Governance of a Community System

The decision to include code or not into a community system depends on several criteria. Of course scientific and technical quality are among the criteria, but usefulness to the community is another very important one. It is in fact the most important. Within the context of a community data assimilation and forecast system, the first role of the governance framework is to make these decisions, with well-defined responsibilities for the internal project leads, JCSDA management, and community oversight.

The review process determines if the scientific and technical quality are sufficient at any point in time. The decision not to include a certain aspect in the community code is not a judgement on its scientific excellence. It could be that aspects that are critical for one user are useful only for that user. In that case, the code should be kept in a separate repository and it is the responsibility of the build system to include what is required for a given application without affecting the others. In that respect, modern software development architectures are absolutely essential to provide this level of functionality in a data assimilation and forecasting system; previous programming technology simply did not make this possible.

In old style Fortran, separating code that was specific to a user from a community code meant that some subroutine calls would be left dangling and possibly some global variables would be left in a unknown state. This was addressed with dummy routines that would be provided with the common code. Unfortunately, this approach doesn’t scale and quickly becomes unmanageable. The solution was then to include everything in the shared code, which quickly became bloated, difficult to manage, and unpopular.

In modern programming this situation can be avoided. Common practices such as modularity, generic programming, and separation of concerns permit more versatile and efficient workflows. On one hand, a specialized sub-class in an inheritance structure leaves no trace behind when it is removed. Examples can be the use of specific observation types in a DA system, or a specific physics package in a model; many other circumstances are possible. On the other side of the spectrum, a high-level application constructed from a collection of objects does not have any impact on other applications using all or some of the same objects. Software packages might have only low level extensions (e.g. browsers or applications like photoshop that support plugins) or high level extensions (system libraries or MPI) or both. JEDI is in the latter category.

However, this will only work if the interfaces in the middle layer are stable. If interfaces of a base class change, all subclasses will need to adapt. If interfaces of the objects used by high level applications change all those applications will need to change. If that happens often, the system will quickly become unpopular. The second role of a governance framework for a community unified data assimilation and forecasting system is to ensure that changes in the interfaces are infrequent and fully justified. If such changes are justified, they must then be documented and communicated.

The third role of the governance framework is to establish who has authorization to review and administer code at each level, most importantly at the release preparation level. Typically, this means designating a small pool of reviewers for each main component of the code, and a criterion, such as a minimum number of reviewers approving the pull request, for accepting it. The size of the pool of reviewers and number of approvals should ensure enough scrutiny, while maintaining an efficient process. As explained above, reviewers should be trusted to add other reviewers or delegate their roles on a case by case basis, particularly for small changes.

We now describe how JEDI achieves such a governance framework.

JEDI Roles and Responsibilities

Management Oversight Board (MOB)

The JCSDA MOB includes representatives from JCSDA partner organizations and the broader community. The MOB is responsible for the approval of policies, goals and priorities of the JCSDA, including recommendations on the observing systems planned for use in the operational systems. The MOB is tasked to ensure cooperation among sponsoring organizations and institutions and in extreme cases – for making project decisions if the normal community-based process breaks down.

The MOB provides oversight into the overall scope, vision, and direction of the project, including strategic collaborations with other organizations, policies, and other general management issues. They must make high-level decisions when regular community discussion doesn’t produce consensus on an issue in a reasonable time frame.

Executive Team (ET)

The JCSDA Executive Team (ET) consists of Associate Directors who work to assist the JCSDA Director. The overall role of the ET is to ensure, with input from the community, the long-term well-being of the project, both technically and as a community.

It is the responsibility of the ET to assist the JCSDA Director and the MOB in making decisions about the overall scope, vision and direction of the JEDI project, including strategic collaborations, and policies. Because of their expert knowledge of the project software and services, the ET members are also expected to provide guidance, both technical and in terms of project direction, to potentially less experienced contributors.

Project Leads

Management responsibility of The JEDI Project lies primarily with the Project Leads. The JEDI management hierarchy includes the JEDI Project Leader as well as subordinate project team leaders responsible for Software Infrastructure, Model and Observational Interfaces, Data Assimilation, and Cloud Infrastructure.

The project leads are responsible for managing the JEDI project according to the tenets identified in the JCSDA Software Governance and Oversight document Rev 1, in coordination with the JCSDA Director and Associate Directors, and with those JCSDA Partners that have a direct, vested interest in the success and ultimate application of the project.

The project leads assume responsibility for delivery of the JEDI software to the various stakeholders and for coordinating the efforts of both core and in-kind contributors, as identified in the JCSDA Annual Operating Plan (AOP) and any individually designated work plans. This includes generating requirements, responding to stakeholders, initiating collaborative efforts, identifying parallel efforts, reducing duplication of effort, bringing new partners on board, and assisting partners with implementation, testing, development, and technical support. It also includes quarterly reporting to the MOB and the ET and the execution of code sprints and training events.

In terms of direct software development, project leads serve as contributors, reviewers, and administrators to the GitHub repositories that host the JEDI code. Administrators are responsible for controlling access to the repositories and merging pull requests after they pass code reviews, utilizing the do-no-harm approach. No code is merged until other developers attest to its scientific and technical quality and verify that it satisfies coding standards, is well documented, and passes all tests.


A contributor is anyone who writes code, documentation, designs, or other work to the project; a person becomes a developer when their pull request is accepted;. This includes JCSDA core staff, in-kind staff, and external contributors or contractors. Contributors participate in the JEDI project by submitting, reviewing and discussing GitHub pull requests and issues and participating in open and public project discussions on GitHub, mailing lists, forums, and other channels. A contributor who contributes code is a developer. In principle all developers should be involved in reviewing other developer’s code.

Developers have the responsibility to document their developments, to update them to the level of the develop branch and to test them before submitting a pull request.

The JEDI Community also consists of users. Contributors work on behalf of and are responsible to the larger JEDI Community and we strive to keep the barrier between contributors and users as low as possible.