AIDA - Abstract Interfaces for Data Analysis

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AIDA - Abstract Interfaces for Data Analysis
Andreas Pfeiffer for the AIDA group andreas.pfei
ffer_at_cern.ch
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Outline

• Motivation
• Architectural issues
• Abstract Interfaces
• Components
• Status and future Plans

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The AIDA project

• AIDA project (Abstract Interfaces for Data
  Analysis) was initiated at the HepVis99 workshop
  in Orsay
• Presently active mainly developers from existing
  packages
• Tony Johnson (JAS)
• Andreas Pfeiffer (Lizard/Anaphe)
• Guy Barrand (OpenScientist )
• Mark Dönszelmann (Wired)
• Developers from LHCb/Gaudi

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Introduction

• Design Interfaces for Data Analysis (in HEP)
• The goals of the AIDA project are to define
  abstract interfaces for common physics analysis
  tools, such as histograms. The adoption of these
  interfaces should make it easier for developers
  and users to select to use different tools
  without having to learn new interfaces or change
  their code. In addition it should be possible to
  exchange data (objects) between AIDA compliant
  applications. (http//aida.freehep.org)
• Open for contributions of any kind
• questions, suggestions, code, implementations

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Motivation

• Minimize coupling between components
• Provide flexibility to interchange
  implementations of these interfaces
• Allows and try to re-use existing packages
• even across language boundaries
• e.g., C analysis using Java Histograms
• Allow for faster turn-around time

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Use of Components withAbstract Interfaces

• User Code uses only Interface classes
• IHistogram1D hist histoFactory-gt
  create1D(track quality, 100, 0., 10.)
• Actual implementations are selected at run-time
• loading of shared libraries
• No change at all to user code but keep freedom to
  choose implementation

User Code
Histo-IF
Fitter-IF
Histo- Impl. 1
Fitter- Impl. X
Histo- Impl. 2
Fitter- Impl. Y
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Architectural issueAbstract Interfaces

• Abstract Interfaces
• Only pure virtual methods, inheritance only from
  other Abstract Interfaces
• Components use other components only through
  their Abstract Interface
• Defines a kind of a protocol for a component
• Allow each component to develop independently
• reduces maintenance effort significantly
• Maximize flexibility and re-use of packages
• Re-use of existing packages to implement
  components reduces start-up time significantly

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Architectural issue Components (I)

• Identify components by functionality
• Define protocol using Abstract Interfaces
• Emphasize separation of different aspects for
  each component
• Example Histogram
• statistical entity (density distribution of a
  physics quantity)
• view of a collection of data points (which can
  be a density distribution but also a detector
  efficiency curve)
• command to manipulate/store/plot/fit/...

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Architectural issue Components (II)

• Users view is different from implementors
  (developers) view
• separate Abstract Interfaces for both aspects
• command-layer vs. implementation-layer(s)
• UserInterface as a separate component
• by definition couples to most of the other
  components
• Facade pattern
• promotes weak coupling between the other
  components
• interfaces to scripting and/or GUI

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Initial Categories and dependencies
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History

• started in Sept. 1999 (HepVis 99, Orsay)
• several (mini-) workshops since then
• main ones Paris 2000 and Boston 2001
• release 1.0 summer 2000
• concentrated on developers view
• Histogram package only
• IAxis, IHistogram, IHistogram1D, IHistogram2D,
  IHistogramFactory
• release 2.0 May 2001 (Boston release)
• about 20 Interface classes
• aiming at discussion and gathering feedback

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AIDA Workshop Autumn 2000 (Orsay)

• Start working from users view
• Concentrated discussions on
• Histogram
• developer vs. user view
• Management
• directory-like Tree
• Store (developer only, hidden from user)
• Tuple

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AIDA Workshop Spring 2001(Boston)

• Continued discussion on Interfaces
• concentrated on open issues from Paris workshop
  and Infrastructure
• New developments
• JAida C access to Java libs
• Java reference implementation
• Infrastructure
• CVS repository, mailing lists, web, ...
• Very constructive

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Across the languages

• JAida C access to Java libs
• using C proxies implementing the C Abstract
  Interfaces to the Java interfaces

CUserCode
AIDA-IF C
AIDA-IF Java
JAida
Java Lib
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Infrastructure (I)

• Location of repository (Java and C)
• Anonymous CVS access
• pserveranoncvs_at_cvs.freehep.org/cvs/aida
  (passwd aida)
• module aida
• Release area for C code
• /afs/cern.ch/sw/contrib/AIDA/ltversiongt/AIDA/
• include ltAIDA/IHistogram.hgt
• version x.y.p
• tarballs (C) available in /afs/cern.ch/sw/contri
  b/AIDA/tar/AIDA-ltversiongt.tar.gz

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Infrastructure (III)

• Mailing lists (archived)
• ltlistNamegt_at_cern.ch
• project-aida-dev (open)
• project-aida (open)
• project-aida-announce (posting moderated,
  subscription open)
• Web page (http//aida.freehep.org/)
• Updated automatically from repository
• On web page links to implementations
• from whoever provides one (and informs us)

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Status of Components
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Time schedule / release plan

• Release for discussion and feedback
• even if not (yet) complete
• V 2.0 mid May 2001 (Boston release)
• C and Java version of the Interfaces
• V 2.1 Aug. 2001 (Genova release)
• updates from discussions at Geant-4 workshop
• fixed some problems with C version
• Aiming for 2-3 month release frequency

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Use-cases of AIDA

• Java reference implementation in FreeHEP
  repository
• JAS, OpenScientist and Lizard/Anaphe plan for
  implementations of version 2.x by Dec. 2001
• Used by Gaudi/Athena (LHCb, Atlas, Harp)
• Gaudi people involved in design
• Adopted and used in Geant-4 examples/testing
• new category created in Geant-4 for analysis
• No need to go for least common denominator
• use reasonable superset and concentrate on
  design

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Summary

• Design of Abstract Interfaces for Data Analysis
• Maximize flexibility and re-use
• Allow for faster turn-around time
• Allows for and try to re-use existing packages
• No need to go for least common denominator
• use reasonable superset
• concentrate on proper design
• http//aida.freehep.org