IGT Software Design and Process

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IGTSoftware Design and Process

• Bill Lorensen
• GE Research

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Outline

• Background
• Design Principles
• Software Process
• Challenges

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Open Source Menu for Success

• A Community with a common vision
• A pool of talented and motivated
  developers/scientists
• A mix of academic and commercial
• An organized, light weight approach to software
  development
• A leadership structure
• Communication
• A business model

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Guiding Principles

• Open is good
• Proprietary is bad
• Reuse is good
• NIH is bad
• Modularity is good
• Monolithic is bad

Not invented here
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Design Principles
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Toolkits and Libraries

• Visualization - VTK
• Segmentation/Registration - ITK
• State machines IGSTK
• UI KWWidgets, ??
• Tracking OpenTracker, ??
• DICOM dcmtk, gdcm
• File I/O nrrd, meta, pnglib,

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Object-Oriented Design

• Dominated software systems throughout the 1990s
• Continues to be the accepted software design
  technique
• Particularly useful for dealing with complexity
• Provides programmatic abstractions to deal with
  generalization and encapsulation
• C and Java have mechanisms to support OOD

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Generic Programming

• Organize libraries consisting of genericor
  reusablesoftware components.
• The essential ideas of generic programming are
  containers to hold data, iterators to access the
  data, and generic algorithms that use containers
  and iterators to create efficient, fundamental
  algorithms.
• ITK uses generic programming to process
  n-dimensional images.

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Design Patterns

• Good object-oriented software systems have
  recurring designs (patterns) that occur
  frequently
• ITK employs a number of powerful design patterns
• object factories
• command/observer
• smart pointer memory management

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Frameworks

• Define how a group of participants can be put
  together to solve a particular task.
• Particularly suitable for describing complex
  flows or algorithms that have a number of steps
  that can be varied
• ITK Frameworks
• A demand-driven data processing pipeline that
  connects algorithms to process n-dimensional
  image data
• Registration framework
• Level-set framework

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Separation of Algorithms from Interfaces

• Implement the algorithms with a clear separation
  from the applications and especially the user
  interfaces.
• Uses the Command/Observer design pattern that
  permits applications to watch for significant
  events during the execution of an algorithm
• ITK has no built-in visualization, but has been
  interfaced to several systems including 3D
  Slicer, Analyze, SciRun and Volview.

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Slicer 3 Execution Model Goals

• Provide interface to batch programs
• Simplify and unify command line processing
• Auto generate C command line processing
• Simplify and unify GUI
• Auto generate GUI

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Slicer 3.0
User Desktop
Algorithms
ITK
VTK
Slicer Modules
Slicer 3.0
Scripts of Slicer Mods
VTK Apps Using ITK
Batch Programs
Non-NAMIC Cmd tools
LONI Pipeline
Birn Grid Data/Compute
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Execution Model Plugins

• XML Interface Description
• Describes command line options
• Describes suggestions for GUI
• GenerateCLP
• Generates C command line processing code from
  XML
• Reports XML description

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Program Flow
User Desktop
Slicer Modules
Slicer 3.0
prog.xml
GenerateCLP
progCLP.h
prog.cxx
Non-NAMIC Cmd tools
LONI Pipeline
Birn Grid Data/Compute
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Resample --xml
ltlabelgtIOlt/labelgt ltdescriptiongtInput/output
parameterslt/descriptiongt ltimagegt
ltnamegtInputVolumelt/namegt ltlabelgtinput
Volumelt/labelgt ltchannelgtinputlt/channelgt
ltindexgt0lt/indexgt ltdescriptiongtInput
volume to be resampledlt/descriptiongt
lt/imagegt ltimagegt ltnamegtOutputVolumelt/nam
egt ltlabelgtOutput Volumelt/labelgt
ltchannelgtoutputlt/channelgt ltindexgt1lt/indexgt
ltdescriptiongtResampled Volumelt/descriptiongt
lt/imagegt lt/parametersgt lt/executablegt

• lt?xml version"1.0" encoding"utf-8"?gt
• ltexecutablegt
• ltcategorygtfilteringlt/categorygt
• lttitlegtResample Volumelt/titlegt
• ltdescriptiongtResamples a volumelt/descriptiongt
• ltversiongt1.0lt/versiongt
• ltdocumentationurlgtlt/documentationurlgt
• ltlicensegtlt/licensegt
• ltcontributorgtBill Lorensenlt/contributorgt
• ltparametersgt
• ltlabelgtResampling Parameterslt/labelgt
• ltdescriptiongtParameters used for
  resamplinglt/descriptiongt
• ltfloat-vectorgt
• ltnamegtoutputPixelSpacinglt/namegt
• ltflaggt-slt/flaggt
• ltlongflaggt--spacinglt/longflaggt
• ltdescriptiongtSpacing along each dimension
  (0 means use input spacing)lt/descriptiongt
• ltlabelgtSpacinglt/labelgt
• ltdefaultgt0,0,0lt/defaultgt

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Resample.cxx

• .
• .
• .
• include ResampleCLP.h
• Main (int argc, char argv)
• PARSE_ARGS
• algorithm code

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Resample --help

• USAGE
• ResampleVolume
• --xml
  --echo -s ltstdvectorltfloatgtgt
• --
• 
  --version -h ltstdstringgt
• 
  ltstdstringgt
• Where
• --xml
• Produce xml description of command line
  arguments (default 0)
• --echo
• Echo the command line arguments (default 0)
• -s ltstdvectorltfloatgtgt, --spacing
  ltstdvectorltfloatgtgt
• Spacing along each dimension (0 means use
  input spacing) (default 0,0,0)
• --, --ignore_rest
• Ignores the rest of the labeled arguments
  following this flag.
• --version
• Displays version information and exits.
• -h, --help
• Displays usage information and exits.

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Software Process
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NA-MIC Rhythms

• Yearly All-Hands Meeting
• Bi-annual Programmers Week
• Weekly Engineering T-Cons
• Nightly Build/Test
• ITK
• VTK
• Slicer

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NA-MIC Tools

• CMake
• Cross-platform build
• Dart 2
• Build/Test server
• CTest
• Build/Test client
• Cpack
• Packaging and Distribution
• Media Wiki
• Reporting/discussion forum
• POTS
• T-cons

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How DART Enables Collaboration
CVS/SVN maintainssource code revisions
DART compilessource code, runs tests
CVS SVN
Developers check-in code
Developers review results
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Dart
Dart
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Multi-Platform Builds
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IGT Challenges

• Define an architecture tailored to IGT
  requirements
• Leverage existing toolkits
• Fill in toolkit gaps

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IGTSoftware Design and Process

• Bill Lorensen
• GE Research