HDF Software Process - Lessons Learned & Success Factors
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The HDF group has experienced remarkable successes, producing high quality open source software that is widely used throughout the world. This talk presents a collection of thoughts on the HDF Project's approach to software engineering. In writing these notes we have come to realize that any success the group has had are due to several factors, including: o Strong, responsible, and continuing relationships with users o An approach to needs identification, software design, and software implementation based on sound principles of software engineering o Effective technical processes for developing, testing, integrating and maintaining software o Business and social processes based on sound group management principles These factors are little more than platitudes, however. The manner in which they are successfully applied can only be understood by examining the details. In this talk, we describe some of the details, emphasizing mostly those areas in which we have had success.
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HDF Software Process - Lessons Learned & Success Factors
- 1. HDF Software Process Lessons Learned & Success Factors Mike Folk, Elena Pourmal , Bob McGrath National Center for Supercomputing Applications University of Illinois at Urbana-Champaign NOBUGS 2004 HDF-EOS Workshop VIII -1- HDF
- 2. Outline • • • • • • • What is HDF? and Who is HDF? HDF “Architecture” Some statistics How do we measure success? How can we achieve success? Group practices Summing up – strengths, weaknesses, needs -2- HDF
- 3. What is HDF? Who is HDF? -3- HDF
- 4. HDF in a nutshell – what it is • File format and I/O Libraries for storing, managing and archiving large complex scientific and other data • Tools and utilities • Open source, free for any use (U of I license) • Well maintained and supported • From HDF group, NCSA Univ of Illinois • http://hdf.ncsa.uiuc.edu -4- HDF
- 5. HDF in a nutshell - features • General – simple and flexible data model • Flexible – store data of diverse origins, sizes, types – supports complex data structures and types • Portable – available for many operating systems and machines • Scalable – works in high end computing environments – accommodates date of any size or multiplicity • Efficient – fast access, including parallel i/o – Stores big data efficiently -5- HDF
- 6. HDF in a nutshell - users • Apps in industry, academia, government – More than 200 distinct applications • Large user base – E.g. NASA estimates 1.6 million users • Underlying format for community standards – E.g. HDF-EOS, SAF, CGNS, NPOESS, NeXus -6- HDF
- 7. Example of HDF file: mixing and grouping objects Text : This file was create as a part of… see http://hdf.ncsa.uiuc.edu foo a 3-D array z 1GB lat | lon | temp ----|-----|----12 | 23 | 3.1 15 | 24 | 4.2 17 | 21 | 3.6 c b palette x _foo_y Table Raster image Raster image -7- 2-D array HDF
- 9. HDF “Architecture” Tools & Applications HDF5 Applications Programming Interface Low level Interface Utilities and applications for managing, manipulating, viewing, & analyzing data. HDF I/O library – High-level, object-specific APIs. – Low-level API for I/O to files, etc. File or other data source File -9- HDF
- 10. User’s controlled I/O and “storage” • Data pipeline – – – – HDF I/O Library HDF “File” Data transformation Compression Encryption Storage layout • Virtual file options – – – – – – - 10 - Stdio (normal file) Split file MPI-IO & other parallel Network Memory custom HDF
- 11. Supported languages and compilers • C • Wrappers: – C++ – Fortran90 – Java • Vendors’ compilers (SUN, IBM, HP, etc.) • PGI and Absoft (Fortran) • GNU C (e.g. gcc 3.3.2) - 11 - HDF
- 12. Supported Machines and OS • • • • • • • Solaris 2.7, 2.8 (32/64-bit) IRIX6.5 IRIX64-6.5 HPUX 11.00 AIX 5.1 (32/64-bit modes) OSF1 FreeBSD Linux (SuSe, RH8, RH9) including 64-bit - 12 - • • • • • • • Altix (SGI Linux) IA-32 and IA-64 Windows 2000, XP MAC OS X Crays (T3E, SV1, T90IEEE) DOE National Labs machines Linux Clusters HDF
- 13. Architecture in context Tools & Applications C C++ F90 Java HDF5 Applications Programming Interface Low level Interface IA32 SGI Wintel Cray File Linux RH IRIX32 XP SV1 Serial - 13 - Parallel HDF
- 14. Architecture in context Tools & Applications HDF-EOS SAF CGNS C C++ F90 Java HDF5 Applications Programming Interface Low level Interface IA32 SGI Wintel Cray Linux RH IRIX32 XP Serial - 15 - SV1 Parallel File HDF
- 15. The testing challenge Machines × operating systems × compilers × languages × serial and parallel × compression options × configuration options × virtual file options × backward compatibility = a large number - 16 - HDF
- 16. “Diversity makes our code better…” Todd Smith, Geospiza - 17 - HDF
- 17. Some statistics - 18 - HDF
- 18. HDF Statistics • HDF Group – 15 FTE + 3-5 students – $2.1million annual budget • HDF5 source code distribution – 2073 files – 917,186 Lines of code • HDF Project – HDF5, HDF4, H4toH5, H5Lite, Java – 3,000,000 lines of code (estimate) - 19 - HDF
