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

Agenda 1. Introductions 2.Review of EXPRESS/Binary Project 3.Overview of EXPRESS/HDF5 mapping Version 0.2 and workshop comments 4.Issues and actions

EXPRESS/HDF5 Workshop Report ISO SC4 Vico Equense March 2006

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.

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?

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

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

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

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

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 they will deliver open-source STEP toolkits

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 – Prototyping will follow V0.3

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