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Community Development of LAPS. Ligia Bernardet NOAA ESRL GSD. 2 nd LAPS Users Workshop 23 October 2012 Boulder, CO. A word about the speaker. I work in FAB but not with LAPS I am bringing the perspective of an outsider to this community

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community development of laps

Community Development of LAPS

Ligia Bernardet


2nd LAPS Users Workshop

23 October 2012

Boulder, CO

a word about the speaker
A word about the speaker
  • I work in FAB but not with LAPS
  • I am bringing the perspective of an outsider to this community
  • I work in projects of the Developmental Testbed Center (DTC)
    • Our mission is to facilitate transfer of NWP research to operations
    • One strategy to facilitate R2O is to make operational codes available and supported to the community (downloads, documentation, help desk etc)
    • We also facilitate users in transitioning their development back to the centralized code
overview of this talk
Overview of this talk
  • How LAPS development is done
    • In NOAA GSD
    • In the community
  • Issues related to community software development
  • Is everything working great or is there room for improvement?
  • Pose some issues for discussion in breakout session
laps development
LAPS Development
  • LAPS development started with the group now called NOAA/ESRL/GSD/FAB (then NOAA FSL) in the early 1990s
  • LAPS has been adopted operationally by the US NWS and others
  • Main development occurs in FAB
  • Development also takes place in the community
communication in the laps community
Communication in the LAPS community
  • Scientific publications
  • LAPS Workshops
  • Other conferences and workshops
  • LAPS Forum
    • Announcements of new releases
    • Bug reports (~2 per year)
    • Development/General discussion (~30 per year)
  • Is there enough exchange among users? Are users aware of what others are doing? And benefitting from each other to the fullest extent possible?
laps code and releases
LAPS code and releases
  • LAPS code is housed in a CVS code repository at NOAA
  • Links to CRTM library maintained by NOAA JCSDA
  • Repository access only given to FAB
  • Repository not used for code development
    • Development is done on disk
    • Repository has mature development, ready for parallel testing
  • LAPS releases: ~5 times per year, tarfile in website
  • Seems that transfer from FAB to community works well
laps testing at fab
LAPS testing at FAB
  • New development put in repository frequently (weekly build)
  • Parallel runs start using new code
  • Parallel runs cover a variety of computational platforms and domain configuration
  • After “sufficient” testing, developments are transitioned to production runs
  • No formal protocols for testing and acceptance of code
    • Is this an issue? Only if questionable code is being accepted, or code is taking too long to be accepted or ???
    • Who should determine is code is acceptable? Should there be more participation from users and WFOs?
laps community developments
LAPS Community developments
  • FAB development easily gets to repository and community
  • Unclear path for community development to make its way back to central repository and to other
  • Some user development does not get back to FAB
  • Other user development makes it back in outdated versions so it is challenging to integrate with current code
  • Why is that and can it be improved?
motivations for community code
Motivations for community code
  • Users need to perceive an advantage in a community development. Most users do not contribute code out of altruism
  • Advantages for users
    • Access to development from other users
    • My code available in the official release means I do not have to maintain it myself
    • When next release is available, I can easily upgrade and benefit from bug fixes and updated science
issues that prevent code integration
Issues that prevent code integration
  • Programmatic
    • Development is proprietary
    • Developer wants to publish first
    • Developer wants to be the only one to take advantage of it (can only be overcome if user sees advantage in community)
  • Technical
    • Code does not meet standards
      • Coding practices (declaring all variables, indentation etc)
      • Development is not general enough, not applicable to other users
        • Can be isolated and only triggered with a namelist
    • Code in outdated version is difficult to integrate
addressing technical issues
Addressing technical issues
  • There is a cost to this! And the perceived benefit needs to be higher than the cost.
    • Planning
    • Education, training
    • Implementation of new system
    • Code reviews
    • Testing
coding practices and testing
Coding practices and testing
  • Community agrees on coding and testing practices
  • Developers follow practices
  • It can be that simple!
a solution for synchronization of distributed development
A solution for synchronization of distributed development
  • Make code repository available to all developers -> SVN or Git
    • [Provide anonymous checkout?]
  • Reserve trunk for vetted code
  • Use branches for development, keep up to date
  • Once development is ready, propose it for adoption in the trunk
  • Committee reviews the code
  • Test (various computational platforms, various applications)
  • Approve code or send it back to developer to address concerns
d etails on possible code management
Details on possible code management

Contributions from FAB


Developers branch

this solution makes people nervous
This solution makes people nervous
  • Community intimidated by code version control (CVS, SVN)
    • Requires training but, even I can do it, it cannot be that bad 
  • Main developers feel lack of control about opening repo
    • Not an issue, as repositories can be setup to prevent inadvertent write to trunk and, if it happens, can be reverted
    • A two-repository solution can be considered, in which the main repository is mirrored for the community
      • Discouraged: prone to error and increased labor costs
can we do something simpler
Can we do something simpler??
  • Suppose we do not open the code repository…
  • If we make the weekly build available to the community…
    • Can community developers commit to putting their code in the latest version email it back? No sending old code!!
    • With code in the latest version, easier for FAB to integrate.
  • Does this meet our needs??
  • Scalability: this may work if we have a handful of developers but not if we have tens…
discussion topics1
Discussion Topics
  • Communications among users and developers
    • Enough? Efficient?
  • What is the best way for users to contribute code back
    • Avoid version divergence
    • Avoid Steve having to integrate code from old versions
    • Make new developments available to all users timely
  • Cost/benefit analysis of solutions (open repository)
  • Testing protocols and standards
  • Coding standards
  • Other issues?