Defense Of Research

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Defense Of Research

• Ian Smith

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Overview

• Motivational scenario
• The problem
• Approach
• Tool explanation (example)
• Local state problem
• Contribution Summary
• Related work

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Scenario

• Alice Bob want to change the org chart together
• They worked together before but now Alice travels
  more often...
• Alice is remote, Bob is at his desk
• Alice has a pilot, Bob has a workstation.

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Workstation Org Chart App
App Controls
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Org Chart App On A Pilot?(Bad Idea 1)
Pilot Display?
App Controls
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Org Chart App On A Pilot?(Bad Idea 2)
Pilot Display
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Pilot Org Chart Application
Org Chart
Reports To
President (John)
VP of Eng. (Jane)
Staff Eng. (Bill)
VP of Finance (Fred)
Principal Sci. (Mary)
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The Problem?

• People want to work together, but have different
  devices
• Two structurally different views of same data
• UIs have different underlying structures
• Views must be synchronized

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Graphical Formulation
Pilot
Workstation
Org Chart
Reports To
President (John)
App Controls
VP of Eng. (Jane)
Staff Eng. (Bill)
VP of Finance (Fred)
Window
Pilot App
Principal Sci. (Mary)
Scroller
Palette
Scroller
Tree Control
...
Tree Node
Line
Rect
Rect
Tree Node
Tree Node
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My World
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Problem Generalization

• Given a UI tree A, compute a new UI tree B from A
• If A is computed from a model, compute B from the
  same model

Ultraman
A
B
Model
Ultraman
Ultraman
A
B
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Approach

• End-programmer declares constraints on the
  structure of an interface
• Constraint here is a function of a tree which
  computes a tree (not values!)
• Constraints apply over an entire input tree
• When you see a node of type foo, create a node
  of type bar and attach to this structure
• Constraints are applied dynamically, as the
  application runs

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Using Ultraman

• Ultraman is a tool and a runtime
• Tool allows you to declare patterns and
  transformations
• Pattern is a structural relationship of nodes in
  the source tree
• Transformation is a computation to run when a
  pattern is found

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Ultraman Tool Summary

• Several ways to specify computations and
  structural patterns
• Tool generates a lexer/parser specification which
  implements the pattern matching
• Lexer/parser pair is built on ANTLR 2.20
• Generated parser calls into user code to
  implement transformations
• Transformations are run after each event

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Example App
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Transformations? But.
Column
Pull-Down Menu
Ultraman
...
RadioButton
MenuItem
MenuItem

• Pull-Down menus have state the currently
  displayed item.
• If we regenerate the menu how do we get the right
  item displayed in the Pull-Down?

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Local State Problem

• Tree T1 produces tree T2 by some transformation
  F.
• User manipulates T2 in some way, modifying T2s
  state.
• We make a change to T1 and rerun transformation F
  producing tree T3.
• How do we reconcile the freshly created T3 with
  the old, stateful tree T2?

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Value Numbering

• Nodes created by the transformations are given a
  label called a value number
• The value number (VN) is a representation of
  where and when in the transformation node was
  created.
• Nodes with the same VN are from the same spot
  in the transformation process.

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Shadow Objects

• Shadow objects are objects which represent
  interior nodes in the UI tree.
• Shadow objects mimic the API of an interactor,
  but actually buffer calls
• End programmers build dynamic structures
  underneath shadow objects.
• Effectively, shadow objects build a shadow
  version of the interactor hierarchy during the
  transformation.

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Grafting Algorithm

• After the transformation is complete...
• Walk the interface on the screens tree (T2)
  collecting pairs (VN,node).
• Walk the shadow interfaces tree (T3) and compare
  VNs of its nodes to the table.
• If a VN is in the table, exchange the
  corresponding nodes.
• Replace the interface on the screen with the
  shadow.

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Grafting Algorithm Example
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Issues With Grafting

• Value numbering is a sensitive and bottom-up
  change metric.
• Changes at the top of a tree can be missed due
  to shadow objects.
• End-programmer can be surprised when objects
  which are created never appear!
• Garbage collector can be a problem...

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Contribution Summary

• Developed a taxonomy for multi-viewed
  transformation (4 categories) identified
  salient characteristics of multi-viewed
  transformation system (7 properties)
• Implemented a specification tool for composing
  patterns and transformations

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Contributions (contd)

• Developed and implemented algorithms for
  converting specifications into grammars
• Developed and implemented algorithms for handling
  the local state problem
• Implemented 2 demo applications
• Cards Transform to a very different device
• Contact Transform someone elses data model

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Related Work

• UI Software (excluding toolkits)
• Patterson Hill, Foley/Szekely, Olsen
• Constraints
• Borning, Hudson, Myers, Vander Zanden
• Compilers/Parsing
• Early, Parr, Graham Glanville, Brotsky/Wills,
  Alpern
• Transformation Systems
• TXL, REFINE

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Characteristics Of A Multi-Viewed Transformation
System

• Semantic Predicates
• Aggregation
• Multiple recursive patterns
• Input output trees have different shapes
• Control the progress of the pattern match
• Multi-tree input
• Take input from a model

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Taxonomy Of Transformations

• Filtering - projection (N to 1)
• Aggregating - Computing a function of the entire
  input
• Reordering - order change only (1 to 1)
• Decorating - adding nodes to the input (1 to N)