- 19. HDF5 source distribution by categories (lines of code) Library Tests 13% Tools Tools tests 4% 4% Configure 15% Docs 33% Libraries 30% Examples 1% - 20 - HDF
- 20. HDF5 staff investment Comm. with users 2% Meetings, etc. 9% Code dev. 33% Peer-to-peer comm. 12% User's support 14% Test writing 7% Docs, design, consult 14% - 21 - Porting/release testing 9% HDF
- 21. How do we measure success? - 22 - HDF
- 22. How do we measure success? • • • • • • • Mission Goals and objectives Strong and continuing relationships with users High quality software Strong committed development team Great working environment Adequate funding - 23 - HDF
- 23. Mission, goals and objectives • Mission – To develop, promote, deploy, and support open and free technologies that facilitate scientific data exchange, access, analysis, archiving and discovery • Goals (examples) – Innovate and evolve the technologies in concert with a changing world of technologies – Maintain a high level of quality and reliability – Collaborate and build communities – Build a team - 24 - HDF
- 24. Mission, goals and objectives • Objectives - how we reach the goal • Example: – Goal • Maintain a high level of quality and reliability – Objectives • Improve testing • Implement a program to insure excellent software engineering practices • Develop and execute a plan to meet quality/reliability standards - 25 - HDF
- 25. Users • • • • Number of users Happy users Unhappy users Users achieve their goals by using HDF technologies • Users coming back with new needs • Financial support from users - 26 - HDF
- 26. Software • Technology that addresses users’ needs and demands (current and future) – E.g. big files, parallel access, multiple objects • Usability – – – – Number and types of applications Appropriate APIs and data models Available tools Interoperability with other software • E.g. IDL, MatLab, Mathematica - 27 - HDF
- 27. Software • Stability – Can data be shared? – Can software run on needed platforms • Sustainability – Can read data written 15 years ago on obsolete platform – Is software available in 15 years? • Acceptability – De facto standard • Open standard for exchange of remote-sensed data • Over 3,000,000,000,000,000 bytes stored in HDF and HDF-EOS - 28 - HDF
- 28. How can we achieve success? - 29 - HDF
- 29. How can we achieve success? • Maintain strong, responsible, and continuing relationships with users • An approach to needs identification, software design, and software implementation based on sound principles of software engineering • Effective technical processes for developing, testing, integrating and maintaining software • Business and social processes based on sound group management principles - 30 - HDF
- 30. Stages of software development at HDF • • • • • Getting started Creating an implementation approach Implementation and maintenance Relations with users and sponsors Group practices - 31 - HDF
- 31. Getting started • • • • Discover a need Identify a sponsor Clarify the need, its role, and its importance Enter task into the project plan – – – – Make initial estimate of time and resources for the task Give it a priority Identify task’s lead Identify a person who will work on the task - 32 - HDF
- 32. Creating implementation approach • Write up a needs/approach RFC (Request For Comment) – Actively solicit feedback from developers/sponsors – Revise until satisfied • Write up a design/approach RFC – Get feedback from developers/sponsors – Revise until satisfied • Revise project plan according to RFC results • Archive RFC - 33 - HDF
- 33. Implementation and maintenance • Identify validation plan (need improvement) • Implement – Library or tool – Tests – Documentation • Ask sponsor and friendly users for feedback • Review results and repeat appropriate steps above as needed • Clean up (documentation, Web, etc.) and announce • Support (debug, fix, add more tests, advertise) - 34 - HDF
- 34. Relations with users and sponsors • Who are our sponsors? – Organizations and communities with institutional and financial commitment to HDF • NCSA, NASA, DOE ASCI, Boeing, … – Agencies supporting R&D • NCSA, NASA, DOE, NSF, … – Collaborators who make in-kind contributions • Cactus, PyTables, NeXUS, CGNS … – HDF group members - 35 - HDF
- 35. Relations with users and sponsors • Each task is associated with a sponsor • Each task has a priority, which should be confirmed with sponsor • Each task falls into one of these categories – Research – R&D (research, possibly integrate into product) – Development • Technology infusion • Library or tools enhancement - 36 - HDF
- 36. Group practices - 37 - HDF
- 37. Group practices - technical • Source code management: CVS • Bug tracking: Bugzilla – Bugs entered by support staff and developers – Prioritized by staff – Easy bugs fixed “on the fly” - 38 - HDF
- 38. Group practices - technical • The testing challenge • Code testing – – – – – Testing before code check-in Regression testing Remote testing Different configurations testing Backward compatibility testing - 39 - HDF
