1 software visualization lauren wilkinson shahar maoz picasso bhowmik

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SOFTWARE VISUALIZATION

Lauren WilkinsonShahar Maoz

Picasso Bhowmik

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What is Software Visualization?

Software visualization categorization* Algorithm visualization

Static (flow chart) Animation

Program visualization Static code / data viz (e.g. UML, ERD) Code / data animation (execution)

* Stasko et al, 1998

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What to visualize?

Source code and configuration: data and text, metadata, file and function size, access history, bug locations and fixes

Code and data structure: data structures, data flow, function calls

Execution: data and algorithms animation, message passing, control flow, memory and resource utilization

Code and human interaction: development process

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Things to think about

Key challenges* Scale

Existing applications work well on toy programs Transition between levels

Code, control flow, class diagram, package, application

Design time, run time Automation

Layout

* Stasko et al, 1998

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Algorithm Animations

Algorithms in Action – A program for learning basic algorithms, developed by Linda Stern, Lee Naish, and Harald Sondergaard, at The University of Melbourne.

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BUBBLE SORT

Simplest sorting method. For a list of size n the algorithm passes

through the list n-1 times. At each pass, every two adjacent elements that are not in correct order are swapped.

http://www.csse.monash.edu.au/~dwa/MELB/BubbleSort.html

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Selection Sort

Sorts by repeatedly choosing the largest item among the unsorted items, and exchanging it with the item in its correct position.

http://www.csse.monash.edu.au/~dwa/MELB/SelectionSort.html

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QuicksortQuicksort

Recursively partitions an array around a partition element (Divide & Conquer) – One partition contains elements less than or equal to

the partition element,

Other partition contains elements greater than or equal to the partition element.

http://www.cs.mu.oz.au/aia/QuickSort.html

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2-3-4 Tree

In the 2-3-4 tree, nodes can contain one key (plus links to 2 children, so called 2-nodes), two keys (3-nodes), or three keys (4-nodes).

New items are always inserted into already existing leaf nodes, converting 2-nodes to 3-nodes, and 3-nodes to 4-nodes.

http://www.cs.mu.oz.au/aia/Tree234.html

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Work by choosing a minimum cost edge at each step.

In Prim's algorithm, we start with an arbitrarily chosen vertex as the root of a tree T, and at each step we add to T the edge e = VW of minimum cost, where V is already in T and W is not in T.

http://www.csse.monash.edu.au/~dwa/MELB/Spanning.html

Minimum Spanning Tree Algorithm

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Flow Diagrams

The two most important modeling techniques used in analyzing and building information systems are :–Data Flow Diagrams (DFDs)Entity-Relationship Diagrams

(ERDs)

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Data Flow Diagrams Data Flow Diagrams (Dfds)(Dfds)

DFD PrinciplesBasic DFD NotationsERD PrinciplesBasic ERD Notations

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What processing is done? When? How? Where? By which component?

What data is needed? By which component? for what? When?

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PrinciplesPrinciples

System can be decomposed into subsystems.

Subsystem represents a process or activity in which data is processed.

Each 'process' in a DFD has the characteristics of a system.

Process must have input and output. Data Input – Data Flows – Data Output

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ExampleExample

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Entity Relationship Entity Relationship DiagramsDiagrams

A simple entity-relationship diagram

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PrinciplesPrinciplesThere are three

basic elements in ER models:

Entities are the "things" about which we seek information.

Attributes are the data we collect about the entities.

Relationships provide the structure needed to draw information from multiple entities.

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The Unified Modeling Language (UML)

A modeling language for specifying, visualizing, constructing, and documenting systems

Based on the Object Oriented Paradigm Accepted as industry standard (~1997) Nine types of diagrams: class, object, use

case, sequence, collaboration, statechart, activity, component, and deployment.

