• Shared layer
• VNC and NetMeeting share different user-interface
  layers
• Benefits of different sharing different layers.
• Can we dynamically change shared layer?
• Dynamic policies, performance model

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Infrastructure-based

• Scheduling
• Feedback vs. Feedthrough processing
• Give sufficient time to both using proportional
  scheduling.
• Energy-aware collaboration
• Energy dissipation a function of amount and rate
  of information communication
• Can study and adjust the coupling (send summary
  information in batches)

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Infrastructure-based

• Locking
• Many locking schemes
• Lock whole spreadsheet vs. individual cell.
• Provide one comprehensive mechanism.
• Partly designed but not implemented.
• Lock-free Consistency management
• Locking ensures displays are consistent no race
  conditions.
• Consistency without locks operation
  transformation
• Called optimistic CC - misnomer

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Infrastructure-based

• Context-specific presence
• Can synchronously monitor idle time.
• Can synchronously monitor every input in shared
  apps.
• Synchronously summarize application-specific
  information
• E.g. whose mail are you reading?
• Access control
• Needed because we collaborate
• But it is a pain
• Let us collaborate on setting access control.

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Application-based

• Qual scheduler
• Automatic did not work.
• Semi-automatic, collaborative.
• Students enter courses and time constraints
• Faculty members enter expertise and time
  constraints
• Schedulers form committees and assign times
  based.
• System checks qual constraints met.
• TA/RA Matcher
• Students and faculty enter preferences.
• Administrators can see all data.
• Students and faculty can see filtered data.
• E.g. one on one matches.

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