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EXPRESS/Binary Report

EXPRESS/Binary Report. David Price ISO SC4 Vico Equense March 2006. Agenda. Introductions Review of EXPRESS/Binary Project Overview of EXPRESS/HDF5 mapping Version 0.2 and workshop comments Issues and actions. EXPRESS/HDF5 Workshop Report. ISO SC4 Vico Equense March 2006. Workshop.

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EXPRESS/Binary Report

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  1. EXPRESS/Binary Report David Price ISO SC4 Vico Equense March 2006

  2. Agenda • Introductions • Review of EXPRESS/Binary Project • Overview of EXPRESS/HDF5 mapping Version 0.2 and workshop comments • Issues and actions

  3. EXPRESS/HDF5 Workshop Report ISO SC4 Vico Equense March 2006

  4. Workshop • Workshop hosted by HDF Group • Workshop Dec 6-8, 2005 • Champaign, Illinois, USA • STEP, ESA, commercial, EXPRESS/Binary and HDF 5 developer attendees • Agenda was • Introduced HDF Group to EXPRESS language and STEP information models • HDF developers provided overview of HDF 5 Concepts and Structures • Walkthrough of EXPRESS/HDF Mapping Draft 0.2 • Presentation by domain experts : AP209 Analysis, STEP TAS, SINDA/G, Ship AP Analysis Needs • Issues/requirements around APIs, programming languages, etc.

  5. API Questions • What are the requirements for APIs? • Is there a need for an EXPRESS-specific HDF5 API? • Is there a need for Higher-than-EXPRESS APIs (aka Business Object APIs)? • Can we generate better performing, configured APIs? • What layers of API/standard might be involved • How we can align APIs or how the build upon each other?

  6. HDF 5 Technical Comments (1) • Files are identical no matter how written • Should we use HDF attributes directly? They are in memory as soon as you open the file. They are not shared. • Use Link concept for path names in documentation • Use NATIVE datatypes in your appl and library will convert whatever is in the file to NATIVE for your platform, when using H5DWrite tell it source is NATIVE datatype • Selection – this is an area where we need work to understand how to use this

  7. HDF 5 Technical Comments (2) • Can we use fill values to deal with unset? • Should variable length arrays be used for Bag, Set, List? • Fixed length arrays should be used for Array • Use H5Tget_native_type to find compound type in file and make in memory • Combine shuffle with compression for even better results on space and IO time

  8. HDF 5 Technical Comments (3) • How he can have access to control block size – physical block? • HDF Chunking concept is aimed at this • Parallel IO is also a way to do this • HDF are looking at caching chunks and giving applications control of this • Chunks are organized by B-trees but there is no user accessible algorithm for hashing at lower level • “User blocks” can be added in front of HDF5 file, this can even be an executable program, PDF, etc. • HDF Indexing project • Adding an Index API • Create Index • Query returns dataspace with subset

  9. Domain Model Discussions • STEP TAS • STEP TAS/HDF project 4-5 months started in Nov, Alain Fagot lead • Why did they not use HDF enum for boolean and logical? • Defined specific values for “unset” but may allow that to be set • Is there value in storing Dictionary in HDF5? • Does its use impact performance? • H-P says NO – They read the dictionary in as instance data in HDF • AP209 • FEA needs HDF but perhaps PDM does not, should we look at a hybrid approach? • Abaqus is working with HDF folks and does non-linear so may be interested in AP209 E2

  10. Domain Model Discussions (2) • Network Analysis • Already working on using HDF as central database, storing FEA model at the moment • Need higher level API to simulate database capabilities (i.e. index hashing for fast random access), C and F90 wrap HDF • Next three months are critical for them in getting the database working • HDF Group are working on an indexing capability and would like us to provide feedback • Ron says he can give user guide for API and model for review • Ship APs • NSRP/PDES involvement • AP227, 216, 218 -> 209 somehow? ISE project uses XML to mediate between these and the AIM/ARM files • At www.isetools.org they will deliver open-source STEP toolkits

  11. Summary • Many core issues on V0.2 addressed at the workshop • The basic approach was flawed, V0.2 did not use enough of the HDF capability • V0.3 will be an improvement and should allow better control of efficiency by the application • http://www.exff.org/express_binary • Prototyping will follow V0.3

  12. Actions • David Price – Publish EXPRESS/HDF Mapping V0.3 due March 24 • Mats Lindeblad – Create New Work Item for June SC4 meeting • David Price - contact Hans-Peter about linking a one-day workshop with the NASA/ESA PDE at the end of April (a day before Monday?) • Keith Hunten – plan session at Eng Analysis sessions at PDES, Inc. Offsite end of March • David/Mats – plan for technical work at June SC4 meeting

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