- 39. Daily test report From: HDF group system admin <hdfadmin@ncsa.uiuc.edu> To: hdf5lib@ncsa.uiuc.edu Subject: HDF5_Daily_Tests_FAILED!!! *** HDF5 Tests on 041022 *** ============================= Watchers List ============================= HDF5 Daily test features/platforms watchers and procedure --------------------------------------------------------Procedure: The watcher will investigate and report the cause of failure by 11am. The developer who checked in the error code may report so by then too. The watcher or the developer should get the failure fixed and report it by 3pm. - 41 - HDF
- 40. Group practices - technical • Release levels – Development release – Official release – Past releases - 42 - HDF
- 41. Group practices - technical • • • • • • Coding standards Maintaining platform-independence Maintaining time-independence Rules for changing APIs Documentation Rapid prototyping - 43 - HDF
- 42. Group practices – business and social HDF Project HDF Project • Staff breakdown – – – – – – – User support Documentation QA Software development Testing Team leadership System administration Support, Support, doc, QA, doc, QA, maintenance maintenance - 44 - Basic library Basic library development development Tools and Tools and Java Java Parallel I/O, Parallel I/O, Grid, Grid, big machines big machines • Team lead for each team • Most staff in two or more teams • Staff relationships – Complement each other – Overlap each other – Keep each other honest HDF
- 43. Group practices – business and social • Accountability of everyone to the whole process • Help desk • Approaches to carrying out tasks – Paying attention to technical proposals – Weekly HDf5 developer’s meetings – HDF seminars • Management and administration – Performance reviews with emphasis on goals, development – Critical to success – That’s another talk - 45 - HDF
- 44. Summing up Strengths, weaknesses, needs - 46 - HDF
- 45. Strengths • User support • Staff – High quality, diverse staff with good morale – Staff commitment and enthusiasm • Ability to address all aspects of product development – Emphasis on quality control – Fast bug fixing and frequent releases – Ability to focus on a single product over a long term • High level of support from sponsors • Project’s visibility through NCSA, NASA, DOE, users - 47 - HDF
- 46. Weaknesses • Software development team – – Library expertise still concentrated among too few developers Team communication is challenging • Processes – – – – – Release/maintenance take too much time and resources Configuration and porting are a huge time sink We don’t do enough prototyping Hard to keep up with new technologies Parallel I/O hard to support - 48 - HDF
- 47. More weaknesses & challenges • Usability – – – – Software too hard to use for casual users Insufficient documentation Insufficient tools for high level users Insufficient interoperability with common tools and formats • Marketing – Marketing effort is inadequate – Need to connect better with users and potential users • Viable long-term support - 49 - HDF
- 48. Most immediate needs • • • • Configuration and build Testing and prototyping Marketing Reporting – Performance reports – General reports to users – HDF book • Sustainable business model - 50 - HDF
- 49. Thank you - 51 - HDF
Editor's Notes
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- Format and software for scientific data. HDF5 is a different format from earlier versions of HDF, as is the library. Stores images, multidimensional arrays, tables, etc. That is, you can construct all of these different kinds structures and store them in HDF5. You can also mix and match them in HDF5 files according to your needs. Emphasis on storage and I/O efficiency Both the library and the format are designed to address this. Free and commercial software support As far as HDF5 goes, this is just a goal now. There is commercial support for HDF4, but little if any for HDF5 at this time. We are working with vendors to change this. Emphasis on standards You can store data in HDF5 in a variety of ways, so we try to work with users to encourage them to organize HDF5 files in standard ways. Users from many engineering and scientific fields
- Like HDF4, HDF5 has a grouping structure. The main difference is that every HDF5 file starts with a root group, whereas HDF4 doesn’t need any groups at all.
- It is useful to think about HDF software in terms of layers. At the bottom layer is the HDF5 file or other data source. Above that are two layers corresponding the the HDF library. First there is a low level interface that concentrates on basic I/O: opening and closing files, reading and writing bytes, seeking, etc. HDF5 provides a public API at this level so that people can write their own drivers for reading and writing to places other than those already provided with the library. Those that are already provided include UNIX stdio, and MPI-IO. Then comes the high-level, object -specific interface. This is the API that most people who develop HDF5 applications use. This is where you create a dataset or group, read and write datasets and subsets, etc. At the top are applications, or perhaps APIs used by applications. Examples of the latter are the HDF-EOS API that supports NASA’s EOSDIS datatypes, and the DSL API that supports the ASCI data models.