http://forge.gridforum.org/projects/dfdl- DFDL WG Session 1 Summary of Status WG Co-Chairs: Mike Beckerle, Ascential Software Alan Chappell, PNNL Martin Westhead (Two note takers please?) Tuesday, 2004-09-21 17h30+02:00 Brussels (BE.CEST) in Room D005. 11h30 New York, (US.EDT, UTC-4) 08h30 San Francisco (US.PDT, UTC-7)
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Http://forge.gridforum.org/projects/dfdl-wg/ DFDL WG Session 1 Summary of Status WG Co-Chairs: Mike Beckerle, Ascential Software Alan Chappell, PNNL.
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http://forge.gridforum.org/projects/dfdl-wg/
DFDL WG Session 1Summary of StatusWG Co-Chairs:
Mike Beckerle, Ascential Software Alan Chappell, PNNL Martin Westhead
(Two note takers please?)
Tuesday, 2004-09-21 17h30+02:00 Brussels (BE.CEST) in Room D005.
11h30 New York, (US.EDT, UTC-4) 08h30 San Francisco (US.PDT, UTC-7)
http://forge.gridforum.org/projects/dfdl-wg/
Abstract
Progress and Status Review - This session will review the progress since GGF11 which is substantial, and also provide enough context for those interested in getting involved who haven't been following along.
http://forge.gridforum.org/projects/dfdl-wg/
ADF BoF
Sep 22 11h00-12h30ACCESS TO DATA IN FILES-WG CHARTER DISCUSSION BOF (DATA) Calendar: QB (200p)Details:Title: ADF - Access to Data in FilesSession Leaders: Neil Chue Hong, Brian M CollinsAgenda:- Summary of General Focus, Milestones and Objectives- Discussion of Relationships specifically with DFDL and DAIS as well as other GGF Groups- Charter Update
DFDL Represenation Properties: Basic Set document/ggf-dfdl-rep-properties-
proposal-basic-001.doc
http://forge.gridforum.org/projects/dfdl-wg/
DFDL-WG Session 1 Summary of Status
Agenda Review of purposes/goals
XML / XSD impact: Data ModelExamples w/latest updates
• as evolved now: different from primer document
General discussion (40 mins) Overview of other sessions (5 mins)
http://forge.gridforum.org/projects/dfdl-wg/
Data Interchange Formats
Prescriptive: Put your data in this format! XML – textual Binary – ASN.1, XDR, NetCDF, HDF, EBML,…
Descriptive: What format is your data in? Commercial products ASN1 Encoding Control Notation
• ITU-T X.692
DFDL
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Why Descriptive?
Allows us to achieve two goals simultaneously:
1. Interoperability Modern and Legacy data formats
2. Performance! Density
• Fewest bytes to represent data without resorting to compression
Optimized I/O• Seekable random access• Memory mapped, aligned
• Without sacrificing general access
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Why the GGF for DFDL?
Grids are about big-data and big-computation problemsSimplistic solutions like “use XML”
won’t cut it! Grids are about universal data
interchange
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General Features
Basic ASCII/Binary Read capabilities Inclusion of static info, e.g. “units” Validated input (from XML Schema) Defaulted input for missing values Reference – use of a previously read value in subsequent
expressions Choice – use of a previously read value to select among format
variations Multi-layer – description of an intermediate representation not
exposed in the final result Multiple input streams Basic Math – in DFDL expressions Basic Math – to generate new representations/values “Push-back” capability New type/transform specification
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Desires
Support very efficient parsers Hints about lengths so data can be accessed
randomly Avoid requiring data copies But allow caching (e.g. based on hints) Allow ‘black-box’ transforms (e.g. unzip)
Support round-tripping Link transforms and inverses Infer inverses for lossless transforms
Keep simple cases simple Default transforms and parameters
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Related Standards Efforts
Prescriptive systems:W3C binary XML
(http://www.w3.org/XML/Binary/)• Formed, but discussion group has no
items.• CORRECTION - there is activity now.
Descriptive systems:ASN1 Encoding Control Notation
• ITU-T X.692
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XML Synergy
Use XSD to describe the logical data Use annotations within the XSD to