Supporting Systems Analysis and Design Through Fisheye Views

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Supporting Systems Analysis and Design Through
Fisheye Views

• Presented by
• Jeff Webb
• Sept 22, 2004

SE 516
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Supporting Systems Analysis and Design Through
Fisheye Views

• Published in
• Communications of the ACM
• Sept 2004

Written by Ozgur Turetken, David Schuff, Ramesh
Sharda, and terence T. Ow
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Problem

• The task of systems analysis has become
  increasingly complex
• The emergence of integrated, enterprise systems
• Systems now cross many organizational boundaries,
  and contain an abundance of information

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Problem

• Analyst who must understand how a system operates
  may face an information overload

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Problem

• On the other hand.One argument states that to
  fully understand a detail, one must understand
  the context in which it exists.

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Problem

• One way of coping with information overload is to
  create a grouping structure within the collection
  of information.

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Problem

• Consequently, graphical models representing
  information systems are often visualized through
  a grouped, hierarchical structure
• Systems and sub-systems modeling

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Problem

• Understanding the system details within the
  context of the overall system
• Forces the analyst to mentally integrate detail
  and context
• Causes disorientation

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Possible Solution

• Fisheye distortion shows how high granularity
  details are related to there context, by
  combining them within the same diagram.

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Fisheye Overview

• Pay greater attention to details in our immediate
  surroundings
• Acknowledging only major landmarks that are
  farther away
• These landmarks, however, constitute the context
  within which details have meaning

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Fisheye Overview

• Fisheye views apply this idea to graphical
  interfaces
• Details can be shown within the context of their
  surroundings

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Implement This Idea

• Assign a degree of interest to each object
• New degree value is determined by its original
  importance and its proximity to the current area
  of focus
• Proximity can be based on either physical
  distance or semantic distance (such as the time
  between two events)

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Implement This Idea

• Degree of Interest
• Original Importance Distance from Focus

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Implement This Idea

• The views are constructed such that the size of
  each object in the view is proportional to its
  degree of interest
• Accordingly, the in focus elements will appear
  larger than the out of focus elements

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Application of Fisheye Views to Systems Analysis

• Visualization is nothing new
• Entity-relationship
• Data flow
• Class diagrams
• Are - all visual models
• Not - context-aware

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Application of Fisheye Views to SA

• They can represent an entire system
• A specific part of a larger system
• But not both at the same time

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Application of Fisheye Views to SA

• Use many large and complex diagrams
• A series of smaller less complex diagrams
• Information overload and disorientation

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Process Modeling Data Flow Diagrams (DFD)

• Represents flow of data between an organizations
  business processes

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Good Candidate for Fisheye View Because

• To model and then try to comprehend every
  business activity with its associated data flows
  can be overwhelming

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Common Structuring Method Could Cause Distortion

• Single high level diagram (level 0) that shows
  all major processes
• A series of more detailed diagrams that breaks
  down the processes into sub-processes of
  increasing levels of granularity

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Create Fisheye Views

• Details of the sub-process are embedded into a
  higher level diagram (the context)

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Determine Size and Position of Elements

• Based on a degree of interest (DOI)
• DOI 1 k DF

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DOI 1 K DF

• 1 is the level of original importance of all
  level 0 elements
• DF number of levels in the hierarchy between
  the element and the focus
• Coefficient k (a percentage) amount of
  reduction in the degree of interest as the
  distance from the focus increases

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  Example DOI 1 k DF

• k .2
• Current focus is on a level 2 process
• the level 0 contextual elements will be 1 (.2
  2) .60 OR60 of their original size

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• Elements where the DOI is 0 or less can be
  aggregated together or excluded from the view
  altogether

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Conclusion

• Benefits
• Increase the efficiency of system design
• Recognize and eliminate redundancy
• Create effective linkages between sub-systems

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Conclusion

• Benefits
• Facilitate greater efficiency in system
  enhancements
• Quicker navigation of the system model
• Identification of interrelated components

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Conclusion

• Where used
• The value will be realized for systems that are
  complex
• The subsystems should be interrelated
• The system should be hierarchically organized

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