Examples from Ideogramic

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Issues with UML Class Diagrams Aesthetics and Usability: empirical study*

Goal Identify the most important aesthetics for the automatic layout of

UML class diagrams from a human comprehension point of view Procedure

CS students were given short UML class with examples, then read a textual spec and asked to identify correct / incorrect class diagrams

Diagrams shown in random order, each with specific aesthetic metric value set to very high or very low (bends, orthogonality, edge variation, node distribution, direction of flow)

Correctness and time-to-response measured Conclusions

“Tempting to say that none of the aesthetics really matters” Domain specific algorithms are required Semantic grouping of related objects (e.g. position subclasses in an

inheritance hierarchy close to each other) “A nice layout is unlikely to be sufficient for intuitive use”

* Purchase et al, 2001

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Visual Programming Languages

• A purely visual language relies completely on visualization

• No textual representation at all

• The programmer manipulates icons or other graphical representations to create a program, which is then executed and debugged in the same visual environment

• Examples: VIPR, Prograph, Cube

Marat Boshernitsan and Michael Downes. Visual Programming Languages: A Survey. CS Division, UC Berkeley. http://www.cs.berkeley.edu/~maratb/cs263/paper/paper.html

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VIPR: Visualization of Program Execution

Citrin et al. 1994 Citrin, W., Doherty, M., and Zorn, B. Design of a completely visual object-oriented programming language. In Burnett, M., Goldberg, A., and Lewis, T., editors, Visual Object-Oriented Programming. Prentice-Hall, New York, 1994.

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VIPR: Control Statements and while loops


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VIPR: Function Calls


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Prograph: A Completely Iconic Programming Language

http://www.mactech.com/articles/mactech/Vol.10/10.11/PrographCPXTutorial/

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Loops in Prograph

http://www.mactech.com/articles/mactech/Vol.10/10.11/PrographCPXTutorial/

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Cube: Function for the Factorial of a Number

Najork & Kaplan 1991 Najork, M. and Kaplan, S. The cube language. In Proc. 1991 IEEE Workshop Visual Languages, pp. 218-224, Kobe, Japan, 1991.

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Graphical Development Tools

• Related to visual programming, but the language itself is not visual

• Textual languages with a graphical interface

• Great for layout/GUI development

• Examples: Foam, Visual Basic, Dreamweaver

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Foam: A Java Swing Developer

http://www.computersinmotion.com

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SeeSoft: a look at the source code*

Visualizes text files by mapping each line into a thin row, colored according to a statistic of interest. Any text and any statistics about the text may be used.

Interesting case is source code with statistics such as the age, programmer, or functionality of each line. These statistics are derived from a variety of sources, such as version control systems, static analysis, and profiling.

Examples in 2D and a new application in 3D

* Eick et al, 1995

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Building on the SeeSoft Metaphor: Source Viewer 3D (sv3D)

• 3D representation for visualizing large software systems

• Extends the SeeSoft metaphor

• Applications include:

• fault localization (debugging)

• visualization of execution traces

• source code browsing

Marcus et al. 2003 Marcus, A., Feng, L., and Maletic, J. 3D Representations for Software Visualization. ACM Symposium on Software Visualization, San Diego.

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Customized Program Visualizations in sv3D

• Users can define mappings between software elements and visualization components

• Data can be mapped to visual elements of color, position, height and depth


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Viewing Complex Source Code with sv3D

2D Overview of Source Code 3D Overview of Source Code

Color represents nesting level

• Each cylinder is a line of source code

• Color represents control structure type

• Height represents nesting level


Color represents control structure

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Overcoming Occlusion in sv3D


Transparency

Elevation

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Tarantula: Localizing Program Faults

http://www.cc.gatech.edu/aristotle/Tools/tarantula/index.html

Food for Thought: Could sv3D improve this visualization?

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Design Exercise

Design a better visualization for the UML diagram handed out and discussed by Shahar.

Remember: Maintain the same logic Encouraged: Use 3D, Animation, Colors

1 software visualization lauren wilkinson shahar maoz picasso bhowmik

Documents

data input data flows

data structures

development process

control flow

existing leaf nodes

fixes code

levels code

source code